Modifications of electrophysiological parameters in patients with multiple sclerosis

Multiple sclerosis (MS) is the most frequent disabling disease of the young adult. Progression of the disease must be documented in order to properly conduct the treatment. Transcranial magnetical stimulation is able to assess the function of the motor system. Corpus callosum lesions are relatively specific and frequent in MS. As transcallosal inhibition (TI) is able to evaluate interhemispheric interactions, it might be useful in assessing cortico-spinal function in MS patients. We have evaluated the central motor conduction time (CMCT), transcallosal inhibition latency (LTI) and duration (DTI) in 40 patients with MS and 18 healthy subjects. Both LTI and DTI showed significant changes in MS patients, proportionate to the degree of clinical impairment. DTI was more sensitive in detecting motor pathway pathology than CMCT (increased CMCT in 80% of patients while DTI was increased in 92.5% of patients). Analysis of TI is a useful and sensitive tool in evaluating motor involvement in MS.