[Structural and functional analysis of the cortico-spinal tract in multiple sclerosis]

The study aimed at comparison of transcranial magnetic stimulation (TMS) parameters to MRI data in multiple sclerosis (MS), taking into account clinical course of the disease. TMS was conducted in 56 patients and in 10 age- and sex-matched healthy controls. According to stage of activity and variant of the course, the patients were divided into 2 groups: one at the stage of exacerbation and another--at the stage of remission with secondary progressive MS. Latency of segmental evoked motor response was similar in patients and controls. Statistically significant between-group difference or trend toward changing of some TMS parameters were found that indicates a slow-down of the impulse conducting along the cortico-spinal tract, which is characteristic of demyelinization process. The changes were more pronounced in secondary-progressive MS. According to MRI data, a square of the spinal cord on the level of the intervertebral disk center C2/C3 was significantly smaller in the group of patients with secondary progressive MS than in that with exacerbation of the disease. The TMS parameters correlated both with the level of the focal demyelinization process and with the square of the spinal cord on a level selected. It allows to estimate expression of atrophic changes caused, in its turn, not only by myelin loss but also by axon loss.