The relation between motor evoked potential and clinical motor status in stroke patients

Forty-one stroke patients and 41 normal controls of matched age, sex and body height were studied by magnetic stimulation of the motor cortex and lower cervical area. The cortical and cervical motor evoked potentials (MEPs) were detected from the abductor pollicis brevis muscle. The amplitudes and latencies of cortical MEPs, central conduction time (CCT), and interside difference of bilateral CCT (DCCT) in stroke patients showed significant difference in comparison with normal controls. The degree of motor weakness was statistically correlated with the severity of cortical MEP findings, but not with the deep tendon reflex and Babinski sign. The abnormal rate of cortical MEP was higher in patients with hemorrhage than in those with infarction. Six out of 17 patients with hemorrhage had prolonged CCT or DCCT, but only 3 out of 24 patients with infarction had the same findings. The cortical MEP findings in putaminal hemorrhage were more severe than in thalamic hemorrhage. In instances of infarction involving total middle cerebral artery territory (cortical and subcortical areas), the cortical MEP was absent in all cases (4/4). It was concluded that cortical MEP findings in stroke patients examined by magnetic stimulation showed good correlation both with the lesion radiologically and the motor deficit clinically. This is an acceptable method for quantitative evaluation of motor system function in stroke.