Neuroleptic malignant syndrome

Question 1

Describe the natural history of neuroleptic malignant syndrome.

Answer 1

• Typically occurs within the first 2 weeks of starting an antipsychotic
• It is an idiosyncratic reaction (unpredictable and not dose-dependent)
• Majority of episodes resolve within 2 weeks of stopping the drug

Question 2

What are the risk factors for neuroleptic malignant syndrome?

Answer 2

• Higher anti-psychotic doses
• High-potency anti-psychotics
• Concomitant drug use (e.g., lithium)
• Depot formulations
• Acute medical illness
• Acute catatonia
• Previous NMS

Question 3

What are the clinical features of NMS?

Answer 3

• Altered mental status - usually presents with agitation and delirium
• Rigidity
• Fever
• Dysautonomia - tachycardia, labile BP, profuse sweating, and/or arrhythmias

Question 4

What derangements can be seen on blood tests in NMS?

Answer 4

AKI - electrolyte derangement, raised urea and creatinine

Rhabdomyolysis - hypophosphataemia, hypomagnesaemia, hyperkalaemia, metabolic acidosis, sodium disruption

Mildly deranged LFTs and leukocytosis

Raised creatine kinase due to muscle rigidity

Question 5

What is the management for NMS?

Answer 5

• Supportive therapy
• Medical therapy:
  1. Dantrolene - ryanodine receptor antagonist (hyperthermia and rigidity)
  2. Bromocriptine - dopamine agonist (restore dopaminergic tone)

Question 6

What are the potential complications of NMS?

Answer 6

• Mortality is 5-20%
• Cardiac arrest
• Cardiac arrhythmias
• AKI
• Rhabdomyolysis
• DIC
• VTE
• Seizures
• Respiratory failure