Three Patients with Neuroleptic Malignant Syndrome: Differential Diagnosis and the Causes of Predisposition

Neuroleptic malignant syndrome (NMS) is a life-threatening idiosyncratic reaction that occurs after the administration of neuroleptic drugs. It usually appears within the first two weeks of neuroleptic treatment. The tetrad of NMS seen in 50% of patients includes fever, muscle rigidity, altered mental status and evidence of autonomic instability. NMS may be overlooked or its diagnosis may be difficult due to its similarities with some organic and psychiatric disorders. Due to its heterogeneous character, differential diagnosis and supportive treatment are very important when managing these patients. We aimed to present the differential diagnosis and the causes of predisposition in three patients, two with a diagnosis of schizophrenia and one with psychomotor impairment, who were admitted to the medical intensive care unit with a diagnosis of an NMS-like condition related to antipsychotic (olanzapine) treatment.