Clinical Usefulness of Silent Period after Transcranial Magnetic Stimulation in Stroke Patients

ABSTRACT

Background Transcranial magnetic stimulation(TMS) of the motor cortex is well established as a valuable method for noninvasive examination of the central motor system. The purposes of this study are to establish technical method and normal data and to evaluate clinical usefulness of silent period(SP) study in stroke patients. Methods Central motor conduction time(CMCT) and SP were measured from the first dorsal interossei muscle by TMS. The subjects were 41 normal persons and 15 stroke patients, who were proven radiologically to have unilateral infarction or hemorrhage at various regions of brain. Patients group had lateralizing neurologic signs clinically, but most of them showed no definite motor weakness. Results In the control group we found no statistically significant interside difference in CMCT and duration of the SP, which showed a marked interindividual variation. In patients with prior stroke who showed minor neurologic deficits, there was a significant increase in the interside difference of SP. However, that of CMCT wasn't a sensitive parameter in determining the abnormality. Conclusion These findings suggest that the SP elicited by transcranial magnetic stimulation is a useful and sensitive neurophysiological parameter in the evaluation of stroke, particularly for the detection of subclinical motor dysfunction.