Effect of 4-aminopyridine on gait in ambulatory spinal cord injuries: a double-blind, placebo-controlled, crossover trial

Animal and human research have shown that the drug 4-aminopyridine (4-AP) may improve gait in spinal cord lesions by enhancing nerve transmission to affected muscles. Study design: Prospective, randomized, double-blind, placebo-controlled, crossover trial. Objectives: To determine the efficacy of 4-AP in improving lower limb muscle strength and biomechanical gait patterns of chronic spinal cord injuries (SCI). Setting: The Rehabilitation Centre (Ottawa, Canada). Methods: In all, 15 chronic, ambulatory SCI persons were randomized to an initial 2 weeks of 40 mg/day, oral medication of either placebo or immediate-release, 4-AP and subsequently crossed over to the alternate medication for the following 2 weeks. Evaluations were conducted at baseline (before starting 4-AP or placebo medication), 2 weeks, and 4 weeks. Measures included dynamometer lower limb isometric muscle force and biomechanical gait measures including temporal-spatial parameters, electromyographic activation patterns, joint kinematics and kinetics. Subjective impressions of the drug by the participants were obtained from an exit survey. Results: Despite some positive comments from subjects, statistical and clinical analyses showed no within-subject differences between placebo and 4-AP measures of lower limb muscle force and objective gait analyses (ANOVA statistic P>0.05). Conclusion: Results demonstrated the importance of placebo-controlled trials and quantitative outcome measures for the evaluation of 4-AP aimed to enhance gait for chronic, ambulatory SCI persons. Energy expenditure measures and mood may relate more to subjective comments and is suggested for future investigations.