An Unusual Cause of Persistent Tachycardia: Atypical Neuroleptic Malignant Syndrome

Abstract

Neuroleptic malignant syndrome (NMS) is a rare, life-threatening emergency caused more commonly by typical antipsychotics. However, unusual presentations of NMS are intermittently reported with the use of atypical antipsychotics. We present the case of a 42-year-old gentleman with schizoaffective and bipolar disorder who was admitted for change in mentation and lithium toxicity. His mentation did not improve despite being dialyzed and the resolution of lithium level to baseline. He developed persistent tachycardia and hyperthermia, initially attributed to Streptococcal infection. But despite appropriate antibiotic therapy, his clinical symptoms did not improve. An extensive workup for his neurological symptoms, including lumbar puncture, 5-hydroxy indole acetic acid urine test, and brain magnetic resonance imaging, was inconclusive of any underlying etiology. Given the suspicion of atypical NMS, bromocriptine 2.5 mg three times daily was initiated. This led to the gradual resolution of his symptoms and a return to his baseline mental status. Diagnosing atypical NMS can be challenging and must be differentiated from similar disorders. Lithium toxicity can predispose patients to develop NMS.

An Unusual Presentation of Serotonin Syndrome and Subsequent Catatonia in a Patient With a Family History of Huntington’s Disease

“…According to the Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) [ 5 ], a diagnosis of NMS requires exposure to a dopamine-blocking agent, severe muscular rigidity, fever, and at least two of the minor criteria: diaphoresis, dysphagia, tremor, incontinence, altered level of consciousness, mutism, tachycardia, elevated or labile blood pressure, leucocytosis, and elevated CPK (Table 2 ). According to many diagnostic criteria, fever is a defining symptom of NMS, however, many atypical presentations of NMS [ 6 ] (especially in the early course) are constantly reported in the literature.…”

“…Upon initial laboratory results, the leukocyte count was within normal limits and CPK levels were normal, findings which are not suggestive of NMS. Atypical presentations of NMS with normal levels of CPK have been described in the literature [ 6 , 9 ]; furthermore, in the initial stages of the syndrome when rigidity is not well developed, CPK levels may be within normal limits. The patient’s clinical status improved under supportive care and benzodiazepine therapy.…”