Serotonin syndrome in the perioperative period

Question 1

Triad of serotonin syndrome

Answer 1

• Change in mental status
• Neuromuscular irritation
• Autonomic hyperactivity

With recent exposure (within 48hrs) to a medication with serotonergic activity

Question 2

Hunter’s criteria for serotonin syndrome

Answer 2

• Serotonergic trigger
• Spontaneous clonus
• Or Inducible clonus with agitation, hypertonia, pyrexia or diaphoresis
• Or tremor and hyperpyrexia

Question 3

Common lab abnormalities in serotonin syndrome

Answer 3

• Metabolic acidosis
• Raised LFTS
• Raised Cr
• Raised CK

Question 4

Differential diagnosis for serotonin syndrome and differences

Answer 4

• Malignant hyperthermia: no clonus, rigidity and hyporeflexia
• Anticholinergic syndrome: bradycardia, salivation, diarrhoea, cramps, miosis
• Opioid toxicity: miosis, resp depression
• Neuroleptic malignant syndrome: gradual onset, lead pipe rigidity
• Delirium: no clonus, hyperreflexia
• Sedative withdrawal: no clonus

Question 5

Management of serotonin syndrome

Answer 5

• Discontinue trigger
• Cyproheptadine 12mg stat then 2mg 2 hrly
• Benzodiazepines
• Esmolol and GTN for HTN
• Supportive care