ACCELEROMETRIC MOTION ANALYSIS: A NEW METHOD FOR MOBILITY
DIAGNOSIS AND THERAPY
Sabelman, EE; Troy, BS; Kenney, D; Gabrielli, S; Yap, R; Jaffe, DJ; Nakahara, A; Winograd, CH
Rehab R&D Ctr & GRECC, VA Palo Alto HCS; Functional Restoration Dept., Stanford Univ.
OBJECTIVES: We are developing a Wearable Accelerometric Motion Analysis System ("WAMAS") to record unrestrained human movement, perform real-time balance and gait analysis, be valid and reliable for a wide range of clinical diagnosis, and warn the wearer of pre-fall behavior.
RESEARCH PLAN: Project organization was designed to simultaneously advance technology, obtain data from normal and mobility-impaired (e.g., Parksinson's disease, stroke, hip arthritis) subjects, involve consumers and other investigators, and explore channels for commercialization.
METHODS: The WAMAS consists of four 3-axis sensors, belt-mounted computer and batteries, and remote control; it fits into a briefcase. A study of normal elders is underway to establish reliability and validity. WAMAS equipment is loaned to VA and non-VA researchers for testing other subject populations.
FINDINGS: We have identified accelerometric equivalents to published standing balance scoring methods and to gait and ADL functional measures. Clinicians and test subjects report that the WAMAS is easy to use; they are enthusiastic about improvements such as a smaller, faster, lighter weight unit with digital input, voice output and real time feedback. A proposal for WAMAS-based therapy for Parkinson's disease has been submitted to Rehabilitation R&D. Development of "normal" algorithms for complex tasks continues. Two companies are interested in utilizing this technology.
CLINICAL RELEVANCE: As veterans age, they become increasingly at risk for injurious falls; hence the need for a balance orthosis to help maintain independence. Therapists also need the ability to quickly and accurately monitor and improve these individuals' balance and gait.
ACKNOWLEDGMENTS: VA RR&D pilot project E972-PA, Merit Review projects E601-RA, -2RA, -3RA, design/development project E2182-DA; Maven Technologies donation to PAIRE; PAIRE "flex-fund" grants for student support; statisticians D. Bloch, J. Oehlert, M. Willits; former staff: J. Martino, D. Chesney, J. Gadd, P. Merritt, C. Morris; summer students: M. Liu, J. Lin, C. Washington.
EXAMINATION OF STAGES OF SIT-TO-STAND PERFORMED BY
HEALTHY ELDERLY AND YOUNG SUBJECTS USING ACCELEROMETRY
Troy BS, Sabelman EE, Kenney DE, Yap R, Gabrielli S, Winograd CH
Rehab R&D Ctr & GRECC, VA Palo Alto HCS; Functional Restoration Dept., Stanford Univ
OBJECTIVES: We report here on characteristics of accelerometric motion patterns for the task of sit-to-stand from a chair performed by "normal" individuals.
RESEARCH PLAN: This study is part of a larger project which is developing a wearable motion analysis system using accelerometry, ultimately to be developed as a real-time fall prevention aid. Currently, the system has the capability to acquire and store data for download and analysis. Sit-to-stand is one of a number of activities currently included in the balance test protocol for definition of "normal" motion pattern signatures using acceleration -- setting a standard from which "abnormal" motion patterns will be determined.
METHODS: Ten healthy elderly (58-80yrs.) and 8 young (18-37yrs.) subjects performed sit-to-stand at comfortable speed with arms folded across the chest. Trials were repeated 5 times. Accelerations recorded from two accelerometers placed at the waist on a Velcro belt were used for analysis. Seeking particular characteristics of the accelerometic signals, data were partitioned into distinguishable intervals for examination of timing and acceleration motion patterns.
FINDINGS: Six intervals (flexion momentum, momentum transfer, seat-off, extension/forward, extension/upward, stabilization) were determined. On average, elderly subjects required more time in all phases, except during extension. This may have been related to shorter height of the elders (ave. 65.5in.) compared to young (ave 68.81in.) subjects.
CLINICAL RELEVANCE: Sit-to-stand is prerequisite to various functional activities, including gait. A clear understanding of its normal characteristics can provide important information for clinicians to distinguish and improve performance and independence where abnormalities exist. Accelerometry can provide quantitative data important for diagnosis, therapy, or task retraining.
ACKNOWLEDGMENTS: (Merit Review projects E601-RA, -2RA, -3RA; statistics: M. Willits; hardware support: Jaffe DL, Nakahara A; former staff: Chesney D, Gadd J, Martino J, Merritt P.)
COMBINING COMPUTATIONAL MODELS AND ADVANCED COMPUTED
TOMOGRAPHY (CT) IMAGING WILL IMPROVE OUR UNDERSTANDING OF
BONE ADAPTATION AND DISUSE OSTEOPOROSIS
Beaupre GS, Whalen RT, Carter DR, Drace J, Giddings VL, Kiratli BJ, Napel SA, Perkash I, Sims G, Yan CH
VA Palo Alto Health Care System; NASA Ames Research Center; Stanford University
OBJECTIVES: The objectives of this study are: 1) to improve our understanding of the role of mechanical forces in bone adaptation; and 2) to accurately measure bone density changes in vivo.
RESEARCH PLAN: Our plan involves the development of a computational model of the foot to study the relationship between external loads and internal musculoskeletal forces and stresses and the development of new tools for improving the accuracy and precision of CT measurements of bone density.
METHODS: A non-linear finite element model of the foot was developed from CT data. High-speed cine-radiography and force plate analysis were used to determine foot kinematics and ground reaction forces (GRF) during walking and running.
To measure changes in bone density we developed: 1) improved techniques for the registration of serial CT images; and 2) new algorithms to reduce CT beam hardening artifacts, improving the accuracy and precision of bone density measurements in vivo.
FINDINGS: Our models show that calcaneal loading history can be greatly simplified because the stress distribution for running scales directly from walking. Stresses are highest at 60-70% of stance phase for both walking and running. In a disuse simulation our model predicts bone changes that compare well with results from bedrest studies. The combination of these models and new in vivo measurement capabilities will significantly improve our understanding of bone loss from disuse.
CLINICAL RELEVANCE: An improved understanding of the role of mechanical stimuli in bone adaptation will provide new clinical insights into osteoporosis countermeasures.
(VA: B802-RA; NASA: NCC2-5088; NASA-NCC2-5121; NIH: P41 RR09784)
EVALUATION OF NEW TOILET DESIGNS FOR OLDER PEOPLE
Sanford, JA, Malassigne, P.
Rehab R&D Center, VAMC Atlanta; C.J. Zablocki VAMC, Milwaukee, WI
OBJECTIVES: The purpose of this study was to develop and evaluate three new toilet seat inserts with integral horizontal, recessed, and vertical handles that foster safer and more independent toileting among older individuals.
RESEARCH PLAN: Differences in safety, difficulty, and effectiveness of handles between each of the three inserts and a typical ADA raised toilet/grab bar configuration were evaluated in a full-scale, transportable mockup of a toilet room.
METHODS: Demographic, cognitive, and medical background data were collected for each participant. Participants were then videotaped getting on and off each of the four test toilets. A post-trial questionnaire rated safety and ease of use.
FINDINGS: Test results indicate that the insert designs not only were more effective in providing assistance in transfer than a typical raised toilet, but also enabled safer and easier transfers. The insert with vertical handles as well as the ones with horizontal and recessed handles were rated as the safest and best by ambulatory/semi-ambulatory and nonambulatory individuals, respectively. Conversely, the standard toilet was consistently rated as the most difficult. Participants also tended to use the grab bars less often when integral handles on the inserts were available, suggesting that the handles were better positioned to assist in transfer.
CLINICAL RELEVANCE: Safe and independent toileting is important for older people in the community as well as in healthcare settings. This project indicates that the new designs potentially offer a much better alternative to a standard accessible toilet for older individuals both with and without mobility impairments.
(The project reported in this paper was funded by the Department of Veterans Affairs Rehabilitation Research and Development Service, Merit Review Project E-666-RA)
EVALUATION OF INTERVENTIONS TO PREVENT ELOPEMENT AMONG
NURSING HOME RESIDENTS
Connell BR, Sanford JA, Furbush LI
Rehab R&D Center on Geriatric Rehabilitation, Atlanta VA Medical Center
OBJECTIVES: The primary objectives of the study were to: describe subjects' elopement behavior; and determine the impact of 2 interventions (less aversive wanderer alarm system (WAS) signal and access to outdoor space) on the frequency of elopement behavior among demented NH residents at risk of exiting the unit.
RESEARCH PLAN: A three phase (9 weeks minimum), single subject design was used to compare the effect of conventional wanderer alarm system alert signals and 2 interventions on elopement frequency at 2 sites. The first intervention was continued when the second was introduced. Intervention order was varied across sites.
METHODS: Elopement behavior at exit points from study units equipped was assessed with video observation. Subjects' cognitive status, gait/balance, ADL independence, and dementia-related behavioral disturbance were assessed with an instrument adapted from the MDS.
FINDINGS: Seven subjects completed all phases of the study. Incident frequency varied widely across subjects (range 23 to 823). The most common type of incident involved being close enough to an exit to trigger the WAS without exiting or operating the door. For 4 subjects meaningful decreases in elopement frequency were observed between the baseline (conventional WAS signal) or first intervention phase and the final phase with both interventions in place. There were no meaningful concomitant changes in cognitive or mobility status that would account for these decreases.
CLINICAL RELEVANCE: Reducing aversive environmental stimulation (voice signal) and providing escapes from it (access to outdoor space) appear to be useful strategies in managing exiting behavior among some demented NH residents.
(Funded by Rehabilitation Research and Development Service, Department of Veterans Affairs, Washington, DC, Merit Review Project #E759)
POLESTRIDING EXERCISE FOR MANAGEMENT OF CLAUDICATION
Collins EG, Langbein WE, Orebaugh C, Maloney C, Edwards L, Littooy F
Rehab R&D Section, Medicine and Surgery Services, Edward Hines Jr., VA Hospital
OBJECTIVES: The objectives of this randomized clinical trial are to determine the efficacy of Polestriding (PS) exercise (walking with poles in a movement similar to cross-country skiing) and/or Vitamin E (Vit E) to increase exercise tolerance and improve quality of life (QOL).
RESEARCH PLAN/METHODS: The following tests were performed at baseline and at selected time periods through six-months: wheelchair ergometer test, symptom-limited ramp treadmill test (TMT), steady-state TMT, and a QOL battery.
FINDINGS: Results presented are from the baseline and one month follow-up time periods. Comparisons were made between exercise (E) and no exercise (NE) since investigators remain blinded to the Vit E status of the subjects. Twenty-five subjects were randomized into the E (n=13) and NE (n=12) groups. Subjects were elderly (mean age = 65 yr), moderately obese (BMI = 30) men. Duration on the ramp TMT (P<0.001) and steady-state TMT (P<0.04) improved significantly in the E group and not in the NE group. Subjects' perception of walking distance (P<0.01) and speed (P<0.03) significantly improved in the E group but not the NE group. Trends, measured by the SF-36, are developing toward improved physical function, vitality and social function between baseline and one month in the E group but not the NE group. Data collection continues to determine QOL changes and ascertain the influence of Vit E on pain free walking.
CLINICAL RELEVANCE: Polestriding may be an inexpensive, practical alternative to improve pain free walking time in veterans with intermittent claudication.
(Rehab R & D Section, Dept. of Veterans Affairs, Washington, DC)
ELEVATED POSTURAL MUSCLE ACTIVITY IN HEALTHY ELDERS AND
ITS EFFECT ON QUIET-STANDING DYNAMICS
J.J. Collins, B.L. Greenhalgh, A.E. Pavlik, A.T. Stamp, and L.A. Lipsitz
Dept. of Biomed. Eng. and Ctr. for BioDynamics, Boston Univ., Hebrew Rehab. Ctr. for Aged, Div. on Aging, Harvard Med. School, Boston VA OPC
OBJECTIVES: Our objectives were to examine cross-sectionally age-related changes in postural control dynamics and to gain insight into the physiological meaning of stabilogram-diffusion analysis (SDA) parameters extracted from quiet-standing posture data.
RESEARCH PLAN: We tested the hypotheses that: (1) healthy older adults adopt a postural control strategy whereby they increase the level of muscular activity across the joints of their lower limbs, and (2) lower-limb muscle activity levels are directly correlated with SDA measures of short-term postural sway.
METHODS: Twenty healthy young subjects (aged 21-28 years) and 20 healthy older adults (aged 72-83 years) were included in the study. Subjects were studied under quiet-standing conditions for multiple 60 s trials. A force platform was used to measure the time-varying displacements of the center of pressure (COP) under each subject's feet. Surface electromyographic (EMG) signals were recorded bilaterally from five lower-limb muscles: tibialis anterior, soleus, gastrocnemius, vastus lateralis of quadriceps, and biceps femoris of hamstrings. The COP trajectories were analyzed as one-dimensional random walks, according to SDA. We considered two SDA measures of short-term postural sway: short-term scaling exponents and short-term effective diffusion coefficients. The following parameters were computed from the EMG signals: (1) the mean root-mean-square (RMS) amplitude of each muscle, (2) ON%: the percentage of trial time for which a given muscle was activated, and (3) antagonistic ON%: the percentage of trial time for which both muscles in an antagonistic muscle pair were simultaneously activated.
FINDINGS: We found the RMS amplitude and ON% of each muscle and the antagonistic ON% of each antagonistic muscle pair, respectively, to be significantly greater in the elderly subjects. We also found the RMS amplitude of hamstrings to be significantly correlated with the short-term anteroposterior (AP) scaling exponent and the short-term AP effective diffusion coefficient, respectively. We also found the ON% of hamstrings to be significantly correlated with the short-term AP effective diffusion coefficient.
CLINICAL RELEVANCE: This study demonstrated cross-sectionally that healthy aging is associated with elevated postural muscle activity during quiet standing. This work also showed that SDA parameters can be directly related to the neuromuscular mechanisms underlying balance control.
(Supported by the Rehab R&D Service of the Department of Veterans Affairs, the National Science Foundation, and the Whitaker Foundation.)
EVALUATION OF BACK MUSCLE FUNCTION IN THE ELDERLY WITH
LOW BACK PAIN
Bonato P and Roy SH
Research Services Boston VA Medical Center and the NeuroMuscular Research Center, Boston University
OBJECTIVES: The purpose of this project is to study whether the high incidence of low back pain (LBP) among the elderly can be explained in part by the deleterious effects of aging and/or disuse of muscle function.
RESEARCH PLAN: The study is an outgrowth of previous investigations concerning LBP muscle impairment in which a new device, referred to as a Back Analysis System (BAS), was used to objectively measure back muscle disorders by analyzing the electrical signals from muscles.
METHODS: A total of 59 elderly male and female subjects (65-80 yrs) with complaints of sub-acute LBP and 29 matched controls without LBP were tested in the BAS using a standardized protocol. Subjects also completed an Oswestry Low Back Disability Scale, a Visual Analog Scale for pain assessment, and a survey of general physical activity. Subjects with LBP were recruited from an outpatient physical therapy practice where they had just begun a referral for treatment of their back pain. Control subjects were recruited from a neighboring elderly housing complex adjacent to the clinic.
FINDINGS: A significant correlation (p<0.05) was noted between EMG indices of muscle impairment and disability and pain scores. Those persons with high levels of disability and pain associated with LBP had the highest muscle impairments as measured by the BAS. The type of muscle impairment identified in the elderly LBP group was also found in a significant number of the elderly persons without LBP (p<0.05). This finding suggests that back muscle impairment may be generally more prevalent in the elderly than in the young.
CLINICAL RELEVANCE: Demographics within and outside of VA patient care mission point to a dramatic increase in the population of elderly persons seeking medical care. Back pain is one of the most common complaints requiring rehabilitation in the elderly.
(Supported in part by the Rehabilitation Research and Development Service of Veterans Affairs)
DEVELOPMENT OF AN OBJECTIVE TREATMENT OUTCOME MEASURE FOR
LOW BACK PAIN
Roy SH, Jabre J, De Luca CJ
Research Services Boston VA Medical Center and the NeuroMuscular Research Center, Boston University
OBJECTIVES: The purpose of this study was to validate the use of the Back Analysis System (BAS) to monitor and predict treatment outcome for patients with chronic and sub-acute low back pain (LBP).
RESEARCH PLAN: The research plan was: 1) to quantify the effects of physical rehabilitation on the BAS parameters; 2) to compare BAS parameters with standard clinical measures of muscle function; and 3) to demonstrate the predictive validity of the BAS parameters for LBP treatment outcome.
METHODS: The BAS is an assessment device for paraspinal muscle impairment that analyzes the electrical signals recorded from the muscles of interest. The study was conducted in a young adult male (n=60) population undergoing rehabilitation for chronic and sub-acute LBP. Subjects underwent BAS testing at intervals of 2-3 weeks during the course of their rehabilitation which lasted from 6 weeks to 3 months. Follow-up testing in a sub-set of these patients was conducted at 6 weeks, 3 months and 1 year following discharge from the program. A comprehensive test battery that included clinical measures of muscle performance, psychological factors, disability, physical impairment and pain indices were implemented at the same time as the BAS test.
FINDINGS: The results among the younger LBP sample demonstrated a significant improvement following rehabilitation as measured by the EMG parameter that related specifically to muscle fatigability and deconditioning. This difference was muscle site specific. Correlations between BAS scores and the Oswestry (disability) index (r=0.89) and Pain Intensity scores (r=0.50) were significant. Pre- vs. post-treatment differences in EMG impairment classifications were also significantly correlated to changes in Oswestry scores (r=0.95) and pain intensity (r=0.58).
CLINICAL RELEVANCE: The results supported the clinical efficacy of BAS measurements for identifying impairments and monitoring outcome.
(Supported by the Rehabilitation Research and Development Service of Veterans Affairs and the Liberty Mutual Insurance Company)
IMPROVEMENT IN LOCOMOTION FOLLOWING TREADMILL TRAINING IN
ELDERLY CHRONIC HEMIPARETIC STROKE PATIENTS
Silver K, Dobrovoiny L, Macko R, Smith G, and Goldberg A
Baltimore VA Geriatrics Research, Education, and Clinical Center (GRECC), and the University of Maryland Claude D. Pepper Center, Baltimore, MD
OBJECTIVE: To determine if a program of regular treadmill exercise improves locomotor ability in elderly, chronic hemiparetic stroke patients.
RESEARCH PLAN: In a non-controlled, prospective study, neurologically plateaued and ambulatory hemiparetic subjects with a mean post-stroke interval of 2 yrs (range: 6m - 6.7yrs) and mean age 65 years (range:58-85) received 6 months of treadmill exercise, Outcome measures pre- and post-exercise included 30 foot-timed and 6-minute walks.
METHODS: Treadmill training 3 days/week began at 40 - 50% and advanced to 60 - 70% maximal heart rate reserve. Thirty-foot timed walks were performed at both a self-selected and a fast pace. Six-minute walk assessments used standard protocols at a quick pace.
FINDINGS: Data are presented for several subsets of the subjects tested to date. For N=13, walking velocity at the self-selected pace increased 25.3% (1.42 MPH ±0.7, mean ± SD vs. 1.78 MPH ± 0.87 [p=.001]). For 12 of these subjects assessed also at the faster pace, walking speeds increased 13.6% (1.77 MPH ±1.1 vs. 2.01 MPH ±1.0 [p=.001 1]). For 8 subjects tested on the six-minute walk, distances increased 40% (621 ft. ± 311 vs. 873 ft. ± 386 [p=.001]).
Elderly chronic hemiparetic patients receiving 3 months of graded treadmill exercise significantly improved walking velocity and distance walked. These findings correlate positively with other data from this study (not presented here) showing improved aerobic capacity and lower extremity strength following task-specific treadmill training.
CLINICAL RELEVANCE: These findings support the relevance of treadmill-based exercise as a potent stimulus for locomotor recovery for individuals with chronic hemiparesis. Public health impact of exercise-mediated gains in physical endurance and reductions in cardiovascular disease risk in this typically sedentary population may be significant.
TRUNK FUNCTION AND RISING FROM A BED IN NURSING HOME
N. B. Alexander, MD; J. C. Grunawalt, RNC; J. Augustine, BA; S. Carlos, BA; A.B. Schultz, PhD; J. A. Ashton-Miller, PhD; V. Skiba
Dept of Veterans Affairs Medical Center GRECC, Ann Arbor MI, and the Division of Geriatric Medicine and Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI 48109-0926
OBJECTIVES: We previously found that trunk and extremity movements help characterize bed rise difficulty in community older adults. What is the importance of trunk and extremity movements in nursing home older adults who require bed transfer assistance?
RESEARCH PLAN/METHODS: We compared the bed rise performance of independent, retirement center-dwelling older adults (RC, n=29, mean age=84), with nursing home older adults requiring assist in transfers from bed (NH, n=20, mean age=77). As a marker of difficulty, we timed subjects as they rose from supine to sitting at the edge of a bed (SS). Subjects performed 21 bed mobility tasks (BMT) focusing on the contribution of the trunk and extremity movements to rising from bed, including a 10-second lateral trunk lean (LTL), and a 10-sec single leg elevation off the bed surface (ELG). To facilitate trunk elevation in the very disabled, subjects also sat up in bed with the addition of an overhead trapeze (TRA) and with 30° elevation of the head of the bed (HBE).
FINDINGS: Using a hand-held stopwatch, the NH were slower in SS (mean seconds ±sd, RC 5.3 ±5.2, NH 14.7 ±17.0, p<0.005). There were few differences in ability to perform BMT between RC and NH; challenging tasks such as LTL were equally difficult for both groups (42% NH vs 41% RC unable), while few subjects had trouble with easier tasks such as ELG (range of 0-16% unable in both groups). Twenty percent of NH were unable to complete TRA (vs none of RC, p<0.01). In addition 20% of NH (vs 3% of RC) were unable to complete HBE (p<0.03). Stepwise regression was then used to determine which BMT might best predict SS. Only TRA was significant, predicting 29% of the variance in rise time (p<0.005).
CLINICAL RELEVANCE: In summary, these data suggest that the ability to perform two sitting-up in bed tasks, using a trapeze and with head of the bed elevation, may be useful in identifying older adults with difficulty in rising from a bed. Frail older adults unable to perform these two tasks may have such severe trunk elevation difficulty that rehabilitation might focus on trunk strengthening to improve bed rise performance.
REHABILITATION UNITS AND GERIATRIC UNITS - DO THEY DIFFER?Hoenig H, Zolkewitz M, Sloane R, Reker D, Horner R.
OBJECTIVES: To examine the relationship of geriatric and rehabilitation units to resources and patient outcomes
RESEARCH PLAN: Cross-sectional study.
METHODS: Data - 2 surveys of VHA acute and post-acute care (PAC) stroke resources, computerized and centralized VHA databanks. VA hospitals were classified as (i) No PAC, (ii) Basic PAC, (iii) Geriatric Unit alone or with Basic PAC (+GEMU); (iv) Rehabilitation Unit alone or with any other PAC (+RBU). VA hospitals thus classified were compared to rehabilitation resources using Spearman correlation coefficient. Outcomes (discharge to community (DCHOME) and length of stay (LOS)) were compared for stroke patients in these hospitals using multivariable regression techniques controlling for patient characteristics.
FINDINGS: Twenty-seven percent of acute stroke patients in VA did not have on-site access to either a geriatric or rehabilitation unit, and 50% lacked an on-site rehabilitation unit; however, only 4% (256/6905) were transferred to another VA. The was a statistically significant correlation between level of PAC and rehabilitation resources, with VA hospitals with +GEMU having intermediate resources compared to Basic PAC or +RBU. Level of PAC predicted LOS (p=.001) and DCHOME (p=.004). Compared to stroke patients in VAs with Basic PAC, patients in +RBU VAs were 50% more likely (OR1.59, 95% CI 1.38-1.84), and +GEMU VAs were 25% more likely, to return home (OR 1.26, 95% CI 1.03-1.44). We conclude geriatric and rehabilitation units differ from one another in important ways.
CLINICAL RELEVANCE: Availability of post-acute care services has important implications for health care managers and for patient care providers.
(Funding: VA Rehab R&D, Dr. Hoenig is currently an American Federation on Aging Research Beeson Scholar.)
THE EFFECT OF EXERCISE ON GLYCATED HEMOGLOBIN IN TYPE-2
DIABETES IN SUPERVISED VS. HOME EXERCISE PROGRAMS
VA Albuquerque PM&R; U of New Mexico SOM PT Program
OBJECTIVES: 1) To evaluate the effectiveness of exercise intervention with respect to glycemic control in type-2 diabetics. 2) To compare the effectiveness of two methods of monitoring. 3) To evaluate the relative contributions of change in fitness, change in body fat, and change in body mass with respect to change in glycemic control. Research Plan: Diabetic subjects (150), not on insulin, will be screened by Exercise Tolerance Test (ETT) and randomly assigned to a Home Exercise, Supervised Exercise, or Control Group for a three-month intervention followed by a six-month maintenance period.
METHODOLOGY: Cardiorespiratory fitness, glycemic control, body fat, and body mass will be assessed at the three time intervals. The intervention will be moderate intensity walking. Monitoring will be by phone for the home group and three times a week at the fitness center for the supervised group
FINDINGS: The Control Group will be compared to the Supervised Group using t-tests. The Supervised Exercise Group will be compared to the Home Exercise Group using t-tests. Outcome measures will be analyzed by multiple regression.
CLINICAL RELEVANCE: Studies have shown that exercise can increase insulin sensitivity, even without weight loss. However, patient compliance is poor. Findings may be useful to primary care providers in the clinical management of diabetes. The project may be extended to type-2 diabetics who use insulin, are newly diagnosed, or living in rural areas.
COGNITIVE IMPAIRMENTS AS AN IMPORTANT CONTRIBUTOR TO
DISABILITY IN SCHIZOPHRENIA
Morris Bell, PhD, VA Connecticut HCS & Yale Univ. School of Med; Edward Kaplan, VA Connecticut HCS; Gary Bryson, PsyD, Connecticut HCS
OBJECTIVES: Cognitive impairments may be an important contributor to disability in schizophrenia and may limit the rate of improvement in work rehabilitation.
RESEARCH PLAN AND METHODS: Thirty-three outpatients with schizophrenia or schizo effective disorder who participated in a work rehabilitation program were administered neuropsychological testing at intake and their work performance was evaluated biweekly using the Work Behavior Inventory.
FINDINGS: On each of five domains of work performance, 76% to 91% of subjects improved significantly over 26 weeks. Individual differences in rate of improvement were robustly predicted by neuropsychological variables: Work Habits, R2 = .79; Personal Presentation, R2 = .73; Cooperativeness, R2 = .67; Work Quality, R2 = .56; Social Skills, R2 = .24; Total, R2 = .45. Neuropsychological measures had differential relationships to work domains.
CLINICAL RELEVANCE: These findings lend support to theories linking cognitive impairment to disability in schizophrenia. Severity of cognitive impairment significantly limits the rate of improvement in work rehabilitation, and remediating or accommodating such deficits may be a necessary feature in successful rehabilitation.
SELF-ASSESSED COMMUNICATION DIFFICULTY AMONG ADULTS WITH
AND WITHOUT PRIOR HEARING AID EXPERIENCE
Schuchman G (1), Beck LB (1), Williams D (2), Sandvik H (1) and Larson V (1, 3) for the participants of the NIDCD/DVA Hearing Aid Clinical Trial;
1. VAMC, Washington, DC; 2. VA CSPCC, Hines, IL; 3. George Washington Univ., Washington, DC
OBJECTIVES: Our goal was to evaluate the effect of prior experience with amplification on an individual's self-assessed communication difficulties.
RESEARCH PLAN: The Profile of Hearing Aid Benefit (PHAB), a self-assessment questionnaire designed to quantify the benefits of a hearing aid in everyday situations, has gained widespread acceptance among audiologists. For this metric to yield meaningful information, it is essential that individuals with and without prior hearing aid experience provide equally valid and reliable assessments of their unaided communication difficulties to serve as a baseline for subsequent aided comparisons. As part of the NIDCD/DVA Hearing Aid Clinical Trial, unaided PHAB scores were analyzed from experienced and from first time hearing aid users.
METHODS: 188 male and 142 female volunteers (mean age = 67.3 yrs.), each with a bilaterally symmetrical sensorineural hearing loss, provided PHAB data at the time of their hearing aid fitting and at three, six, and nine month follow-up visits. Approximately half the subjects had never used amplification, while the others had an average of 10.0 years of hearing aid experience.
FINDINGS: There was no effect of gender on any of the 7 PHAB subscales; however, an individual's prior hearing aid experience, degree of hearing loss and age all had significant effects on the PHAB results.
CLINICAL RELEVANCE: Unaided PHAB scores form the baseline for evaluating the efficacy of our hearing aid intervention. We must be aware of, and account for, the factors which may influence the self-assessed benefit of a hearing aid and thus affect our clinical treatment strategy.
THE NIDCD/DVA HEARING AID CLINICAL TRIAL: PEAK CLIPPING,
COMPRESSION LIMITING, AND WIDE DYNAMIC RANGE COMPRESSION
Larson VL1,2, Henderson WG3, Huerta L4, Beck LB1, Bratt GW5, Fausti SF6, Haskell G7, Kang JS1, Noffsinger D8, Rappaport BZ9, Schuchman G1, Shanks JE1010, Williams D3, and Wilson RE11 for the participants in the IDCD/DVA Hearing Aid Clinical Trial
1VAMC, Washington, D.C.; 2George Washington University, Washington, DC; 3VA Cooperative Studies Center, Hines, IL; 4NIDCD; 5VAMC, Nashville, TN; 6VAMC, Portland, OR; 7VAMC, Iowa City, IA; 8VAMC, West Los Angeles, CA; 9VAMC, Albuquerque, NM; 10VAMC, Long Beach, CA; 11VAMC, Mountain Home, TN
OBJECTIVES: This clinical trial was designed to compare the benefit adults with sensorineural hearing loss received when wearing a hearing aid programmed to control its output using peak clipping, compression limiting, and wide dynamic range compression.
RESEARCH PLAN: Three hundred sixty adult males and females with bilateral sensorineural hearing loss were enrolled in the trial. The trial was conducted using a three-treatment, three-period crossover design. In this double-blind protocol, patients were tested at baseline condition without a hearing aid and then after having used each of the three circuit options for a period of ninety days.
