Assessment of motor function in patients with multiple sclerosis treated with Fampridine using motor-evoked potentials

1) Background: the purpose of the study is to consider the utility of Transcranial Magnetic Stimulation (TMS) in patients with Multiple Sclerosis (MS) and walking impairment, treated with Fampridine, as correlated with the 25-Foot-Walk test (T25-FW). Clinical benefits are usually seen within 2-4 weeks of starting treatment, and if not, discontinuation is required. (2) Methods: fifteen MS patients with gait impairments, classified between 3-5 and 7 on the EDSS (Expanded Disability Status Scale), were enrolled in the study and investigated by T25-FW and TMS. Assessments were performed before Fampridine 10 mg twice daily, at 5 and 12 days thereafter, and at 1 and 3 months later. The mean age was 42.8 years and the mean disease duration was 12.06 years. (3) Results: The evaluated patients recorded a 2.1-second improvement in gait measured on T25-FW after the first 12 days in 9 patients, which correlated with a 2-millisecond improvement in central motor conduction time (CMCT). In the other 6 patients, there was no visible clinical improvement. The CMCT, decreased by 0.5 ms and motor conduction velocity by 1 millisecond in 4 of these 6 patients. Fampridine administration was continued in the 4 cases. At the end of the 3-month period, their walking speed measured as on the T25-FW also improved by 2 sec. (4) Conclusions: the amelioration of TMS parameters anticipated the improvement of speed on the T25-FW. In spite of the early false negative clinical response, electrophysiological findings could predict a future clinical improvement if treatment is continued.