RELIABILITY OF PERCUTANEOUS INTRAMUSCULAR ELECTRODES FOR UPPER EXTREMITY FUNCTIONAL NEUROMUSCULAR STIMULATION IN ADOLESCENTS WITH C5 TETRAPLEGIA

Chronically indwelling percutaneous intramuscular electrodes were impl anted in the upper extremity muscles of five adolescents with C5 or C5 -6 tetraplegia in an effort to provide lateral and palmar prehension u sing the neuroprosthetic system designed by Case Western Reserve Unive rsity. The responses from 177 electrodes were evaluated at 3-month int ervals and included measurements of electrical impedance and an assess ment of recruitment properties. Electrode failures were categorized as breakage, an altered stimulated response of adverse sensation during stimulation. Survival probabilities were generated for all electrodes, each muscle group, the volar and dorsal exit sites, intrinsic and ext rinsic muscles, and according to the subjects' time postinjury. The ov erall probability of an electrode surviving to 6 months was 0.75 and t he 1 year survival probability was 0.56. Among muscle groups, the fing er extensor and thumb adductor electrodes had the highest proportion o f failures and the poorest survival likelihoods within the first year after implant. According to the Breslow test, significantly smaller su rvival chances were predicted for electrodes exiting dorsally and for the newly-injured adolescents (<1 year postinjury). The cumulative sur vival likelihoods of this study are smaller than those reported in adu lt applications using the same electrode design. Factors that may acco unt for the disparate results are discussed. (C) 1994 by the American Congress of Rehabilitation Medicine and the American Academy of Physic al Medicine and Rehabilitation