METHODS: The outcome test battery included monosyllabic and sentence tests of speech intelligibility presented through a loudspeaker (aimed at the subject's head) at three sound pressure levels with three levels of competing multi-talker babble presented through two additional loudspeakers. The battery also included a quality rating test administered with speech stimuli presented in quiet and in a competing background. Finally, patients completed self-assessments of hearing aid benefit and provided a preference ranking of the three circuits.
FINDINGS: The data collection phase of the trial has been completed. Data analyses are underway. The focus of this presentation will be to present patient characteristics and outcome test battery results for the unaided conditions.
CLINICAL RELEVANCE: This trial was designed because of the lack of carefully controlled studies of hearing aid benefit. The results will add to the body of knowledge regarding hearing aid performance in diverse listening situations and will contribute to our understanding of patient characteristics that are important to predicting hearing aid benefit.
(Sponsors: NIDCD, VA Cooperative Studies)
DEMOGRAPHIC AND SATISFACTION DATA FROM VETERANS SERVED BY
DVA BLIND REHABILITATION CENTERS IN 1997-1998
De l'Aune, WR
Rehab R&D Ctr, VA Atlanta; Rehabilitation Medicine Department, Emory University School of Medicine; Department of Mental Health and Human Services, Georgia State University; Vision Rehabilitation Graduate Program, Pennsylvania College of Optometry
OBJECTIVES: The purposes of this project are to establish the psychometric properties of instruments used to gather data relevant to blind rehabilitation outcomes, to refine the scaling and scoring protocols for the instruments, and to revise and refine the instruments.
RESEARCH PLAN: Development of data gathering instruments was accomplished in conjunction with the National Blind Rehabilitation Task Group on Rehabilitation Outcomes. The demographic database consists of the extensive information about the blinded veteran demographic, rehabilitation, and medical history. The satisfaction survey consists of eighteen items pertaining to programmatic issues in residential blind rehabilitation. These instruments will be administered to all veterans going through the residential blind rehabilitation program of the Department of Veterans Affairs.
METHODS: A blind rehabilitation clinical staff person at the completion of the residential blind rehabilitation program enters the database items. All demographic data are sent to the Atlanta Rehabilitation R&D Center at the time of the subject's discharge. A research associate from the Rehabilitation R&D Center then telephones the subject within a month of completion of Blind Rehabilitation. After informing the subject of his right to refuse the interview and gaining permission to continue, the research associate administers the Blind Rehabilitation Service Satisfaction Survey. All information is transmitted in aggregate form on a quarterly basis to the referring BRC and to Blind Rehabilitation Service.
FINDINGS: Initial data obtained from the demographic and satisfaction instruments will be discussed in this presentation. As of March 26, 1998, data from 1,282 veterans have been collected for the demographic instrument and from 689 veterans for the satisfaction instrument.
CLINICAL RELEVANCE: These findings and the further development of outcome instruments in this area will contribute to greater efficiency and effectiveness of the delivery of blind rehabilitation services by the Department of Veterans Affairs. (DVA Rehabilitation R&D C813-RA and C2179-RA)
EVALUATION OF LIQUID CRYSTAL SUNGLASSES FOR PEOPLE WITH
Ross DA, Mancil GL
Rehab R&D Ctr, Atlanta VAMC; Vision Rehab Research Lab, Salisbury VAMC
OBJECTIVES: Evaluated visual performance of low vision subjects wearing fast-darkening (30 millisecond) sunglasses.
RESEARCH PLAN: Employed liquid crystal (LC) technology and light sensors to design fast-darkening sunglasses with a continuous light-dark range, and evaluated the visual performance of low vision subjects wearing these LC sunglasses versus existing subject-preferred sunwear.
METHOD: LC sunglasses prototypes were developed via an iterative process of laboratory testing and subject testing of existing LC technologies. In both clinical and mobility test trials, the visual performance of 107 subjects wearing the final prototype was compared with their performance while wearing existing preferred sunwear. Measures included visual acuity (VA), contrast sensitivity (CS), mobility travel times, and mobility errors recorded under normal, dim, and bright ambient lighting conditions. Multiple t-tests identified main effects and interactions of subject condition: age-related macular degeneration (ARMD), retinitis pigmentosa (RP), cloudy media, and no vision loss by device (habitual prescription, preferred sunwear, LC prototype).
FINDINGS: The final prototype employed a variable polarization LC lens and a "flip-up" indoor/outdoor polarizer with a light-to-dark range of 68% to 2%. Test results included: 1) overall functional mobility improvement with LC sunglasses; 2) most significant improvement by ARMD subjects; 3) significant correlation of VA and CS with mobility task scores; and 4) significant improvement in CS and VA for subjects with ARMD.
CLINICAL RELEVANCE: A product similar to the final LC prototype can have a positive impact on the mobility of persons with low vision, and in particular, people with ARMD.
(Support for this project was received from VA Rehabilitation Research and Development Service)
LAPTOP COMPUTER-BASED SYSTEM FOR COMMUNICATION,
ENVIRONMENTAL CONTROL, AND COMPUTER ACCESS VIA SINGLE-SWITCH
ACTIVATION: A CASE STUDY
Fehr L, MS
Rehab R&D Section, Research Service, Hines VA Hospital, Hines, IL
OBJECTIVES: The purpose of this endeavor was to develop a mobile speech system, operable by a single switch and entirely configurable by the patient himself and to add to the system word processing, general computer access, and environmental control capabilities.
RESEARCH PLAN: The 24-year-old patient has a C-1/brainstem level injury and what is commonly called the "locked-in syndrome." The patient's ability to communicate with non-family members is limited to yes/no responses given by an up/down gaze of the eyes. A team of professionals at Hines assembled to explore alternatives for facilitating richer communication. A review of communication systems commercially available at the time revealed no suitable alternative.
METHODS: Commercially available components of the system include a laptop computer, speech synthesizer, environmental control unit, wireless data link, and scanning software for Windows. The speech software and input switch were developed at Hines.
FINDINGS: All software operates in "scanning mode." Options are selected when the patient activates a simple mouth switch consisting of a small plastic pipette connected to a pressure sensor. The speech software allows the patient to: 1) send a stored phrase to the speech synthesizer; 2) using a spelling board with word prediction and a custom dictionary, construct and "speak" new phrases which may then be stored or discarded; 3) modify the system by changing the scanning rate, deleting unneeded words or phrases, or reorganizing existing phrases which are stored by patient-defined categories. With commercial software, the patient may operate devices with infrared remote controls; appliances plugged into household AC outlets; a speaker phone; and personal computing applications such as word processing.
CLINICAL RELEVANCE: Features of the speech software allow the patient to structure his own environment for speech in a way that serves him best. The system will give the patient significant independence given the severity of his disability.
INDUCTION OF RETINAL AND CORTICAL POTENTIALS BY
SUBRETINALLY IMPLANTED MICROPHOTODIODE-BASED RETINAL
Peachey NS, Pardue MT, Perlman JI, Chow VY, Chow AY
Hines VA Hospital, Loyola Univ Med Ctr, Optobionics Corp, LSU Eye Center
OBJECTIVES: To evaluate biocompatibility and function of PiN and NiP semiconductor microphotodiode-based retinal prosthetic devices implanted into the subretinal space.
RESEARCH PLAN. Implants were placed in the subretinal space of adult cats using a retinotomy approach; cats were followed post-operatively, to evaluate implant function and the response of the retina to the implant.
METHODS. Retinal and cortical potentials were recorded using electrodes placed on the cornea and over the visual cortex, respectively. Photographs of the ocular fundus were made using a fundus camera. Implant-mediated responses were isolated by infrared stimuli; while conventional ERGs were recorded to white light stimuli. Retinal histology was analyzed by light microscopy.
FINDINGS: The electrical implant response increased to a stable level during the first weeks post-operatively. Retinal and cortical recordings also included slow wave components that were reproducible across recording sessions and different animals; these components were not seen when a retinal detachment occurred, when the infrared stimulus was blocked, nor when using an inactive implant. Conventional ERGs recorded from implanted eyes were similar in waveform to those of fellow eyes, but slightly smaller in amplitude. In the retina above the implant, the outer nuclear layer was lost, while the inner nuclear and ganglion cell layers were relatively well preserved; neighboring retinal areas appeared normal.
CLINICAL RELEVANCE: Since these implants appear to be capable of mediating visual function, this approach may be useful to restore visual function to patients blinded by disorders that induce selective degeneration of the photoreceptors, including age-related macular degeneration and retinitis pigmentosa.
(Supported by the Department of Veterans Affairs and National Eye Institute grant R43 EY 11828)
VISUAL PERFORMANCE RELATIONSHIP TO PRL ABILITY ASSESSED
BY A LOW VISION REHABILITATION SYSTEM (SLO LVRS)
Schuchard RA, Fletcher D, Maino J, Timberlake G, Ceron O, Young J.
Kansas City VAMC, Univ of Missouri-KC, Univ of Kansas
OBJECTIVE: To determine how visual performance in activities of daily living (ADLs) relates to the ability of PRLs (preferred retinal loci) to make basic eye movements in fixation, saccade, and pursuit.
RESEARCH PLAN: The ability to make efficient and effective eye movements to compensate for scotomas is considered to be one of the most important visual skills for successful visual rehabilitation. This research project is investigating the basic eye movements of fixation, saccade, and pursuit in low vision people with macular scotomas.
METHODS: The scanning laser ophthalmoscope was used to: 1) evaluate the PRL ability of low vision people referred to a private practice and a VICTORS program and 2) determine the retinal location of the PRL and of all macular scotomas relative to the PRL or fovea. Standard clinical assessments of visual acuity, contrast sensitivity, and reading rate were also done. Finally, a self-analysis of ADLs was done by administering part of the VFQ from NIH/NEI.
FINDINGS: The ability to use a PRL was significantly correlated to ADLs. While the existence of macular scotomas degrade visual performance in ADLs, the characteristics of macular scotomas nor the standard clinical assessments were not as strongly correlated to ADLs as the ability to use a PRL.
CLINICAL RELEVANCE: The Scanning Laser Ophthalmoscope Low Vision Rehabilitation System (SLO LVRS) provides the low vision clinician with an effective, efficient, and easy to use visual rehabilitation system to diagnose and train the use of PRLs to compensate for macular scotomas in low vision people.
(Rehabilitation Research & Development Program and NIH/NEI Shannon Directors Award)
OBJECTIVES: To obtain auditory brainstem responses (ABRs) using two methods and to compare the responses to determine differences.
RESEARCH PLAN: ABRs were obtained in 20 human subjects using two different methods, a conventional method with stimuli presented singly and a multiple stimulus method using a train of stimuli.
METHODS: Stimuli in both methods were tone-bursts at frequencies of 1, 2, 4 and 8 kHz shaped with a Blackman-Harris window and intensity levels up to 100 dB peak-equivalent SPL. The single tone-bursts were presented with a 110 ms interstimulus interval. The multiple stimulus consisted of a 20 tone-burst train of four frequencies at five intensities (separations between tone-burstsi of 9 to 12 milliseconds) with 109 ms, off-time between trains.
FINDINGS: A comparison of responses to the stimuli presented singly and those obtained using the 20-stimulus train showed small differences in response latencies and amplitudes.
CLINICAL RELEVANCE: The use of a specifically designed stimulus train can result in a significant time savings in ABR data acquisition (up to 90%). These findings demonstrate the feasibility of the rapid acquisition of brainstem responses using tone-burst trains.
This method would be useful in the objective determination of auditory dysfunction and in determining hearing loss from ototoxic agents, noise exposure or other agents. This method could be. particularly useful in preventing additional hearing losses in Veterans, many of who have preexisting hearing losses and can ill afford any additional loss, and could also aid various rehabilitative strategies.
(Support for this project was provided by the Department of Veterans Affairs Medical Center, National Center for Rehabilitative Auditory Research and grant H235K3001 from the U.S. Department of Education. Rehabilitation Services.)
INDIVIDUAL SPONDAIC WORD PSYCHOMETRIC FUNCTIONS: MALE AND
Wilson RH, Strouse-Carter A
VA Mountain Home, TN and Dept. of Surgery, ETSU
OBJECTIVES: Spondaic words spoken by the VA female were analyzed in an attempt to create a more homogenous set of spondaic words.
RESEARCH PLAN: Two experiments were performed with the 36 W-1 spondaic words spoken by the VA female and the original male speaker version recorded by Hirsh. In Experiment 1, psychometric functions were established for each word and for each subject. In Experiment 2, the levels of the words for the female speaker were equated and the experiment repeated.
METHODS: W-1 spondaic words by both speakers were compiled digitally into 14 randomizations and recorded on compact disc. Twenty young adults with normal hearing served in 2, 1-hour sessions. During each session, the listener was familiarized with one list of words presented at 14 dB HL. Then, 13 randomizations of the 36 words were presented monaurally at each 2-dB step randomly between -10 and 14 dB HL. Each session was devoted to one of the speakers, counterbalanced across subjects.
FINDINGS: In Experiment 1, thresholds for the words spoken by the female speaker ranged from -3.4 dB HL (armchair) to 4.1 dB HIL (eardrum). For Experiment 2, the levels of the spondaic words spoken by the female speaker were adjusted digitally to a common level of 0 dB HL. For example, armchair was decreased 3.4 dB, whereas eardrum was increased 4.1 dB. Data collection is on progress for 20 young adults using the adjusted female spondaic words. Analysis of this data will show whether increased homogeneity results in less variability in measurement of the SRT.
CLINICAL RELEVANCE: Clinically, it is important that each spondaic word used as a stimulus item can be perceived at essentially the same level, since the measure of interest is the level necessary for a 50% correct response. It would be ideal to use a homogeneous set of test words, as we are able with pure-tone signals to increase the precision with which the SRT can be established.
AUDITORY EVOKED RESPONSES IN APHASIC ADULTS: SEVERITY AND IMPROVEMENTAuther, LL1,2, Wertz, RT1,2, Burch-Sims, GP3, Miller, TA1, and Kirshner, HS2
OBJECTIVES: Our purpose was to determine whether auditory evoked responses (AERs) differ between normal and aphasic adults and are related with the severity of or change in aphasia.
RESEARCH PLAN: We compared AERs in aphasic and normal adults. A battery of language tests and a battery of AERs were administered to the normal subjects once and to the aphasic subjects before and after a two-month treatment trial.
METHODS: Behavioral tests included the Porch Index of Communicative Ability (PICA); Western Aphasia Battery Aphasia Quotient; and Token Test. AERs included the mismatch negativity response (MMN) and the N400 response.
FINDINGS: More normal subjects displayed AERs than aphasic subjects. The groups did not differ on any MMN measure. Differences were seen in two latency windows, pretreatment, on the N400. Severity of auditory comprehension on behavioral measures was significantly related with MMN duration pre- and post-treatment and post-treatment N400 mean amplitude. Pretreatment N400 mean amplitude was significantly related with improvement in discriminating the nouns used in the N400 task.
CLINICAL RELEVANCE: While the MMN AER displays some precision in predicting aphasic severity, neither the MMN or the N400 appears to predict change in aphasia. Subject variability, especially that related to time postonset and initial severity of aphasia, may have influenced results. Continued exploration of AERs to predict aphasic severity and prognosis for improvement may be more fruitful if confined to aphasic people who are early postonset and who display severe to moderate auditory comprehension deficits.
(Supported by a Department of Veterans Affairs Rehabilitation, Research & Development Service Pilot Study and Career Development Award and the Medical-Surgical Research Service HBCU Initiative).
SOUND PRODUCTION TREATMENT FOR APRAXIA OF SPEECH
Julie L. Wambaugh, Ph.D. and Patrick J. Doyle, Ph.D.
Dept. of CMDIS, University of Utah, Salt Lake City, UT 84112
INTRODUCTION: Apraxia of speech (AOS) is an acquired neurogenic speech disorder, typically resulting from relatively focal damage to the language-dominant cerebral hemisphere. AOS is characterized by inaccurate production of speech sounds, trial and error groping of the articulators, increased durations of sound and word productions, disrupted prosody, and overall reduced efficiency of communication. Severity may range from a complete inability to speak to relatively minor articulation problems. A variety of treatments have been advocated for AOS, however, most have not received sufficient empirical study to allow researchers and clinicians to predict their effects. Over the period of two successive Veterans Affairs RR&D projects, we have systematically studied the acquisition, generalization, and maintenance effects of sound production treatment for AOS. The proposed poster presentation will highlight the methods and findings of this line of research.
DESCRIPTION OF POSTER: The following information will be provided on the poster:
Rationale and Description of the Problem: The characteristics of AOS will be described briefly and a rationale for conducting sound production treatment research will be provided. Results from descriptive studies that we have conducted that pertain to description/rationale will be briefly summarized (Wambaugh & Doyle, 1994; Wambaugh, Doyle, Kalinyak, & West, 1995; Wambaugh, West, & Doyle, 1997).
Methods: The experimental methods relating to our treatment investigations will be described in terms of types of subjects studied, experimental designs employed, specific treatment(s) examined, and dependent variables measured.
Results: Because our investigations have employed single-subject experimental designs, results from several representative subjects will be presented graphically (along with summarizations of groups of subjects). Results will be presented to highlight findings relative to a) acquisition effects, b) response generalization effects, c) stimulus generalization effects, and d) maintenance effects of treatment. Textual summarizations will accompany all graphed data. Previously published data (Wambaugh, Doyle, Kalinyak, & West, 1996; Wambaulgh, Fliszar, West, & Doyle, in press; Wambaugh, West, & Doyle, 1998) will be presented along with ongoing research findings.
Discussion/Conclusions: Results will be discussed primarily in terms of the clinical significance of this treatment research. Potential theoretical implications will also be addressed, as will directions for future research.P26
FREQUENCY SELECTIVITY: IMPLICATIONS FOR AUDITORY
Kane, J.K., VAMC Huntington, WV, & Dept. Comm. Sci. & Dis., Univ. of Pittsburgh, Pittsburgh, PA, Durrant, J.D., Dept. Comm. Sci. & Dis., Univ. of Pittsburgh, Pittsburgh, PA
OBJECTIVE: The purpose of this study is two-fold: 1) to evaluate the relationship between the maximum distortion-product (fd*) generated by the DPOAE f2/f1 paradigm to the "tip-tail" slope change (Fxb) inpsychophysical tuning curves (PTCs) at 2 kHz and 4 kHz. 2) to relate salient parameters, e.g., Q factor, slopes, of DPOAE data to existing knowledge of frequency selectivity based on psychophysical studies.
RESEARCH PLAN: 100 subjects (ears) will participate in this study representing 5 categories of hearing threshold level (HTL) at 2 kHz and 4 kHz. Three groups will define the "clinically-normal" sensitivity range (25 dB HTL) and two groups will define the mild, sensorineural loss range (>25 dB HTL - 45 dB HTL).
METHODS: Low-intensity and high-intensity PTCs were generated using a 2-alternative forced-choice (adaptive) procedure with a forward-masking paradigm. DPOAE magnitude was assessed as a function of stimulus frequency separation at 2 kHz and 4 kHz at three intensity levels by sweeping f1 from approximately one-half octave below f2 to f2 .
FINDINGS: Preliminary results to date from normally-hearing subjects (34) showed that fd* and Fxb were related across test frequency and sound pressure level.
CLINICAL RELEVANCE: The DPOAE f2/f1 paradigm may have utility as a clinical tool for assessing frequency selectivity in patients with a mild to moderate, sensorineural hearing loss who are appropriate for amplification.
(This material is based upon work supported by the Office of Research and Development (R&D), Rehabilitation R&D Service, Department of Veterans Affairs.)
THE EFFECT OF PARTIAL FOOT AMPUTATION ON SOUND LIMB
Burnfield JM, Boyd LB, Mulroy SJ, Perry J
Pathokinesiology Laboratory, Rancho Los Amigos Medical Center, Downey, CA
OBJECTIVES: The purpose of this investigation was to determine the impact of transmetatarsal amputation (TMA), ray resection (RA), and toe amputation(TA) on barefoot sound limb loading forces.
RESEARCH PLAN AND METHODS: Individuals with unilateral TMA (7), RA (7), and TA (7) participated. Seven healthy adults (NORM) served as a control group (mean ages: MA=54.1±5.9; RA=54.1±8.1; TA=54.4±5.7; NORM=63.4±3.7). Subjects walked at a self-selected speed (10 m). Data collected included: stride characteristics, peak vertical ground reaction force (loading), and maximal isometric plantar flexion torque.
FINDINGS: Residual vs. Sound Foot (TMA, RA, and TA): Plantar flexion torque was lower in the residual versus sound limb for TMA (33.5±9.5 vs. 47.5±6.9; p=.003) and RA (35.1±16.7 vs. 56.6±16.6; p=.008). Peak vertical ground reaction forces were higher for the sound foot for TMA (11.3±0.9 vs. 10.3±0.8; p=.008). RA and TA demonstrated no significant between limb differences in peak vertical ground reaction forces. Sound limb peak vertical ground reaction forces inversely correlated with residual foot length for TMA (r=-.893, p=.007) and RA (r=-.808, p=.028). Group Differences (TMA vs. RA vs. TA vs. NORM): Compared to NORM, TMA, RA and TA demonstrated significant reductions in walking velocity, stride length, and cadence (p<0.05; post hoc testing). After adjusting for velocity, TMA, RA, and TA had significantly higher sound limb peak vertical ground reaction forces when compared to NORM (ANCOVA, post hoc testing p<.05). TMA adjusted force was significantly higher than for TA; RA was not significantly different from MA or TA. High TMA sound limb peak load forces resulted from reduced residual limb foot length and lack of forefoot rocker contour. Although no significant differences between residual and sound foot length were noted for RA and TA, the absence of 1-3 rays or toes likely distorted (narrowed) the forefoot contour. Weakness of residual limb plantar flexors was present in more proximal amputation levels (TMA, RA). Load forces on the residual limb (TMA, RA, and TA) were below normal due to a combination of reduced gait velocity and a preserved sound limb forefoot.
CLINICAL RELEVANCE: Individuals with an amputation secondary to diabetes mellitus are at high risk for subsequent amputation(s). Maximal preservation of the residual forefoot may help decrease sound limb load forces and reduce the risk of future skin breakdown.
(Funding for this work was provided by the Department of Veterans Affairs, #A861R)
HYDROSTATIC PRESSURE AND CARTILAGE REPAIR: ANALYSIS OF
CHONDROCYTE COLLAGEN GENE EXPRESSION
Smith RL, Lin J, Kajiyama G, Shida J-I, Yerby S, van der Meulen MCH, Vu R, Hoffman AR, Schurman DJ, Beaupré GS, Carter DR
Rehab R&D Ctr, VA Palo Alto HCS, Palo Alto, CA ; Mech Eng & Functional Restoration Depts, Stanford Univ., Stanford, CA
OBJECTIVE: Determine the effects of mechanical loading on cartilage matrix repair and regeneration.
RESEARCH PLAN: Quantify the effects of physiological levels of hydrostatic pressure on type II and type I collagen mRNA expression in cultured articular chondrocytes.
METHODS: Adult bovine articular chondrocytes were isolated and maintained in high density monolayers in DMEM containing 10% fetal bovine serum for five days. The cells were transferred to serum-free medium (DMEM/F12 with selenium and a lipid supplement). Hydrostatic pressure was cyclically applied at a loading dose of 10 MPa and a frequency of 1 Hz for periods of 2, 4, 8, 12 and 24 hours. Total RNA was isolated by the phenol/chloroform method and quantified by absorbance. cDNA was prepared by reverse-transcription and PCR was performed with primers for type II collagen, type I collagen and beta-actin. Signal levels were in the linear range of amplification and DNA concentration. Collagen content in the culture medium was analyzed using SDS-PAGE and western blotting techniques.
RESULTS: Type II collagen mRNA levels responded to hydrostatic pressure in a biphasic pattern. The ratio of type II collagen to beta-actin mRNA signal increased following loading for 4 and 8 hours but returned to resting levels by 1 and 24 hours. The type I collagen mRNA signal was detectable but not altered by hydrostatic pressure.
CLINICAL RELEVANCE: Repair and regeneration of articular cartilage may depend on critically defined mechanical loading conditions. The results are important to the fields of orthopaedic surgery, rheumatology and rehabilitation medicine.
This work is supported by a VA Rehab Merit Review Grant, #A857-RC.
TENDON ADAPTATION AND ACHILLES TENDON INJURY
Wren TAL, Beaupré GS, and Carter DR
Rehab R&D Ctr, VA Palo Alto HCS and Biomech. Eng. Div., Mech. Eng. Dept., Stanford Univ.
OBJECTIVES: Our objective is to understand the mechanics of tendon adaptation and injury so that tendon injuries can be prevented.
RESEARCH PLAN: This study involves a combination of computer modeling and in vitro mechanical testing. We have developed a model for normal tendon adaptation, and we plan to include damage and repair in the model in the future. The in vitro tests will measure loading-dependent changes in the mechanical properties of excised human Achilles tendons.
METHODS: The computer model predicts changes in the cross-sectional area, modulus, and strength of a tendon. Quantitative rules determine biological and mechanobiological rates of change for the tendon properties based on age and a daily strain stimulus.
During the in vitro mechanical testing, we will use monotonic tests to failure to establish baseline material properties. Fatigue properties will be established using cyclic loading.
FINDINGS: The computer models produce results consistent with animal studies, lending support to the proposed adaptation rules. These rules suggest that strains are the primary mechanical stimulus for tendon adaptation.
We expect the Achilles tendon to have the same failure strain as other tendons (10-15%) but a higher modulus (>1 GPa) and failure stress (>100 MPa). During the cyclic tests, we expect the modulus to degrade over time with the degradation accelerating as the tendon nears failure.
CLINICAL RELEVANCE: The Achilles tendon is the most frequently injured tendon in the body. If we can understand the mechanics of tendon adaptation and injury, many painful and debilitating Achilles tendon injuries may be avoided.
(This study was funded by the Department of Veterans Affairs.)
MECHANICAL CHARACTERIZATION OF VERTICAL SHOCK-ABSORBING
PYLONS FOR LOWER-LIMB PROSTHESES
Gard SA and Childress DS
VA Chicago Health Care System, Lakeside Division & Northwestern University Prosthetics Research Laboratory, Chicago, IL 60611
OBJECTIVES: The purpose of this investigation was to perform engineering analyses on three commercially-available vertical shock-absorbing pylons: Flex Foot's Re-Flex Vertical Shock Pylon, Seattle Limb Systems' AirStance Pylon, and Ohio Willow Wood's Stratus Impact Reducing Pylon.
RESEARCH PLAN: Vertical shock pylons are intended to replace lost physiological shock absorption and leg compliance normally provided by the anatomical ankle and knee. As a preliminary investigation prior to conducting clinical testing, we performed static and dynamic testing of the three vertical shock pylons.
METHODS: Static testing was performed by slowly loading and unloading the pylons while recording the linear displacement of the pylons with the applied load. The dynamic testing involved step-loading and step-unloading the pylons to approximately body mass while recording pylon displacement. From the static and dynamic data we are able to determine the spring stiffness, resonant frequency, damping coefficient, damping ratio, and energy efficiency for each pylon and mass combination.
FINDINGS: All of the pylons demonstrate hysteresis in their force-displacement curves from the static testing, indicative of energy loss during the loading/unloading cycle. The pylons demonstrated damped oscillatory responses to the step loading and unloading in the dynamic testing, suggesting that they may be approximately modeled as 2nd-order mechanical systems. Data reduction and processing of the dynamic data from the mechanical testing of the vertical shock pylons are ongoing.
CLINICAL RELEVANCE: Vertical shock pylons increase prosthetic limb compliance, apparently making gait smoother and more comfortable for the user. These devices may provide long-term benefits by preventing back pain and joint problems that may arise from walking with a rigid limb.
(This work was supported by the Department of Veterans Affairs, Rehabilitation Research and Development Service, and is administered through the VA Chicago Health Care System, Lakeside Division, Chicago, IL.)
CLINICAL EVALUATION OF A NEW ABOVE-ELBOW BODY POWERED
Sheredos, SJ; Cupo, ME
VA BRITAC, Tech Transfer Section, Baltimore, MD
OBJECTIVE: This clinical evaluation was conducted on precommercial models of the VA-developed AdVAntage ArmTM to determine its acceptance by consumers; assess its potential for improving functional levels of independence; validate the effectiveness of the design features; and identify any modifications that may be needed to optimize clinical use and enhance its marketability.
RESEARCH PLAN: The Department of Veterans Affairs (VA) Technology Transfer Section, with collaboration from VA Headquarters Prosthetic and Sensory Aids Service (PSAS), developed the protocol and managed this multi-center study. Study methodology encompassed procurement of evaluation models; IRB process; subject selection, fitting, training; and clinical trials.
METHODS: A total of 16 subjects participated. Subjects completed pre- (present prosthesis) and 30/90-day post-fitting (AdVAntage ArmTM) data instruments. Participating prosthetists provided information pertaining to fitting/training and maintenance & repair procedures.
FINDINGS: The majority of subjects reported its overall lightweight, separation of elbow and terminal device operation, and cable recovery system provided functional advantages over their conventional arms. They experienced a more fluid manner of use and were able to do more activities from waist level and above, especially in the outstretched and overhead positions. Ten subjects (nine unilateral and one bilateral) elected to keep the arm for continued use.
CLINICAL RELEVANCE: Upper extremity amputees desired a better mechanical arm. The AdVAntage Arm has made significant technical improvements in the area of AE body-powered prostheses and provides the amputee with a more natural moving prosthesis to perform activities of daily living.
ACKNOWLEDGMENTS: Development and Tech transfer funded by VA Rehab R&D Service. A special thanks is expressed to all veterans who most graciously gave of their time to participate in the trials and provide critical information. Special gratitude is extended to VA Headquarters PSAS for their contribution in planning and accomplishing this evaluation).
TISSUE BIOMECHANICAL & VASCULAR STUDIES FOR IMPROVED
PROSTHETIC SOCKET DESIGN
Houston, V.L.ab; Luo, G.ab; Mason, C.P.a; Arena, L.a; Beattie, A.C.ab; LaBlanc, K.P.a; Garbarini, M.A.ab; Cruise, C.M.ab
aDept. Veterans Affairs Med. Ctr. New York; bNew York Univ. Med. Ctr.
OBJECTIVE: To investigate amputee residual limb geometry, tissue biomechanical and vascular characteristics, and prosthetics loading for derivation of principles and designs yielding better fitting, more comfortable, and more functional sockets.
