A case of lithium intoxication with downbeat vertical nystagmus.

Lithium carbonate has recently been used in the treatment of manic diseases. However, since the marginal range between therapeutic and toxic doses is very narrow, close attention should be paid to the development of adverse reactions in its application. Lithium intoxication is manifested by neurological symptoms. Neurotological tests were performed on a patient with lithium intoxication that occurred in the course of psychiatric treatment of mania. The observed sequelae included marked downbeat vertical nystagmus and truncal ataxia. The main lesions in the present case were considered to be located in the cerebellum. Close observation, including neurotological tests, is of greatest importance because in cases of lithium intoxication the development of cerebellar as well as brainstem disorders must not be overlooked.