Dysphagia and Nutrition:

Joanne Robbins, PhD

Dysphagia, or swallowing difficulty, is associated with numerous neurologic conditions. Swallowing disorders resulting from stroke, Parkinson's disease, and other neurogenic processes have received a lot of research attention in recent years. The burgeoning efforts to identify the presence of dysphagia, and to understand the natural history of it in numerous disease processes, are most likely related to the hope of preventing the life-threatening and costly medical outcomes that are brought upon by dysphagia. These include malnutrition, dehydration, weight loss, aspiration pneumonia, and reflux.

A major focus of research in the University of Wisconsin/VA Swallowing Laboratory has been the study of biomechanical and physiological changes in swallowing with aging. Not only have we been studying dysphagia secondary to age-related disease but also swallowing as a function of the aging process in the absence of identifiable disease entities. What we call our "reserve'' level, that is, our anatomic/physiologic stores that provide our ability to adapt to stress, is reduced as we get older putting older individuals more at risk for dysphagia. In fact, we notice ourselves coughing a little more as we're either drinking quickly or speaking and eating at the same time. In the frail elderly, this "reserve" is reduced even more. Thus, it is a logical speculation that older individuals with neurodegenerative conditions are extremely susceptible to dysphagia and its secondary deleterious medical outcomes.

The leading cause of death in MS is bronchial pneumonia. Although a causal link has not been demonstrated in that population, recently, aspiration from swallowing dysfunction documented by video-fluoroscopic swallow study has been shown to significantly increase the risk of pneumonia in other neurologic conditions associated with dysphagia. In fact, in the stroke population, it has been shown that dysphagia may result from specific lesions in the cortex, the subcortex, and/or the brain stem. Further, dysphagia severity ratings are correlated with white-matter lesion identified as hyperintensities seen on MRI, even in healthy older people. Generally, dysphagia severity worsens, as do other areas of function with MS, with larger or multiple lesions of varying etiologies.

The literature on swallowing dysfunction and its relation to disability in MS is very sparse. Work by Herrara in the Denver area, is becoming more frequently recognized and indicates that the presence of dysphagia and its severity are most related to severity of the neurologic involvement. Those findings are supported by work in dysarthria, (Darley, Brown, Goldstein, with indirect support from Mayo Clinic), which reported an incidence of dysarthria in 41 percent of their 168 patients with a diagnosis of MS. They found that the presence of dysarthria in this group correlated highly with multiple system demyelinization and severity or progressive symptoms. Duration of illness, age, or onset of MS did not correlate highly with the presence of the dysarthria. That is, the motor speech disorder worsened as additional motor systems became implicated. Given the presence of spasticity, ataxia, and cranial nerve damage in MS, such findings are not surprising; yet they remain very poorly documented relative to dysphagia in multiple sclerosis.

While dysarthria involves much of the same head and neck anatomy that swallows, so to speak, the esophagus also comes in to play for the latter function. A manometric study by Daly, et al (J Neurol,12:250-256, 1962), found upper and lower esophageal sphincter dysfunction in 50 percent of their patients (13 of 26) with MS. Eleven of those 26 had esophageal dismotility as well, indicating that aspiration may not only be occurring due to misdirection of food or liquid "on the way down" when the MS patients are drinking or eating, but also may be caused by reflux, that is, food or liquid that comes back up the system. These two ways of aspirating are treated very differently. Therefore, a differential diagnosis for the underpinnings of the aspiration is essential to putting the best treatments into place.

Daly, et al (J Neurol,12:250-256, 1962), state that while the incidence of abnormal swallowing in MS patients far exceeds that anticipated in a comparable group of "normals", no single pattern of swallowing disorder characterizes their findings. Coughing, choking, food sticking, as well as trouble initiating the swallow, are interpreted frequently as evidence of dysphagia in MS. However, these patient reports could be evidence of paraphasia or cognitive deficits and should be questioned with regard to validity. Much more groundwork has to be done in the area of dysphagia and MS in order for us to learn more about how to best help this population.

Unfortunately, instrumental approaches clinically for research purposes have not been conducted with any frequency for dysphagia in the MS population. This may reflect an historic perceived lack of importance of these symptoms. Matthews, et al (McAlpine's Multiple Sclerosis, Churchill Livingstone: Edinburgh, 1985: 135) wrote that dysphagia becomes a problem when patients are terminal and that it is a nursing problem. More recent studies indicate that the incidence of dysphagia was present in 43 percent of 525 patients studied by Abraham, et al in 1997 in New York, and in 48 percent of the 50 patients surveyed by the Rocky Mountain group. These self-reported incidence rates indicate that this population seems ripe for swallowing examinations with more objective measures; specifically, instrumentally obtained measurement of swallowing of which the clinical gold standard is video-fluoroscopy.