RESEARCH PLAN: For a "representative" sample of transtibial amputees: (a) measure residual limb geometry, tissue morphology and biomechanical characteristics; (b) derive non-linear residual limb finite element (FE) models; (c) measure socket/limb interface stresses during stance and gait; (d) compute and validate FE predicted tissue stresses and displacements for the subjects in their sockets under loading; (e) map the geometry and measure flow velocities and volumes in the subjects' principal residual limb vasculature, without and with their sockets; (f) measure changes in socket/residual limb stresses and tissue perfusion produced by socket design variations; (g) analyze results compiled, formulate socket design principles, implement the designs, and clinically measure degree of fit, comfort, and function achieved.
METHODS: Step (a) was performed for twenty-four subjects. Steps (a) -- (f) have been completed for four subjects (one with "firm" durometer, two with "average" durometer, and one with "soft" durometer tissues).
FINDINGS: Results show: (i) the residual limb FE models derived predict tissue stresses and displacements (strains) reasonably accurately; (ii) considerable differences in intrinsic stress and strain occur for "firm", "average", and "soft" durometer tissues (e.g., between young and geriatric amputees', and between men's and women's, residual limb tissues); (iv) FEA and magnetic resonance arterial flow velocity and volume measurements show socket design variations can markedly affect tissue perfusion.
CLINICAL RELEVANCE: Development of devices and methods to quantitatively characterize amputees' residual limb geometry, tissue mechanical properties, vascular states, and prosthetics loading will enable production of better fitting, more comfortable and more functional prostheses.
Sponsor: G.T.H. LAMB Group, New York, NY
NEOCARTILAGE REPAIR TISSUE IN A NEW IN VIVO MODEL
McGuire HH, MD; McDowell CL, MD; Wayne JS, PhD; Smith NL, LVT
McGuire VA Medical Center, Richmond, Va. 23249
CLINICAL RELEVANCE: Injury to articular cartilage or degenerative arthritis in the major weight bearing joints is a major problem in medicine and constitutes the main cause of joint impairment.
OBJECTIVES: Useful repair of hyaline cartilage has eluded research and clinical efforts so far. Our attempt to help resolve the problem is based upon our thesis that neocartilage will grow on a subchondral bone surface if there is a source of progenitor cells and the new tissue is shielded from joint stresses during the early stage of growth. The model described in our poster creates these 2 conditions.
RESEARCH PLAN: The first object of this study was to show that new cartilage would grow upon a subchondral bone surface after all of the normal hyaline cartilage had been removed. No previous work has produced neocartilage tissue on a large joint surface in vivo with the joint being used normally. Our model (dog patella) facilitates the above by accessing a source of progenitor cells from raw bleeding subchondral bone and the model shields the young tissue during the first 12 weeks of growth and maturation.
The second object of this study was to evaluate the quality of the new cartilage using histological, biomechanical, and chemical means.
METHODS: The patellar surface of the dog patello-femoral joint was used for the neocartilage growth production. The normal hyaline cartilage was completely removed from the infrapatellar surface to raw bleeding subchondral bone. Then, two high density polyethelene spacing devices were inserted to produce a shielded area in which neocartilage could grow and not be subjected to normal joint stress for a prescribed amount of time. Tissue grown in the model was studied using histologic, biomechanical, and biochemical methods.
FINDINGS: Upon completion of this phase of our work, we have observed that regenerated neocartilage would grow to cover the entire denuded patellar surface.
The devices we used to shield the new tissue were removed at various time points, the longest being 12 weeks after the first operation when all normal cartilage was removed. Then, 12 weeks later, after normal joint stress was reintroduced, we saw that the neocartilage was capable of surviving and remaining connected to the subchondral bone. Fortunately, the devices inserted to shield the new tissue did minimal damage to the contralateral normal joint surface (femur).
The clinical and biomechanical studies showed that the new tissue was softer and more permeable than normal, but its characteristics improved after reintroduction of stress.
EFFECT OF RESTORING POSTERIOR TIBIAL TENDON FUNCTION IN
AN ACQUIRED FLATFOOT MODEL
Niki Hisateru, *Ching RP, *Kiser PK, Sangeorzan BJ
St. Marianna University School of Medicine; *Harborview Orthopaedic Biomechanics Lab; University of Washington Department of Orthopaedics, Seattle VA Medical Center, Seattle, WA
OBJECTIVES: This study uses an acquired flatfoot model to test the hypothesis: Restoring PTT (posterior tibial tendon) function (simulating repair) will significantly affect the kinematic orientation of the hindfoot complex during heel strike, stance, and heel off.
RESEARCH PLAN: An experimental flatfoot model with PTT deficiency is used to examine the effect of simulated tendon repair.
METHODS: Eight normal, human cadaver, lower leg and foot specimens were obtained for this study and prepared for biomechanical testing. Electromagnetic 3-D motion sensors were used to track the orientation of the hindfoot complex (calcaneus, talus, navicular, and cuboid) while simulating three different loaded positions of the foot: (i) heel strike (at 5% of gait cycle), (ii) stance (at 30% of gait cycle), and heel off (at 45% of gait cycle). To create the flatfoot model, the spring ligament was divided and the specimen subjected to cyclical loading on a servohydraulic load frame. The test protocol for each specimen entailed the collection of 3-D motion data in each of three conditions: (i) initial position (all tendons unloaded), (ii) all tendons loaded except the PTT (All - PTT) and finally (iii) all tendons loaded including the PTT (All + PTT). This protocol was repeated for each of the three different foot positions. A non-parametric, Wilcoxon Signed Rank paired analysis was then used tostatistically compare the angular orientation of the four bones for the All - PTT and All + PTT conditions.
FINDINGS: Restoring function to the PTT in an acquired flatfoot model had little effect on the kinematic orientation of the hindfoot complex and suggests that restoring PTT tendon function alone may not fully correct a radiographically documented flatfoot deformity.
CLINICAL RELEVANCE: Rupture of the posterior tibial tendon (PTT) has been etiologically associated with progressive or acquired flatfoot deformity.A number of treatment modalities have been advocated including various fusions, lateral column lengthening, ligament reconstruction and tendon transfer. This study examines the effect of restoring posterior tibial tendon function (simulating repair) in an acquired flatfoot model.
(Acknowledgments: This work was supported by VA Rehabilitation Research & Development Grants A553-RA and A0806-C)
COMPARISON OF THREE METHODS OF GLUTEAL MUSCLE ATTACHMENT
TO AN ALLOGRAFT/ENDOPROSTHETIC COMPOSITE DURING TOTAL HIP
Pluhar GE, *Heiner JP, Manley PA, Bogdanske JJ, *Vanderby R, Markel MD
Sch. Vet. Med., *Dept. of Surg., Univ. of Wisconsin-Madison, Madison, WI
OBJECTIVES: Our goal was to define an optimal method of hip reconstruction following severe bone loss in the proximal femur.
RESEARCH PLAN: This study compared changes in radiographs, bone density, gait analysis, and mechanical testing among three methods of muscle attachment to allograft/endoprosthetic composites (APC) in dogs over 9 months.
METHODS: A total hip replacement was performed and the proximal femur was replaced with an APC in 24 dogs. The three methods of attachment were: 1) host tendon sutured to graft tendon (tendon), 2) host bone to graft bone with a cable grip (cable), and 3) host bone wrapped round graft bone and secured with cerclage wires (wrap). Serial radiography, dual energy x-ray absorptiometry (DXA), and weight bearing studies were performed. After euthanasia, specimens were tested in tension to failure. Analysis of variance and post-hoc t-tests were used to compare data (p<0.05).
FINDINGS: The tendon group had a higher fracture rate than the grip and wrap groups (p = 0.001). The wrap group had less graft resorption (p = 0.001) and better bone healing (p = 0.03) than the other groups. The wrap group had significantly greater bone mineral densities in the greater trochanter and calcar (p = 0.001). No significant differences in weight bearing were seen among the three groups until postoperative month 9 when the wrap group returned to preoperative weight bearing. Initially, the wrap and grip groups were stiffer and stronger than the tendon group (p = 0.001), however, the tendon group increased stiffness and strength over the nine months. Overall, the wrap method resulted in the best functional and mechanical outcome and is the method of choice for gluteal tendon attachment to an APC when sufficient bone can be safely salvaged.
CLINICAL RELEVANCE: Patients with failed tendinous attachments to reconstructions have long-term pain, high dislocation rates, and abnormal gait leading to poor limb function and diminished quality of life.
(This study was supported by the Department of Veterans Affairs (A94-791A) and NIAMS/National Institutes of Health Grant AR08419. The authors would like to thank Howmedica Inc. For the use of the Dall Miles cable grip system instrumentation and Jennifer Devitt and Ron McCabe for their technical assistance.)
RECONSTRUCTION FOLLOWING MULTILEVEL CORPECTOMY IN THE
CERVICAL SPINE: A BIOMECHANICAL STUDY
Levy, J.A., Kirkpatrick, J.S., Carillo, J., Moeini, S.R.
Birmingham VA Hospital Spine Biomechanics Laboratory; University of Alabama at Birmingham
OBJECTIVES: This study was performed to determine the biomechanical behavior following multilevel corpectomy and reconstruction with strut graft supplemented with anterior and posterior plates.
RESEARCH PLAN: The plan of this project was to determine the relative flexibility characteristics of three methods used to reconstruct the cervical spine following multilevel vertebrectomy. Following nondestructive testing, failure analysis was performed.
METHODS: Flexibility testing was performed on eleven cervical spine preparations followed by corpectomy of C4,5,6 and reconstruction with strut graft, graft with anterior plate and graft with lateral mass plates. Physiologic moments were applied dynamically and three-dimensional motion of the specimen was recorded with stereophotogrammetry. Failure testing was performed on specimens with plates in compression and load displacement curves and failure modes were analyzed.
FINDINGS: It was demonstrated that after a multilevel corpectomy, range of motion compared to control was decreased 24% after strut graft, 43% after anterior plate, and 62% after posterior plate. Similarly, flexibility coefficients noted that the posterior plate technique was the least flexible, followed by the anterior plate technique, with the graft alone being the most flexible reconstruction construct. Load to initial failure tended to be higher in posterior than in anterior plate specimens and screw pullout was the predominant failure mode.
CLINICAL RELEVANCE: The application of plates to the cervical spine as an adjunct to bone graft may improve the surgeons ability to stabilize the spine following multilevel corpectomy. Understanding the biomechanics of these devices and the potential mode of failure is important in their use.
(Implants used in this study were provided by Danek, Inc., Memphis TN)
INCREASED EFFORT ENHANCES PEDALING EXERCISE IN PERSONS
WITH POSTSTROKE HEMIPLEGIA
Kautz SA, Brown DA
Rehab R&D Ctr, VA Palo Alto HCS; Functional Restoration Dept., Stanford Univ.
OBJECTIVES: A principle of poststroke rehabilitation is that undue effort should be avoided since it leads to increased spasticity and produces widespread associated abnormal movements. However, weakness also contributes to poststroke movement dysfunction, and exercises to improve functional strength entail increased effort. Thus, we tested whether increased effort really does exacerbate poor motor performance.
RESEARCH PLAN: Quantify the effects of increased workload and cadence on motor performance during pedaling exercise in person with poststroke hemiplegia.
METHODS: Twelve healthy age-matched control subjects and fifteen subjects with poststroke hemiplegia pedaled at twelve randomly ordered workload and cadence combinations. Pedal reaction forces were measured and used to calculate work done by each leg, including net positive and negative components. EMG was collected from seven muscles.
FINDINGS: The main finding was that, in nearly all cases, net mechanical work done by the plegic leg increased as workload increased without increasing the percentage of inappropriate muscle activity.
CLINICAL RELEVANCE: This study shows that persons with hemiplegia increase force output by their plegic limb when pedaling against higher workloads without further impairing their motor performance. Furthermore, the impaired motor control does not appear to be exacerbated by increased pedaling speed. Therefore, exertional pedaling exercise can achieve gains in muscular force output without further impairing motor control.
(Supported by the RR&D service of the Dept. of Veterans Affairs and the Foundation for Physical Therapy)
DETERMINATION OF RISK FACTORS UNDERLYING LONG BONE
FRACTURE IN INDIVIDUALS WITH SPINAL CORD INJURY
Smith AE, O'Mara G, Rhee-Dechario JT, Sims GE, Perkash I, Kiratli BJ
SCI Center and Surgical Service, VA Palo Alto Health Care System; Epidemiology Program, Stanford University
OBJECTIVES: The objective of this study was to better understand the risk factors associated with fracture in the spinal cord injured (SCI) population.
RESEARCH PLAN: We have taken an epidemiological approach toward determining fracture risk and patterns of fracture occurrence in SCI individuals. We hope to identify the contributions of relevant physiologic, demographic, and behavioral factors in order to develop models for fracture prevention.
METHODS: Demographic and medical data were gathered through medical record abstraction, review of radiographic records, and mailed questionnaires on 700 individuals.
FINDINGS: The majority of post-SCI fractures were found in the lower extremities, and paraplegics were more likely to sustain these fractures than quadriplegics. High-level quadriplegics (C5 and above), however, had an elevated frequency of upper extremity fractures. Greater body weight and less spasticity were associated with higher fracture occurrence in both paraplegics and quadriplegics, and completeness of SCI was a significant risk factor in paraplegics. History of multiple fractures prior to SCI appears to be associated with greater fracture risk post SCI.
CLINICAL RELEVANCE: Long bone fractures are prevalent in the SCI population commonly attributed to reduced bone mass and strength. However, low bone mass alone does not fully explain fracture risk in this population. With an improved understanding of the non-skeletal risk factors associated with fracture, protocols can be created to assess individual risk, implement prevention programs, and improve treatment and outcome of unavoidable fractures. New clinical approaches should reduce the incidence of fracture and the impact (medical and financial) on the individual and the health care system.
(American Paraplegia Society Seed Grant #809; VA Rehab R&D Merit Review Grant #A2014-RA)
UNDERSTANDING ACTIVATION PATTERNS IN MUSCLES OF THE THUMB
TO IMPROVE HAND FUNCTION IN PATIENTS WITH SPINAL CORD
Johanson ME1, Valero-Cuevas FJ1,2, Towels JD1,2, Burgar CG1,3, Zajac FE1,2,3,and Hentz VR1,3
1Rehab R&D Ctr, VA Palo Alto HCS; 2Mech Eng & 3Functional Restoration Depts, Stanford Univ.
OBJECTIVES: To expand rehabilitation strategies and surgical intervention procedures that restore functional pinch and grasp to patients with spinal cord injuries.
RESEARCH PLAN: Computer modeling and functional studies are combined to understand how individuals control thumb and finger forces during pinch and rasp. Muscle activation patterns and force magnitudes are recorded as subjects produce maximal pinch force in different directions in selected functional postures. Validated biomechanical models are used to predict functional outcomes of treatment modalities.
METHODOLOGY: Fine-wire electrodes recorded muscle activation from the 9 muscles of the thumb. Normal subjects produced their maximal isometric forces against a force sensor mounted on a robotic arm. The positioning of the force sensor was programmed to oppose the thumb in reproducible thumb postures simulating opposition and key pinch. Muscle activation patterns were identified from electromyographic recordings normalized to the maximum amplitude recorded for each muscle in each posture.
FINDINGS: Muscles were grouped according to their level of activation. During key pinch, intrinsic muscles, flexor pollicis longus and extensor pollicis longus were most active. The same muscles were most active during opposition pinch, except flexor pollicis longus was among the least excited muscles and abductor pollicis brevis became highly active. The activation of extensor pollicis brevis was the lowest in both tasks.
CLINICAL RELEVANCE: Knowledge of muscle coordination during pinch will provide a scientific basis for assessment and improvement of functional outcomes of rehabilitation procedures to restore functional pinch in spinal cord injured individuals.
Supported by VA Rehabilitation Research and Development project B898R
ESTIMATION OF ENERGY EXPENDITURE IN SPINAL CORD INJURED
INDIVIDUALS DURING MANUAL WHEELING AND ARM CRANKING
ACTIVITIES: A PILOT STUDY
Kim KJ, Myers J, Voodi LK, Kiratli BJ
SCI Center and Cardiology Service; VA Palo Alto HCS, Palo Alto, CA
OBJECTIVES: The objective of this study was to evaluate several methods and relevant variables for estimating energy expenditure in individuals with SCI during common activities.
RESEARCH PLAN: Our plan is to develop an approach for evaluating physical activity and fitness in the SCI population.
METHODS: Heart rate and ventilatory gas exchange responses (VO2) were determined for manual wheeling and arm crank activities, and subjects' ratings of perceived exertion (RPE) were recorded for each period of activity (n=9). We concurrently monitored activity via a telemetric heart rate belt and activity sensors placed on subjects' wrist and waist (MiniLogger 2000).
FINDINGS: Mean heart rate and oxygen uptake values were consistently higher in paraplegics than quadriplegics during periods of activity while resting heart rates were nearly identical. Heart rate measurements, percentage of peak heart rate, wrist activity counts, percentage of maximal RPE values, and level of injury were included in a forward stepwise regression analysis to predict measured VO2 during submaximal arm cranking. These variables combined to explain 83% of the variance in measured VO2. We conclude that these non-invasive variables offer potential for estimating energy expenditure in persons with SCI outside of the laboratory setting.
CLINICAL RELEVANCE: The ability to assess physical activity and fitness in individuals with SCI should prove helpful in predicting cardiovascular disease risk within this sedentary population. This type of measure can also be used in the rehabilitation setting, where a portable means of activity and energy assessment could be incorporated into designing physical therapy programs and evaluating patient progress.
(Funded by Western PVA/SCI Summer Scholars Program; MiniLogger 2000 unit courtesy of the MiniMitter Co. Inc., Sunriver, OR)
ROBOT-AIDED THERAPY FOR RECOVERY OF UPPER LIMB MOTOR
FUNCTION FOLLOWING STROKE
Lum PS, Burgar CG, Shor P, Van der Loos HFM
Rehab R&D Ctr, VA Palo Alto HCS, Dept. of Functional Restoration, Stanford University
OBJECTIVES: Evaluate the efficacy of robot-aided exercise for recovery of upper limb motor function in chronic stroke subjects.
RESEARCH PLAN: A clinical trial is underway to determine the therapeutic efficacy of a robot-aided exercise program relative to a conventional Neurodevelopmental (NDT) therapy program.
METHODS: Chronic stroke subjects are randomly assigned to a test group or control group. Both groups receive 24 one-hour sessions over a two month period. The test group practices reaching movements (tabletop and vertical) and planar tracing of circles and polygons. The movements are performed in three modes: 1) passive -- the limb is moved by the robot, 2) active -- the robot provides a viscous resistance in the direction of movement and spring-like loads in all other directions, 3) bilateral -- the subject attempts bilateral mirror-image movements while the paretic limb is assisted by the robot, which is slaved to movement of the contralateral limb. Forces from the paretic limb are measured throughout. The control group receives conventional NDT therapy. A blinded therapist evaluates all subjects pre and post treatment with standard clinical scales.
FINDINGS: All subjects tested so far have shown improved Fugl-Meyer scores following treatment. Kinetic and kinematic data from the exercise sessions are presented.
CLINICAL RELEVANCE: Integration of robot-aided therapy into clinical exercise programs will allow repetitive, time-intensive exercises to be performed without one-on-one attention from a therapist. Detailed performance data recorded during the sessions will allow insight into the mechanisms of motor recovery following stroke.
(Funded by VA RR&D Merit Review project B96-1052R)
IMPROVING INDEX-FINGERTIP FORCES IN THE QUADRIPLEGIC HAND
THROUGH COMPUTER MODELING AND CADAVERIC EXPERIMENTS
Valero-Cuevas FJ1,2, Hentz VR1,3, Towles JD1,2 and Zajac FE1,2,3
1Rehab R&D Ctr, VA Palo Alto HCS; 2Mech. Eng. & 3Funct. Restoration Depts., Stanford Univ.
OBJECTIVES: To improve functional grasping in quadriplegics. Uncertainty in the functional outcome of surgical procedures hinders our ability to improve the treatment of quadriplegics.
RESEARCH PLAN: Biomechanical computer models of the hand serve as test beds to find the anatomical parameters most affecting finger forces, and to evaluate and improve functional outcomes. The predicted functional gain of modified or novel surgical procedures is rigorously quantified in cadaver hands.
METHODS: In ulnar palsy (UP, the loss of function of the intrinsic muscles of the hand), claw hand deformity is often prevented by the "Zancolli Lasso" (ZL) surgical transfer of flexor superficialis tendon. A generic 7-muscle 3-D index finger model predicts that the ZL reduces palmar force magnitude, and that modifying the ZL by Inc reasing the moment arm of flexor profundus at the proximal interphalangeal joint would enhance palmar force magnitude. To test these predictions, the mechanical action of each of the 7 muscles of the index finger was characterized in cadaver fingers (n = 4) by pulling on each tendon with a known load and measuring fingertip force. We applied optimization algorithms to these data to predict the combination of muscle forces that produces the maximal magnitude of palmar force that is biomechanically possible in 4 conditions: normal finger, simulated UP, UP with ZL, and UP with modified ZL. We implemented these predictions by pulling on tendons with the prescribed force combinations for each case.
FINDINGS: UP reduces palmar force to about a quarter of normal. Performing the ZL reduces it further, but modifiying the ZL counteracts the reduction in palmar force production.
CLINICAL RELEVANCE: Successful functional outcomes of surgical restoration of grasp contribute to the important rehabilitation goal of improving the independence and quality of life of spinal cord injured persons.
Supported by VA Rehab R&D project B898R.
INTRAOPERATIVE MEASUREMENTS OF MUSCLE DURING
Lieber, RL and Fridén, J
Depts. of Orthopaedics, UCSD and VAMC San Diego and Göteborg University
OBJECTIVES: The purpose of this study was to develop an intraoperative sarcomere length measurement technique to optimize attachment of muscle during reconstructive surgery.
RESEARCH PLAN: Sarcomere lengths were measured in the prime movers of the wrist using laser diffraction. Cadaveric biomechanical and architectural measurements were also used to develop models that could validate and understand intraoperative measurements.
METHODS: The device used was a low powered Helium-Neon laser beam with a prism that projected the laser through a small muscle fiber bundle. The device was calibrated using diffraction gratings. Sarcomere lengths were measured during passive joint rotation.
FINDINGS: Human ECRB measurements during wrist joint rotation revealed that this muscle operated on the descending limb of its length tension curve and generated maximum tension with the wrist fully extended. The synergistic extensor carpi radialis longus (ECRL) also operated on its descending limb but over a much narrower sarcomere length range due to differences in fiber length and moment arm. Sarcomere lengths measured from wrist flexors were shorter compared to the extensors. The net result was a nearly constant ratio of flexor to extensor torque over the wrist range of motion and a wrist that is most stable in full extension.
CLINICAL RELEVANCE: This method can now be used to study and develop methods for reattachment of skeletal muscles in surgery to provide optimal functional outcome.
WHEELCHAIR EXERCISE AND DIGITAL ECHOCARDIOGRAPHY
FOR THE DETECTION OF HEART DISEASE
Langbein WE, Edwards LC, Louie EK, Maki KC, Hwang M, Orebaugh C
Rehab R&D Section, Research Service, Hines VA Hospital, Hines, IL; Dept of Medicine, Loyola Univ. Medical Center, Maywood, IL
OBJECTIVE: Evaluate the clinical usefulness of a novel exercise testing technique that combines wheelchair ergometry graded exercise with digital two-dimensional echocardiography (WCexwithECHO) for the diagnosis of coronary artery disease (CAD).
RESEARCH PLAN: Develop an effective method of exercise testing to serve individuals who cannot adequately undergo traditional treadmill or leg-cycle ergometer exercise testing due to a variety of lower limb disabilities. It was hypothesized that wheelchair-graded exercise testing would produce ample stress on the cardiovascular system to be a sufficiently sensitive and specific technique for diagnosing significant CAD in persons with lower limb disabilities. Moreover, when echocardiography is used in combination with wheelchair-graded exercise testing the sensitivity and specificity of wheelchair-graded exercise test will be improved.
METHODS: The patient population included 202 consecutive patients. Twenty patients (10%) had inadequate acoustic windows for assessment of regional wall motion abnormalities. Pre and post exercise echocardiographic assessments were performed in the remaining 182 patients. Based on the judgement of the referring physician coronary angiography was performed in 55 patients within six months of the WCexwithECHO test.
FINDINGS: The final study group consisted of 36 patients who had no prior revascularization procedure. The sensitivity, specificity, predictive value of a positive, and of a negative WCexwithECHO test in this group was 90, 85, 90, and 85 percent, respectively.
CLINICAL RELEVANCE: For persons with lower limb disabilities, WCexwithECHO testing is a clinically useful diagnostic technique for assessing cardiovascular disease and fitness in a noninvasive cost-effective manner.
(Rehab R&D Service, Dept. of Veterans Affairs, Washington, DC)
TISSUE RECONSTRUCTION AND GENE THERAPY IN
Sayers ST, Chauhan NB, Brigell M and Khan T
Neuro-Regeneration Laboratory, Research Service, Hines VAMC, Hines, IL; Dept. of Neurology and Cell Biology, Neurobiology & Anatomy, Loyola University Medical Center, Maywood, IL
OBJECTIVES: The objective of this study was to evaluate the applicability of genetically engineered Schwann cells-coated carbon filament implant as a bridging material after spinal cord injury.
RESEARCH PLAN: Carbon filaments cultured with Schwann cells which are genetically engineered to secrete brain derived neurotrophic factor (BDNF) or Neurotrophin-3 (NT-3) were implanted in the lesion site of severely contused rat spinal cord. At fourteen weeks post-trauma all animals were evaluated electrophysiologically, behaviorally, and histologically.
METHODS: The injured animals were divided into four groups: contusion only, implanted with BDNF-secreting NF-1T cells, NT-3-secreting NF-1T cells, or NF-1T cells which were not engineered to secrete neurotrophic factors. Somatosensory evoked potentials (SSEPs) and Motor evoked potentials (MEP) were done before injury, and then monthly throughout the experimental period. For functional testing open field, placing and withdrawal responses were performed. Animals were perfused for immunocytochemistry.
FINDINGS: Open field behavioral performance was significantly better in the animals implanted with non-secreting NF-1T cell (p<0.006) and animals with NT-3 secreting cells (p<0.05) when compared to injury alone. Placing responses also improved significantly (p<0.04) in the animals implanted with NT-3 secreting cell. All treated groups showed moderate recovery of SSEPs and MEPs. Histological results showed all implants were fully &ly;ncorporated within the spinal cord parenchyma, and that Schwann cells migrated from the lesion site into the host spinal cord. Considerably more neuronal processes were observed growing on the carbon filaments in the group with the NT-3-secreting NF-1T cells.
CLINICAL RELEVANCE: Continuous supply of Neurotrophins through genetic manuplation may provide a basis for treatment of SCI.
(Supported by the Department of Veterans Affairs, Rehabilitation Research and Development Service, TK B742-RA)
HOME BLADDER PRESSURE MEASUREMENT IN SPINAL CORD INJURY
AND MULTIPLE SCLEROSIS PATIENTS
Damaser MS, Walter JS, Wheeler JS, and Chintam R.
Res. & Ed. and SCI Services, Hines VAMC, Hines, IL; Dept. of Urology, Loyola Univ. Med. Center, Maywood, IL
OBJECTIVES: Spinal cord injury and multiple sclerosis patients can develop renal dysfunction due to high bladder pressures. The standard method of monitoring bladder pressures is urodynamics, an expensive clinical test. The objectives of this study were to test a method for measuring bladder pressures at home for accuracy, reliability, and ease of use.
RESEARCH PLAN: Subjects underwent urodynamics and once a week recorded bladder pressures at home.
METHODS: During urodynamics, the bladder was filled with water while rectal and bladder pressures were measured. Detrusor pressure is bladder minus rectal pressure. Bladder pressures at home were obtained with the bladder full and nearly empty. Bladder volume was also recorded. Detrusor pressure was estimated as full pressure minus nearly empty pressure.
FINDINGS: Eight subjects were enrolled: 6 underwent urodynamics and 5 made 27 ± 21 home recordings over 3.5 ± 2.9 months. Home bladder pressures did not vary significantly with volume or time, suggesting home bladder pressures are reliable. Home full and nearly empty pressures were significantly lower than urodynamic bladder and rectal pressures, respectively. Home detrusor pressure was not significantly different from urodynamic detrusor pressure. Therefore, home bladder pressures are lower than in urodynamics, but detrusor pressure can be easily and accurately estimated.
CLINICAL RELEVANCE: Home bladder pressure monitoring could prevent renal deterioration by early detection and treatment of high bladder pressures. Home monitoring would improve quality of life for the patient and provide a cost savings to VA.
(This research supported by VA RR&D Service and Hines VAMC)
DEVELOPMENT OF A STROKE-SPECIFIC OUTCOMES SCALE
Duncan PW, Wallace D, Lai S, Studenski S
Kansas City Department of Veterans Affairs Medical Center, Center on Aging, University of Kansas Medical Center, Kansas City, KS
OBJECTIVES: To develop a stroke specific outcome measure, the Stroke Impact Scale (SIS) with strong clinical relevance, based on three levels of measurement (impairments -- I, disabilities -- D, handicaps -- H) and generated from the patient's perspective.
RESEARCH PLAN: Focus groups and cross-sectional pilot testing
METHODS: Thirty individuals with mean age = 66 years with mild or moderate stroke participated in focus groups to identify stroke related I, D, and H. Twenty-three stroke caregivers and 9 stroke experts participated in similar focus groups. Qualitative analysis of the transcripts generated a list of potential items to represent domains within the levels of measurement. Based on the domains defined by the focus groups, we are developing a self-report measure of stroke-related impairments, disabilities, and handicaps.
FINDINGS: The I domains were motor, sensory, memory and thinking, affect, emotion, and language. D included self-care, IADLs, communications, basic mobility, community mobility and upper extremity function. The H domain included work or volunteer activities, social, leisure and spiritual activities, family role functions, intimacy, control of life and ability to help others. The first draft of the instrument has been pilot tested in 60 stroke patients (mean age 71). Cronbach's alpha for the specific domains range from .60 to .95.
CLINICAL RELEVANCE: Patients with mild and moderate stroke deficits have significant residual impairments, disabilities, and handicaps that are not captured by current stroke outcome measures. A stroke specific outcome measure is needed to capture the full impact of stroke.
(Funding: Department of Veteran Affairs Rehabilitation Research and Development Service and Glaxo.)
