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Neuroleptic Malignant Syndrome (NMS) 





  • Rare, potentially fatal condition due to antipsychotic drug therapy

  • May reflect dopamine depletion in the CNS

  • Can occur anytime during the course of antipsychotic treatment but often is manifest during the first few weeks of therapy or following an ↑ in drug dosage.

  • Clinical manifestations usually develop over 24-72 hours, remember the mnemonic FEVERS:

    • F ever 

    • E ncephalopathy 

    • V ital signs unstable 

    • E levated labs

    • R igidity (vs myoclonus in serotonin syndrome) 

    • S weating 





  • Emergency situation, full stomach 

  • Potentially life-threatening situation with high mortality: 

    • ↓ LOC: coma which may mandate airway management

    • Autonomic instability: tachycardia, hypertension, cardiac dysrhythmias (most likely cause of death)

    • Hypermetabolic state: fever, severe muscular rigidity, volume depletion

    • Tachypnea & potential respiratory insufficiency from hypoventilation/rigidity

    • Rhabdomyolysis, renal failure, acidosis 

  • Psychiatric patient, potentially uncooperative





  • Resuscitation & ICU monitoring following trigger

  • Stop offending agents 

  • Supportive treatment: cooling, treat acidosis/electrolyte abnormalities, hemodynamic support

  • Pharmacologic (case reports, no strong evidence): 

    • Bromocriptine: PO/NG 2.5 mg q8-12 hrs 

    • Dantrolene: IV 2.5mg/kg bolus, up to 10mg/kg/day

    • Amantadine: initial dose is 100 mg PO/NG & titrated upward as needed to a maximum dose of 200 mg q12h

    • Benzodiazepines

  • Rule out other high risk conditions on differential diagnosis 

  • "Trigger free” anesthetic in patients with history of NMS (controversial) 



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