Surface-electromyographic analysis of the upper extremity muscles can aid in the rehabilitation of hemiparetic stroke survivors

Abstract

Objective To explore any changes in the surface electromyography (sEMG) signals measured from the biceps brachii, flexor pollicis brevis and the first dorsal interosseous muscles of stroke survivors with hemiparesis during maximum isometric voluntary contractions. To correlate them with motor function recovery so as to provide a reference in making up individualized rehabilitation programs. Methods Twenty stroke survivors with hemiparesis were selected as the experimental group, and 10 healthy counterparts were recruited as the control group. For all of them, sEMG signals were recorded bilaterally from the biceps brachii, flexor pollicis brevis and the first dorsal interosseous muscles during maximum isometric voluntary contractions involving elbow flexion, thumb flexion and index finger abduction. For the stroke patients, such recording was performed repeatedly on the paretic side during the course of convalescence. Both root-mean-square (RMS) amplitude and median frequency (MDF) were calculated for the recorded surface EMG signals. The upper-extremity component of the Fugl-Meyer assessment scale (FMA-UE) and manual testing (MMT) of each muscle examined were performed with each stroke patient to assess motor function and upper extremity muscle strength. Results There were no significant differences in either RMS amplitude or MDF between the left and right sides of the healthy control subjects. Significant differences in both RMS amplitude and MDF were observed for the stroke survivors and between their values and those of the controls. The patients' unaffected side had significantly larger RMS amplitude and MDF than either side of the healthy control group. For the affected side of the stroke patients, both RMS amplitude and MDF tended to increase during the course of rehabilitation, with significant differences between the values obtained at the first and the last sessions. The FMA-UE scores and MMT results on the affected side were positively correlated with the RMS amplitudes and MDF results for the upper extremity muscles. Conclusions Surface electromyography is able to reflect the rehabilitation process and the recovery of muscle strength and motor function. It can be considered as a quantitative index for evaluating rehabilitation and a useful reference for designing targeted functional training programs. Key words: Stroke; Upper extremities; Surface electromyography; Rehabilitation