PILOT STUDY: DOES INTENSIVE PHYSICAL THERAPY IMPROVE
Duncan P, Richards L, Wallace D, Stoker J, Ogle A, Studenski S
Center on Aging, University of Kansas Medical Center, Kansas City, KS and Kansas City Department of Veterans Affairs Medical Center
OBJECTIVES: To develop a therapy program based on principles of exercise physiology and motor learning and to assess the effect size of interventions.
RESEARCH PLAN: Pilot randomized clinical trials
METHODS: Twenty minimally and moderately impaired stroke patients (Mean Orpington Score 2.6, mean age 67, 11 RDVA, 8 LCVA, and 1 Brainstem, 11 M and 9 F, 14 W and 6 B) who had completed inpatient rehabilitation and who were 30-90 days post stroke were randomized to usual care or to a therapist supervised 8 week, 3 times per week, home based exercise program of progressive strength, balance, endurance, and bimanual exercises.
FINDINGS: The intervention group tended to improve more than the control group in motor function (Fugl-Meyer UE median change score 10 vs. 3.5, Fugl-Meyer LE 5 vs. -.5), gait velocity (median change .27m/sec vs. .11m/sec), 6 minute walk (164 ft vs. 107.5 ft), and MOS physical function (22.5 vs. 5). There were no trends in differences in change scores for Jebsen hand scores or in IADLs. The results of this pilot study suggest improvements in UE and LE motor function and LE physical function with the intervention. The effects are of a magnitude that we consider to be clinically meaningful. It is less clear if the UE dexterity is enhanced.
CLINICAL RELEVANCE: These results will guide us as we modify our therapy program and prepare for a larger randomized trial of the intervention.
EFFECTS OF HAND DOMINANCE ON MOTOR UNIT FIRING
Adam, A., De Luca, C.J. and Erim, Z.
Research Service Boston VA Medical Center, and NeuroMuscular Research Center, Boston University
PURPOSE: Daily preferential use of a muscle has been associated with higher fatigue resistance and possibly increased percentage of slow-twitch fibers in muscles of the dominant hand. The present study was aimed at revealing any differences in the control properties of contra lateral muscle pairs in individuals who show a clear preference for one hand and hence exercise one side more than the other.
RESEARCH PLAN: Motor unit firing patterns were studied in both hands of three right-handed and four left-handed male subjects.
METHODOLOGY: The first dorsal interosseous muscle was studied during voluntary abduction of the index finger at a force level of 30% of maximal voluntary contraction. Electromyographic signals detected via the quadrifillar needle electrode and the surface bipolar electrodes were recorded along with the force generated by the muscle. The Precision Decomposition Technique was used to identify firing times of motor units.
FINDINGS: The recruitment thresholds and the firing rates of motor units in the dominant hand were lower when compared to motor units in the non-dominant hand. Contra lateral differences were less pronounced in the left-handed subjects, possibly due to the certain level of ambidexterity among this group. A greater delay between common fluctuations of mean firing rates and the force were observed in the dominant hand. No difference was seen in the maximal voluntary contraction strength between the dominant and non-dominant sides. The measured lower firing rates, lower recruitment thresholds, and greater firing rate-to-force lead times in the dominant hand are consistent with the notion of an increased percentage of slow-twitch fibers in the preferentially used muscle. Since slow-twitch fibers exhibit twitch fusion at lower contractile rates, motor units in the dominant muscle are able to generate force at lower firing rates than their counterparts in the non-dominant hand.
CLINICAL RELEVANCE: Understanding the effects of exercise on motor control is a precursor to the design of well-tailored training regimens for the rehabilitation of patients with various motor deficiencies.
(Supported by the Liberty Mutual Insurance Company and the Rehabilitation Research & Development Service of the Dept. of VA.)
TREADMILL AEROBIC EXERCISE IMPROVES THE "PHYSIOLOGICAL
FITNESS RESERVE" IN CHRONIC HEMIPARETIC STROKE PATIENTS
R.F. Macko, G.V. Smith, K.H. Silver, C.L. Dobrovolny, A.P. Goldberg
Baltimore VA Geriatrics Research, Education and Clinical Center, Departments of Neurology, Rehabilitation and Division of Gerontology, and The University of Maryland Department of Physical Therapy and Claude D. Pepper Center, Baltimore, MD
OBJECTIVE: Advancing age and physical deconditioning compound neurologic disability, compromising patients' tolerance for the high energy costs of hemiparetic gait. We investigated the hypothesis treadmill aerobic training will improve peak fitness while lowering the energy cost of hemiparetic gait in chronic stroke patients.
RESEARCH PLAN: In a non-controlled study, 21 patients age 67 ± 7 yrs (mean ± SD) with mild-moderate hemiparetic gait abnormalities following remote stroke (>6 months) entered a program of low-moderate intensity treadmill aerobic exercise. Repeated measures of submaximal and peak effort treadmill exercise testing were performed with open circuit spirometry.
METHODS: Peak fitness levels (VO2 peak) were determined using a constant velocity graded treadmill exercise test. Economy of gait was defined as the mean VO2 determined from 3 consecutive minutes constant load submaximal effort treadmill walking (e.g., 1 MPH) at steady state VO2 kinetics.
FINDINGS: Three months treadmill training increased peak exercise VO2 (16 ± 3.5 vs 17.2 ± 4.4, ml/kg/min, p<0.03) while reducing VO2 required to perform the same submaximal effort treadmill walking task (9.2 ± 1.7 vs 8.6 ± 1.35 ml/kg/min, N=19, p=0.002). Patients required 18% less of their peak exercise capacity (fractional utilization: VO2 submax÷peak VO2) to perform the same submaximal effort walking task following 3 months training (59 ± 15.2 vs 48.3 ± 15.6%, p<.003).
CLINICAL RELEVANCE: Treadmill training increases peak fitness while reducing VO2 demands of submaximal effort hemiparetic gait, improving fractional utilization in 15/19 patients tested. Findings suggest task-oriented aerobic exercise may enable chronic hemiparetic stroke patients to perform activities of daily living at a lower percentage of their maximal cardiovascular fitness.
(Funding Agencies/Sources: This study was funded in part by a VA Career Development Award to Dr. Macko, The Baltimore VA Geriatrics Research, Education and Clinical Center, and a National Institute of Aging - Claude D. Pepper Center Pilot Study at The University of Maryland.)
EFFECTS OF VITAMIN E AND SELENIUM ON SPERM MOTILITY
Linsenmeyer, T. MD; Ottenweller, J. Ph. D.; Anesetti, R
Kessler Institute for Rehabilitation, W. Orange, NJ; Dept. of Veterans Affairs Medical Center, East Orange, NJ; UMDNJ-New Jersey School of Medicine School, Newark, NJ
OBJECTIVE: To determine if Vitamin E/Selenium will help maintain sperm motility following SCI.
RESEARCH PLAN: Obtaining ejaculates in men with SCI can be difficult. Therefore, this study was conducted in a well-established SCI infertility animal model.
METHODS: Sprague Dawley rats underwent T9 transection or T9 sham surgery. SCI and SCI sham controls were randomized into 4 groups, and were given 1 ml of treatment by gavage daily for 10 weeks. Group I -- untreated; Group 2 -- base solution of corn oil; Group 3 -- 3-4IU of Vitamin E in corn oil; Group 4 -- 3-4 IU of vitamin E and 0.4 µg of selenium in corn oil. After 10 weeks, epididymis were harvested and punctured 6 times, placed in a Petri dish with BSA solution, and incubated at 37 °C for 3 minutes. 10 µl underwent microscopic viewing. 8 random fields were videotaped. Analysis was done to determine the number of sperm and motility. Analysis of variance was used to determine statistically significant change in counts and motility between the groups.
FINDINGS: The mean total sperm count for controls (N=70) was 80.41 ±7.85 million with motility of 65.67 ± 1.77%. SCI animals - untreated and base solution only (N= 38) had a total sperm count of 0.93 ± 0.54 million with a 3.09 ±1.67% motility. Vitamin E/Selenium treated SCI (N= 11) had a total sperm count of 2.29 ± 1.37 million and 14.82 ± 5.72% motility. Only the Vitamin E/Selenium group had a statistical increase in sperm motility (t=1.87 with 27 df and p<0.05), suggesting selenium is important.
CLINICAL RELEVANCE: Since sperm motility is the major problem in men following SCI, and animal studies showed improved motility with Vitamin E/Selenium, this study justifies clinical studies.
Supported by a grant from The Department of Veterans Affairs, Rehabilitation Research and Development Service.
SOFT TISSUE BODY COMPOSITION DIFFERENCES IN MONOZYGOTIC
TWINS DISCORDANT FOR IMMOBILIZATION
1Spungen AM, 2Wang J, 2Pierson Jr. RN, and 1Bauman WA
1Spinal Cord Damage Research Center, Depts. of Med. and Rehab Med., Mt. Sinai Med. Ctr, NY, NY and VAMC, Bronx, NY. 2Body Composition Unit, St. Lukes/Roosevelt Hospital Center, NY, NY.
OBJECTIVES: The objective of this study was to determine the extent of lean tissue loss and percent body fat gain due to immobilization from spinal cord injury (SCI).
RESEARCH PLAN: An identical twin model, one with traumatic SCI, was used to investigate the effect of immobilization on body composition independent of genetic variability and the normal aging process.
METHODS: Eight male pairs of monozygotic twins were studied. Age was 40±10, range, 25-58 years. Duration of injury of the SCI twins was 16±9, range, 3-26 years. Total and regional soft tissue compartments of lean body mass (LBM in kg), fat mass (FM in kg) and percent fat (%F) were determined by dual energy x-ray absorptiometry. Paired t-tests, linear regression analyses and intrapair difference scores were determined for the variables studied. The results are reported as mean ± SD.
FINDINGS: TB LBM was significantly decreased by 12.6±7.9 kg (p<0.005) in the SCI twins compared with their able-bodied co-twins. Trunk and leg LBM were significantly lower in the SCI twins (-3.0±3.3 kg, p<0.05 and -10.1±4.0 kg, p<0.0005, respectively). The SCI twins had significantly higher %F in the legs (17.5±11.7%, p<0.005). TB and leg LBM loss in the SCI twins were significantly related to duration of injury, independent of age (r=0.87, p<0.005). TB LBM was lost (predominantly from the legs and trunk) at a rate of 3.91±0.18 kg per each 5 year period of injury.
CLINICAL RELEVANCE: Lean tissue loss in the SCI twins continues throughout chronic immobilization, an accelerated form of sarcopenia from disuse atrophy.
(This work was funded, in part, by a grant from the Spinal Cord Research Foundation, Washington, D.C. Additional sources of support were from the Mount Sinai Medical Center, New York, NY and VA Medical Center, Bronx, NY.)P53
CLINICAL EVALUATION OF AN IMPLANTED NEUROPROSTHESIS FOR
Peckham PH, Keith MW, Kilgore KL
Department of Veterans Affairs, MetroHealth Medical Center; Case Western Reserve University; Cleveland, OH
OBJECTIVES: The objective of this study was to evaluate the safety, effectiveness, and clinical utility of a hand neuroprosthesis to restore grasp/release function in individuals with C5-C6 level tetraplegia.
RESEARCH PLAN: This study is a prospective multi-center clinical trial which used the implemented hand of each patient as his/her own control. This is possible because the neuroprosthesis can be turned on and off.
METHODS: A multi-center clinical trial was performed at several spinal cord injury centers, including VA hospitals in Baltimore, Cleveland, Palo Alto and West Roxbury. Candidates for the neuroprosthesis were C5 and C6 level tetraplegic individuals with at least one year post-injury. All patients were implemented with a neuroprosthetic system consisting of an implanted stimulator, an externally worn sensor, and an external control unit. The impact of the neuroprosthesis was evaluated by measuring pinch strength, stimulated range of motion, grasp-release function, and performance in activities of daily living. In addition, a survey of user satisfaction was used to assess general satisfaction, device impact, occupation, and external assistance required.
FINDINGS: The neuroprosthesis has now been implemented in over 85 individuals. There was a statistically significant increase in grasp and pinch strength, in the stimulated range of motion, and in the performance in grasp-release tests. Performance in activities of daily living demonstrated improved independence in many activities, including eating, grooming and office tasks. Users reported a high level of satisfaction with the device and reported that it has a positive impact on their lives and activities. We conclude that the neuroprosthesis is safe, efficacious, and provides clinical utility.
CLINICAL RELEVANCE: This device has now received pre-market approval from the US FDA and is sold by NeuroControl Corporation as the "Freehand" System.
ASSESSMENT OF HAND FUNCTION IN TETRAPLEGIC INDIVIDUALS
USING A NEUROPROSTHESIS FOR ACTIVITIES OF DAILY LIVING
Wuolle KS, VanDoren CL, Bryden AM, Peckham PH and Keith MW
Cleveland VAMC, MetroHealth Medical Ctr., Case Western Reserve Univ.
OBJECTIVE: The objective of this study was to measure hand performance in activities of daily living (ADL) for tetraplegic individuals using a hand neuroprosthesis.
RESEARCH PLAN: Hand performance in activities of daily living (ADL) with and without a hand neuroprosthesis was tested in twenty-five individuals with C5 and C6 motor level spinal cord injury at five institutions.
METHODS: Each individual was scored for assistance needed to complete the task, the quality of the activity outcome and preference for performing the task with or without the neuroprosthesis in the laboratory and at home. The assistance score, quality rating and laboratory preference were then synthesized into a composite performance score for each activity.
FINDINGS: Use of the neuroprosthesis reduced the need for assistance in a median of 55% of the activities performed by each individual. Use of the neuroprosthesis decreased the amount of physical assistance and adaptive equipment in 80% of those activities across participants in which it was required. The participants preferred to use the neuroprosthesis in 77% (median) of the activities they performed in the laboratory, yielding improved performance scores in 78% (median) of the activities. A subset of the participants who were studied preferred to use the neuroprosthesis for 59% (median) of the activities when performed at home.
CLINICAL RELEVANCE: The results of this investigation show that the neuroprosthesis provides significant improvements in the ability of C5 and C6 individuals to perform ADL, both in the laboratory and at home, reducing their functional limitations.
OBJECTIVES: The objective of this project was to increase the range and type of upper extremity functions that patients with C5 and C6 spinal cord injury could perform by providing them with elbow and forearm function in addition to hand grasp/release.
RESEARCH PLAN: We augmented the VA/CWRU hand grasp neuroprostheses of 8 individuals by stimulating the paralyzed triceps and pronator quadratus (PQ) to restore elbow and forearm control. Neuroprostheses were used regularly outside the lab.
METHODS: Triceps and PQ were stimulated at constant levels via implanted epimysial or intramuscular electrodes. Individuals achieved graded control of each degree of freedom in a natural way by voluntarily opposing the stimulated antagonist (Voluntary Antagonist Control). For example, stimulating the triceps was sufficiently strong to extend the arm against gravity. The arm could be flexed voluntarily to oppose extension. Pronosupination was controlled analogously.
FINDINGS: Triceps stimulation increased the arm's controllable workspace; individuals could grasp and move objects over a wider range of locations and orientations. Movement quality also improved, since they required less time to acquire objects. They performed functional tasks such as acquiring an object from a shelf, or making a call from a wall phone with greater independence and ease. Stimulating PQ increased the pronation strength and provided stable and controllable pronosupination movements.
CLINICAL RELEVANCE: The simple addition of one or two stimulation channels greatly improved the ability of these individuals to use their arms to each and manipulate objects, thus increasing their independence in unstructured environments.
(Funded by VA Rehab. R&D Program)
CLINICAL EFFECTS OF A BLADDER AND BOWEL STIMULATOR IN
SPINAL CORD INJURY
Creasey GH, Kachourbos MJ , Takaoka Y, Bodner DR
VA Medical Center, Wade Park, Cleveland, OH 44106; MetroHealth Medical Center, Cleveland, OH 44109
OBJECTIVES: To evaluate the effects of an implanted electrical stimulator on bladder and bowel function following spinal cord injury.
RESEARCH PLAN: Evaluation of bladder and bowel function before and after surgical implantation of an electrical stimulator in 20 subjects. Each subject served as his or her own control.
METHODS: Human subjects with suprasacral spinal cord injury and bladder or bowel complications were evaluated clinically, urodynamically and radiographically. They then underwent surgical implantation of an electrical stimulator attached to electrodes in contact with the sacral nerves innervating the bladder and lower bowel. The majority of subjects also underwent posterior sacral rhizotomy. The stimulator was controlled by a portable unit outside the body and operated by the subject 4-6 times per day for producing micturition and several times per week to assist in bowel evacuation. Subjects were re-evaluated at 3, 6 and 12 months and then annually. Life care plan analysis was used to estimate health care costs.
FINDINGS: All subjects have been able to produce micturition on demand with residual volumes under 50ml., and report decreased symptomatic urinary tract infections. Continence has improved, and the use of catheters, urine collection appliances and medications has decreased. Users spend less time in bladder and bowel management, and some are able to defecate with the device. At follow-up six months to six years after implantation, 19 of 20 subjects continue to use the device on a daily basis.
CLINICAL RELEVANCE: The use of an implanted electrical stimulator can improve function of the neurogenic bladder and bowel, reduce complications, reduce the use of medications and appliances, and reduce health care costs for persons with spinal cord injury.
Funding agencies/sources, and other acknowledgments: VA Rehabilitation R&D Service, VA National Center for Medical Rehabilitation Research, NIH Paralyzed Veterans of America.
SURGICALLY IMPLANTED FNS SYSTEMS FOR STANDING, TRANSFERS
AND UPRIGHT MOBILITY AFTER SPINAL CORD INJURY
Davis JA1, Triolo RJ2,3, Ulir JP1, Bhadra N1, Sharma M3, Marsolais EB3
1MetroHealth Medical Center; 2Case Western Reserve University; 3Cleveland VA Medical Center, Cleveland OH
OBJECTIVES: This study was designed to develop and verify implementation protocols and surgical approaches for implanting multi-channel lower extremity FNS systems in individuals with SCI.
RESEARCH PLAN: Standard orthopaedic exposures were adapted, based on cadaveric studies, to access the vastus lateralis (VL), gluteus maximus (GM), posterior portion of adductor magnus (PA). These approaches were verified by successfully implanting complete FNS systems in four volunteers. Systems consisted of an 8-channel CWRU/VA implantable receiver stimulator, six epimysial (VL, GM, and PA bilaterally) and two intramuscular (IM) electrodes for the erector spinae.
METHODS: While prone, IM electrodes were inserted through small incisions into the L1/L2 foramen. Epimysial electrodes were sutured to the PA fascia through longitudinal incisions on each posteromedial thigh. The GM were implanted through incisions centered between the greater trochanter and the midpoint of a line connecting the coccyx to the posterior iliac spine. Blunt dissection through the muscle fibers enabled suturing the electrodes to fascia near the inferior gluteal nerve. Leads were passed to the flank and, after repositioning supine, routed to abdominal connector sites. While supine, the VL were instrumented through an incision on each anterolateral thigh distal to the greater trochanter. Implantation was followed by two weeks of bedrest and four additional weeks of restricted activity.
FINDINGS: The implantation procedures were well tolerated and all four subjects now use the systems to stand, transfer or exercise at home.
CLINICAL RELEVANCE: This work indicates that a lower extremity neuroprosthesis based on available implantable technology can be successfully deployed in individuals with SCI.
ACKNOWLEDGMENTS: VA Center of Excellence in FES, Office of Orphan Product Development-Food and Drug Administration, VA Merit Review B681
RESTORATION OF SHOULDER FUNCTION IN TETRAPLEGIA
Kirsch, R.F., Yu, D., Acosta, A.M., Keith, M.W., Kilgore, K.L. Bryden, A., Hart, R., Parikh, P.P.
Cleveland VA FES Center of Excellence, Case Western Reserve University, MetroHealth Medical Center, Cleveland, OH
OBJECTIVES: To restore shoulder function in individuals with C1-C6 tetraplegia.
RESEARCH PLAN: Demonstrate the feasibility of restoring shoulder and elbow function to individuals with C1-C6 tetraplegia using functional neuromuscular stimulation (FNS). Determine which muscles to stimulate, measure the forces and moments produced, and evaluate the functionality of these stimulated contractions.
METHODS: In C5-C6 tetraplegia, percutaneous stimulating electrodes are implanted into the paralyzed pectoralis major and latissimus dorsi muscles to restore adduction and horizontal flexion moments. In higher level injuries (C1-C4), electrodes are implanted into the biceps, triceps, pectoralis major, latissimus dorsi, posterior deltoid, anterior deltoid, and infraspinatus muscles. In both groups, maximum stimulated shoulder and elbow moments are measured.
RESULTS: The C5-C6 shoulder-elbow neuroprosthesis has been found to provide approximately 5 Nm of shoulder horizontal flexion and adduction moments in two individuals with C5 tetraplegia. The C1-C4 shoulder-elbow neuroprosthesis, used in combination with a balanced forearm orthosis, has produced elbow flexion and shoulder elevation strength adequate to draw the hand to the mouth and face in one individual with C3 tetraplegia.
CLINICAL RELEVANCE: The C5-C6 shoulder neuroprosthesis will increase the workspace of the hand, increasing the functional impact of restoring hand unction via FNS, and may also assist in weight shifts and transfers. The 1-C4 shoulder-elbow neuroprosthesis will provide the simple yet essential movements needed for feeding and scratching the face in these highly impaired individuals, increasing their very limited independence.
(Support for this project provided by the Cleveland VA FES Center of Excellence, NIH R29 HD3265 to RFK, Spinal Cord Research Foundation #1826 to RFK, and by NIH K12 HD01097 to DY)
ELECTRICAL ACTIVATION OF THE DIAPHRAGM FOR VENTILATORY
Aiyar H and Mortimer JT
Rehab R&D, VA Cleveland; Dept. of Biom. Eng., Case Western Reserve Univ., Cleveland, OH
OBJECTIVE: The objective of this project is to develop a diaphragm pacing system for clinical applications.
RESEARCH PLAN: We propose to: 1) develop endoscopic methods to place stimulating electrodes in the diaphragm muscle using an abdominal approach to access the targeted region of the muscle, and 2) evaluate the suitability of the methods and devices for clinical applications.
METHODS: Intramuscular electrodes have been implanted in canine diaphragms for periods up to 11 months. To facilitate transferring this technology to humans, the diaphragm muscle in cadavers have been examined.
FINDINGS: A mapping paradigm consisting of a vacuum electrode and custom software to locate the ideal placement site to within 2.0 cm has been developed and tested in the canine model. Our findings from the cadavers indicate that the motor points of the human diaphragm cannot be predicted precisely based on anatomical landmarks alone, thus necessitating the use of the mapping procedure.
An implant instrument has been developed to safely and accurately place intramuscular electrodes in the diaphragm muscle at locations determined by the mapping procedure. The results from both acute and chronic studies in canines indicate that our method of diaphragm pacing is capable of supporting full-time ventilation.
CLINICAL RELEVANCE: Our approach to pacing the diaphragm is less risky to the patient and less costly to the health care delivery system than conventional treatment methods. The combined effects are expected to enhance the quality of life and independence of the ventilator dependent population and will make electrical activation of phrenic nerves available to a broad range of patients.
(This project is supported by the Department of Veterans Affairs.)
IMPROVED VOLUNTARY GAIT IN CHRONIC STROKE PATIENTS AFTER
FUNCTIONAL NEUROMUSCULAR STIMULATION
Janis J. Daly, Ph.D., R.L. Ruff and E.B. Marsolais, PhD
VA Medical Center, Cleveland, OH 44106
OBJECTIVE: To determine if functional neuromuscular stimulation (FNS) using intramuscular electrodes (FNS-IM) improves voluntary gait in chronic stroke patients.
BACKGROUND: Conventional rehabilitation is often unable to restore independent gait after a stroke. FNS-IM is a rehabilitation technique that directly stimulates muscles under computer control to produce functional activity. FNS-IM is used for rehabilitation of spinal cord injured patients, but FNS-IM has not been extensively used with stroke patients.
METHODS: We studied five gait-impaired patients more than one year after a stroke, which is beyond the expected time for spontaneous return of function. Patients received conventional rehabilitation for at least three months until their gait reached a steady-state. Then, we inserted electrodes into four muscles: tibialis anterior, quadriceps and biceps femoris, short and long heads. Patients received FNS-IM muscle conditioning exercises (about three months) followed by FNS-IM gait training (about three months). Outcome measures, evaluated before and after FNS-IM treatment using a video-based motion analysis system, included kinematics of stance and swing phases of voluntary gait. FNS-IM was inactive during gait measurements.
FINDINGS: Patients tolerated the FNS-IM treatment well. We designed stimulation paradigms that minimized discomfort associated with electrical stimulation of a leg with preserved sensation. Monolimb stimulation, using the FNS protocols we developed, did not increase cardiac output above that of volitional activity. Patients could exercise at home using FNS-IM. Knee flexion at toe-off (p<0.001), peak-swing phase knee flexion (p<.0001) and late-swing phase knee extension (p<.001) improved in all patients. Three patients also improved stance phase knee control (p<.001). FNS-IM electrodes were removed at the end of FNS-IM gait training and patients were examined at least six months after electrode removal. Functional gains persisted after removing the FNS-IM electrodes including advancement from wheelchair use to walking from car to restaurants, malls or medical appointments (i.e., walking independently more than one block).
IMPACT/SIGNIFICANCE: 1) FNS-IM can be used in stroke patients without discomfort or excessive increases in cardiac output. 2) FNS is a useful stroke rehabilitation technique that can restore voluntary gait function beyond that attained by spontaneous recovery and conventional rehabilitation. 3) The improved gait persists after completion of FNS-IM treatment.
FUNDING SOURCE: The Office of Research and Development, Medical Research Service of the Department of Veterans Affairs.
POST-STROKE DEPRESSION AND ANXIETY
Schramke CJ1,2, Stowe RM1,2, Ratcliff G2,3, Goldstein G1,2, & Condray R1,2
1VA Pittsburgh HCS, 2Univ. of Pittsburgh, 3Health South Harmarville Rehabilitation Hospital
OBJECTIVES: To examine whether different methods of assessing psychopathology in stroke patients alters estimates of the severity and incidence of depression and anxiety. To determine whether left hemisphere lesions are associated with a higher incidence of psychopathology in patients who are neurologically stable.
RESEARCH PLAN: Right and left hemisphere stroke patients and a control group were administered a structured clinical interview (SCID-R) and rating scales for anxiety and depression (CES-D, BAI, and HDRS).
METHODS: All stroke participants were more than one year post stroke and all participants were between the ages of 55 and 75.
FINDINGS: The groups did not differ when compared for the mean level of distress on the rating scales or frequency of mood or anxiety disorder diagnosis using the SCID-R. Participants with left hemisphere stroke were more likely to be classified as distressed using rating scales cut scores and when scores were compared between stroke groups. The rating scales were sensitive to psychiatric disorders, but lacked specificity in all groups. There were significant correlations between scales suggesting the rating scales measure a common factor in the controls, while in the stroke groups associations were weaker and less likely to be significant.
CLINICAL RELEVANCE: Depression and anxiety following stroke interfere with a patient's ability to cooperate with and benefit from rehabilitation. These results suggest the need for caution in using rating scales of psychopathology in neurologic patients and support the notion these scales are sensitive to distress rather than specific for identifying depressive and anxiety disorders.
INERTIAL AND IMPACT FORCES OF A HYBRID II TEST DUMMY
DURING POWER WHEELCHAIR BRAKING
Michael Joseph Dvorznak
Human Eng. Research Lab., VA Pittsburgh HCS, Dept. of Rehab. Sci. and Tech., Univ. of Pittsburgh, Pittsburgh, PA
OBJECTIVES: To obtain inertial and impact forces of a Hybrid II test dummy during power wheelchair braking using computer simulation software and previously obtained kinematic data.
RESEARCH PLAN: The model will provide force data for comparison with injury criteria. Virtual testing can be performed on wheelchairs using ISO 7176 test data in conjunction with the dummy model to predict the driver's response and potential risks. In the future, we intend to use a hybrid III test dummy equipped with accelerometers and load cells to record impact force data.
METHODS: The software application, Working Model 2D, by Knowledge Revolution, is used to model power wheelchair braking tests. Body segments are modeled as masses and joints as pins. Joint stiffness and friction are added through rotational springs and dampers. Experimental position, velocity, and acceleration data of the power wheelchair will be imported into Working Model as the input to the system. The output, motion data of the test dummy, is compared to experimental Hybrid II data. Refinements are made to the model until the kinematics in the simulation match the actual motion of the Hybrid II. Once an accurate model is made, force and moment data of joints and body segments can be calculated through the software.
FINDINGS: Simple models have been made with particular attention to non-pin joints such as the neck and trunk. Preliminary simulations show that these models are accurate in low speed and static loading conditions.
CLINICAL RELEVANCE: The model can provide insight into injury mechanisms and risk of secondary injuries by uncovering the loads due to impacts and restraining devices. Simulations can be used as a clinical tool in prescribing a wheelchair that best suits the client.
Sponsors: Paralyzed Veterans of America, Washington, DC 20006; Eastern Paralyzed Veterans of America, Center for Injury Research, Center for Disease Control (R49/CCR310285-04)
THREE-DIMENSION VIBRATION EXPERIENCED BY WHEELCHAIR AND
Tai C, Liu D, Cooper RA, DiGiovine MM, Boninger ML
Human Engineering Research Laboratories; VA Pittsburgh HCS, Pittsburgh, PA 15206; Dept of Rehab Sci & Tech, Univ. of Pittsburgh, Pittsburgh, PA 15261
OBJECTIVES: Quantitatively evaluate the vibration experienced by a manual wheelchair and its user.
RESEARCH PLAN: The vibration of the wheelchair and subject's head will be recorded while the subject is propelling a wheelchair over several simulated daily obstacles.
METHODS: A triaxial accelerometer was mounted on the wheelchair and another one on a bite-bar held in the subject's mouth. The simulated daily obstacles are: Dimple Strip, Carpet, Door Threshold, Ramp, Rumble Strip and three Bumps with different heights. The power and frequency of the vibration were evaluated by PSD analysis. The effect of cushion on whole body vibration was also investigated by linear systems analysis. ANOVA and T-test were performed for a total 10 subject's data.
FINDINGS: The average intensities of the wheelchair vibrations exceeded most of the ISO fatigue-decreased proficiency boundaries. The average powers of wheelchair vibrations are larger than those of head vibrations in the forward-backward direction, but they are smaller for most of the obstacles in the medial-lateral and superior-inferior directions. The resonance frequency at the head is below 5 Hz. The wheelchair cushion plays a role in reducing vibrations. Our results indicate that the vibration experienced by the wheelchair and its user is a considerable factor in inducing discomfort and secondary injuries.
