Changes in patterns of EMG activity in post-stroke subjects following robot-assisted hand rehabilitation.

A feasibility study of robot-assisted hand rehabilitation post-stroke was conducted to investigate changes in activation patterns of forearm and hand muscles. Four stroke survivors received robot-assisted hand rehabilitation twice a week for two months. Eight healthy age-matched control subjects performed the same exercises as stroke subjects in a single training session. The pattern of activation of forearm and hand muscles was analyzed by performing Principal Component Analysis on the root-mean-square electromyogram. No differences were found in the number of principal components required to account for 95% of the variance between stroke and healthy subjects or pre- and post-rehab even though the majority of subjects used different muscle activation patterns for different exercises and changed their activation patterns from pre- to post-rehab. Stroke subjects were found to have more co-contraction of antagonistic muscles than healthy subjects pre-rehab. In most cases, the amount of co-contraction did not decrease from pre- to post-rehab.