[Neuroleptic malignant syndrome after 30 years treatment with clozapine: a rarely seen differential diagnosis on intensive care units]

Abstract

The neuroleptic malignant syndrome (NMS) is a rare, but potentially lethal side effect of conventional and atypical antipsychotic drugs. We present a 62 years old male patient who was admitted to our institution because of sudden onset of mild hyperthermia, muscle rigidity, stupor, leucocytosis and massive rhabdomyolysis after 30 years uneventful treatment with clozapine. The medication with clozapine was suspended because of the suspicion of NMS. When the acute symptoms were abated, the treatment with clozapine was resumed again after 14 days. The very next day, the patient suffered again from raised body core temperature, leucocytosis, elevated serum creatine kinase and new catatonia. The therapy with clozapine was stopped definitively and benzodiazepines were administered assuming a relapse of an alleviated, probably reconvening NMS. Under the treatment with benzodiazepines the patient was free of symptoms even after 1 month. To our knowledge, the latency of 30 years between the beginning of the treatment with clozapine and the onset of NMS is the longest period in the literature. According to our case, the differential diagnosis of NMS is not always trivial and is therefore discussed.