Equilibrium disorder in carbamazepine toxicity.

Three cases of acute carbamazepine intoxication were evaluated neurotologically and neurologically. Findings included symptoms of equilibrium, gait and speech disorders, drowsiness, gaze nystagmus, depressed optokinetic nystagmus and disturbances of smooth pursuit eye movement. These findings, suggestive of a space-occupying lesion, disappeared after the cessation of the medication. On the basis of the clinical findings it is felt that carbamazepine affects structures within the brain stem and the cerebellum. It is well known that equilibrium disorders caused by anticonvulsant intoxication are due to cerebellar disorders, but from our present study it should be noted that they originate not only from cerebellar lesions but also from brain stem lesions.