Effectiveness of short-term training with a synergy-based FES paradigm on motor function recovery post-stroke

Introduction/Background The objective of this study is to test the clinical effectiveness of a synergy-based multi-muscle functional electrical stimulation (FES) strategy to accelerate post-stroke motor function recovery via a new task-oriented training protocol. Material and method A randomized, single-blind, placebo controlled protocol was designed and tested in this study. Daily FES interventions were applied to patients, approximately one hour each day for 5 consecutive days. Stimulation parameters were determined for each patient using an algorithm based on muscle-synergies obtained from healthy subjects. The task-oriented training protocol required patients to repeat forward and lateral reaching movements, with concurrent assistance from FES. Sham interventions were tested with all FES electrodes attached but without actual stimulations.20 patients with ischemic post-stroke hemiparesis participated in this study. FES interventions were applied to 10 patients, and 10 patients received sham interventions. We measured kinematics, electromyography, and upper-extremity Fugl-Meyer scores of patients before and after intervention. Results After 5 days of FES intervention, all patients showed increased Fugl-Meyer scores and peak movement velocity. Interestingly, the post-intervention muscle synergy in patients became more similar to that of healthy controls. No comparable improvements were observed after sham interventions. Particularly, a self-comparison in the patient received both sham and FES interventions highlighted the effectiveness of FES with task-oriented training. Conclusion Our results provided early evidence that there is clear clinical benefit to concurrently stimulate multiple muscles to assist residual movements using FES, and synergy-based FES induces restoration of more normal kinematics and muscle activation pattern. The FES and task-oriented training protocol showed initial indications of effectiveness with a short-term intervention.