Case history
Case history #1
A 60-year-old man with a longstanding diagnosis of schizophrenia presents to the emergency department with recent-onset delirium. He has hyperthermia, tachycardia of 140 bpm, and generalized muscle rigidity. Medication has been recently changed from ziprasidone to perphenazine. Investigations for possible causes, including sepsis, are all normal. He has mild elevation in white blood cell count and elevated serum creatine kinase levels (1200 units/L).
Case history #2
A 26-year-old man with first episode of psychosis, who is highly agitated and has required several intramuscular injections of an antipsychotic medication, has been in seclusion and restraint during the past 24 hours. Nursing staff notice some slurring of speech and unsteadiness of gait. Vital signs are checked and reveal hyperthermia of 104°F (40°C), blood pressure of 180/100 mmHg, and tachycardia of 110 bpm. He is disoriented to time and place (not to person). The patient also has cogwheel muscle rigidity.
Other presentations
While the typical presentation involves the tetrad of symptoms (altered mental status, autonomic dysfunction, muscle rigidity, and hyperthermia) in the presence of antipsychotics, NMS has also been reported in other circumstances, such as with antidepressant/lithium therapy and withdrawal of dopaminergic drugs.[7][8][9]
There is ongoing controversy as to whether mild or incomplete presentations of NMS are "forme fruste" or atypical NMS (e.g., delirium, tachycardia, and muscle rigidity but temperature of <99°F [<37.2°C]).[8][10][11][12][13]
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