TRANSCRANIAL MAGNETIC STIMULATION IN PATIENTS WITH CEREBELLAR STROKE

Conduction time of the central motor pathways (CMCT) by transcranial m agnetic stimulation (TMS) was performed within the first two weeks in 7 patients with isolated hemicerebellar lesions after stroke. Cerebell ar infarcts were small (< 2 cm in diameter) in 5 patients and no brain stem structure was involved in CT studies. The threshold (3 cases) and CMCT (4 cases) were abnormal or asymmetric by stimulation of the moto r cortex contralateral to the impaired hemicerebellum. The follow-up s tudy in 2 patients revealed electrophysiological improvement closely r elated to clinical cerebellar recovery rate. CMCT was significantly lo nger by cortex stimulation contralateral to the impaired hemicerebellu m than by ipsilateral stimulation. Prolonged CMCT was significantly co rrelated with the rated severity of cerebellar signs. Increased thresh old may be due to depressed facilitating action of the deep cerebellar nuclei on contralateral motor cortex. Abnormal CMCT might result in r educed size and increased dispersion of the efferent volleys, Recovery of electrophysiological results could represent in part true potentia lly reversible functional deficit. Whichever the pathophysiological me chanisms involved, our results demonstrate that the cerebellum dysfunc tion plays a role in the abnormalities of CMCT elicited by TMS.