This study was undertaken to evaluate the clinical usefulness of magnetic motor evoked potentials (MEP) in localization of motor pathway lesions and the relation between motor weakness and MEP alterations. The patient group consisted of 50
patients
(33
men and 17 women) with various diseases involving motor pathway, among which were 21 cerebral infarction, 15 intracerebral hemorrhage, 3 cervical spondylosis, 3 amyotrophic lateral sclerosis and 8 peripheral polyneuropathy, confirmed by
neurological
findings, CT or MRI, EMG and nerve conduction velocity. The results were compared with 20 healthy subjects(11 men and 9 women) as a control group.
MEP were recorded by using Digitimer magnetic stimulator model D190 and Medelec ER 94a/sensor apparatuses, and MEP were evoked by mgnetic ˙stimulations over the vertex, the 7 th cervical vertebra and Erb's point, and central motor conduction
time
(CMCT) was calculated by substiacting the onset altency of abduetor pollicis brevis muscle responses obtained by stimulation over the C7 vertebra from that obtained by stimulation over the scalp.
The mean latencies of MEP after transcranial magnetic stimulations were prolonged in patients with motor pathway lesicn, and mean CMCT were prolonged in patients with stroke. Cortical MEP were prolonge in patients with stroke.
Cortical MEP wre not elicited in stroke patients with profound motor weakn-ess below motor power 2/5 in arm, Prolongation of mean latency of cortical MEP and mean CMCT were correlated with motor weakness below motor power 4/5.
These results suggest that magnetic MEP test is safe and useful in evaluation of motor pathway lesions.
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