Consecutive patients with stable multiple sclerosis are being recruited from the neurological services of Social Security Mexican Institute (IMSS) at the National Medical Center (CMN) "Siglo XXI" Specialties Hospital over the period of 1 year. Of those meeting inclusion criteria, 24 will be selected for the study. After signing an informed consent, they will be randomized into 12 for the intervention arm and 12 for the placebo arm. All patients will receive capsules for daily consumption according to their assignment, with no visible difference between capsules. Dosage will be 6.5-7.5 mg/kg to a limit of 50 mg. These capsules will be taken for a period of 22 weeks. A battery of neuropsychological tests will be administered at baseline, after 22 weeks, and after an additional 22 weeks of follow-up to assess cognitive performance and motor function. Emotional state will be assessed with the Beck Depression Inventory at each of the three afore mentioned points.
After the follow-up period, all test results will be analyzed and compared to determine the efficacy and safety of 4-aminopyridine on the cognitive performance and motor function of patients. Mann-Whitney U will be used for statistical analysis.
