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Neuroleptic Malignant Syndrome

Neuroleptic malignant syndrome, NMS, is a rare disease which is induced by the use of neuroleptic drugs. It is estimated that only 0.2% of those treated with neuroleptic medication will develop NMS. Neuroleptics are a class of drugs used to treat psychiatric disorders. Clinically this disease manifests itself in four ways:

  1. Hyperthermia: Patients with NMS have a high fever which is drug-induced. About 40% of patients have a temperature above 104 degrees F and fever can reach as high as 108 degrees F. Hyperthermia occurs because neuroleptics affect those portions of the brain which are responsible for regulating body temperature down.
  2. Muscle rigidity: Generalized muscle rigidity occurs in all patients with NMS. Individuals often have muscle tremors as well as myoclonus (shock-like contractions of a group of muscles). In addition, muscle rigidity can be manifested as trouble swallowing (dysphagia), excess secretion of saliva (sialorrhea), difficulty performing voluntary movements (dyskinesia), and uncontrolled rotation of the eyeball (oculogyric crisis).
  3. Altered mental status: Victims of NMS suffer from clouding of consciousness. Consciousness can be altered to the point of stupor (an impairment of consciousness in which only continual stimulation can arouse the patient), or even to the point of coma. In addition, patients afflicted with NMS are often delirious, meaning that they are confused, disoriented, and agitated
  4. Autonomic dysfunction: Patients with NMS commonly experience disorders of the autonomic nervous system. This is manifested as rapid heart rate (tachycardia), high blood pressure (hypertension), and rapid breathing (tachypnea).

What complications are associated with NMS?

The high fever and muscle rigidity associated with NMS can give rise to the following complications: metabolic acidosis (increased acidity of the blood); respiratory failure, which results from rigidity of the chest muscles and diaphragm; muscle breakdown (rhabdomyolysis); and renal failure, which can result from myoglobinuria. If these complications are uncontrolled, NMS can be fatal.

How is NMS treated in a neuro-ICU?

Neuroleptic malignant syndrome, although rare, is extremely amenable to treatment in a neuro-ICU. Such treatment vastly improves the prognosis of patients with NMS. Therapy involves:

  1. The immediate discontinuation of all neuroleptic drugs and/or drugs affecting the brain's levels of dopamine.
  2. Pharmacotherapy with two drugs specialized to treat this condition: dantrolene and bromocriptine. Both of these agents serve to decrease muscle rigidity. Dantrolene is rarely used in most medical centers, and familiarity with its use can lead to more effective treatment.
  3. Aggressive temperature reduction is accomplished with cooling blankets.
  4. Intravenous fluid replacement.
  5. Proper breathing is ensured by intubation with a breathing tube, and placement of the patient on a mechanical ventilator.


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