CLINICAL RELEVANCE: This study will be helpful and valuable for understanding and protecting wheelchair secondary injuries reported clinically and improving wheelchair riding comfort.
SKIN STRUCTURE CHANGES AFTER SPINAL CORD INJURY:
RELEVANCE TO INCIDENCE OF PRESSURE ULCERS
Rodriguez GP and Markowski J
Phys. Med. & Rehab. Dept., Baylor Coll. of Med.; Spinal Cord Unit, VA Med. Ctr., Houston, TX
OBJECTIVES: Correlate changes in skin amino acid content and ratio of collagen type I to type III to development of pressure ulcers.
RESEARCH PLAN: Determine content of amino acids characteristic of collagen and ratio of type I to type III collagen in skin biopsies of able-bodied persons and persons with SCI that have never had a pressure ulcer and compare results with biopsies from persons with a history of pressure ulcers. In persons with SCI, biopsies were taken from skin above the level of injury and below the level of injury.
METHODS: Collagen typing done according to method of Armendariz-Borunda and Rojkind (Collagen Rel Res 4:35-47, 1984) utilizing gel electrophoresis and densitometry. Amino acids measured were hydroxyproline, proline, hydroxylysine and lysine; used HPLC standard methods with dabsyl chloride as derivatizing reagent.
FINDINGS: Biopsies from below the level of injury in subjects with a history of pressure ulcers had a decreased content of hydroxylysine and lysine and a much lower ratio of type I to type III collagen compared to biopsies from above the level of injury, from subjects without a history of pressure ulcers, and from able-bodied subjects. We conclude that skin structure plays an important role in the increased susceptibility to development of pressure ulcers of persons with SCI.
CLINICAL RELEVANCE: Pressure ulcers are one of the most onerous sequelae of SCI. Identifying the factors that contribute to the increased risk of pressure ulcers is a necessary first step to devising strategies to decrease that risk.
Research sponsored by VA Rehabilitation Research and Development Service.
DEVELOPMENT OF A PLATFORM FOR TESTING THE MULTISEGMENTAL
SPINE IN LOAD AND DISPLACEMENT CONTROL
Molz FJ, Partin JI, Kirkpatrick JS
Orthopaedic Research, Department of Rehabilitation Research and Development, The Birmingham VA Hospital, Birmingham, Alabama, 35233
OBJECTIVE: To develop a computer controlled platform capable of operating in both load and displacement control while collecting kinematic and kinetic data on the multisegmental spine.
RESEARCH PLAN: To interface available computer, electronic, and pneumatic technologies to create a platform for spinal analysis.
METHODS: A platform designed to apply physiological moments was developed. Through moment application, six primary motions were possible: flexion, extension, right/left lateral bending, and right/left axial rotation. Control algorithms were developed to analyze the effect of a single level fusion on the multisegmental spine. A PID algorithm used intact position vs. time data from a three-axis goniometer as a set point to force the fused spine to have the same gross position vs. time history. A second algorithm used the intact loading rate while allowing the fused spine to reach the maximum intact position. The final algorithm used the intact loading rate, but holds the maximum intact position for a period of 5 minutes (simulating previously published protocols). All experimental data (forces, moments, and motion) were synchronized and collected at 10 Hz.
FINDINGS: To date, the operation of the platform has been verified with one multisegmental swine spine. Future testing will analyze the effect of fusion and testing protocols on regions of the goat and human spine.
CLINICAL RELEVANCE: The platform will provide data on the effect of fusion on the multisegmental spine using multiple testing protocols. Recommendations for an optimal spine testing procedure will be possible. This will allow more productive comparison between future data.
(Research was funded as part of an ongoing grant from VA Rehabilitation Research and Development Service entitled: The Effect of Spinal Instrumentation)
FUNCTIONAL MAGNETIC STIMULATION OF THE EXPIRATORY MUSCLES
IN PATIENTS WITH SPINAL CORD INJURY
Vernon W.H. Lin, MD, PhD; Harwinder Singh, MD; Roy Sasaki, MD; Inder Perkash, MD
Functional Magnetic Stimulation Laboratory, Spinal Cord Injury Service, VA Palo Alto Health Care System and Department of Functional Restoration, Stanford University
Patients with spinal cord injury (SCI) often have impaired cough due to deprivation of supraspinal control on the expiratory muscles, resulting in frequent pulmonary complications. The purpose of this study was to evaluate the usefulness of functional magnetic stimulation (FMS) as a non-invasive technique for assisting cough in SCI patients. Thirteen male SCI subjects, with injury levels between C4 and C7, were recruited. Pulmonary function tests (PFT) were performed in all subjects, and the following parameters were recorded: maximum expired pressure (MEP), expiratory reserve volume (ERV), and maximum forced expiratory flow. FMS of the expiratory muscles was performed at the end of normal inspiration, using a stimulation of 70% intensity. 20 Hz frequency, and 2 seconds burst length. Optimal magnetic coil (MC) placement was determined by moving the center of the coil along T6-T12 spinous processes while measuring the changes in airway pressure ("P). This optimal placement was subsequently used for obtaining maximal expired pressures, volumes, and flow rates in these subjects. Results showed that optimal MC placements varied from T9 thru Tl1. Mean maximum expired pressure, volume, and flow rate generated by FMS were 68.2±24.1 cm H20, 0.77±04.8 L, and 5.27±1.49 L/s, respectively. They were 121%, 167%, and 110% of their voluntary maximum. Eight subjects generated pressures and volumes greater than their voluntary maximum. We conclude that: (1) FMS of the expiratory muscles produced significant expired pressures, volumes, and flow rates when compared with their voluntary maximum efforts; (2) optimal MC placement for expiratory muscle stimulation was between the T9 and T11 spinous processes; (3) the expiratory function produced by FMS was comparable to other existing methods for producing cough in SCI patients, e.g., assisted cough (quad cough) and functional electrical stimulation of the abdominal muscles; (4) FMS is non-invasive, relatively painless, and well tolerated by all subjects.
Supported by VA Rehabilitation R&D and PVA/SCRF Grant #1692P67
DIFFERENTIAL EFFECTS OF FUNCTIONAL ELECTRICAL STIMULATION
AND VOLUNTARY EXERCISE ON SKELETAL MUSCLE BLOOD FLOW
MEASURED WITH POSITRON EMISSION TOMOGRAPHY
Scremin, A.M.E.2,4; Scremin, O.U.1,5; Shannon, B.2; Dietrick, R.2; Brown, C.V.3; and Mandelkern, M.A.3
PM&R2, Nuc. Med.3 and Res.1 Depts, West Los Angeles VAMC and Medicine4 and Physiology Depts5, UCLA Med. School, Los Angeles CA 90073
OBJECTIVES: Functional electrical stimulation (FES) induced unloaded knee extension causes a greater skeletal muscle blood flow (MBF) response in SCI subjects than the same exercise performed voluntarily by able-bodied subjects. We tested the hypothesis that this phenomenon was due to the greater relative load imposed on deconditioned muscle of SCI subjects.
RESEARCH PLAN: 4 subjects with neurologically complete SCI, and 7 able-bodied age-matched controls participated in the study. MBF measurements were performed in every subject on the same session at rest (BL), during exercise (EX), immediately after ending 16 min EX (IPOST-EX), and 20 min after the end of EX (DPOST-EX).
METHODS: MBF of the thigh was measured with H215O PET in a Siemens 953-31 scanner. Subjects performed repetitive FES induced or voluntary 30 knee extension with a load equivalent to 30% of the maximum they could lift once (SCI = 2 lb, AB= 15 to 22 lb). Subjects exercised during 16 minutes lying supine on the scanner table with 150 hip flexion.
FINDINGS: In AB subjects, MBF increased significantly over BL during EX (p<0.001), and it returned to a level not statistically different from BL immediately after EX: BL (ml/100g/min, mean ± standard error) = 3.34 ± 0.70, EX= 11.5 ± 1.24, IPOST-EX= 4.54 ± 0.66, DPOST-EX = 3.29 ± 0.88. In SCI subjects, MBF was higher than in AB subjects in EX (18.5 ± 1.01, p<0.004), and immediately after EX (20.9 ± 0.99, p<0.0001). These results tend to disprove the hypothesis tested.
CLINICAL RELEVANCE: This study suggests a greater metabolic impact of FES-induced than voluntary exercise even at comparable relative loads.
Supported by the Department of Veterans Affairs Rehabilitation Research and Development. Project #B 603-RA.
CELL-SEEDED ARTIFICIAL GRAFTS FOR REPAIR OF NERVE AND
Sabelman, EE; Hentz, VR; Lineaweaver, W; Hui, K; Hu, M; Zhang, F; Eng, D; Komorovska-Timek, E.
Rehab R&D Ctr, VA Palo Alto HCS; Functional Restoration Depts., Stanford Univ
OBJECTIVES: We are engaged in two projects in which an extracellular matrix is designed and constructed to accommodate a patient's own ("autologous") living cells: replacement of connective tissue in deep pressure sores and repair of peripheral nerves.
RESEARCH PLAN: We hypothesize that cells will synthesize factors that promote healing if they are placed in a biocompatible matrix with suitable micron-scale geometry. We have worked closely with surgeons to develop these grafts, since successful implantation of a tissue-engineered graft is as dependent on microsurgical technique as on the biomaterials.
METHODS: For nerve repair, Type I collagen matrix is formed into linear channels and combined with cultured Schwann cells inserted into a biodegradable conduit. The pressure sore graft is constructed of biomaterial matrices inoculated with connective tissue and fat cells, nourished either by an external fluid loop through artificial capillaries, or by a microsurgically relocated arteriovenous loop.
FINDINGS: In animal experiments, the Schwann-cell-seeded artificial nerve graft has shown the same functional recovery as an autograft. Preparations are underway for a small-scale clinical trial in patients having traumatic nerve loss in the hand. The pressure sore graft is still in early stages of development; the most promising matrix is a composite of collagen protein and hyaluronic acid derivatives.
CLINICAL RELEVANCE: As a substitute for autografts or surgical flaps, tissue engineered grafts obviate major donor site surgery (cells are obtained from small biopsies or from the margins of a wound).
ACKNOWLEDGMENTS: VA RR&D pilot projects B92-476AP, B1839-PA, Merit Review projects B382-RA, B588-RA, -2RA, -3RA; Plastic Surgery Education Foundation grant to PAIRE; VA PA HCS RR&D core funds; past staff: J. Rosen, V. Dhaka, P. Koran (Kadlcik), J. Kipp, R. Keeley, T. Atagi, J. Padilla, K. Nguyen, N. Diep; summer student: C. Angle.
CARDIOVASCULAR RESPONSES TO STATIC AND DYNAMIC
ELECTRICALLY STIMULATED LEG EXERCISE COMBINED WITH ARM
Smith SE, Myers JS, Froelicher V, Perkash I, Phillips WT, Kiratli BJ
SCI Center, Cardiology Service, and PM&R Service, VA Palo Alto HCS; Center for Research in Disease Prevention, Stanford University
OBJECTIVES: The overall objective of this study is to evaluate methods for reducing coronary heart disease (CHD) related mortality and morbidity in persons with spinal cord injury (SCI).
RESEARCH PLAN: Our plan is to determine appropriate clinical exercise intervention strategies for reducing cardiac risk in the SCI population.
METHODS: The use of lower limb functional electrical stimulation (FES) during concurrent upper body ergometry (UBE), "hybrid" exercise, has been consistently reported to augment acute cardiovascular and hemodynamic responses compared with UBE performed alone. We are evaluating hybrid exercise in a two-phase study. The initial phase involves comparative testing of four exercise protocols: UBE alone, cycle FES, UBE plus static FES, and UBE plus cycle FES. Testing is being conducted on three SCI subject groups -- athletes, healthy sedentary individuals, and individuals with CHD risk factors. Outcome variables include cardiovascular responses determined via open circuit spirometry and EKG, and peripheral blood flow measurements. Initial physiologic variables include blood lipid levels and body composition.
FINDINGS: This work is in progress. Cardiovascular and hemodynamic variables will be evaluated for each exercise protocol and across subject cohorts. We anticipate greater responses during cycle-hybrid exercise compared with static-hybrid and arm cranking alone and in subjects with lower fitness levels. We also expect blood lipid levels and body composition to be associated with cardiovascular and hemodynamic responses.
CLINICAL RELEVANCE: These results will allow us to evaluate the potential for exercise to modify or control heart disease risk factors and will be applicable towards informed cost-benefit decisions for implementation of exercise training programs.
(VA Rehab R&D Merit Review Grant #B2110-RA)
NON-SKELETAL DETERMINANTS OF FRACTURE IN CHRONIC SPINAL
CORD INJURY: IMPACT LOADS DURING A FALL
Kallfelz-Klemish CF, Oriedo SE, and Kiratli BJ
SCI Center, VA Palo Alto HCS; Dept of Mech Eng, Stanford University
OBJECTIVES: The objectives of this study were 1) to quantify external loads during a fall to the knees, and 2) to determine likelihood of fracture by comparing estimated peak loads to appropriate failure criteria.
RESEARCH PLAN: Our goal is to generate accurate loading estimates for activities common to individuals with SCI using both experimental and computational methods. These estimates can then be combined with bone strength measures to generate patient-specific fracture risk profiles. Preventive measures and/or alternatives can be recommended for activities which put patients at risk for fracture.
METHODS: A "generalized" SCI patient was represented by a two-dimensional model composed of multiple segments, adjusted according to adult SCI body composition, and a representative set of initial conditions was established through interviews with patients and medical professionals. Analytical rigid-body dynamics was used to determine the configuration and velocity of the patient immediately prior to impact. The numerical penalty method was implemented to monitor contact force during impact. The maximum value of impact force was compared to published values of bone failure loads to obtain an initial estimate of likelihood of fracture.
FINDINGS: Preliminary results indicate that the maximum value of impact force falls within the range of failure loads of lower extremity bones. We continue to refine both our modeling techniques and our failure criteria.
CLINICAL RELEVANCE: Lower-extremity fractures are particularly difficult to treat in the chronic SCI population. Until better therapies for increasing bone strength are developed, identifying and avoiding activities which put a patient at risk for fracture may be the best form of prevention.
(VA Predoctoral Associated Health Rehabilitation Research Fellowship; American Paraplegia Society Seed Grant #809, VA Rehab R&D Merit Review Grant #A2014-RA)
PREDICTING BONE STRENGTH AND FRACTURE RISK FROM
DENSITOMETRIC MEASUREMENTS IN INDIVIDUALS WITH SPINAL CORD
Kiratli BJ, Smith AE, Sims GE, van der Meulen MCH, Perkash I
SCI Center, Surgery Service, and Rehab R&D Center; VA Palo Alto HCS
OBJECTIVES: The objectives of this program were 1) to validate assessment of lower extremity bone mass and strength in individuals with spinal cord injury (SCI) and 2) to evaluate the usefulness of these measurements in predicting fracture risk.
RESEARCH PLAN: We have examined several methods for determining lower extremity bone strength in skeletal regions susceptible to fracture following SCI. Our goals are to determine whether we can reliably predict fracture risk by 1) measuring bone response in specific skeletal sites where fractures are most predominant and 2) enhancing our bone mass measurements by calculations of bone strength.
METHODS: Bone densitometry was performed on individuals with chronic SCI, and history of post-injury lower extremity fracture was determined. Measurement sites included proximal femur, midshaft femur - a novel measurement site described in our lab, and the total body - with regional analysis of the femoral midshaft. Bone mechanical properties were estimated from bone mass and geometric data using beam theory.
FINDINGS: All measured and calculated bone values were reduced in individuals with SCI compared with ambulatory controls, and bone mass and cortical thickness were reduced in those who had previously sustained lower extremity fracture. However, bone strength parameters did not consistently discriminate those with lower extremity fractures.
CLINICAL RELEVANCE: Rapid bone loss occurs in skeletal regions below the lesion level. With chronic SCI, risk of fracture increases presumably due to reduced mechanical loading. Susceptibility to fracture is a function of both bone structural and mechanical properties. Our quantitative results will allow better evaluation of which parameters are most predictive of fracture risk.
(VA Medical RAG Grant; VA Rehab R&D Merit Review Grant #A2014-RA)
APPLICATION OF ADVANCED QUANTITATIVE IMAGING TECHNIQUES
TO STUDY MUSCULOSKELETAL FUNCTION
Pappas G1,2,3; Sheehan FS6; Zajac
FE1,3,4; Drace JE2,5
1Rehab R&D and 2Diag Radiology Ctrs, VA Palo Alto HCS; 3Mechanical Eng, 4Functional Restoration, 5Radiology Depts, Stanford University; 6Mechanical Eng Dept, University of Delaware
OBJECTIVES: We are applying cine phase contrast and real-time magnetic resonance imaging (MRI), along with ultrasound and positron emission tomography (PET), to study the in vivo motion of muscle tissue, trabecular bone, and tendon in humans.
RESEARCH PLAN: Advanced imaging methods are being developed and applied to measure musculoskeletal motion, architecture, and metabolism. These techniques allow us to quantitatively track the kinematics of trabecular bone, measure the strain distribution within myotendinous tissue, and determine strain in tendons.
METHODS: Cine phase contrast and real-time MRI allow direct measurement of 3D velocity, from which kinematics, displacement, and strain can be computed. Cine ultrasound enables us to measure muscle fiber and myotendinous junction architecture. PET provides a direct measure of 18-fluorodeoxyglucose uptake and indicates the level of muscle activation.
These techniques have been combined into an integrated approach for determining musculoskeletal architecture, kinematics, and metabolism.
FINDINGS: We have been able to dynamically track trabecular bone and muscle tissue in vivo. Under physiologic loads, patellar tendon strains of 7% during knee extension and highly non-uniform strain within the biceps muscle during elbow flexion have been measured.
CLINICAL RELEVANCE: This research has advanced our understanding of normal and pathologic musculoskeletal structure and function. These techniques have significant implications for tracking bone and muscle tissue, understanding tendon and joint function, and modeling and rehabilitating musculoskeletal dysfunction.
ACKNOWLEDGMENTS: This research is supported by the Dept. of Veterans Affairs and NIH Grant HD31493 to JED.
DRIVER'S SIMULATION ENVIRONMENT FOR ARM THERAPY
Michelle Johnson, MSME (predoctoral student, Stanford University) H.F. Machiel Van der Loos, Ph.D. (co-P.I.), Charles G. Burgar, M.D. (co-P.I.) VA Palo Alto Health Care System, Palo Alto, CA
OBJECTIVES: The Driver's Simulation Environment for Arm Therapy (SEAT), a prototype stroke rehabilitation device, has been designed to explore new strategies of and provide effective rehabilitation of the upper extremities.
RESEARCH PLAN: Driver's SEAT uses a bimanual functional activity (steering) to motivate persons with hemiplegia to engage their paretic side. By individually measuring the right and left side wheelrim forces, and then applying computer-controlled assistance and resistance torques to the wheel, Driver's SEAT allows us to explore the differences between promising therapy techniques.
METHODS: To explore the effectiveness of bimanual exercise, we studied 5 normal subject performances using 3 torque strategies with 4 different steering conditions while subjects simulated a flaccid limb condition.
FINDINGS: The study showed the ability of Driver's SEAT to measure forces and kinematics accurately, to present a rudimentary steering task to subjects, and to simulate therapy conditions. The study pointed to several design modifications, which are being completed. A follow-on VA Pilot Project proposal is pending. This study will explore the effectiveness of bimanual therapy in eight chronic stroke subjects.
CLINICAL RELEVANCE: Hemiplegia, a common post-stroke condition, affects many of the 400,000 stroke survivors per year in the U.S. Upper extremity return of function often lags behind that of the legs. However, upper extremity function of both limbs is important for many activities of daily living. The goal of Driver's SEAT is to develop techniques for enhancing function and reducing dependence on caregivers.
[Funding from VA RRDC Core grant and NASA graduate student fellowship]
OBJECTIVES: The purpose of this study was to determine if muscle injury was related to sarcomere strain or sarcomere stress during eccentric contraction (EC) or skeletal muscle.
RESEARCH PLAN: Sarcomere lengths were measured using laser diffraction in small fiber bundles from the frog anterior tibialis muscle during EC. Prior to and after EC treatment, contractile properties were measured to assess muscle injury.
METHODS: Fiber bundles were divided into three different nominal strain groups (10%, 25%, and 35% of fiber length; n = 5-6/group) and each was subjected to 10 ECs. Sarcomere lengths measured during each EC, by projecting a He-Ne laser through the fiber bundle, were used to calculate sarcomere strain. Also, some fiber bundles were subjected to a passive stretch treatment or an isometric treatment to test the effect of stretching or stimulation alone on muscle injury.
FINDINGS: Actual sarcomere strain calculated during EC from fiber bundles deformed nominally 10, 25, and 35% of their fiber lengths was 6±.5%, 19±4%, and 30±2%, respectively. Maximum tetanic tension following EC treatment decreased by 15.4±2.3%, 41.8± 2.6%, or 60.8± 2.1% (p<0.05) with increased sarcomere strain (p<0.05, r2=.998). Passive stretch and isometric treatments resulted in an insignificant 2.3±0.6% (p>0.5) loss of maximum tetanic tension following treatment. Thus, active sarcomere strain is a good predictor muscle injury after EC.
CLINICAL RELEVANCE: This type of investigation provides further information necessary to implement measures to reduce injury or expedite recovery after muscle injury.
COMPARISON OF DIFFERENT CURRENT LEVELS IN THE RECOVERY OF
FUNCTION AFTER SEVERE SPINAL CORD INJURY
Khan T, Havey R, Sayers ST, King W and Chauhan NB
Neuro-Regeneration Laboratory, Research Service, Hines VAMC, Hines, IL; Dept. of Neurology and Cell Biology, Neurobiology & Anatomy, Loyola University Medical Center, Maywood, IL
OBJECTIVES: The objective of this study was to evaluate the functional benefit of the application of pulsed DC electrical current following severe contusion injury to the cat spinal cord.
RESEARCH PLAN: Pulsed DC currents of 10µA, 20µA or 33µA were applied to the lesion site of severely contused spinal cord of cats. Behavioral recovery was tested six months post-contusion injury.
METHODS: The cats were divided into four groups. All animals sustained a severe contusion injury and, two hours later received battery powered implantable stimulators with stimulation parameters 14µA, 20µA or 33µA pulsed DC which results in a 100 Hz unipolar square wave with a 20% duty cycle. In the control group, cats sustained a severe contusion injury only. Behavioral tests consisting of open field, placing and withdrawal responses were performed before injury, and then monthly throughout the experimental period.
FINDINGS: Open field behavioral performance was significantly better in the 33µA stimulation conditions when compared to injury alone. These animals have consistently shown weight bearing and minimum ambulation. Performance improved significantly when stimulation level increased from 20µA to 33µA (p<.05). Placing responses also improved with increasing levels of electrical stimulation. Withdrawal reflexes only showed improvement for the 33µA stimulation condition. These reflexes were significantly abnormal for the 14µA and 20µA groups, but the 33µA groups were similar to normal animals.
CLINICAL RELEVANCE: This work provides a new potential therapeutic strategy for clinical trials, with direct contributions towards improving the health and well being of the patients with SCI.
(Sponsored by the Department of Veterans Affairs, Rehabilitation Research and Development Service, 423-3RA).
PUDENDAL NERVE REGENERATION FOR REHABILITATION OF URINARY
Sakamoto K, Jones KJ and Damaser MS
Res. & Ed. Service, Hines VAMC, Hines, IL; Depts. of Urology and Cell Biology, Neurobiology and Anatomy, Loyola Univ. Med. Center, Maywood, IL
OBJECTIVES: Stress urinary incontinence is an expensive medical problem without any animal model to test experimental medications and rehabilitation. Injury to the pudendal nerve, innervating the external urethral sphincter, has been described as one of the causes. The objective of this study was to correlate nerve regeneration with behavioral recovery after pudendal nerve injury.
RESEARCH PLAN: Voiding and neuro-regeneration patterns were studied in female rats after bilateral pudendal nerve crush.
METHODS: Voiding patterns were evaluated pre-operatively and on post-operative days (POD) 2 and 6. Spinal cords were harvested on POD 7 for in-situ hybridization with ²II tubulin (cytoskeletal protein) cDNA. Grain density of ²II tubulin mRNA in pudendal motoneurons and retrodorsolateral motoneurons (internal control) was counted.
FINDINGS: There was a statistically significant (p<0.05) increase in grain density in crushed pudendal motoneurons compared to the control, suggesting axonal regeneration in crushed pudendal nerves. There was no statistically significant difference in the voiding patterns between the crush and control groups because of large variability, probably resulting from unknown factors affecting voiding patterns in rats.
CLINICAL RELEVANCE: We have shown that pudendal nerves undergo axonal regeneration. Therefore, pharmacological treatments and rehabilitations such as nerve growth factors may be useful. The voiding test in this study is not sensitive enough to determine subtle changes in voiding patterns. This is a feasible animal model for testing medical and rehabilitative treatments for pudendal nerve regeneration in urinary incontinence.
(This study was funded in part by the Society of Women in Urology, RR&D Service and Hines VAMC)
EFFECT OF ELECTRICAL STIMULATION AND CARBON FILAMENT
PROSTHESES IN EXPERIMENTAL SPINAL CORD INJURY
*Chauhan NB, Figlewicz HM, Sayers ST and *Khan T
Neuro-Regeneration Laboratory, Research Service, Edward Hines Jr. VA Hospital, Hines, IL 60141; * Department of Neurology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153
HEADINGS: Spinal cord injury, Electrical stimulation, Carbon filaments, Axonal regeneration, Phosphorylated neurofilaments
OBJECTIVE: The objective of current investigation was to evaluate the efficacy of carbon filament-prostheses in combination with electrical stimulation for the structural and functional restoration of injured neurons following severe contusion injury to the cat spinal cord.
RESEARCH PLAN: The research plan was designed to assess the astroglial response following injury by detecting (1) immunoreactive glial fibrillary acidic protein, a marker of reactive astroglia, and (2) immunoreactive phosphorylated neurofilament protein, a marker of regenerating axons, at the lesion site of injured spinal cord.
METHODS: The effect of electrical stimulation with and without carbon filament-prostheses on the regeneration of neurons following severe contusion injury in a cat model was investigated by in situ immunofluorescence.
FINDINGS: The contusion injury resulted in: (a) increased GFAP-IR indicating injury-associated reactive astrogliosis, (b) increase in NF-IR, which normally occurs in the regenerating neurons, indicating postlesional axonal plasticity. Application of electrical stimulation or carbon filaments alone following contusion injury did not show any remarkable change. However, the implantation of carbon filaments together with electrical stimulation showed anatomical evidence of astroglial migration and axonal growth. The results indicate that the regenerative effects of electrical stimulation on axonal regeneration are further enhanced by carbon filaments as neuroprostheses.
CLINICAL RELEVANCE: A combinational approach of using electrical stimulation along with carbon filaments as prosthetic device may be a potential device for the functional recovery following spinal cord injury.
(Sponsored by the Department of Veterans Affairs, Rehabilitation Research and Development Service, 423-3RA.)
URINARY BLADDER REHABILITATION WITH CARBON FILAMENTS AND
NEUROTROPHINS AFTER EXPERIMENTAL SPINAL CONTUSION
Damaser MS, Khan T, and Uvelius B
Res. & Ed. Service, Hines VAMC, Hines, IL; Depts. of Urology and Neurology, Loyola Univ. Med. Center, Maywood, IL; Dept. of Urology, Lund University, Lund, Sweden
OBJECTIVES: The objective of this study was to determine if carbon filaments with neurotrophin-secreting Schwann cells could restore function to the bladder after severe spinal contusion.
RESEARCH PLAN: Carbon filaments coated with Schwann cells that secrete brain derived neurotrophic factor (BDNF) or neurotrophin 3 (NT-3) or both, were implanted in rats with severe spinal contusion. Bladder function was tested three months post-contusion.
METHODS: The contused animals were divided into 5 groups: contusion only, nonsecreting Schwann cells, BDNF-secreting Schwann cells, NT-3 secreting cells, and BDNF+NT-3 secreting cells. For in vivo functional testing, the bladders were filled with saline while bladder pressure was measured. The bladders were excised, weighed, and fixed for histology.
FINDINGS: Bladder weight, capacity, and wall thickness for all contused rats (1.30 ± 1.30g, 9.6 ± 8.2ml, and 434 ± 226µm, respectively) were significantly higher than in non-contused controls (0.17 ± 0.04g, 2.1 ± 1.1ml, and 140 ± 28µm, respectively). Rats with BDNF secreting cells had the least increase in all 3 parameters (0.84 ± 0.05mg, 10.3 ± 6.7ml, and 365 ± 11µm for BDNF only and 0.78 ± 0.47g, 6.0 ± 1.3, and 335 ± 122µm for BDNF+NT-3). Untreated contused rats had the greatest increase in wall thickness (627 ± 495µm) and rats with NT-3 only had the greatest increase in bladder weight and capacity (1.84 ± 2.56g and 14.1 ± 14ml).
CLINICAL RELEVANCE: Spinal cord injury causes urinary tract complications. This study suggests that implantation of BDNF-secreting Schwann cells can diminish bladder deterioration after spinal cord injury.
(This research supported by VA RR&D Service, and Hines VAMC)
TESTOSTERONE PROPIONATE (TP) ACCELERATES FUNCTIONAL
RECOVERY AFTER SCIATIC NERVE INJURY IN THE RAT
Brown, TJ, Khan, T and Jones, KJ
Rehab. R&D Center, Hines VA Hospital, Hines, IL; Depts. of Cell Biol., Neurobiol. & Anatomy, and Neurology, Loyola Univ. Chicago, Maywood, IL
OBJECTIVES: Injury to the sciatic nerve, which is the longest nerve in the body, can have devastating consequences to the affected individual, including loss of locomotion and sensation. Part of the problem is the slow rate of regeneration of this long nerve. Systemic treatment with the gonadal steroid, testosterone (T), accelerates recovery from facial paralysis after facial nerve crush in rodents. The objective of this study was to determine if T treatment will accelerate functional recovery from lower limb paralysis following rat sciatic nerve crush.
RESEARCH PLAN: The effects of systemic administration of T on the recovery of locomotion were behaviorally analyzed in adult male rats following unilateral sciatic nerve crush.
METHODS: Adult male rats received a right side sciatic nerve crush at the level of the sciatic notch, with the left side serving as control. Half the animals received T, the others did not. Weekly testing using the Sciatic Functional Index (SFI), a quantitative measure of locomotion, was done for 7 weeks postoperative (wpo).
