J Korean Neurosurg Soc.  1990 Jan;19(1):108-115.

Motor Evoked Potentials by Transcranial Magnetic Stimulation

  • 1Department of Neurosurgery, Kangdong Sungshim Hospital, College of Medicine, Hallym University, Korea.


The human motor cortex can be stimulated by electric shock or by brief intense magnetic fields. Transcranial magnetic stimulations(TCMS) cause only a trivial scalp sensation, compared with electrical stimulations. TCMS caused contralateral hand muscle responses and the resultant compound muscle action potentials or motor evoked potentials can be recorded. Central motor conduction time(CMCT) can be estimated by stimulating over the scalp and over the cervical area. In healthy subjects, the CMCT is 10.3+/-1.8ms(n=70 sides). Facilitation of responses in hand muscle is produced by voluntary contraction and the overall latency from scalp to hand muscle is shorter by 2.4ms(n=24 sides). TCMS is a non-invasive method to evaluate the central motor pathways and inaccessable portion of the peripheral pathways and so it has important implications not only for the diagnosis of disorders in the central motor pathways but also for evaluating treatments.


Transcranial magnetic stimulation; Motor cortex; Motor evoked potential; Facilitation; Central motor pathway
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