Objectives: Dalfampridine exerts beneficial effects on walking ability in a subgroup of patients with multiple sclerosis (MS). These patients are termed "responders". Here, we investigated whether the responder status with respect to mobility measures would determine whether dalfampridine treatment exerts a beneficial effect on other MS symptoms. We therefore assessed walking ability, upper limb function, cognition, fatigue, visual evoked potentials (VEPs), depression, and quality of life in patients before and after dalfampridine treatment.
Methods: Patients with MS and impaired mobility were recruited. Maximal walking distance, timed 25 Foot Walk, nine hole peg test, paced auditory serial addition test (PASAT), fatigue severity scale (FSS), VEPs, Beck Depression Inventory (BDI), EuroQol five dimensional questionnaire, and quality of life visual analogue scale were determined before and after 12-14 days of dalfampridine treatment. Repeated measures analysis of variance was applied to determine the effect of dalfampridine treatment.
Results: Of the 34 patients who completed the study, 22 patients were responders and 12 patients nonresponders, according to their performance in mobility measures. Treatment effects for the entire patient cohort were observed for PASAT (p = .029) and BDI (p = .032). Belonging to the responder cohort did not predict the response to treatment in these tests. For the FSS, response to dalfampridine treatment was dependent on the responder status (p = .001) while no effects in the total patient cohort were observed (p = .680). Other neurological functions remained unaltered. For VEP latencies, no significant improvements were detected.
Conclusion: In this study, we observed beneficial effects of dalfampridine on cognition, depression, and fatigue. These effects were not limited to patients who responded to dalfampridine with improved mobility measures. These findings underscore the need to assess the beneficial effects of dalfampridine on neurological deficits in MS patients in additional randomized clinical trials.
Keywords: cognition; dalfampridine; dexterity; fatigue; multiple sclerosis; symptomatic therapy; visual evoked potentials.