FES Application with Different Off Times in Paraplegic Subject during Open Chain Movement: Case Report

摘要

Functional electrical stimulation (FES) improves paraplegic subjects rehabilitation and may be used in neuroprosthesis systems. Superficial mechanomyography (MMG) monitors the contracting muscles oscillations. The goal of this paper is to compare the relationships between MMG features and knee angles during open chain movements artificially evoked by different FES off times (5s; 10s and 15s) in a spinal cord injured volunteer. FES waveform consisted of a monophasic square wave, 1kHz pulse frequency, 300us active pulse period and 3ms active burst period with burst frequency of 70Hz. Sixteen artificial contractions were generated by FES applied to the quadriceps femoral muscle pre- and pos-interval of 15min, totalizing thirty two contractions. Temporal (RMS value) and spectral (median frequency) MMG features were analyzed for rectus femoris and vastus lateralis muscles. MMG_(RMS) and MMG_(MF) variations were inversely related, with correlation coefficients values from -0.30 until -0.79. These results may help create new FES closed-loop control strategies by MMG features.