22 migraine patients with a history of chronic ergotamine abuse were compared with 12 patients with a similar intake of dihydroergotamine. The study of somatosensory-evoked potentials showed that 50% of the patients with a history of ergotamine abuse had increased central conduction times after stimulation of the tibial nerve. Corticomotoneuronal latencies obtained by noninvasive electrical stimulation of the motor cortex were normal in 5 patients. The functional sensory deficits were not related to clinical impairment and were more frequently observed in patients with a comparatively high mean daily and cumulative intake.