Effect of EMG feedback on paretic muscles and abnormal co-contraction in the hemiplegic arm, compared with conventional physical therapy

Abstract

The effectiveness of EMG feedback in hemiparetic patients with an impaired arm and hand function was compared with conventional physical therapy in 18 patients, who were assigned to two groups. EMG feedback in the experimental group (n = 9) was confined to augmenting the reduced muscle activity in one proximal and one distal agonist, and to decreasing the excessive activity in one proximal antagonist and in two distal muscle groups. The control group (n = 9) was treated with conventional physical therapy. Overall duration for both treatments was 2 1/2 moths, which included 28 sessions of one hour, three times a week. Major differences in the effect of EMG feedback were found in abnormal co-contractions as compared with reduced muscle activity in agonists. The most prominent effect was found at the end of the EMG feedback training in abnormal co-contractions. Several days after ending the EMG feedback a decrease in abnormal co-contractions in the exclusively trained muscles could still be demonstrated, compared with abnormal co-contractions in untrained muscles and abnormal co-contractions in muscles treated with conventional physical therapy. However, part of the effect was lost. By contrast, intensive EMG feedback therapy had no specific effect on proximal and distal agonists of the hemiplegic arm, when compared with conventional physical therapy of a long duration. The performance of isolated voluntary movements, the occurrence of pathological associated movements and the function of the arm and the hand were not affected by the EMG feedback therapy, or by conventional physical therapy.