Cerebellar and brainstem disorders due to after-effects of lithium poisoning - A case report

We report here a rare case of vertical nystagmus, dysarthria and broad-based gait due to after-effects of lithium intoxication.A 65-year-old man was admitted with dysarthria and gait disturbance. About 14 years ago, he had begun treatment with lithium carbonate for manic psychosis. Ten years ago, he developed dysarthria and a broad-based gait due to lithium intoxication.Neuro-otological examination demonstrated, downbeat nystagmus in the primary position, rebound nystagmus and direction changingopposing vertical positioning nystagmus.Failure of fixation-suppression of caloric nystagmus was noted in both sides. Eye-tracking test revealed saccadic eye movements, and slow phase OKN velocity was limited billaterally. The equilibrium disturbances observed in this patient's neurological and ENG findings might be attributed to pathological conditions of cerebellar vermis, flocculus and partly brainstem.He was treated with thyroid stimulating hormone (2mg/day) for 18 days.Thereafter, gradually he recovered from some of his neurological symptoms : dysarthria, gait disturbance, rebound nystagmus and direction changing opposing vertical positioning nystagmus.His vertical nystagmus, however, remained unchanged.