TREATMENT OF STABLE CHRONIC DEMYELINATING POLYNEUROPATHY WITH 3,4-DIAMINOPYRIDINE

Objective: To determine whether 3,4-diaminopyridine (3,4-DAP) would im prove clinical or electrophysiologic function in patients with stable chronic demyelinating polyneuropathy. Design: We conducted a prospecti ve, randomized, placebo-controlled, blinded, crossover study of 3,4-DA P in 34 patients with demyelinating polyneuropathy. Material and Metho ds: Of the 17 men and 17 women, who were 21 to 80 years of age, 27 had hereditary motor and sensory neuropathy type I and 7 had acquired dem yelinating polyneuropathy. Treatment consisted of stepped doses of 3,4 -DAP (increasing to 20 mg four times daily) or placebo for 4 days. Pre treatment and posttreatment determination of the Neurologic Disability Score (NDS); isometric muscle strength testing; median, ulnar, and pe roneal nerve conduction studies; and measurement of serum 3,4-DAP were performed. Quantitative computer-assisted sensory examinations mere d one in five patients. Results: The results for the final day of treatm ent with 3,4-DAP or placebo and the differences between pretreatment a nd posttreatment findings for total NDS, sensory NDS, isometric muscle strength testing, compound muscle action potential amplitude, sensory nerve action potential amplitude, motor and sensory conduction veloci ties, and vibration and cold detection thresholds did not vary signifi cantly. A small improvement of 4 points in the motor NDS (P < 0.05) wa s found. Five patients with electrophysiologic conduction block had no significant reduction in the degree of block. Conclusion: Because no improvement was noted in most measurements of neurologic function, des pite use of high doses of drug, 3,4-DAP is unlikely to be beneficial i n the treatment of stable chronic demyelinating polyneuropathy.