Cortical silent period and motor evoked potentials in patients with multiple sclerosis

In order to determine the importance of central motor conduction time (CMCT) and silent period (SP) in patients with multiple sclerosis (MS), we enrolled this clinical and electrophysiological study. Additionally, we planned to compare the correlation between electrophysiological findings and clinical status. We examined 58 patients with definite MS and 31 controls. Patients were classified as relapsing-remitting (N: 37), secondary progressive (N: 21) groups. Eleven out of 58 patients with MS had no neurological findings (subclinical patients). We evaluated CMCT and the duration of SP. Prolonged CMCT latency was shown in 75.2% of patients. We observed SP abnormalities in 69% of patients. In subclinical patients, SP abnormalities (six of 11) were observed more common than CMCT (two of 11). The duration of SP was extremely prolonged in MS patients with cerebellar dysfunction. When the both electrophysiological parameters are taken into account, the abnormality ratio was determined as 89.7%. Our results indicate that CMCT and SP analysis are complementary tests in evaluating motor pathways of patients with MS. We observed a relationship between cerebellar dysfunction and SP prolongation. It is suggested that, SP can be applied in patients with pure cerebellar dysfunction and it can be a valuable test in subclinical cases with MS.