[A Case of Neuroleptic Malignant Syndrome Associated with Undiagnosed Dementia with Lewy Bodies].

A 78-year-old woman was transferred to our hospital for clouded consciousness and a high fever. She had been diagnosed with Parkinsonian syndrome, which was controlled with amantadine. Hallucination appeared a week prior to the transfer and she was treated with haloperidol. Suspecting neuroleptic malignant syndrome, dantrolene sodium was administered along with symptomatic treatment with mechanical ventilation and cooling. Her symptoms were reversed and she was transferred to another hospital for neurological evaluation. Magnetic resonance imaging revealed dementia with Lewy bodies (DLB). The high drug sensitivity of DLB was considered the cause of neuroleptic malignant syndrome induced by haloperidol. DLB should be considered in neurological emergencies in patients with Parkinsonism.