Implanted functional electrical stimulation: case report of a paraplegic patient with complete SCI after 9 years

Backgrounds: Experience of an implanted functional electrical stimulation neuroprosthesis (FES) associating 8-channel epimysial and 4-channel neural stimulations. The primary objective consisted in presenting clinical and technological experiences based on a 9-year follow-up of one patient implanted with this FES device. The secondary objective consisted in assessing resulting functional benefits. Methods: One patient recruited in 1996 within the European Stand Up and Walk Project benefited from a 9-year follow-up with clinical and technological evaluations. Results: The patient was still using the system nine years later making this a unique case, even when compared to other similar studies. The analysis of muscular response to FES underlined the great variability of stimulation thresholds evolution (-26% to + 360%, mean + 110%) and quality of the induced contraction. Three muscles out of five scored at least 4/5 on the Medical Research Council scale, all stimulated via neural pathways. The patient used the system once a week for 6 years, up to 2006, due to lack of use, the FES-induced muscular response worsened even though the implant was properly functioning, leading to significant decline in gait performances (best 3.45 m/s on 2.9 m), due to muscle fatigue and loss of muscle mass. Conclusion: Two major issues arise: first the importance of muscle fatigue, underlining the relevance of muscle strength training, and second technological hurdles raising up the question of neural vs. epimysial FES. This advanced technology proves the concept of restoring lower limb motor functions in patients with spinal cord injury. The main features of the stimulation device remain stable even after long periods of inactivity, yet there is a real need for close clinical and technological monitoring.