J Korean Neurol Assoc.  1992 Mar;10(1):59-71.

Magnetic Motor Evoked Potentials in Motor Pathway Lesions

• Kim KS
• Park YC

Abstract

This study was undertaken to evaluate the clinical usefulness of magnetic 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 vanous diseases involving motor pathway, among which were 21 cerebral infarction, 15 intracerebrai 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 Dl90 and Medelec ER 94a/Sensor apparatuses, and MEP were evoked by magnetic stimulations over the vertex, the 7th cervical vertebra and Erb's point, and central motor conduction time (CMCT) was calculated by substracting the onset latency of abductor 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 lesion, and mean CMCT were prolonged in patients with stroke. Cortical MEP were 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. In stroke patients, there were prolongation of mean CMCT and mean latency of cortical MEP evoked by stimulation to the undamaged hemisphere. These results suggest that magnetic MEP test is safe and useful in evaluation of motor pathway lesions.

MeSH Terms

Amyotrophic Lateral Sclerosis
Arm
Cerebral Infarction
Evoked Potentials, Motor*
Hemorrhage
Humans
Magnetic Resonance Imaging
Male
Neural Conduction
Polyneuropathies
Scalp
Spine
Spondylosis
Stroke
Transcranial Magnetic Stimulation