Behavioral dysphagia management, since its inception, has been guided by bolus-flow measures. We traditionally look at the direction the bolus goes, the duration of bolus movement, and the completeness. Direction means that if it goes in the wrong direction, it's likely to go up through the nose or down into the airway rather than descend directly through the digestive tract. An estimate of completeness addresses whether the entire bolus all moves through the oral pharynx and esophagus, or if there is residue which increases risk for aspiration.

Misdirection most often results in airway penetration or aspiration. In Madison, we developed a tool, with VA funding, that offers multidimensional information about the occurrence of airway invasion relative to swallowing (Rosenbek, Robbins, et al, Dysphagia, 11:93-98, 1996). ALIGN="JUSTIFY">It is an eight-point scale that increases the specificity of information.

Table 1. Multidimensional depth of airway invasion and residue, single-digit scoring system for the Penetration-Aspiration Scale. (Rosenbek et al, Dysphagia 1996; Robbins et al, Dysphagia, 1999)

If airway penetration occurs, it tells us that it is penetration. If aspiration or penetration is occurring, it tells us and it also defines the anatomic level to which the material invades. That is, it indicates if material invades above the vocal folds, at the folds, or below, and what is the patient's response? Does the patient try to eject the material? Does he eject successfully or is he, what we call a silent aspirator?

We have recently used this scale to learn that it does differentiate aspiration/penetration patterns in patients with different etiologies of dysphagia (Robbins, et al, Dysphagia, 14:228-232, 1999). In looking at head and neck cancer patients and at stroke patients, the eight point scale shows a different profile distinguishing the two different patient groups. This scale appears to be a tool that is sensitive to progression of disease, as well as to response to interventions and, therefore, could give the MS clinical research community important evaluative information about swallowing and its response to disease progression and interventions.

Currently, we are evaluating effectiveness of various interventions on improving bolus flow. Rehabilitation therapy is designed to directly address the muscles and the structures. This includes therapies like strength building and range of motion. These might not be top priority when working with someone who has multiple sclerosis. Rather, therapists working with MS patients often choose to go with a compensation type of approach. These are interventions that are directed at reducing the effects of biomechanical abnormalities on the bolus flow. That is, the patient is guided to use what he/she has in tact and make it work in a unique way. Postural adjustment is a good example of a category of compensatory intervention. Head flexion (also known as "chin tuck") has been shown in a number of neurogenic patients to effectively divert food or liquid from its' misdirected path into the airway, keeping it in the digestive tract for safe swallowing.

So far, treatment effectiveness has been limited to measurement of the physiologic, the biomechanical, and the bolus flow outcomes. While this foundation has served the profession well, modern practice must expand to meet the demands of an increasingly patient-focused, cost-conscious, and evidence-based healthcare environment. Critical to that expansion is a multidimensional repertoire of outcome measures designed to understand more completely the treatment value and treatment effectiveness. With the exception of a few cost studies and quality-of-life data largely focused on the cancer population, outcome measurement in swallowing in the area of dysphagia continues to be limited primarily to measures of bolus flow. However, we are beginning to realize the need for measurement of the indirect outcomes such as mortality, health status, and quality of life.

In terms of function, people have used the indicators of dehydration and nutrition (type of food intake). Those are valid outcome measures limited to the clinician's point of view because they are manipulated by a clinician and do not incorporate the patient's perspective and what the patient wants to do in terms of intake. The latter is important because physiological functioning is not synonymous with patient functioning and well being.

In the last three years, with funding from the VA, we, at the Madison VA, have developed a dysphagia-specific quality-of-life tool developed from patient focus groups. We brought in 70 dysphagia outpatients. They were a mixed group with regard to etiology of dysphagia, with a percentage having MS. The result is the SWAL-QOL, the quality of life swallow evaluation. The quality of life evaluation is done by the patient, or in conjunction with their caregiver. We anticipate that this tool will be beneficial in expanding our outcome measures from a patient perspective.

In summary, given the state of what we know or don't know about swallowing and related outcomes secondary to multiple sclerosis, video-fluoroscopy, the penetration-aspiration scale, and the SWAL-QOL provide us with methodologies that can be put to work in a variety of research designs. Thus, as a field we are equipped to obtain objective information about the disease process relative to dysphagia from the clinician's and the patient's point of view. Hopefully, so doing will facilitate improvement in patient care.

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