Neuroleptic Malignant Syndrome

What is Neuroleptic malignant syndrome?

Neuroleptic malignant syndrome is a life-threatening, neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic drugs. Symptoms include high fever, sweating, unstable blood pressure, stupor, muscular rigidity, and autonomic dysfunction. In most cases, the disorder develops within the first 2 weeks of treatment with the drug; however, the disorder may develop any time during the therapy period. The syndrome can also occur in people taking anti-Parkinsonism drugs known as dopaminergics if those drugs are discontinued abruptly.

What are the presenting symptoms of NMS?

The classic triad involves the:

  • fever in 100% of cases
  • rigidity
  • cognitive changes

The two  characteristic laboratory findings reported in 75% of cases are:

  • a high CPK and
  • leukocytosis

Other clinical features:

  • Excessive saliva secretion
  • Sweating
  • Pale skin
  • Difficulty swallowing or feeling of chocking
  • Rapid heart rate
  • High blood pressure
  • Shakiness
  • Tremors
  • Urinary incontinence
  • Shuffling gait
  • Agitation
  • Delirium
  • Lethargy

Laboratory work up

Laboratory studies are mainly used to rule out other diagnostic possibilities.

  • Complete blood count and Differentials
  • Blood cultures as indicated by clinical findings
  • Liver function tests (LFTs)
  • Blood urea nitrogen (BUN) and creatinine levels
  • Calcium and phosphate levels
  • Creatine kinase (CK) level
  • Serum iron level
  • Coagulation studies
  • Serum toxicologic
  • Urine drug tests


  • Early identification of and treatment for individuals with neuroleptic malignant syndrome improves outcome.
  • If clinically indicated, a low potency neuroleptic can be reintroduced very slowly when the individual recovers, although there is a risk that the syndrome might recur. Another alternative is to substitute another class of drugs for the neuroleptic.
  • Benzodiazepines are helpful with calming patient down
  • Neuroleptic medications need to be stopped or their dose to be reduced
  • IV fluids to correct volume loss
  • Fever reduction with cooling blankets, ice pack, Tylenol
  • Dantrolene
  • Bromocriptine
  • Pancuronium


  • Neuroleptics should be increased very slowly
  • Regular monitoring of clients for symptoms is helpful with early diagnosis of NMS and timely intervention


  • Keck PE Jr, Pope HG Jr, Cohen BM, McElroy SL, Nierenberg AA. Risk factors for neuroleptic malignant syndrome. A case-control study. Arch Gen Psychiatry. 1989 Oct. 46(10):914-8.
  • Berman BD. Neuroleptic malignant syndrome: a review for neurohospitalists. Neurohospitalist. 2011 Jan. 1 (1):41-7.
  • Rosebush PI, Stewart T, Mazurek MF. The treatment of neuroleptic malignant syndrome. Are dantrolene and bromocriptine useful adjuncts to supportive care?. Br J Psychiatry. 1991 Nov. 159:709-12.
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