VOLUNTARY MOVEMENT AT THE ELBOW IN SPASTIC HEMIPARESIS

The relative importance of hyperreflexia and paresis in disturbances o f voluntary arm movement was studied in a group of patients (n = 25) w ith spasticity arising from a unilateral ischemic cerebral lesion. Pat ient performance was evaluated against data obtained from normal subje cts (n = 15). Spastic patients achieved lower maximum movement velocit ies during flexion or extension than did normal subjects. The more mar ked the paresis of the elbow flexor and extensor muscles of the patien ts, relative to the strength of the normal subjects, the greater was t his reduction in maximum velocity. For a given velocity, however, the time taken to complete a movement and the time to reach the peak veloc ity were normal. No relationship was found between the degree of impai rment of voluntary movement and the level of passive muscle hypertonia in the antagonist. Although overactivity of the antagonist muscle may play some role in disturbance of movements made at low velocities wit hout an opposing load, antagonist activity during movements made again st a load (i.e., under more natural conditions) was at or below normal levels, even in those patients with the most marked passive muscle hy pertonia. It is concluded that agonist muscle paresis, rather than ant agonist muscle hypertonia, plays the dominant role in the disturbance of voluntary elbow movement following stroke.