Podcast 914: Neuroleptic Malignant Syndrome (NMS)

Contributor: Taylor Lynch, MD

Educational Pearls:

What is NMS?

Neuroleptic Malignant Syndrome

Caused by anti-dopamine medication or rapid withdrawal of pro-dopamenergic medications

Mechanism is poorly understood

Life threatening

What medications can cause it?

Typical antipsychotics

Haloperidol, chlorpromazine, prochlorperazine, fluphenazine, trifluoperazine

Atypical antipsychotics

Less risk

Risperidone, clozapine, quetiapine, olanzapine, aripiprazole, ziprasidone

Anti-emetic agents with anti dopamine activity

Metoclopramide, promethazine, haloperidol

Not ondansetron

Abrupt withdrawal of levodopa

How does it present?

Slowly over 1-3 days (unlike serotonin syndrome which has a more acute onset)

Altered mental status, 82% of patients, typically agitated delirium with confusion

Peripheral muscle rigidity and decreased reflexes. AKA lead pipe rigidity. (As opposed to clonus and hyperreflexia in serotonin syndrome)

Hyperthermia (>38C seen in 87% of patients)

Can also have tachycardia, labile blood pressures, tachypnea, and tremor

How is it diagnosed?

Clinical diagnosis, focus on the timing of symptoms

No confirmatory lab test but can see possible elevated CK levels and WBC of 10-40k with a left shift

What else might be on the differential?

Sepsis

CNS infections

Heat stroke

Agitated delirium

Status eptilepticus

Drug induced extrapyramidal symptoms

Serotonin syndrome

Malignant hyperthermia

What is the treatment?

Start with ABC’s

Stop all anti-dopaminergic meds and restart pro-dopamine meds if recently stopped

Maintain urine output with IV fluids if needed to avoid rhabdomyolysis

Active or passive cooling if needed

Benzodiazapines, such as lorazepam 1-2 mg IV q 4hrs

What are active medical therapies?

Controversial treatments

Bromocriptine, dopamine agonist

Dantrolene, classically used for malignant hyperthermia

Amantadine, increases dopamine release

Use as a last resort

Dispo?

Mortality is around 10% if not recognized and treated

Most patients recover in 2-14 days

Must wait 2 weeks before restarting any medications

References





Summarized by Jeffrey Olson MS2 | Edited by Meg Joyce & Jorge Chalit, OMSIII