Atypical neuroleptic malignant syndrome associated with clozapine therapy: Case report with literature review

Introduction. Neuroleptic malignant syndrome (NMS) is a potentially fatal complication of neuroleptic drugs. Over the past few decades, it has been mostly considered as idiosyncratic reaction. The aim of this report is to present the case of an atypical NMS associated with clozapine treatment. Case outline. We describe a case of a young male patient treated with clozapine (400 mg), who developed NMS for the first time during the third relapse of schizoaffective disorder. The patient rapidly developed hyperthermia (40°C), tachycardia, labile blood pressure, confusion, elevated creatine phosphokinase, leukocytosis, and rhabdomyolysis, without muscle rigidity or other extrapyramidal signs. Extensive investigations excluded infectious, neurological, endocrine, and metabolic causes. Antipsychotics were discontinued, and treatment with lorazepam, intravenous hydration, and supportive care resulted in complete somatic recovery. Olanzapine was successfully reintroduced after stabilization. Conclusion. Specific pharmacodynamic profile of clozapine hampers early detection of NMS, since muscular rigidity is rare. Therefore, the presentation of NMS in this case is atypical. Atypical development of NMS during clozapine therapy imposes increased clinical attention.