FINDINGS: At 1-3 wpo, the SFI of the TP and control groups were not significantly different. Between 3- 4 wpo, the TP-treated group had a significantly higher SFI score than controls, indicating a greater degree of functional recovery. At these time points, the differences are attributable to the foot print or paw length and are associated with calf muscle reinnervation. Beyond 5 wpo, there were no differences in the SFI scores. The results indicate that testosterone accelerates functional recovery from lower limb paralysis following sciatic nerve injury in the rat.
CLINICAL RELEVANCE: The results of this study indicate that gonadal steroids may be useful in the medical and rehabilitative treatment of peripheral nerve injury in the clinical situation.
(Supported by VA grant #B94-801A)
GONADAL STEROID REGULATION OF CYTOSKELETAL GENE
EXPRESSION IN AXOTOMIZED HAMSTER RUBROSPINAL MOTONEURONS
Storer, P and Jones, KJ
Rehab. R&D Center, Hines VA Hospital, Hines, IL; Depts. of Cell Biol., Neurobiol. & Anatomy, and Neurology, Loyola Univ. Chicago, Maywood, IL
OBJECTIVES: Gonadal steroids can augment the regenerative capabilities of injured peripheral motoneurons. The objective of this study was to determine if gonadal steroids can also improve the regenerative capabilities of injured central motoneurons.
RESEARCH PLAN: The effects of systemic administration of testosterone (T) on the expression of major proteins necessary to rebuild the damage axons were examined in adult hamsters following a partial spinal cord injury.
METHODS: Adult male hamsters were subjected to a unilateral spinal cord hemisection. Half the animals received T; the other half did not. Brainstems were harvested and in situ hybridization was done to determine the effects of injury plus T on the levels of tubulin in rubrospinal motoneurons.
FINDINGS: The results indicate that injury alone initially up-regulates the levels of tubulin in the rubrospinal neuron, but, with time, this up-regulation is reversed and the injured neurons down-regulate tubulin to levels significantly below those of uninjured neurons. T treatment reduced the down-regulation of tubulin mRNA levels. The ability of T to modulate important growth proteins demonstrates the ability of T to positively impact the injury response of central neurons.
CLINICAL RELEVANCE: In order to achieve full functional recovery following spinal cord injury, the intrinsic capacity of central neurons to regrow their axons must be augmented. Gonadal steroids represent trophic factors capable of boosting the regenerative capacity of neurons damaged by spinal cord injury or other trauma.
(Supported by VA grant #B2081-RA)
PROGNOSTIC ABILITY OF ORPINGTON PROGNOSTIC SCALE AND NIH
Lai SM, Duncan PW, Keighley J, Studenski S
Kansas City of Department of Veterans Affairs Medical Center, University of Kansas Medical Center, Kansas City, KS
OBJECTIVES: To compare the prognostic ability of two stroke scales -- the Orpington Prognostic Scale (OPS) and the NIH Stroke Scale.
RESEARCH PLAN: Prospective cohort study
METHODS: 184 consecutive subjects enrolled in the Kansas City Stroke Study were included and were assessed at baseline (within 14 days of stroke) using both the Orpington Prognostic Scale and the NIH Stroke Scale. Outcome measures included Barthel ADL and MOS-36 physical functioning at one-, three-, and six-months post stroke.
FINDINGS: Possible OPS scores range from 1.6 (best prognosis) to 6.8 worst prognosis; NIH scores range from 0 to 42 (fully impaired). Means and standard deviations of OPS and NIH measured at baseline were 3.6+1.32 (median 3.2) and 5.6+4.85 (median 4.0), respectively. The Spearman's rank correlations between baseline OPS and Barthel ADL were --.71, -.58, and --.59 for the one-, three-, and six-months, respectively. The correlations between the NIH and Barthel ADL were --.59, -.45, -.45 for each of the three corresponding time points. All p values were <0.001. R2s were used to assess the ability of these two stroke scales to prognosticate functional outcome and are summarized as follows:
|OPS- 1-month Barthel=62%, 3-month Barthel=44%, 6-month Barthel=35%;|
|NIH- 1-month Barthel=55%, 3-month Barthel=41%, 6-month Barthel=29%; and|
|OPS- 1-month MOS-36=30%, 3-month MOS-36=19%, 6-month MOS=14%,|
|NIH- 1-month MOS-36=22%, 3-month MOS-36=20%, 6-month MOS-36=12.|
Orpington Prognostic Scale and the NIH Stroke Scale explained well the variance in Barthel ADL. However, the Orpington Prognostic Scale explained slightly more variance than did the NIH stroke scale. Similarly, the Orpington Prognostic Score explained more variance in higher level of physical function than did the NIH Stroke Scale. The amount of variance in ADL and MOS-36 PFI which was explained by both stroke severity measures decreased over time.
TIME TO MEDICAL ATTENTION AFTER A MILD OR MODERATE ACUTE
Duncan P, Lai S, Keighley J, Rymer M
Kansas City Department of Veterans Affairs Medical Center; University of Kansas Medical Center, Kansas City, KS; and St. Luke's Hospital, Kansas City, MO
OBJECTIVES: To assess the factors associated with early medical attention (d" 3 hours and (d" 6 hours) in patients with mild and moderate stroke.
RESEARCH PLAN: Prospective Cohort Study
METHODS: As part of the Kansas City Stroke Study, information from the patient or patient's families regarding time elapsed from the onset of initial stroke symptoms until they first saw a nurse or doctor was gathered. Stroke severity was determined by the Orpington Prognostic Scale. Twelve hospitals collaborated to provide patients for enrollment. Subjects enrolled in the study lived in the community and were independent in ADLs prior to stroke. Chi square analysis and logistic regression were used to assess significant (pd"0.05) factors.
FINDINGS: One hundred sixty-two enrolled subjects had mild to moderate strokes; adequate time data was available in 128 patients. Fifty-two percent arrived in d" 3 hours and 64% arrived in d" 6 hours. Time to medical care in d" 3 hours was significantly associated with increasing age, Medicare, Medicaid (later), private insurance, race (Caucasians sooner than African-Americans) and types of symptoms ( numbness and weakness, difficulty talking), severity, and previous history of atrial fibrillation. Regression analysis of independent factors revealed that age, private insurance, and type of symptoms predicted early attention. Time to seek care in d" 6 hours was significantly associated with age, Medicare coverage, marital status, race, type of symptoms, previous history of atrial fibrillation and weekday onset. Independent predictors of early care in d" 6 hours were increased age, symptoms (numbness and weakness) and weekday onset.
CLINICAL RELEVANCE: Availability of medical insurance may be an important modifiable factor to reduce the delay in receiving early medical care.
(Funding -- Department of Veterans Affairs Rehabilitation Research and Development Service)
EVALUATION OF BACK MUSCLE FUNCTION DURING ACTIVITIES OF
Roy SH, Mullen-Rivers D, Emley M
Research Services Boston VA Medical Center and the NeuroMuscular Research Center, Boston University
OBJECTIVES: To extend EMG-based assessment approaches of back muscle impairment to include tasks involved in activities of daily living such as lifting.
RESEARCH PLAN: Conventional EMG signal processing techniques for measuring muscle impairment on the basis of spectral estimates of fatigue have only been applicable to static tasks and cannot be used for dynamic contractions. This problem has prompted us to develop a new EMG signal processing procedure, referred to as time-frequency analysis, to evaluate muscle impairments during dynamic activities.
METHODS: Surface EMG signals were detected from bilateral lumbar and thoracic paraspinal muscles in ten subjects during static holding and dynamic lifting tasks. Sustained static trunk extension at 80% of maximum was conducted following a standardized protocol. The dynamic task consisted of repetitive lifting [12 lifts/min] of a weighted box [20% of maximum] for 5 minutes using a dynamometer that tracks the position of the box in space.
FINDINGS: Significantly different rates and distribution of fatigue (p<0.05) among the back extensor muscles were observed for static and dynamic tasks. A more complex time-dependent behavior of the EMG-based fatigue index for repetitive lifting was observed compared to the static test. Sequential periods of fatigue and recovery during the lifting task was observed during the lifting task that may describe a strategy for loading muscles that limits fatigue in any one muscle group. No such interactions between muscle groups were noted for the static task.
CLINICAL RELEVANCE: Lower back pain is among the most common complaints bringing Veterans in contact with the VA patient care mission. This project will provide a more objective way of measuring functional limitations associated with LBP that result from impairments of the musculoskeletal system during activities of daily living.
(Supported in part by the Rehabilitation Research and Development Service of the Department of Veterans Affairs.)
INFLUENCE OF PROPULSION STYLE ON INJURY POTENTIAL IN
Rodgers MM1,2; Keyser RE2; Gardner ER1; Russell PJ3; Parker JA2; Gorman PH1,2 1R&D Service and Physical Medicine and Rehab Service, VA Maryland Health Care System; 2University of Maryland School of Medicine, Dept. of Physical Therapy and Neurology, Baltimore, MD, 21201 and 3Dept. of Movement Arts, Health Promotion, & Leisure Studies, Bridgewater State College, Bridgewater, MA 02325
OBJECTIVE: To identify propulsion style mediated differences in upper extremity joint kinetics, kinematics and muscle activity in manual wheelchair users (MWCU).
RESEARCH PLAN: The mechanics of MWCU were studied during wheelchair propulsion to fatigue to understand propulsion style differences which may predispose MWCU to overuse injuries.
METHODS: Nineteen MWCU performed a submaximal exercise test on a wheelchair ergometer instrumented to detect 3D handrim forces and moments. 3D motion analysis and handrim data were collected and used to calculate joint kinetics. Electromyographic (EMG) data collected from eight right upper extremity muscles were RMS processed then normalized. Subjects were divided into two groups based on a trunk position of flexion (FG) and non-flexion (NFG). Data were compared between groups at fresh and fatigued states using an ANOVA (p<.05).
FINDINGS: Significant joint kinematic differences existed between groups. The FG (n=9) demonstrated greater trunk flexion, shoulder flexion and elbow extension compared to the NFG (n=10) which was more pronounced with fatigue. Muscle activity proved to be an important difference between groups. When fatigued, the FG demonstrated significant decreases in the peak magnitude of FCU, TRI and MT activity with earlier cessation of FCU and PM activity which did not occur in the NFG.
CLINICAL RELEVANCE: The propulsion style of the FG relies more on trunk excursion for propulsive force generation which may be compensatory for muscle weakness. Training programs designed to prevent overuse injuries may need to emphasize triceps strengthening and endurance for individuals with flexed trunk propulsion styles.
(Supported by the Office of Research and Development, Rehabilitation R&D Service, Department of Veterans Affairs / B92-465A)
TREADMILL LOCOMOTION TRAINING IMPROVES PEAK HAMSTRINGS
TORQUE IN CHRONIC HEMIPARETIC SUBJECTS
H. Scott-Okafor (3); G.V. Smith (1); K.H.C. Silver (2,3); R.F. Macko (2,3)
Depts. of Physical Therapy (1), Neurology(2), and GRECC (3), University of Maryland, School of Medicine and VAMC, Baltimore, MD 21201
OBJECTIVES: Inability to recruit spinal motor units in a timely manner contributes to functional impairment following ischemic stroke. We tested the hypothesis that 3 months of 3 times per week aerobic locomotion training would improve peak hamstring torque over a greater range of motion.
RESEARCH PLAN: Eligible subjects were treadmill trained using a customized cardiac rehabilitation protocol. Patients were tested at baseline and after 3 months of treadmill exercise using isokinetic dynamometry at four angular velocities (30, 60, 90, and 120 deg/sec).
METHODS: 14 chronic (>6 months) hemiparetic stroke patients, aged 66.7 ± 8.13 (Mean ± S.D.) years, were recruited. Testing was conducted at each angular velocity in concentric and eccentric modes.
FINDINGS: Peak concentric torque increased after 3 months by 28.5% (p<0.05) and 23.5% (p<0.08) in paretic and non-paretic limbs, respectively, Gains in peak eccentric torque did not achieve significance. Range of motion to peak torque in the paretic limb improved in the concentric mode by 9% (p<0.05) but not in the nonparetic limb. The range to peak torque did not change in the eccentric mode in either limb.
CLINICAL RELEVANCE: These findings suggest that "task-oriented" locomotion training can improve peak concentric hamstring torque production perhaps by increasing motor recruitment.
FUNDING: Geriatric Research Education Clinical Center, Baltimore VAMHCS. Funded in part by a VA Career Development Award and a NIA R29 to Dr. Macko.
AEROBIC TREADMILL LOCOMOTION TRAINING IMPROVES QUADRICEPS
STRENGTH IN CHRONIC HEMIPARETIC SUBJECTS
G.V. Smith (1), K.H.C. Silver (2,3), R.F. Macko (2,3)
Depts. Of Physical Therapy (1), Neurology (2) and GRECC (3), University of Maryland, School of Medicine and VAMC Baltimore, MD 21201
OBJECTIVES: Decreased muscle strength and altered stretch reflexes contribute to functional impairment following ischemic stroke. Based on recent studies in our laboratory, we tested the hypothesis that 6 months of 3 times per week aerobic locomotion training would improve volitional quadriceps strength and decrease spasticity.
RESEARCH PLAN: Eligible subjects were treadmill trained using a customized cardiac rehabilitation protocol. Patients were tested at baseline and after 3 and 6 months of treadmill exercise using isokinetic dynamometry (Kin-Com AP 125tm) at four angular velocities (30, 60, 90, and 120 deg/sec).
METHODS: 13 males and 2 females, aged 66.7 ± 8.13 (Mean ± S.D.) years, with mild to moderate gait deficits due to remote stroke (>6 months) were recruited. Testing was conducted at each angular velocity in passive, concentric and eccentric modes using a modification of the technique described by Knutsson and Martensson.
FINDINGS: Eccentric torque increased after 6 month of training by 39% (p<0.05) and 34% (p<0.05) in the paretic and non-paretic limbs, respectively. Concentric torque increase after 6 months by 46% (p=0.07) and 50% (p<0.05) in the paretic and non-paretic limbs, respectively. There were no changes in reflexive (passive) torque after 6 months training in either limb.
CLINICAL RELEVANCE: These findings strongly suggest that a "task-oriented" locomotion training paradigm can improve volitional torque production in chronic hemiparetic subjects without substantially altering spastic reflexes.
EXOGENOUS ANDROGEN PREVENTS SPINAL CORD INJURY-INDUCED
REGRESSION OF SPERMATOGENESIS
Huang HFS, Anesetti R, Chow SH, Ottenweller JE, Pogach LM
VA Medical Center, East Orange, N J and UMD-New Jersey Medical School, Newark, NJ
OBJECTIVE: Current study examined the mechanisms leading to the regression of spermatogenesis after spinal cord injury (SCI) and the feasibility of using exogenous hormones to prevent such regression.
RESEARCH PLAN: Spermatogenesis in SCI rats was examined after given exogenous FSH and testosterone replacement.
METHODS: (1) SCI was induced in male rats by surgical transection of the spinal cord at the level of the 9th thoracic vertebra. The SCI rats were treated with FSH or testosterone, or a combination of both. (2) Effects of testicular denervation on spermatogenesis were also examined. (3) Spermatogenesis was examined by histology and quantitative analysis of spermatogonial proliferation. (4) Status of Sertoli cells was determined by Northern blot analysis of mRNA for Sertoli cell proteins.
FINDINGS: (1) Testosterone replacement alone maintained qualitatively normal spermatogenesis in SCI rats. (2) FSH alone or in combination with testosterone enhanced regression of spermatogenesis in SCI rats and these effects were associated with a paradoxical up-regulation of FSH-receptor mRNA by FSH. These findings suggest that an altered FSH signal transduction may contribute to the regression of spermatogenesis after SCI. (3) Denervation of the superior (SSN) or inferior (ISN) spermatic nerve did not affect spermatogonial proliferation during acute phase of the injury. However, denervation of the SSN resulted in total regression of spermatogenesis These results illustrate that disruption of neuronal input to the testis is a contributing factor for the regression of spermatogenesis after SCI.
CLINICAL RELEVANCE: Current results provide cellular mechanisms leading to male infertility after SCI and suggest the feasibility of using exogenous androgen as a remedy to preserve spermatogenic function in SCI men.
(Supported by VA Rehab R & D # B85-863A.)
CONTINUOUS LOSS OF BONE DURING CHRONIC IMMOBILIZATION:
A MONOZYGOTIC TWIN STUDY
1Bauman WA, 1Spungen AM and 2Schwartz E 1Spinal Cord Damage Research Center, Depts. of Med. and Rehab Med., Mt. Sinai Med. Ctr., NY, NY and VAMC, Bronx, NY; 2Met. Bone Unit, VAMC, Bronx, NY and Met. Bone Ser., Hospital for Special Surgery, NY, NY
OBJECTIVES: Acute immobilization is associated with the rapid loss of bone. Prevailing opinion, based on cross-sectional data, assumes that bone mass stabilizes thereafter. In order to rigorously characterize the long-term course of whole body and regional skeletal mass loss in persons with chronic immobilization due to spinal cord injury (SCI) a monozygotic twin control design was employed.
RESEARCH PLAN: The research design consisted of the co-twin control method using 8 pairs of male monozygotic twins, one of each twin pair having chronic spinal cord injury (SCI) ranging from 3 to 26 years.
METHODS: The twins (mean±SD age, 40±10, range 25 to 58 years) were compared by paired t-tests for total and regional bone mineral content (BMC) and bone mineral density (BMD) measured by dual energy x-ray absorptiometry. Linear regression analyses were performed to determine the effect of age and duration of injury on the differences between twin pairs for total and regional skeletal bone values.
FINDINGS: In the SCI twins, total body BMC was significantly reduced (22±9 percent, p<0.001), with the predominant sites of reduction for BMC being the legs (42±14 percent, p<0.0001), and pelvis (50±10 percent, p<0.0001). Duration of spinal cord injury, not age, was found to be linearly related to the rate of leg bone loss in the SCI twins (r2=0.60, p<0.05).
CLINICAL RELEVANCE: Significant loss of total and regional bone has been demonstrated in subjects with SCI. Leg bone continues to be lost throughout chronic immobilization in individuals with SCI, thus progressively increasing the risk of fracture.
This work was funded, in part by, a grant from the Spinal Cord Research Foundation, Washington , D.C. Additional sources of support were from the Mount Sinai Medical Center, New York, NY and the Dept. of Veterans Affairs Medical Center, Bronx, NY.
SELECTIVE ACTIVATION OF SACRAL ROOTS FOR CONTROL OF
MICTURITION AND DEFECATION
Bhadra N and Mortimer JT
Applied Neural Control Laboratory, Department of BioMedical Engineering, Case Western Reserve University, Cleveland OH 44106
OBJECTIVES: The purpose of this project was to improve control of bladder and bowel function following spinal cord injury through selective electrical activation of the parasympathetic fibers in the sacral nerve roots.
RESEARCH PLAN: The difference in size of the nerve fibers to the bladder, rectum and the somatic sphincters can allow selective activation to produce bladder and bowel contractions without co-activation of the sphincters. A technique for selective small fiber activation, developed in this laboratory, offers a method for controlled bowel and bladder evacuation during stimulation.
METHODS: This study was carried out on adult female dogs with tripolar spiral nerve cuff electrodes on the sacral spinal ventral roots to the rectum and lower urinary tract. Pressures were recorded from the bowel, bladder, urethral and anal sphincters. Stimulation parameters were determined for selective activation of the bladder or rectum without eliciting sphincter contractions.
FINDINGS: We have demonstrated elimination of artificial fecal material from the rectum during selective electrical activation of the sacral anterior roots. We have also demonstrated effective voiding of fluid, with low bladder pressures and without sphincter activation, during electrical stimulation with the quasi-trapezoidal wave trains after dorsal rhizotomy.
CLINICAL RELEVANCE: This procedure can be implemented clinically for a bladder and bowel assist device for control of defecation and micturition in spinal cord injury.
ACKNOWLEDGMENT: This work was partially supported by the Paralyzed Veterans of America.
RECOVERING EMG SIGNAL TO CONTROL AN IMPLANTABLE
P. Strojnik, S. Pourmehdi, H. Peckham, J. Buckett
Cleveland VA FES Center of Excellence and Case Western Reserve University, Cleveland, OH
OBJECTIVES: Development of implanted EMG electrodes subdermally connected to electronic circuits inside an implant-stimulator will improve the acceptability and usage of implanted neuroprostheses in tetraplegic individuals.
RESEARCH PLAN: It has been shown that myoelectric signals can be effectively used for bimanual control of tetraplegic hands. Implantable EMG electrodes have been proposed, connected to an EMG processing circuit placed within the hermetic case of the implantable stimulator. Back telemetry can be used to send processed EMG signals to the external controller.
METHODS: Retrieving EMG signals during stimulation is usually done by signal blanking, filtering, and electrical isolation between stimulating and amplifying circuits. When stimulation and recording circuits share the same implant case and powering, as in this case, additional methods such as temporal grouping of stimulation channels and stimulus recharge current management must be applied.
FINDINGS: The feasibility of retrieving intramuscular myoelectric signals during intramuscular stimulation was explored in an acute animal experiment. An EMG amplifier and a signal conditioner were added to the existing implant configuration. Stainless steel percutaneous electrodes were utilized for stimulation and recording. A subcutaneously positioned hypodermic needle was used as the reference EMG electrode and as the stimulation anode. During stimulation, the myoelectric signal, free of artifacts, was recovered regardless of the position of the EMG electrodes relative to the position of the stimulation electrode or the distance between the recording and the stimulating electrodes.
CLINICAL RELEVANCE: The subcutaneous EMG signal recovered from the strong background of stimulation artifact offers a new control source for implantable neuroprostheses. By taking advantage of the residual control over muscles that can produce measurable EMG signal, tetraplegic individuals who cannot use "conventional" wrist or shoulder transducers will be able to regain some control of their hands.
This work has been supported by the NIH grant #NS29549 and by the Dept. of Veterans Affairs Medical Center Rehabilitation Research and Development Service.
FUNCTIONAL NEUROMUSCULAR STIMULATION FOR STANDING AND
MOBILITY AFTER SPINAL CORD INJURY
C. Bieri, H. Chizeck, J. Davis, K. Ferguson, R. Kirsch, R. Kobetic, E. Marsolais, G Polando, R. Triolo, J. Uhlir, M. Wibowo, W. Zhao
Case Western Reserve University, Cleveland VA Medical Center, MetroHealth Medical Center, and The Cleveland VA Center of Excellence in FES
OBJECTIVES: Functional Neuromuscular Stimulation (FNS) involves applying small electrical currents to the peripheral nerves to produce useful muscular contractions and purposeful movements of paralyzed limbs. Recent bioengineering advances have resulted in the development of surgically implanted "neuroprostheses" that allow persons with spinal cord injuries (SCI) to exercise, stand, transfer, and negotiate obstacles in the vicinity of their wheelchairs under the power or their electrically activated muscles.
RESEARCH PLAN & METHODS: Standing systems consist of an 8-channel implantable receiver/stimulator (IRS-8), electrodes to activate the knee, hip and trunk extensor muscles, and an external controller that transmits power and command signals to the implant. Ambulation requires a second IRS-8, additional electrodes for hip and ankle flexion, and a specialized controller to coordinate the actions of both implants. A novel brace is also being developed that will allow stair climbing and long-distance walking with the system.
FINDINGS: To date, the neuroprostheses have been implanted in four volunteers with good results. These preliminary small-scale clinical trials are based on over 20 years of research utilizing temporary systems employing surface or percutaneous wire electrodes. The upper extremities are still necessary for support and balance with these systems since the primary mechanisms for regulating posture are disrupted by SCI.
CLINICAL RELEVANCE: Current research is directed toward automatically controlling posture and balance and coordinating multi-muscle and multi-joint systems. Through anatomical modeling, computer simulation, and laboratory experimentation, advanced control systems capable of rejecting postural disturbances are being developed to allow free use of the hands to manipulate objects in the environment while standing with FNS.
Funded by VA Merit Reviews B681 & B683, Office of Orphan Product Development of the Food & Drug Administration, and the National Institutes of Health.
IMPROVING THE TISSUE VIABILITY OF PARALYZED MUSCLES USING
NEUROMUSCULAR ELECTRICAL STIMULATION
KM Bogie, RJ Triolo, *J Chae, PH Peckham, *F Frost
Cleveland FES Center, Case Western Reserve University, Cleveland, OH and *Dept of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH
OBJECTIVES: Neuromuscular electrical stimulation (NMES) provides the possibility of altering intrinsic factors, specifically by reversal of disuse muscle atrophy concurrent with increased regional blood flow.
RESEARCH PLAN: We are carrying out a four-stage pilot study, using subjects as their own controls, to evaluate the effects of long-term stimulation of the gluteus maximus muscle using implanted percutaneous electrodes.
METHODS: Two percutaneous electrodes are implanted in the gluteus maximus bilaterally. Implanted systems provide optimal muscle recruitment combined with ease of daily use. Following implantation, control data are collected during Phase 1 (non-stimulation). Muscle conditioning to improve strength and fatigue resistance is achieved by nightly stimulation for 1-6 hours over a two month period (Phase 2). During Phase 3, the NMES system is used daily in the wheelchair for a period of 6 months. This active stimulation provides an adjunctive therapy to existing pressure relief regimes. Tissue viability status is monitored throughout the study using transcutaneous oxygen measurements, interface pressure monitoring and CT scans. Study participants have a history of one or more severe (Grade IV) ischial pressure sores and have upper motor neuron spinal cord lesions. One subject has currently been recruited for the study.
FINDINGS: Preliminary results indicate that NMES positively affects tissue viability status, i.e. regional blood flow increases and pressure distribution is altered by active stimulation.
CLINICAL RELEVANCE: These early findings imply that long-term use of NMES using implanted systems may improve the regional health of paralyzed muscle, thus reducing the risk of pressure sore development.
Funding Agencies & Support: Funded by a Spinal Cord Research Foundation grant. Supported by Cleveland FES Center & NeuroControl Corporation.
A COMPARISON BETWEEN CONTROL METHODS FOR IMPLANTED FES
HAND GRASP SYSTEMS
Hart RL, Kilgore KL, Peckham PH
Case Western Reserve University, Cleveland VA Medical Center, MetroHealth Medical Center, Cleveland, OH
OBJECTIVES: Implanted neuroprostheses employing functional electrical stimulation (FES) provide grasp and release to individuals with tetraplegia. An appropriate control method is required for the FES user to control the hand grasp system.
RESEARCH PLAN: This paper describes and compares three methods of controlling the stimulated hand movement: shoulder position, wrist position and myoelectric activity from the wrist extensors.
METHODS: Three experienced neuroprosthesis users were evaluated with each of the control methods by performing a Grasp Release Test (GRT).
FINDINGS: A significant improvement was found between each FES method and tenodesis without FES. No significant difference in overall performance was found between the three FES methods of control.
CLINICAL RELEVANCE: Each method of control demonstrated advantages and disadvantages which depend upon characteristics of the individual patient. Factors which must be considered are: injury level, voluntary wrist strength, proximal upper limb strength, the level of cognition of the patient, hand grasp characteristics, cosmeses, importance of using both arms, and personal preference. Due to the unique characteristics of each controller type, it is advantageous to have each type available for the FES patients to adapt the system to the needs and desires of the individual patient.
SATISFACTION AND USAGE OF A HAND GRASP
Wuolle KS, Van Doren CL, Bryden AM, Peckham PH, Keith MW and Kilgore KL
Cleveland VAMC, MetroHealth Medical Ctr., Case Western Reserve Univ
OBJECTIVE: The objective of this study was to assess clinical impact, subject satisfaction and usage of a hand neuroprosthesis.
RESEARCH PLAN: Thirty-six C5 or C6 motor level spinal cord injured individuals from eight different medical centers, participated in the study. All subjects were implemented with a hand grasp neuroprosthesis which provides grasp and release. The study was conducted after subjects completed rehabilitation training and had the neuroprosthesis available for use at home for at least six months. Subjects were a median of 5.2 years post-implantation.
METHODS: A survey was mailed to subjects to determine clinical impact, satisfaction and use. An independent market research firm was contracted to make follow-up calls to retrieve the answers. Subjects were asked questions such as: "If I had it to do over, would I have the hand system implanted again?"
FINDINGS: The subjects were generally very satisfied with the neuroprosthesis, they would recommend the neuroprosthesis to others, they would have the surgery again, and the neuroprosthesis had a positive impact on their life, and improved their quality of life (statistically significant results). Subjects reported using the neuroprosthesis a median of 5.5 days/ week (range 0-7 days/week). All participants had an increase in pinch strength and ability to grasp and release.
CLINICAL RELEVANCE: The results indicate that the neuroprosthesis was accepted and used by most subjects and that subjects generally felt the neuroprosthesis improved their quality of life.
QUALITY OF LIFE OUTCOMES WITH ELECTRICAL STIMULATION OF
NEUROGENIC BLADDER AND BOWEL
Kachourbos MJ ; Creasey GH; Takaoka Y; Bodner DR
VA Medical Center, Wade Park, Cleveland, OH 44106, MetroHealth Medical Center, Cleveland, OH 44109
OBJECTIVES: To identify effects on quality of life of neurogenic bladder and bowel following spinal cord injury. To identify changes in quality of life reported by persons with an implanted stimulator for bladder and bowel control.
RESEARCH PLAN: Questionnaire study of persons with spinal cord injury attending a spinal cord injury unit, including a sub-group with an implanted stimulator for bladder and bowel control.
METHODS: A questionnaire was mailed to 125 persons with spinal cord injury attending a spinal cord injury unit for long-term follow-up, and an additional 13 persons who had received an implanted stimulator intended to improve bladder and bowel function. Data were retrieved by telephone using trained interviewers. Persons with an implanted stimulator acted as their own control with questions asked about quality of life before and after implantation of the electrical stimulator.
FINDINGS: Users of the electrical stimulator spend less time in bladder and bowel management, and report decreased symptomatic urinary tract infections, decreased medications, decreased financial costs, increased independence, and increased comfort going out in public.
CLINICAL RELEVANCE: The use of an implanted electrical stimulator for restoring function to the neurogenic bladder and bowel can reduce health care costs and increase quality of life for persons with spinal cord injury.
Funding agencies/sources, and other acknowledgments: Rehabilitation R&D Service, VA National Center for Medical Rehabilitation Research, NIH, Paralyzed Veterans of America
DEVELOPMENT OF A THREE-DIMENSIONAL BIOMECHANICAL MODEL OF
UNASSISTED STANDING VIA FNS
Zhao W, Triolo RJ, Kirsch RF
Cleveland VA Center of Excellence in FES
OBJECTIVES: The purpose of this research is to develop a realistic model for designing advanced FNS systems to achieve unassisted standing of individuals with paraplegia.
