Volume 43 Number 4, July/August 2006
Pages 553 — 564
Abstract - Interface pressure and cutaneous hemoglobin and oxygenation changes
under ischial tuberosities during sacral nerve root stimulation in spinal cord
Liang Qin Liu, MB;1-2 Graham P. Nicholson, PhD;3 Sarah L. Knight, PhD;1-2 Ramesh Chelvarajah, MRCS;1 Angela Gall, MRCP;4 Fred R. I. Middleton, FRCP;4 Martin W. Ferguson-Pell, PhD; 3 Michael D. Craggs, PhD1-2*
1Spinal Research Centre, Royal National Orthopaedic Hospital (RNOH), Stanmore, United Kingdom; 2Institute
of Urology, University College London, London, United Kingdom; 3Aspire Centre for Disability Sciences, University
College London, London, United Kingdom; 4The London Spinal Cord Injuries Centre, RNOH, Stanmore, United Kingdom
Abstract — Noninvasive functional magnetic stimulation (FMS) of the sacral nerve roots can activate gluteal muscles. We propose the use of sacral anterior root stimulator (SARS) implants to prevent ischial pressure ulcers in the spinal cord injury (SCI) population. In this study, we (1) investigated the acute effects of sacral FMS on ischial pressure, skin blood content, and oxygenation changes in people with SCI and demonstrated the utility of FMS as an assessment tool, and (2) showed that similar effects are possible with electrical stimulation via a SARS implant. Results indicated that sacral nerve root stimulation, either by FMS or implanted electrical stimulation, induced sufficient gluteus maximus contraction to significantly change subjects' ischial pressures and cutaneous hemoglobin and oxygenation during sitting. In addition to these beneficial acute effects, chronic stimulation via a SARS implant may build gluteal muscle bulk and prevent or reduce pressure ulcers in the SCI population.
Key words: functional electrical stimulation, functional magnetic stimulation, gluteal muscles, ischial pressure change, ischial tuberosity, pressure ulcer, rehabilitation, sacral nerve root stimulation, seat interface pressure, spinal cord injury, tissue reflectance spectrometry.