Related Experiment Video
Updated: Jun 4, 2026
Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
Published on: October 7, 2025
Predictive value of motor evoked potentials in clinically isolated syndrome
M Pallix-Guyot1, A-M Guennoc, H Blasco
1Service de Neurologie et de Neurophysiologie Clinique, Hôpital Bretonneau, CHRU Tours, France. maudpallix@aol.com
Objectives:
To assess the predictive role of several measures obtained by transcranial magnetic stimulation (TMS) in patients with clinically isolated syndrome (CIS) for the risk of conversion to multiple sclerosis (MS) during the first 2 years.
Materials And Methods:
We investigated 34 patients with CIS. After 2 years of follow-up and classification into two groups according to MS diagnosis, initial TMS measures were compared to determine their predictive values for conversion to MS.
Results:
Sixteen patients developed MS. We observed a significant difference between the two groups for contralateral silent period and no significant difference for the central motor conduction time, amplitude ratio, motor threshold, ipsilateral silent period, and the transcallosal conduction time.
Conclusions:
Contralateral silent period (SP) seems to be a valuable parameter to early distinguish patients who will develop MS or not. This result about SP during CIS has never been described until now. An increased contralateral silent period would predict a conversion to MS with a positive predictive value of 75%, but this result needs to be confirmed in larger groups.
