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Abstract
Typical antipsychotics (eg, haloperidol) appear to have a higher risk of causing NMS compared with atypical neuroleptics (ie, risperidone, clozapine, quetiapine, olanzapine).5-10 To complicate matters further, NMS has also been reported in patients taking nonantipsychotic medications that may have effects on dopamine receptors such as the antiemetic agent metoclopramide.11 The literature is conflicting on potential risk factors for developing NMS.Symptoms typically appear within 1 week, with almost all cases presenting within 30 days from initiation of a neuroleptic agent.12 The majority of patients initially experience changes in mental status, then muscle rigidity, followed by hyperpyrexia and autonomic dysfunction.13 Physical examination, symptoms, and laboratory findings can lead to a diagnosis of NMS, but other conditions must be ruled out first, such as meningitis, nonconvulsive status epilepticus, malignant hyperthermia, and serotonin syndrome (SS).5 SS presents similarly to NMS, and the 2 syndromes can be difficult to distinguish.14 SS occurs in patients taking serotonin agonist drugs such as selective serotonin reuptake inhibitors (SSRIs).Dantrolene has the potential to cause hepatotoxicity, so liver function tests should be performed at baseline and followed during therapy.17 Other treatment options consist of bromocriptine, a dopamine agonist, and amantadine, which has dopaminergic activity.5 Once NMS is suspected in a patient, neuroleptic medications are avoided for potential recurrence.Psychiatric patients often need neuroleptic medications as part of their medical treatment, and it is possible to reintroduce neuroleptics to a patient who had NMS.