Announced ACTA.FAC.MED.NAISS. 1999; 16(3), 158-162

SILENT PERIOD EVOKED BY TRANSCRANIAL MAGNETIC STIMULATION IN ACUTE ISCHEMIC STROKE

Miodrag Lazarević, Stojanka Djurić, Marina Jolić, Predrag Karabašević
Klinika of neurology, Clinical center, Niš

Transcranial magnetic stimulation (TMS) of the motor cortex produces motor evoked potentials as excitatory affects, but also an independent inhibitory effects termed silent period (SP). SP is presented through the pause of electromyographic activity of muscle studied.

Since conflicting data were presented in recent investigations confirming the change of SP in stroke patients, aim of this study was to determine the SP duration in acute ischemic stroke.

24 patients with consequential slight or moderately serious hand palsy (Medical Research Council grade 3-4) were included. TMS was performed during the first 3 days after the onset of the disease and responses were registrated from m.abductor digiti minimi of both hands during the slight voluntary muscle contraction. Ischemic vascular lesion was confirmed by computerized tomography of the brain.

There were a significant SP prolongation of the affected side (Xsr = 156 ± 39.07ms, range 76-243 ms) in most patients, compared to the unaffected ones (Xsr =121 ± 33.83ms, range 59-181ms) and healthy controls (Xsr = 130 ± 30.82ms, range 49-167 ms).

We may conclude that significant changes found of SP duration on affected side may be added as useful TMS parameter in corticospinal system damage assessment due to ischemic lesion.

Key words: Transcranial magnetic stimulation; Motor evoked potentials; Silent period; Brain infarction.