RESEARCH PLAN: A 3-D biomechanical model is being developed to study the biomechanics and control of unassisted standing of paralyzed individuals via FNS. The model takes account of non-symmetric lower extremity muscle activities, dynamic disturbances introduced by free use of the arms, kinematic constraints for the feet to remain on the ground, and the non-ideal body-mounted sensors. The validated model is used to design advanced controllers to achieve dynamic stable unassisted stance.
METHODS: An anatomically based model of lower limbs and trunk was developed in SIMM (Musculographics Inc.). Kinematic constraints are imposed to form a closed-chain bipedal stance model. It is further extended to a dynamic context by adding body inertial properties. Musculotendon dynamics are modeled by a generic, Hill-type model, and body dynamics are formulated using SD/FAST (Symbolic Dynamics, Inc.). The fully dynamic model is validated using experimentally collected EMG, kinematic, and kinetic data. Optimization techniques are then used to determine muscle activations so that upright posture is maintained with the lowest total energy consumption.
FINDINGS: Forward dynamic simulations with this model and with several different closed-loop control systems demonstrate the feasibility of unassisted standing of individuals with paraplegia via FNS.
CLINICAL RELEVANCE: This research provides a safe and systematic approach for developing a system capable of maintaining stable, prolonged, bipedal standing in paralyzed individuals via FNS.
(VA Center of Excellence in FES and NIH/NINDS Contract N01-NS-6-2351)
EFFECTS OF CONDITIONING ON PASSIVE MOMENT
Amankwah K, Kirsch RF, Triolo RJ
Cleveland VA Center of Excellence in FES
OBJECTIVE: The purpose of this work is to determine the level of significance conditioning has on passive moments generated at lower extremity joints.
RESEARCH PLAN: To accomplish the objective of this work, passive moments of able-bodied and spinal cord injured (SCI) individuals will be measured. For each subject group, tests will be performed on preconditioned and unconditioned joints to determine the effects of conditioning. The results from these experiments will be used to quantify the impact level of conditioning on passive moment measurements.
METHODS: Using a KinCom 500H muscle testing system we will perform isokinetic tests on knee. The unconditioned testing consists of having the subject sit quietly for 10 minutes. The joint is then rotated for ten cycles throughout its range of motion. This procedure is then repeated three more times. The preconditioned testing will follow and consist of rotating the joint through ten cycles of its range of motion followed by another set of ten cycles to measure the passive moment. Each of these tests is repeated on different days to ensure repeatability.
FINDINGS: Our findings suggest that conditioning has only a minimal effect on passive moment measurements.
CLINICAL RELEVANCE: For able-bodied subjects, their joints are relatively conditioned during daily activities and therefore passive moment measurements have been recorded after the joint is conditioned. The joints of SCI individuals are relatively immobile for long periods of time. Consequently it is important to determine whether or not conditioning is significant when making measurements on SCI individuals.
(VA Center of Excellence in FES, NIH/NINDS N01-NS-6-2351, NIH R01-NS-3-3756)
PERFORMANCE OF SELECTED ULTRALIGHTWEIGHT WHEELCHAIRS ON
Rentschler AJ2,3; Cooper RA1,2,3; Boninger ML1,2,3
11Division of PM&R, Univ. of Pittsburgh Medical Center, Pittsburgh, PA 15261; 2Dept. of Rehab. Science and Tech., Univ. of Pittsburgh, Pittsburgh, PA 15261; 3Human Eng. Research Lab., Highland Dr. VA Medical Center, Pittsburgh, PA 15206
OBJECTIVES: The purpose of this study was to compare the durability, stability, and cost effectiveness of four different ultralight wheelchair models: the Kuschall Champion 1000, the Invacare Action, the Everest and Jennings Epic, and the Sunrise Medical Quickie2.
RESEARCH PLAN: The twelve wheelchairs were evaluated by performing the ANSI/RESNA wheelchair standards tests. The results obtained from performing these tests will determine whether there is a significant difference between the performance of these wheelchairs.
METHODS: All twelve wheelchairs were tested in accordance with ANSI/RESNA manual wheelchair standards. Fatigue testing, as mandated in the standards, was performed on a double drum machine for 200,000 cycles and on a curb drop tester for 6,666 cycles. Additionally, each wheelchair was cycled through the double drum and curb drop tests until a Class III failure occurred on the wheelchair. A Class III failure indicates permanent damage, deformation, or failure which renders the wheelchair inoperable.
FINDINGS: There were significant differences in the number of total cycles completed by the four different models of wheelchairs. The mechanism of Class III failure also differed depending on the model of wheelchair. The fatigue lives of the Action XTRA and Champion 1000 are also significantly higher than those of lightweight wheelchairs previously tested.
CLINICAL RELEVANCE: The data collected from this study should provide consumers, clinicians, and manufacturers with information regarding the quality of four different types of commonly available ultralight wheelchairs. Clinicians will be better informed about the quality of different types of wheelchairs and will be able to make better selections and justification for funding.
COMPARISON OF TWO TYPES OF CROSS BRACE DESIGNS USED ON
DiGiovine CP1,2; Cooper RA1,2,3; DiGiovine MM1; Rentschler AJ1,2; Boninger ML1,2,3 1Human Eng. Research Lab., VA Pittsburgh HCS; 2Dept. of Rehab. Sci. and Tech., Univ. of Pittsburgh; 3Division PM&R, Univ. of Pittsburgh Medical Center
OBJECTIVES: Compare the number of cycles to failure using a modified ISO Double Drum Test for two cross-brace designs, one with a rectangular cross section and the other with a circular cross section on rehabilitation manual wheelchair.
RESEARCH PLAN: Determine a cross brace design which will last longer than the present design, but can be retrofitted to manual wheelchair frames which are already in service.
METHODS: The ISO Double Drum Test was modified to apply more stress on the cross brace. The wheelchair used was a manual rehabilitation wheelchair with a seat width of 50.8 cm and a seat depth of 45.72 cm. A 100 kg ISO Standard Dummy was loaded in the wheelchair.
FINDINGS: The cross braces with a rectangular cross section (253,000 ±192,000, n=7) had a significantly larger number of cycles to failure (two sample t-test, equal variances, ±=0.05) than the cross brace with a circular cross section (89,900 ±49,300, n=7). All of the cross brace failures occurred in the rear brace, and were transverse fractures originating at the bolt hole that connects the two braces.
CLINICAL RELEVANCE: A cross brace failure for an individual who uses a wheelchair can be devastating. Also, manufacturers of manual wheelchairs want to produce a reliable product, especially if they are providing a warranty on the frame. This analysis provides data that the new cross brace with a rectangular cross section will last longer than the cross brace with a circular cross section, while being able to retrofit the new cross brace to the original frame.
(This project was supported in part by the U.S. Department of Education (H129E50008) and the U.S. Department of Veterans Affairs, Rehabilitation Research and Development Service (B90-166A.)
WHEELCHAIR PROPULSION BIOMECHANICS AND MEDIAN NERVE
Baldwin MA2,3, Boninger ML1,2,3, Cooper RA1,2,3, Shimada SD4, Connor TJ2,3
1Division of PM&R, Univ. of Pittsburgh Medical Center, Pittsburgh, PA 15261 2Dept. of Rehab. Science and Tech., Univ. of Pittsburgh, Pittsburgh, PA 15261 3Human Eng. Research Lab., Highland Dr. VA Medical Center, Pitt., PA 15206 4California State Biomechanics Laboratory, Sacramento, CA 95819
OBJECTIVE: The purpose of this study was to look for differences in pushrim kinetics in a group of manual wheelchair users (MWUs) with (MN+) and without (MN-) evidence of median mononeuropathy.
RESEARCH PLAN: This research is intended to draw relationships between wheelchair propulsion biomechanics and individuals with paraplegia showing signs of median nerve dysfunction.
METHODS: Bilateral kinetic data was collected on thirty-five (24 male and 11 female) MWUs who propelled their own wheelchairs equipped with SMARTWheels. An average propulsion stroke was created using the first five strokes of steady state propulsion. From the averaged stroke, the maximum rate of rise and presence of an impact spike was determined for the resultant, radial, and tangential forces. Subjects were placed in the MN+ or MN- groups by the results of their NCS for comparison of biomechanical variables. The four parameters used to differentiate groups were the median motor and median sensory nerve amplitudes and latencies of each hand.
FINDINGS: A significantly higher rate of rise in the resultant, radial, and tangential forces was found in the MN+ while propelling at four miles per hour. No differences were seen between the two groups in presence of an impact spike.
CLINICAL RELEVANCE: This study found rapid loading of the arms during wheelchair propulsion to be associated with the presence of median mononeuropathy, an indicator of carpal tunnel syndrome. This information may lead to recommendations on propulsion technique as well as wheelchair setup to prevent repetitive strain injuries.
ACKNOWLEDGMENTS: The U.S. Department of Veterans Affairs Rehabilitation Research & Development Service (Project B689-RA), National Institutes of Health (NIH K08 HD01122-01) and the Paralyzed Veterans of America provided partial funding for this research.
PREVENTION OF RECURRENT PRESSURE ULCERS AFTER
Holmes SA1; Markowski J1; Garber SL2; Friedman JD3; Rintala DH2; Rodriguez GP2 1SCI Service, Houston VAMC; 2Dept. of Physical Medicine and Rehabilitation, Baylor College of Medicine; 3Dept. Of Plastic Surgery, Baylor College of Medicine
OBJECTIVE: The objective of this study is to evaluate the efficacy of education and structured follow-up to reduce the recurrence of surgically repaired pressure ulcers in persons with spinal cord injury (SCI). Additionally, the study will determine if monitoring levels of urinary collagen metabolites assists in early ulcer detection.
RESEARCH PLAN: Subjects are recruited from veterans admitted to the SCI Service, Houston VAMC, for surgical repair of an ulcer. Subjects are randomized to one of three groups. All are followed for two years or until they develop an ulcer at or near the surgical site.
METHODS: Four instruments are administered at the beginning and end of the study: 1)Pressure Ulcer Knowledge Test; 2) Health Beliefs Questionnaire; 3) Modified Major Life Events Questionnaire; 4) Locus of Control Scale. Group 1 (intervention group) participants receive an additional 4 hours of individualized education prior to discharge, are called monthly regarding skin status and ulcer prevention behaviors practiced, and send in urine samples. Group 2 participants receive standard education and monthly calls only to remind them to send urine for collagen analysis. Group 3 participants receive standard education and follow-up. Outcome measures include percentage remaining ulcer free and percentage remaining free of increased urinary collagen metabolite levels.
FINDINGS: Twenty-four subjects have been enrolled. Preliminary results indicate no recurrence in the intervention group. Four have been discontinued because of recurrent ulcers (3 from Group 2 and one from Group 3). Average scores on the Knowledge Test administered prior to discharge are higher for the intervention group than for other groups (77% vs. 58%). Mean concentration of urinary collagen metabolites (glucosylgalactosyl hydroxylysine-glugal) of Group 1 subjects is lower than that of Group 2 subjects. In subjects who developed ulcers, glugal concentration increased steadily, surpassing normal range long before the appearance of the ulcer.
CLINICAL RELEVANCE: Recurrence of surgically managed pressure ulcers results in decreased quality of life for SCI veterans and great expense to the VAMC. The goal of this study is to establish an intervention that will decrease ulcer recurrence in this population.
EFFECT OF LEXICAL DIFFICULTY AND STIMULUS VARIABILITY ON
Donald D. Dirks, Ph.D., Sumiko Takayanagi, Ph.D., P. Douglas Noffsinger, Ph.D., and Anahita Moshfegh, MS.
Portland VA Center for Rehabilitative Auditory Research, West Los Angeles VA Medical Center and UCLA School of Medicine
The objective of this research is to explore the effects of lexical difficulty and stimulus variability on speech recognition among persons with hearing impairment. There is substantial evidence that word recognition involves several underlying perceptual processes in which the speech signal is converted into an acoustic-phonetic representation, normalized for stimulus variability factors such as talker variability, speaking rate and dialect, and then identified by matching the transformed internal representation to items in long-term lexical memory. Regarding the last step, successful recognition of a target appears to be influenced by lexical factors such as the frequency of occurrence of words in lexicon (word frequency), the number of other phonemically similar words with which the target can be confused (neighborhood density), and the frequency of these similar words (neighborhood frequency). The research plan is divided into developmental and investigative phases. In the current developmental phase, over a thousand monosyllabic words (consonant-vowel-consonant) have been divided into four groups of stimuli based on lexical characteristics. The lexical statistics were obtained from a computer-readable version of Webster's Dictionary developed by the Speech Research Laboratory, Indiana University. These groups of words have the following lexical structures: 1) High frequency-high neighborhood density-high neighborhood frequency; 2) High frequency-low neighborhood density-low neighborhood frequency; 3) Low frequency-high neighborhood density-high neighborhood frequency; 4) Low frequency-low neighborhood density-low neighborhood frequency. Intelligibility for each group of words will be assessed to determine the relative importance of each variable category on speech recognition. The words will then be recorded by ten talkers so that the potential interactions between stimulus variability and lexical difficulty can be explored. These investigations should lead to the development of new speech recognition procedures which may more effectively predict speech perception performance outside the laboratory or clinic than currently available tests.
This research is supported by grant RCTR-597-0160, Department of Veterans Affairs Center for Rehabilitative Auditory Research (Stephen Fausti, Ph.D., Principal Investigator) and Rehab. RR & D Grant C2225 RL (Donald D. Dirks, Ph.D., Principal Investigator).
A BIOMECHANICAL EVALUATION OF VISUALLY IMPAIRED PERSONS'
Ramsey, V. K.
Rehabilitation Research & Development Center, VAMC Atlanta; Georgia State University, Department of Kinesiology and Health
OBJECTIVES: The purpose of this study was to compare gait and long cane mechanics between groups of visually impaired mobility trained subjects during normal and multi-tasked walking.
RESEARCH PLAN: Recruitment of subjects was accomplished in conjunction with the VAMC, Center for Visually Impaired and North Georgia Blind and Low Vision Services. Data collection and analysis was performed in the Rehab R&D Center as a Core Funded Project.
METHOD: Twenty subjects mean age 50.32 ± 18.36 years participated in this study. Ten reflective markers were placed on each subject and tracked through a calibrated space using a three camera Motion Analysis Corporation videography system. Twelve dependent variables of gait and long cane mechanics were measured and analyzed. Subjects were grouped into Good or Bad categories based on their long cane techniques. Grouping designations were determined by a three person panel of orientation and mobility experts. Subjects were required to perform seven walking trials consisting of normal walking, walking while reacting to a simulated drop-off, walking while responding to an audible secondary task, and walking while reacting to a simulated drop-off while responding to an audible secondary task.
FINDINGS: Significant differences within groups by trial were found for components of hip flexion velocity, gait velocity, and stride length. These data indicate a significant alteration in the normal walking pattern of visually impaired persons when faced with multi-tasking situations.
CLINICAL RELEVANCE: Attention demanding tasks placed on visually impaired travelers during normal walking could decrease their ability to detect path obstacles thereby increasing the risk potential for falls and injury.
EVALUATION OF LOW VISION READING ASSESSMENTS USING A
SCANNING LASER OPHTHALMOSCOPE
Watson, GR, Schuchard, RA
Watson - Atlanta VA Rehab. R&D Ctr., Emory U. (Rehab. Med.), GA State U. (Dept. of Mental Health/Human Ser.), PA Coll. of Opt. (Dept. of Grad. Studies in V.I.) Schuchard - U. of Missouri-Kansas City Dept. of Oph.
OBJECTIVES: 1) to validate three reading assessments that are commonly used in clinical low vision by assessing the relationship of their scoring (rate, accuracy and error scores) to the preferred retinal locus (PRL) used by individuals with macular disease for viewing using the confocal scanning laser ophthalmoscope (SLO) 2) to assess the effectiveness and efficiency of reading training techniques presently used in clinical low vision.
RESEARCH PLAN: Software was developed using the SLO to evaluate vision function, subjects were recruited from VA and local agencies for the visually impaired. Training was provided by a Certified Low Vision Therapist. The study was double-blind.
METHODS: Data was collected on acuity, fields, contrast sensitivity, reading ability (Pepper VSRT, MNRead, Morgan LVRCA), as well as the preferred retinal loci and its characteristics for readers with macular loss. Subjects were provided with clinical reading training, and half the subjects were provided with an in-home workbook to continue practicing. All testing was repeated after 5 weeks.
FINDINGS: Data from 60 subjects will be presented in the poster session. Initial data analysis confirms the basic hypotheses of the project. One unexpected finding was the number of subjects who gained or lost vision during the 6 weeks of the project.
CLINICAL RELEVANCE: The findings of this project will give low vision rehabilitation professionals more information about the clinical relevance of the three reading assessments, will provide a more complete picture of vision function during reading, and will evaluate the effectiveness of in-home practice for increasing reading ability for this population.
THE USE OF BIOPTIC TELESCOPES BY PATIENTS WITH CENTRAL
J.P. Szlyk1,2; W. Seiple3; D. Laderman2; R. Kelsch4; T.McMahon2; J. Stelmack4; G.A. Fishman2 1West Side VA Medical Center; 2Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago; 3New York University Medical Center; & 4Hines VA Medical Center, Maywood, IL
PURPOSE: To investigate the effective use of an expanded field bioptic telescope in patients with central vision loss.
METHODS: Seventeen patients with macular degeneration were enrolled in a cross-over design study. Low vision training with the use of a bioptic telescope consisted of 5 weeks of visual skills training, and 8 weeks of driving training on a road course. Data were collected on clinical visual function (including visual fields, visual acuity, and letter contrast sensitivity), psychophysical central and peripheral acuity, search and identification of peripherally-presented letter optotypes, mobility, visual memory, scanning, and tracking on three test days (baseline, 3 & 6 mos.).
RESULTS: All tests were coded for improvement relative to a test-retest criterion set by a control group given no training or telescope. Primary visual skill categories showed improvement: "recognition" (49%), "mobility" (41%), "peripheral awareness" (54%), "scanning" (51%), "tracking" (66%), and "visual memory" (58%). Those patients with smaller central scotomas showed significantly greater task improvement in the "tracking" (r(8)=-.68, p<.04) and "visual memory" categories (r(8) = -.85, p<.004) with the telescope.
CONCLUSION: These data quantify the areas of trainable improvement with a bioptic telescope.
Support: US Dept. of Veterans Affairs, Foundation Fighting Blindness. None.
NEUROTRANSMITTER DISTRIBUTION IN CAT RETINA FOLLOWING
SUBRETINAL IMPLANTATION OF MICROPHOTODIODE-BASED RETINAL
Pardue MT, Perlman JI, Stubbs EB Jr, Chow AY, Peachey NS
Hines VA Hospital, Loyola Univ Med Ctr, Optobionics Corp, LSU Eye Center
OBJECTIVES: To evaluate changes in excitatory and inhibitory neurotransmitter distributions in the cat retina following implantation of microphotodiode-based retinal prosthetic devices.
RESEARCH PLAN: PiN and NiP semiconductor-based devices were implanted into the subretinal space of adult cats using a retinotomy approach. After post-operative periods that ranged from 2 to 24 months, the retina was fixed and analyzed using antibodies that recognize excitatory (glutamate) and inhibitory (GABA, glycine) retinal neuro-transmitters.
METHODS: Fixed retinal pieces were embedded in Epon and sectioned using an ultramicrotome. Neurotransmitters were labeled using monoclonal antibodies against glutamate, GABA, and glycine and visualized using silver-intensification.
FINDINGS: The anatomical distribution of glutamate, which is involved with outer retinal function, was slightly decreased in the implant area, which also displayed a loss of photoreceptors. Adjacent to the implant, however, glutamate displayed a normal distribution. The distribution of GABA was decreased directly over the implant in comparison to neighboring retinal areas. In comparison, glycine immunoreactivity, which is usually at an extremely low level in the cat retina, was markedly increased in areas directly overlying the implant but not at locations away from the implant site. A similar increase in glycine was not seen in transgenic mouse models of photoreceptor degeneration, indicating that this change may not be a general response to photoreceptor loss. We are currently carrying out parallel studies in the Abyssinian cat, a model of rod-cone dysplasia.
CLINICAL RELEVANCE: These studies provide important information regarding the manner in which an artificial retinal prosthetic may affect basic processes involved in retinal function.
(Supported by the Department of Veterans Affairs and National Eye Institute grant R43 EY 11828)
EVALUATION OF NON-AUDITORY FACTORS WHICH AFFECT HEARING
AID USE IN ELDERLY VETERANS
Rappaport BZ, VA Medical Center, School of Medicine, Univ. of New Mexico, Albuquerque, NM; Fausti SA, Director, RR&D Ctr., Oregon Health Science University, Portland, OR
OBJECTIVES: The goals of this study were to determine how the non-auditory factors of mental status, visual acuity, fine motor coordination, motivation, and social support affect the use of hearing aids in an elderly veteran population.
RESEARCH PLAN/METHODS: Subjects were hearing-impaired veterans age 60 and above with no previous hearing aid experience. Each subject received a comprehensive evaluation of auditory function; assessment of function of the non-auditory factors using standard and nonstandard measures; and a hearing aid evaluation. Subjects also completed two outcome measures to evaluate perceived hearing handicap and hearing aid benefit. These measures were the Hearing Handicap Inventory-Elderly (HHIE), and the Hearing Disability Inventory/Hearing Aid Benefit Inventory (HDI/HABI). Outcome measures were completed prior to initial hearing aid fitting, and at a follow-up evaluation after four months of hearing aid use. Many of the audiometric tests, and all of the measures of non-auditory function were also repeated at follow-up.
FINDINGS/CLINICAL RELEVANCE: In all, 375 subjects were evaluated. Of the total, 41 subjects are no longer using the hearing aids with which they were fit. An analysis of the reported reasons for not using their amplification demonstrated that 46% felt that their hearing aids were of no benefit. A comparison of these subjects with those who continue to use and report benefit from hearing aid use reveals non-auditory factors to be the distinguishing characteristics between groups. The groups do not differ significantly in age, degree of hearing loss, word recognition ability, and perceived hearing handicap. These findings suggest that current outcome measures may not be sensitive to certain factors that influence successful use of amplification in this population.
DIRECTIONAL HEARING AIDS AND PARTIAL NOISE REDUCTION
Harry Levitt, PhD
Center for Research in Speech and Hearing Sciences, Graduate School and University Center of the City University of New York, NY
The recent introduction of all-digital hearing aids offers new possibilities with respect to the problems of background noise and room reverberation. Several advanced digital signal processing schemes that could be implemented in a wearable digital hearing aid have been developed and evaluated. For the case of a single microphone input, the techniques considered include spectrum subtraction, sinewave modeling, Wiener filtering, and related techniques. Multi-microphone techniques have included directional microphone arrays, adaptive noise cancellation, and binaural cross correlation. Whereas the single-microphone techniques were able to increase speech-to-noise ratio, there were no corresponding improvements in speech intelligibility although improvements in overall sound quality were obtained in some cases. In contrast, the multi-microphone techniques typically provided improvements in both speech-to-noise ratio and speech intelligibility (as well as improved overall sound quality), Multi-microphone techniques, however, were of limited value in highly reverberant environments and also presented problems with respect to physical size and cosmetic acceptability.
RELIABILITY OF TINNITIS LOUDNESS-MATCHES:
COMPUTER-AUTOMATED TECHNIQUE VERSUS MANUAL TESTING
James Henry, Ph.D., Steven Fausti, Ph.D., Mary Meikie, Ph.D., Alison Gilbert, M.S., Roger Ellingson, M.S., Christopher Flick, B.S.
Portland VA RR&D Center for Rehabilitative Auditory Research
OBJECTIVES: Tinnitus is an international health problem that does not have consensus regarding testing methodology to quantify the disorder. It is the objective of this study to address the need for establishing a standardized method for the clinical measurement of tinnitus in order to facilitate inter-clinic uniformity.
RESEARCH PLAN: Because automation is an effective means to achieve standardization, a computer-controlled psychoacoustical system was developed to quantify tinnitus loudness and pitch using a tone-matching technique. The procedure was patterned from a manual testing technique that has been used to measure tinnitus in over 4000 patients, Patients were evaluated using both the automated and manual techniques to compare reliability of the measures.
METHOD: The automated system generates test stimuli and simultaneously controls a, notebook computer positioned in a sound chamber facing the patient. The notebook computer displays instructions for responding, and relays response choices through on-screen "buttons" which the patient touches with a pen device. Twenty subjects with tinnitus were evaluated with the system in two sessions. The manual testing technique was used to obtain the same measurements in 22 subjects with tinnitus.
FINDINGS: Both techniques were analyzed for test-retest reliability of responses between sessions one and two. For the automated technique, Pearson's product-moment correlations revealed r's > .885 at all test frequencies
CLINICAL RELEVANCE: The automated system may ultimately provide optimal reliability for clinical purposes because procedural variations (within- and between-testers) are reduced with automation. Further development of the automated technique is expected to contribute towards promoting standardization of a reliable procedure to measure the acoustical parameters of tinnitus,
(Support for this project was provided by VA Rehabilitation Research and Development Service.)
UNCERTAINTY AND DICHOTIC DIGIT RECOGNITION IN YOUNG AND
Strouse-Carter A, Wilson RH
VA Mountain Home, TN and Dept. of Surgery, ETSU
OBJECTIVES: (1) Develop and evaluate a hierarchy of dichotic digit materials that range in complexity, in an attempt to delineate the boundary where acoustic perception or memory difficulty may begin to occur in the aging listener. (2) Evaluate the clinical reliability of the test materials.
RESEARCH PLAN: Data are being obtained for 210 subjects ranging in age from 20-89 years (30 subjects in each decade age group). Uncertainty is introduced by varying the number of digit pairs in each stimulus set (1-, 2-, and 3-pair) and by varying response criteria to include free and directed recall conditions.
METHODS: Dichotic digits (1-, 2-, and 3-pairs) are presented in free and directed (pre-bias/post-bias) recall conditions. For free recall, subjects identify the digit pairs heard in both ears, in any order. For directed recall, subjects identify only the digits heard in one ear. The ear reported is pre- or post- cued relative to stimulus presentation. Subjects are evaluated twice in each condition to examine inter-test reliability.
RESULTS: Data collection is currently in progress. Preliminary analyses reveal: (1) as the complexity of the listening task is increased, recognition performance for all groups decreases, and the effect is more pronounced for elderly listeners; (2) the decrease in performance with increased complexity is more on materials presented to the left ear; (3) inter-test reliability is high.
CLINICAL RELEVANCE: Differences in performance within and across conditions likely reflect the memory load required for completion of the task in each condition. The test paradigm may be helpful in differentiating auditory from cognitive deficits in elderly listeners. An audio demonstration of the materials will be available.
(This research is supported by a Career Development Award from Rehabilitation Research and Development Service awarded to the first author in October, 1997).
THE EFFECT OF A SILANE COUPLING AGENT ON THE BOND
STRENGTH OF BONE CEMENT AND COBALT-CHROMIUM ALLOY
Yerby SA, Young PM, Beaupré GS, Paal A, Goodman SB
Rehab R&D Ctr, VA Palo Alto HCS; Mech. Eng. & Functional Restoration Depts., Stanford Univ.
OBJECTIVES: The objective was to quantify the bond strength of polymethylmethacrylate (PMMA) and Cobalt Chrome (CoCr) both with and without a silane coupling agent.
RESEARCH PLAN: Silane is a bi-polar compound which bonds an alloy oxide to an open-chain polymer. This bonding technique can potentially be applied to the orthopaedic field where cement-implant debonding is one of the initial causes of implant loosening.
METHODS: Specimens were prepared by placing a phenolic tube concentric with a CoCr rod and filling the space between the phenolic and CoCr with bone cement. After curing, the CoCr rods were pushed out at a strain rate of 0.0013/s until failure. Specimens were grouped into control and silane coated samples. Half of the specimens in each group were tested immediately after preparation, while the other half were tested after soaking in 37 °C saline for 60 days The mean ultimate strengths were compared using an analysis of variance with a level of significance of 0.05.
FINDINGS: The mean strengths of the silane coated specimens ranged from 4621 N to 6099 N, and the mean strengths of the control specimens ranged from 1917 N to 3815N. The strengths of the silane coated samples were significantly different than that of the control samples. There was no significant difference between strengths acquired after soaking.
CLINICAL RELEVANCE: Silane coating may provide an immediate long-lasting bond between the bone cement and the prosthesis, and potentially increase the time to implant failure.
AGE AND TRAINING-RELATED ADAPTATIONS IN CONTROL OF
Patten C & Kamen G
Rehab R & D Center, VA Palo Alto Health Care System; Dept. of Functional Restoration, Stanford University; & Dept. of Exercise Science, University of Massachusetts Amherst
OBJECTIVES: This research was performed in an effort to better understand neural mechanisms involved in age-related change in the control of muscular force and adaptation to exercise interventions used commonly in clinical rehabilitation.
RESEARCH PLAN: Control of important motor tasks including gait, balance, reaching and prehension becomes notably impaired with aging. In common to such tasks is the organization and control of muscular force by the central nervous system. Neural adaptations to training have long been recognized, and it has been the prevailing belief that the benefit to older adults from exercise interventions results from these neural adaptations, rather than muscle hypertrophy or other physiologic change. Thus, examination was made of neural adaptations to both strength and force control training exercise.
METHODS: Healthy young (<30 years) and older (>65 years) adults participated in training programs (6 weeks) to either increase muscular strength or improve force accuracy. Muscular strength, force accuracy, and motor unit activity were examined sequentially with training.
FINDINGS: Young adults demonstrated comparable gains in muscular strength and improvements in force regulation regardless of the training intervention. In contrast, adaptations in older adults were specific to the training modality. Motor unit activity afforded an opportunity to examine age-related differences in the specific neuro-motor mechanisms involved in these disparate adaptations.
CLINICAL RELEVANCE: Methods for effective improvement in health including movements such as gait and balance will promote functional independence with aging. Information gained from this research can be incorporated into exercise prescription guidelines for community-based programs or clinical rehabilitation settings.
(Supported by VA Rehab R & D (Career Development Award PAT-0001129), the Foundation for Physical Therapy, and NIA AG-09662)
COMPARISON OF BICYCLE KINEMATIC & KINETIC PARAMETERS
IN THOSE WITH & WITHOUT DIABETES
Perell KL, Talamo M, Tantraphol M, Peralta M, Kumar R, Scremin AME, Levin S
WLA VAMC Research, PM&R & Medicine Depts.
