A cross-sectional comparison of performance, neurophysiological and MRI outcomes of responders and non-responders to fampridine treatment in multiple sclerosis – An explorative study

Objective: To compare baseline physical and cognitive performance, neurophysiological, and magnetic resonance imaging (MRI) outcomes and examine their interrelationship in participants with Multiple Sclerosis (MS), already established as either responder or non-responder to Fampridine treatment, and to examine associations with the expanded disability status scale (EDSS) and 12-item MS walking scale (MSWS-12). Methods: Baseline data from an explorative longitudinal observational study were analyzed. Participants underwent the Timed 25-Foot Walk Test (T25FW), Six Spot Step Test (SSST), Nine-Hole Peg Test, Five Times Sit-to-Stand Test, Symbol Digit Modalities Test (SDMT), neurophysiological testing, including central motor conduction time (CMCT), peripheral motor conduction time (PMCT), motor evoked potential (MEP) amplitudes and electroneuronography of the lower extremities, and brain MRI (brain volume, number and volume of T2-weighted lesions and lesion load normalized to brain volume). Results: 41 responders and 8 non-responders were examined. There were no intergroup differences in physical performance, cognitive, neurophysiological, and MRI outcomes (p > 0.05). CMCT was associated with T25FW, SSST, EDSS, and MSWS-12, (p < 0.05). SDMT was associated with the number and volume of T2-weighted lesions, and lesion load normalized to brain volume (p < 0.05). Conclusion: No differences were identified between responders and non-responders to Fampridine treatment regarding physical and cognitive performance, neurophysiological or MRI outcomes. The results call for cautious interpretation and further large-scale studies are needed to expand our understanding of underlying mechanisms discriminating Fampridine responders and non-responders. CMCT may be used as a marker of disability and walking impairment, while SDMT was associated with white matter lesions estimated by MRI. ClinicalTrials.gov identifier: NCT03401307.