Vincristine therapy for children with acute lymphoblastic leukemia impairs conduction in the entire peripheral nerve.

Somatosensory evoked potentials were measured prospectively in 38 children with acute lymphoblastic leukemia to evaluate the side effects of vincristine therapy on conduction of the peripheral nerves. Nineteen patients at standard risk received vincristine 12 mg/m2 during induction therapy and 19 patients at intermediate or high risk received 6 mg/m2 during induction therapy and an additional 6 mg/m2 during delayed intensification therapy. These latencies were compared with those of 38 age-, height-, and sex-matched controls. A prolongation in the peripheral conduction time of the posterior tibial nerve was found in the standard risk patients after induction compared with that of the controls, and a delay was found not only from the ankle to the popliteal fossa, but also from the popliteal fossa to the spinal cord (P < .01). The conduction times of the median nerve from the wrist to the plexus (P < .01) and from the wrist to the spinal cord (P < .01) were prolonged after delayed intensification therapy. There was a significant delay in the median and tibial nerve conduction between the intermediate and high risk patients and their controls after a total vincristine dose of 12 mg/m2. These delays were found along the entire length of the nerves, especially in the proximal part of the tibial nerve (P < .001).