Corticomuscular integrated representation of voluntary motor effort in robotic control for wrist-hand rehabilitation after stroke

Abstract

Objective. The central-to-peripheral voluntary motor effort (VME) in the affected limb is a dominant force for driving the functional neuroplasticity on motor restoration post-stroke. However, current rehabilitation robots isolated the central and peripheral involvements in the control design, resulting in limited rehabilitation effectiveness. This study was to design a corticomuscular coherence (CMC) and electromyography (EMG)-driven control to integrate the central and peripheral VMEs in neuromuscular systems in stroke survivors. Approach. The CMC-EMG-driven control was developed in a neuromuscular electrical stimulation (NMES)-robot system, i.e. CMC-EMG-driven NMES-robot system, to instruct and assist the wrist-hand extension and flexion in persons after stroke. A pilot single-group trial of 20 training sessions was conducted with the developed system to assess the feasibility for wrist-hand practice on the chronic strokes (16 subjects). The rehabilitation effectiveness was evaluated through clinical assessments, CMC, and EMG activation levels. Main results. The trigger success rate and laterality index of CMC were significantly increased in wrist-hand extension across training sessions (p < 0.05). After the training, significant improvements in the target wrist-hand joints and suppressed compensation from the proximal shoulder-elbow joints were observed through the clinical scores and EMG activation levels (p < 0.05). The central-to-peripheral VME distribution across upper extremity (UE) muscles was also significantly improved, as revealed by the CMC values (p < 0.05). Significance. Precise wrist-hand rehabilitation was achieved by the developed system, presenting suppressed cortical and muscular compensation from the contralesional hemisphere and the proximal UE, and improved distribution of the central-and-peripheral VME on UE muscles.