OBJECTIVES: The objective was to compare ankle kinematics and pedal forces during bicycling in subjects with and without diabetes.
RESEARCH PLAN: We plan to test 15 subjects in each group on the stationary recumbent bicycle. To date, we have tested 6 subjects with diabetes and 7 without diabetes.
METHODS: Subjects pedaled at self selected speeds on a stationary recumbent bicycle (Cateye 3500) instrumented with pedals which measure normal and tangential forces. A high resolution computer based six camera motion analysis system (Motion Analysis Corp., Santa Rosa, CA) was used to collect kinematic (60 Hz) and kinetic (240 Hz) data during bicycling. Peak pedal forces & amount of ankle range of motion (ROM) (maximum - minimum) during bicycling were compared between groups & across pedaling speed. Nerve conduction velocity studies were done to quantify degree of peripheral neuropathy in subjects with diabetes.
FINDINGS: Preliminary data from 3 subjects in each group demonstrated a trend toward decreased ankle ROM, increased anterior tangential force, and increased downward applied normal force (pushing down on the pedal) in the subjects with diabetes.
CLINICAL REVELANCE: Patients with diabetic peripheral neuropathy have demonstrated increased falls rates, decreased ankle ROM, and increased plantar pressures during walking. Bicycling allows for a safe exercise environment without the risk of falls and provides a platform for feedback regarding ankle ROM and force applied to the pedal. These feedback parameters will be used to "teach" subjects with diabetes to reduce forces during pedaling and increase ankle ROM. Further studies will evaluate the effect of the set types of feedback on walking.
QUALITY OF LIFE OF VETERANS WITH DISABILITIES LIVING IN
ASSISTED LIVING FACILITIES
Whittington, FW, Ball MM, Perkins MM, Connell BR, Sanford J. Patterson V, Morton M, & King S
Rehab R&D Center, Atlanta, GA; Gerontology Center, GA State Univ.
OBJECTIVES: The aims of this pilot study were to determine how veterans with disabilities living in assisted living facilities (ALFs) define quality of life and to identify factors in the environment that contribute to veterans' quality of life.
RESEARCH PLAN: The research sample consisted of 20 ALF residents. Eighteen of these residents lived in 8 ALFs certified for VA's Community Residential Care Program (CRCP) clients; 11 residents were veterans, all male. facilities were located in both urban and suburban areas and ranged in size from 3 to 54 beds. CRCP facilities served low-to-moderate-income residents with both mental and physical disabilities.
METHODS: Data collection strategies included in-depth interviewing, review of residents' records, and observation of the environment of each ALF. All interviews were tape-recorded and transcribed. Analysis of transcribed data followed the grounded theory method and was facilitated by Ethnograph, a computer software package for qualitative analysis.
FINDINGS: We identified 14 domains of quality of life based on the aggregated values expressed by residents in interview data, Domains included aspects specifically related to quality of care as well as components of the broader concept, quality of life, such as autonomy and psychological well-being. While these findings show that the domains included in veterans' definitions of quality of life are similar to those found in studies of non-veterans, specific differences were evident, which relate in part to the type of disability, gender, and socioeconomic status of the veterans. For some veterans, the support provided by the CRCP had significant positive impact on the quality of their lives.
CLINICAL RELEVANCE: These findings will help guide the VA's CRCP in improving the quality of the lives of participating veterans.
(This research was funded by VA Rehabilitation Research & Development Center on Aging, Atlanta, GA)
USEFUL FIELD OF VIEW AND DYNAMIC BALANCE IN ELDERLY
Rehabilitation R&D Center, VAMC Atlanta GA. (Core-sponsored Atlanta Rehabilitation R&D Center)
OBJECTIVES: Useful field of view (UFOV) is an independent predictor of car accident occurrence in older adults as a measure of visual information processing. The purpose of this project was to explain a clinical balance measure known to predict fall risk as a function of UFOV and physical performance measures.
RESEARCH PLAN: Twenty-eight community-dwelling elders aged 71 to 90 (75.9 + 7.3) participated in the two-hour protocol.
METHODS: Subjects were evaluated on gait speed (GS), dynamic balance using timed up and go (TUG), static balance using functional reach (FR), visual acuity (VA) using the Snellen chart, general cognition using the Mini-Mental State Examination (MMSE), and UFOV using the attention analyzer to describe UFOV as a percent reduction.
FINDINGS: UFOV was significantly correlated with FR (441). GS and TUG were highly correlated (0.89). A logistical regression analysis was used to predict FR as a function of the predictor variables. GS was not entered into the regression analysis because of the multicolinearity with TUG. UFOV and VA together accounted for 54% of the performance related to variance in FR. The results suggest that visual attention and visual sensation represent predictors of static balance.
CLINICAL RELEVANCE: We interpret these data to mean that further exploration of UFOV to predict imbalance and falls has merit. UFOV and other visual attention measures need to be considered for mobility performance and for training protocols to improve balance in older adults.
AGE AND STROKE EFFECTS ON STEP STRATEGIES
Lunchies CW, Pohl PS, Yates J, Duncan P, Wallace D
Center on Aging, University of Kansas Medical Center, Kansas City, KS, Kansas City Department of Veterans Affairs Medical Center
OBJECTIVES: The ability to quickly utilize effective balance strategies is needed to respond to balance disturbances. We tested the hypothesis that age and stroke each adversely affect the step strategy often used for balance recovery.
RESEARCH PLAN: Cross-sectional study
METHODS: Three groups of ten subjects were tested: healthy younger adults (YA: 26.3 + 4.9 yrs), healthy older adults (OA: 68.7 + 8.1 yrs), and older adults with mild stroke (SA: 64.0 + 13.5 yrs). Stroke severity was determined by the Orpington Prognostic Scale. Prior to posterior waist pulls, the subject stood with a spontaneous and a symmetric weight distribution.
FINDINGS: All but one SA stepped with their unaffected side in each condition. No preference in step side was observed in the OA and YA. Age and stroke each increased the temporal components of the step strategy as follows: weight shift time - YA=216±46* (all time is in msecs), OA=259±127, SA=289±124; liftoff time -- YA=298±47, OA=350±125, SA=401+121; and landing time -- YA=386±81, OA=446±171, SA=492±167.
The tibialis anterior (TA) latencies in the first step leg increased with age and with stroke (YA: 82+14 , OA 91+11, SA: 111+25). In the SA, TA latencies were longer in the affected leg compared to the unaffected leg (affected: 125 + 24, unaffected: 105+15). In the SA, a symmetric stance decreased the step foot liftoff time (401+121 vs 362+103) by decreasing the weight shift time (289+124 vs 251+83), without affecting the TA latencies (111+25 vs 110+33).
Adults with stroke step with their unaffected leg, leaving the affected leg for stance during the step strategy. Stroke compounds the adverse age effects on abilities to quickly respond to balance disturbances. Improving stance symmetry decreases step liftoff time by decreasing the weight shift time, without affecting the TA latency time.
CLINICAL RELEVANCE: Older subjects and individuals with mild stroke have slower step strategies in response to postural disturbances. Rehabilitation programs should be developed to improve step strategies for balance recovery.
(Funding -- Department of Veterans Affairs Rehabilitation Research and Development Service and Claude Pepper Older Americans Independence Center, National Institute of Aging)
EFFECTS OF AGING ON THE CONTROL OF MUSCLE FIBER
Erim, Z. Beg, M.F., Burke, D.T.* and De Luca, C.J.
Research Service Boston VA Medical Center, NeuroMuscular Research Center, Boston University, * Department of PM&R, Harvard Medical School, Boston
PURPOSE: In this study our goal was to understand the effects of aging on the control of muscle fibers which make up a motor unit.
RESEARCH PLAN: The firing patterns of motor units were studied in 10 young and 10 elderly male subjects in order to determine the effects of aging.
METHODOLOGY: The first dorsal interosseous muscle was studied in male subjects during voluntary abduction of the index finger. Electromyographic signals detected via the quadrifillar needle electrode and the surface bipolar electrodes were recorded along with the force generated by the muscle. The Precision Decomposition Technique was used to identify firing times of motor units.
FINDINGS: Observations on data analyzed reveal three main findings: 1) The highly correlated common fluctuations in the firing rates of concurrently active motor units in the young are not as correlated in the elderly; 2) The phenomenon of onion skin observed in the young whereby motor units recruited earlier during increasing force have a higher average firing rate than motor units recruited later which have a lower firing rate is not observed in the elderly in whom the firing rate plots of motor units "crossover"; 3) Motor unit firing rates which show decreases in the young during constant-force contractions as a result of the potentiation in twitch forces, do not display any decreases in the elderly, suggesting a decrease in the capacity of aged muscle fibers to potentiate. Taken together, these observations suggest an altered control behavior of motor units in the elderly as compared to the young.
CLINICAL RELEVANCE: In parallel with enhanced life expectancy, elderly individuals represent an increasingly larger portion of the Veteran population. The knowledge of age-related alterations in the control of motor units will provide insight into the observed decline in neuromuscular performance. It is hoped that this knowledge will lead to the design of exercise and rehabilitation programs to slow down or reverse the debilitating effects of aging for the elderly Veteran.
(Supported by the Rehabilitation Research & Development Service of the Dept. of Veterans Affairs.)
ASSESSMENT OF STEPPING THRESHOLD A PREDICTOR OF FALLING
Oddsson L.I.E. & Negron V. & De Luca C.J.
NeuroMuscular Research Center, Boston University
OBJECTIVES: Loss of balance is the beginning of a fall and unless a successful step is executed the subject may hit the ground and experience severe injury and even death. Our current understanding of dynamic postural control is largely based on studies of the effect of minor balance perturbations where standing equilibrium was maintained. Only a few studies have exposed subjects to perturbations large enough to force them off balance. The objective of the current project was to assess the stepping threshold, i.e. the level of perturbation an individual can sustain without loosing balance. It was hypothesized that the stepping threshold would vary greatly between healthy subjects and that the stepping threshold would be direction specific.
RESEARCH PLAN: Twenty healthy subjects were exposed to random balance perturbations in eight different directions on a unique high performance balance perturbation platform.
METHODS: An algorithm was implemented that gradually changed the perturbation level to asses at what level of perturbation the subject was forced to take a step. Subjects rated the severity of the each perturbation on a 10 grade Borg scale for perceived exertion.
FINDINGS: The stepping threshold was highest for lateral and backward directed perturbations and lowest for forward perturbations (subject falling backward). A more than three-fold difference in stepping threshold was found across subjects. Significant correlations between the level of balance perturbation and Borg scale rating were found across subjects suggesting that individuals actually perceived the perturbations similarly although they displayed very different stepping thresholds.
CLINICAL RELEVANCE: This test could be used in the clinic to discriminate between subjects prone to falling as well as to train subjects in regaining equilibrium after large balance perturbations.
(Supported by the Whitaker Foundation and the NeuroMuscular Research Center)
THE STRUCTURE AND STRUCTURAL EFFECTS OF VA REHABILITATION
BEDSERVICE CARE FOR STROKE
Reker, D1, Hoenig, H1-4, Zolkewitz, M3, Sloane, R1,4, Horner, R1,2, Hamilton, B4, Duncan, P5
1HSR&D and ERIC, Durham VAMC; 2Dept of Med., Duke Univ. Med Ctr.; 3PM&RS, Durham VAMC; 4Center on Aging, Duke Univ.; 5HSR&D, Kansas City VAMC and Ctr. for Aging Research, KUMC.
OBJECTIVES: To determine if there are differences in organizational resources among VA Rehabilitation Bed Units (RBUs) and to assess the relationship of these differences to patient outcomes (functional gain, length of stay (LOS), and discharge location).
RESEARCH PLAN: Cross sectional survey design linked with 2 years of patient outcome data.
METHODS: Two surveys of VHA acute and post acute stroke resources were joined with 2 years of stroke rehabilitation outcome data (Uniform Data Systems) to create the study dataset. These provided over 100 different organizational characteristics and patient characteristics. Differences among RBUs in organizational resources were determined through descriptive statistics. Effects of organizational resources on patient outcomes were tested with hierarchical linear modeling.
FINDINGS: There is considerable variation in organizational resources among the 59 RBUs. There is also considerable variation among units in case-mix adjusted stroke outcomes (functional gain, length of stay, and discharge to community). Approximately 20-25% of the variation in stroke patient outcomes can be explained by patient level characteristics. An additional amount of variation (6%-13%) in patient outcomes can be attributed to the unit itself. However, no further explanation of variance was provided by organizational resources, such as staffing patterns or the presence of a formal stroke protocol. Thus, differences in organizational resources do not predict differences in patient outcomes.
CLINICAL RELEVANCE: These findings suggest that the remaining unexplained variation in stroke outcomes may be associated with processes of care, more specific patient level characteristics, and/or unique interactions between structure, process, and patient characteristics.
(Funding and support for this research has been provided through the Health Services Research and Development Service and the Rehabilitation Research and Development Service, Office of Research and Development, Veterans Health Administration, Department of Veterans Affairs.)
FATIGUE IN PROSTATE CANCER PATIENTS: A PROSPECTIVE
Monga U, M.D.; Kerrigan AJ, Ph.D.; Thornby J, Ph.D.; Monga TN, M.D.
Houston VA Medical Center; Departments of Radiology, Section on Radiation Oncology and Physical Medicine and Rehabilitation, Baylor College of Medicine; Houston Rehab R&D Center
OBJECTIVE: To prospectively evaluate prevalence of fatigue in prostate cancer patients undergoing radiotherapy (XRT).
RESEARCH PLAN: Evaluations were carried out at Pre-radiotherapy (PRT), completion of radiotherapy (CRT), and 4-5 weeks follow-up (FRT). Phase I: We reported a decline in Neuromuscular Efficiency (NME) and enhanced Neuromuscular Fatigue (NMF) in prostate cancer patients undergoing XRT.1
Phase 11: Hypothesis: Subjective fatigue is independent of depression and sleep disturbance.
METHODS: Instruments used: Piper Fatigue Scale (PFS), Beck Depression Inventory (BDI), Epworth Sleepiness Scale (ESS) and Functional Assessment of Cancer Therapy - Prostate (FACT-P). Thirty-six prostate cancer subjects, mean age of 66.96 years (range 55-79), were assessed.
FINDINGS: On PFS, median scores increased significantly at CRT as compared with PRT values. A significant relationship was found between PFS and Physical Well Being Subscale of FACT-P scale at PRT and CRT. No significant changes were noted in BDI and ESS scores during treatment. Higher scores on PFS at completion, and no change either on BDI or ESS scores, would suggest that fatigue most likely is not the result of depression or sleep disturbance. Based upon our phase I results, we propose that physical expression of fatigue is secondary to decline in NME and enhanced NMF.
CLINICAL RELEVANCE: The impact of fatigue and depression (common symptoms) on rehabilitation outcome is not known. Third phase of the study to evaluate the role of exercise to prevent fatigue and improve psychological functioning in patients undergoing XRT is being formulized.
SKELETAL AND MUSCULAR RESPONSES FOLLOWING BELOW-KNEE
O'Mara GD, Shem KL, Breakey J, Kiratli BJ
SCI Center, VA Palo Alto HCS; Functional Restoration, Stanford University; Prosthetics Dept, Santa Clara Valley Medical Center
OBJECTIVES: Our objective was to evaluate the effect of unilateral below-knee amputation on femoral bone and muscle mass.
RESEARCH PLAN: Our goal is to improve our understanding of how bone and muscle adapt to changes in mechanical loads (ie, altered and reduced weightbearing with amputation and prosthetic use) in clinical situations and identify the factors which may contribute to these responses.
METHODS: Bilateral bone mineral density (BMD) measurements were made of the proximal and midshaft femur in 19 individuals with unilateral below-knee amputation (BKA). All subjects were ambulatory with prostheses. In addition, midshaft cortical thickness and mid-thigh circumferential muscle mass were measured. Differences between sides were evaluated by paired t test analysis and regression analysis was used to examine effects of demographic variables.
FINDINGS: All bone and muscle values of the amputated leg were significantly reduced (10-15%) compared with the intact leg (p<0.001). There were no associations between bone/muscle decreases and duration of amputation, habitual degree of ambulation, age, or weight.
CLINICAL RELEVANCE: While there is some indication of increased fracture risk in individuals with BKA, few data have been reported on musculoskeletal responses following unilateral amputation. These individuals experience greatly reduced muscular activity but maintain nearly normal weightbearing. Substantial loss of muscle mass is expected and observed due to absence of muscle action. The observed bone loss indicates that weightbearing alone is not sufficient to maintain bone integrity. Physical or pharmacologic interventions may be necessary to prevent or reverse bone loss. In addition, these results may be useful in educating BKA patients regarding increased fracture risk.
TOWARDS ACHIEVING THE GOAL OF MEANINGFUL, COORDINATED,
SUBCONSCIOUS, MULTI-FUNCTIONAL, CONTROL OF PROSTHESES
Richard F. ff. Weir, Dudley S. Childress, and Craig W. Heckathorne
Northwestern University Prosthetics Research Laboratory, Chicago, IL 60611
OBJECTIVES: To achieve meaningful, coordinated multi-functional control of prostheses through subconscious, physiologically appropriate sensory feedback, beyond that provided by vision.
RESEARCH PLAN: Body-powered devices get their feedback through the tension felt in the control cable. Externally-powered devices have no such cable. For single degree-of-freedom systems, vision is sufficient. But for multiple degree-of-freedom systems, the mental burden becomes excessive. We believe Dr. David Simpson's concept of extended physiological proprioception (e.p.p.) is a means of providing externally-powered prostheses with similar sensory feedback. We believe significant advances in upper-limb prosthesis control can be achieved through the use of surgical procedures to create additional control sites. For example, procedures such as miniature muscle or tendon cineplasties which can be used to externalize the force and excursion of a muscle. In this way residual muscle is used as a control input to a servo-controller, and being physically attached to the controller in an e.p.p. like manner, enable the muscle's own sensory apparatus to provide physiologically appropriate feedback to the user.
METHODS/FINDINGS: Toward this goal we have developed a prosthetic hand with individually powered fingers. We have quantified the control capabilities of persons with pre-existing cineplasties. These studies showed control with a cineplasty was similar to that of a conventional control harness. We have developed an analog e.p.p. controller and are in the process of developing a microprocessor based e.p.p. controller.
CLINICAL RELEVANCE: Cineplasties in conjunction with e.p.p. controllers may provide both force and excursion amplification while retaining a physiologically-appropriate feedback; eliminate the need for harnessing; provide additional control sources in the fitting of total arm prostheses; and make possible meaningful control of individual fingers in hand prostheses.
ACKNOWLEDGMENT: This work was supported by funds from the US Department of Veterans Affairs, Rehabilitation Research and Development Service, administered through the VA Chicago Health Care System, Lakeside Division.
IMPROVED FATIGUE RESISTANCE OF FIBER REINFORCED BONE
Kumar B1; Cooke FW2; Friis, EA2; Blake, DJ3 1Dept. Aerospace Engineering, Wichita State University, Wichita, KS 2Orthopaedic Research Institute, Wichita, KS 3Phys. Med. & Rehab. Service, Denver VAMC, Denver, CO
OBJECTIVES: The objective of this development study was to determine the extent to which the fatigue resistance of commercial bone cement could be enhanced by short fiber reinforcement without degrading its intraoperative handling characteristics.
RESEARCH PLAN: Bone cement to which small amounts of short fibers had been added were prepared and fatigue tested using standard engineering procedures.
METHODS: Simplex P bone cement with/without 1% by volume of short PET or Carbon fibers was molded into cylindrical specimens and fatigue tested at 2 Hz in a simulated physiological environment.
FINDINGS: The endurance limit, the stress below which the material will survive for an infinite number of load cycles, was determined for the various cement materials. Endurance limit results for Simplex P Bone Cement with and without Fiber Additions are as follows: (1) Standard Cement (without fibers) 11.4 MPa (n = 21), (2) Untreated PET (1 vol %) 11.8 MPa (n= 21), (3) Untreated Carbon (1 vol %) 12.6 MPa (n =25), (4) Treated Carbon (1 vol %) 13.2 MPa. The average number of cycles (X103 ) to failure at a stress of 15 MPa was also determined to be (1) Standard Cement 230 ± 91 (n = 8), (2) PET (1 vol %) 294 ± 79 (n = 9), (3) Carbon (1 vol %) 429 ± 178 (n = 12), (4)Treated Carbon (1 vol %) 487 ± 109 (n = 11).
CLINICAL RELEVANCE: The addition of PET fibers improved fatigue resistance only marginally but the carbon fibers effected a 10% improvement in the Endurance limit and a doubling of the fatigue life at 15 MPa. Such enhancement of bone cement fatigue resistance is of great importance clinically because fatigue failure of bone cement is implicated in virtually all late failures of non-infected total joint arthroplasties. An increased fatigue life would contribute to improved function and a reduced incidence of revision surgery for the growing number of VA patients with total joint replacements.
(This study was supported by VARR&D Grant A796).
USE OF OSTEOGENIC FACTORS TO IMPROVE OUTCOME IN HIP
Chakkalakal DA1,2,3; Garvin KL1,3; Strates BS4; Novak JR1,3; Fritz ED1,2; Mollner TJ1,2; McGuire MH1,2 1VAMC, Omaha, NE; 2Creighton Univ. Biomedical Engineering Center; 3Univ. NE Med. Ctr., Dept. of Orthopaedic Surgery; 4VAMC, Gainesville, F L and Univ. FL Med. Ctr., Dept. of Orthopaedic Surgery
OBJECTIVE: To determine the lowest dose of growth factors for stimulation of osteogenesis from bone marrow and bone ingrowth into non-cemented hip prostheses.
RESEARCH PLAN: The optimal dose of each growth factor for in vivo osteogenesis from bone marrow was determined by a bioassay in traumatized medullary canal of rat femur. This dose was then scaled by volume to the pore space on canine femoral prosthesis to determine the lowest trial dose. Higher trial doses were selected as multiples of the lowest dose and used in a pilot study in a canine hip reconstruction model.
METHODS: Based on the results of bioassay, three doses each of TGF (1 (15, 150 and 1500ng) and PDGF/AA (2, 5 and 15(g) and two TGF(1 + PDGF/AA combinations (1(g + 1(g, 1(g + 2(g) were applied into Ti mesh pads of Zimmer Ti6A1 4V canine femoral prosthesis before implantation in right femur, with one dog per dose. At 6 weeks after surgery the dogs were euthanized and bonding strength of prosthesis to femur was determined by push-out tests in two transverse sections. Scanning electron microscopy (back-scattered electron mode was used to measure bone ingrowth.
FINDINGS: Bonding strength was increased by 150ng TGF (1 and the 1500ng dose was not more effective. Morphological data suggest that the effect of TGF (1 treatment was to increase maturation rather than quantity of bone ingrowth.
CLINICAL RELEVANCE: Patients whose femur has inadequate bone stock, due to old age or prior hip replacement, and those at risk of poor healing associated with disease states, may benefit from early stimulation of new bone formation and ingrowth using growth factors.
(Research was supported by VA Rehabilitation R&D Service. We thank Rick Johnson of Zimmer, USA for providing us the canine femoral prosthesis at no cost.)
THE CASE WESTERN RESERVE UNIVERSITY HYBRID ORTHOSIS
Prof of Orthop. Univ. Hosp. of Cleveland and CWRU School of Medicine Cleveland VAMC, VA FES Center of Excellence, Cleveland OH
OBJECTIVE: The eventual project goal is to evaluate a totally implanted 8-16 channel functional electrical stimulation system in combination with a computer controlled, active orthosis.
RESEARCH PLAN: Six paraplegic patients, injury levels T-1 through T-11, participated in a study to evaluate the functional capabilities of a computer-controlled hybrid orthotic system. Subjects learned to use a custom-built reciprocal gait orthosis without stimulation and with electrical stimulation activating between 4-16 muscles.
METHODS: Outcomes were scored with standard physical therapy measures including the Tinetti test, a timed get up and go, Borg energy exertion, and the Functional Index Measure (FIM).
FINDINGS: Subjects successfully accomplished sit-to-stand, stand-to-sit, and walking maneuvers measured for time, speed, distance and metabolic output. Metabolic output measured in the light work region of 7 METs. Perceived exertion as measured with the Borg scale indicated use of the bracing system with FES was 'easier' than without stimulation. Subjects were able to exhibit distance walking which would allow limited but useful ranges of 500 meters at average speeds of 0.2 - 0.3m/s. Walking speeds for 30 and 50 meters distances reached 4 to 4.5 m/s. Additionally, walking distance with stimulation were two times or greater than those of non-stimulated reciprocal gait.
CLINICAL RELEVANCE: FIM scores indicated system users would become slightly more independent in mobility categories. Results were used to determine the most useful brace modifications for the next generation of hybrid orthoses to allow an expanded functional envelope including stair climbing and side stepping.
(Project funded by NIH RO1 NS33287)
ESTABLISHING STANDARDS OF CARE: UPPER LIMB PROSTHETIC
Monga TN, PM&R Service, Houston VAMC; Atkins DA and Abramczyk RA
Amputee Program, The Institute for Rehabilitation and Research
OBJECTIVES: To develop and test the quality of care standards for persons with upper limb loss in VA and non-VA settings.
RESEARCH PLAN: The Amputee Services Assessment Inventory (ASAI) was developed, which includes quality of care standards and indicators, a protocol for self-assessment, and site visit testing of the standards and indicators. The ASAI will ultimately be a "tool" for the rehabilitation facilities to use in ongoing monitoring and improvement of services to persons with upper limb loss.
METHODS: The ASAI was applied in site visits to five VA facilities and five non-VA rehabilitation facilities nationwide. Results from data on VA-served individuals will be compared with the results on individuals served through other systems to determine if there are special needs or service issues in the VA population that are distinct from those identified for the general population. We will also examine whether VA is a possible model for other rehabilitation programs.
FINDINGS: There was no significant difference in the management of upper limb amputees in VA and non-VA settings.
CLINICAL RELEVANCE: This project will assess the current strengths and weaknesses of the VA's services for persons with upper limb loss, and also provide VA with the ASAI. It will help provide a means of determining if replication of the VA's upper limb loss program merits consideration, in whole or in part, as a model for serving other populations.
(Support provided by the Department of Veterans Affairs, Rehabilitation Research and Development Service)
QUANTIFICATION OF PROSTHETIC OUTCOME: FLEXWALK-II FOOT
VS. SACH FOOT
Coleman KC, Boone DA, Smith DG, Mathews DE, Laing LS
Prosthetics Research Study, Seattle, WA
OBJECTIVES: This study compared the FlexWalk-II prosthetic foot with a SACH foot by quantifying differences in: 1) daily ambulatory activity and 2) subjects' response to and satisfaction with the prosthesis.
RESEARCH PLAN: Differences were measured using two new outcomes evaluation tools: 1) The Step Activity Monitor (SAM) is a small step counter worn on the ankle. 2) The Prosthesis Evaluation Questionnaire (PEQ) is a validated instrument to assess patients' experience with the prosthesis.
METHODS: Thirty-two persons with trans-tibial amputation who functioned at DMERC level 3 or 4 wore the feet in consecutive, randomly ordered 5-week trials. The prosthesis was aligned optimally for each foot. Subjects were allowed to accommodate for 3 weeks before monitoring began. Step counts were recorded every minute throughout the last 2 weeks of each trial. Following monitoring, subjects completed a PEQ.
FINDINGS: While blinded, 22 subjects preferred the FlexWalk-II, 9 preferred the SACH and 1 had no preference. With the FlexWalk-II, subjects walked 9.5% farther per day (p=0.010), spent 7.9% more time in moderate level activity (p=0.031), and walked with a 3.8% longer stride (p=0.0001). Prosthesis Utility (a scale of the PEQ) improved 4.7% (p=0.037). Perceived Responses (subjects' perception of others' responses) improved 4.9% (p=0.028). Other PEQ scores showed no difference. Overall step monitor accuracy was 99.41%.
CLINICAL RELEVANCE: The FlexWalk-II is a "high end" foot, costing over $1,400. The SACH is a "low end" foot, costing about $65. Both are supplied in VA prosthetics clinics. Little objective information has been available to guide foot prescription. These results indicate there is a moderate increase in overall ambulatory activity with the FlexWalk-II foot, and that many, but not all, patients at the higher functional levels prefer the FlexWalk-II over the SACH. Similar data collected for the other components of a prosthesis and compared with these results would be valuable for establishing treatment and reimbursement policies which optimally balance cost with functional outcome.
This work was funded by the Department of Veterans Affairs Rehabilitation Research and Development Service.
VALIDATION OF A TECHNIQUE FOR DETERMINING THE METABOLIC
REQUIREMENTS ASSOCIATED WITH MAINTAINING BALANCE AND POSTURE
Hoffman M.D.*, Millet G.Y.**, Candau R.B.**, and Rouillon J.D.**
*Dept. of PM&R, Medical College of WI and VA Med. Ctr., Milwaukee **Laboratoire des Sciences du Sport, UFR STAPS, Besancon, France
OBJECTIVE: Current physiological and biomechanical measurement techniques do not allow for quantification of the metabolic cost for maintaining balance and posture during walking (Eb). However, a theoretical model suggests that Eb can be estimated by subtracting oxygen uptake (VO2) at rest from the intercept of the curve of VO2 for walking versus velocity (v). In this study, we examine the validity of this model.
RESEARCH PLAN: The validity of the theoretical model was tested by comparing normal walking with walking using "instability shoes" which require the user to balance on added sole material producing a 1 cm wide longitudinal platform. Normal walking was performed with shoes matched with the instability shoes for mass and amount of sole elevation.
METHODS: VO2 measurements were performed on 11 healthy males (mean 1 SD age = 34 ± 9 yr, mass = 72.2 ± 5.1 kg) during level treadmill walking at 1.4-6.6 km/h.
FINDINGS: VO2 (in ml/min/kg) was defined as a function of v (in km/h) by the equations VO2 = 0.32 v^2 + 8.5 and VO2 = 0.33 v^2 + 9.8 for the normal and instability conditions, respectively. Repeated measures ANOVA revealed that the intercept was higher (p<0.01) for the instability condition, but there was no difference between conditions in slope.
CLINICAL RELEVANCE: From these findings, we conclude that the theoretical model for estimation of Eb appears valid and offers a potential method for estimation of Eb in persons with disabilities.
Go to top.
Last revised Tue 05/04/1999 .