Electrophysiological study of hemiplegia. Motor nerve conduction velocity, brachial plexus latency, and electromyography.

Motor nerve conduction velocities of the ulnar and common peroneal but not the median nerves were substantially reduced in the affected limbs in a series of hemiplegic patients. Slowing of conduction velocity of the common peroneal nerve was related to the reduction of skin temperature in the hemiplegic limbs. Brachial plexus latencies to biceps and deltoid muscles were longer in the affected than in the unaffected sides in five of 12 hemiplegic patients. Electromyograms (EMGs) of limb muscles showed absence of spontaneous activity in 83% of patients. Spontaneous EMG activities in 12 of the 13 patients were related to an associated subclinical neuropathy or plexopathy in the involved limbs. Entrapment andtraction causing subclinical or clinical neuropathy or radiculopathy may be present in some hemiplegic patients.