Fampridine for Symptomatic Treatment in Chronic Inflammatory Demyelinating Polyneuropathy: A Randomized, Double‐Blinded, Placebo‐Controlled Crossover Study

ABSTRACT Background and Aims Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is an immune‐mediated neuropathy that may cause persistent disability despite immunoglobulin treatment. Ion channel dysfunction has been demonstrated in CIDP, but no therapies specifically target this mechanism. We investigated whether fampridine improves clinical function and electrophysiological measures in CIDP patients with residual symptoms. Methods In this two‐center, randomized, double‐blind, placebo‐controlled crossover trial, patients with CIDP receiving stable subcutaneous or intravenous immunoglobulin were assigned to 4 weeks of fampridine (10 mg twice daily) or placebo, separated by a washout period. Co‐primary outcomes were changes in Six‐Spot‐Step Test (SSST) and Nine‐Hole Peg Test (9‐HPT). Secondary outcomes included clinical scores, patient‐reported outcomes, nerve conduction studies, and nerve excitability testing. Results Twenty‐eight patients were included in the study. No significant differences were observed between fampridine and placebo for SSST ( p = 0.154) or 9‐HPT ( p = 0.857). Grip strength and R‐ODS worsened during fampridine compared with placebo (Bonferroni‐adjusted p = 0.007 for both), while other clinical outcomes showed no differences. Median nerve CMAP amplitude with proximal stimulation increased significantly during fampridine treatment (adjusted p = 0.040). No significant changes were observed in other electrophysiological variables, including nerve excitability testing. No serious adverse events occurred and adverse effects were predominantly mild. Interpretation Our study did not provide evidence that fampridine improves clinical function in CIDP patients with residual disability during stable immunoglobulin therapy. Targeting ion channel dysfunction in CIDP remains of interest, but alternative strategies may be required.