Neuroleptic Malignant Syndrome

Idiosyncratic reaction to initiation or change of an antipsychotic or dopamine antagonist characterised by:

Epidemiology and Risk Factors

Pathophysiology

Dopamine antagonism at the:

  • Hypothalamus
    Hyperthermia.
  • Mesocortical and nigrostriatal region
    Mental state change and extrapyramidal symptoms.

Aetiology

Clinical Features

  • Fever
  • Encephalopathy
  • Haemodynamic instability
  • Rhabdomyolysis

Investigations

Bedside:

  • Blood
    • FBE
      Leukocytosis.
    • UEC
    • CK
    • Coag

Laboratory:

Imaging:

Other:

Diagnostic Approach and DDx

Diagnosis requires:

  • Use of neuroleptic medication
  • Muscle rigidity
  • Fever
  • ⩾2 of:
    • Tremor
    • Altered conscious state
    • ↑ HR
    • HTN or labile BP
    • Diaphoresis
    • Leukocytosis
    • Rhabdomyolysis
    • Leukocytosis

Serotonin Syndrome is a common differential for NMS.

The key differentiating features are that:

  • Serotonin syndrome has an:
    • Earlier onset
    • Hyper-reflexia and clous
    • Dilated pupils
    • ↑ Bowel sounds
  • NMS has:
    • A slow onset over days
    • Extrapyramidal features
    • Rigidity but no clonus
    • Normal or ↓ bowel sounds

Management

  • Cease offending agent
  • Manage hyperthermia
  • Give dopaminergic

Specific therapy:

  • Pharmacological
    • Dopaminergic agent
      • Bromocriptine 2.5-5mg PO/NG Q8H
      • Amantadine
  • Procedural
  • Physical

Supportive care:

  • D
    • Sedation
      • Benzodiazepines
  • E
    • Manage hyperthermia
      • Neuromuscular blockade
      • Active cooling

Disposition:

Preventative:

Marginal and Ineffective Therapies

Anaesthetic Considerations

Complications

  • B
    • Respiratory failure
  • C
    • Arrhythmias
  • F
    • AKI
    • Rhabdomyolysis
  • H
    • DIC

Prognosis

Key Studies

References

  1. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.