Neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) is a life-threatening complication of treatment with dopamine antagonists, or occasionally abrupt withdrawal of dopamine agonists.

It is characterised by hyperthermia (>38.0°C [>100.4°F] on at least two occasions, measured orally), altered mental status, sympathetic nervous system lability, and hypermetabolism, as well as elevated creatine kinase. Generalised rigidity, described as 'lead pipe' in its most severe form and usually unresponsive to antiparkinsonian agents, is a cardinal feature and may be associated with other neurological symptoms.

Other causes should be excluded before a diagnosis of NMS is made. Common differential diagnoses are sepsis and drug reactions.

NMS is a medical emergency. Treatment consists of immediate cessation of the dopamine antagonist (or restarting or continuing of the dopamine agonist) and supportive measures (rehydration, cooling, and treatment of rhabdomyolysis if present). Additional treatment may be considered if supportive interventions fail.

A delay of at least 2 weeks in restarting antipsychotic treatment is advised following full resolution of NMS.

Documenting this reaction in the medical records is important.

NMS is an uncommon, idiosyncratic, life-threatening complication of treatment with dopamine antagonists. NMS has also been associated with other agents that block central dopamine pathways (e.g., metoclopramide) and occasionally with abrupt cessation of dopamine agonists.

This topic covers the diagnosis and management of neuroleptic malignant syndrome in adults.