Fast Five Quiz: Serotonin Syndrome

Differentiating serotonin toxicity from other syndromes that have similar manifestations may be difficult. Such syndromes include, but are not limited to, neuroleptic malignant syndrome; malignant hyperthermia; anticholinergic toxicity; and infectious diseases, such as meningitis and encephalitis (Table).

Table. Differentiation of Serotonin Syndrome From Similarly Presenting Conditions

Clinical Feature	Serotonin Syndrome	Anticholinergic Toxidrome	Neuroleptic Malignant Syndrome	Malignant Hyperthermia
Medication history	Serotoninergic drug	Anticholinergic agent	Dopamine agonist	Inhalational anesthetic
Average onset time	< 12 h	< 12 h	1-3 d	0.5-24 h
Vital signs	Hypertension, tachycardia, tachypnea, fever (>105.8 °F [41 °C])	Hypertension, tachypnea, tachycardia, fever (<102.2 °F [39 °C])	Hypertension, tachycardia, tachypnea, fever (>105.8 °F [41 °C])	Hypertension, tachycardia, tachypnea, hyperthermia
Pupils	Mydriasis	Mydriasis	Normal	Normal
Bowel sounds	Hyperactive	Decreased or absent	Normal or decreased	Decreased
Tone	Increased in lower extremities	Normal	"Lead-pipe" rigidity in all muscle groups	Rigor mortis–like rigidity
Reflexes	Hyperreflexia clonus	Normal	Bradyreflexia	Hyporeflexia
Mental status	Agitation, coma	Agitation, delirium	Stupor, alert, mutism, coma	Agitation
Adapted from Boyer EW, Shannon M. N Engl J Med. 2005;352:1112-1120.

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Cite this: Richard H. Sinert. Fast Five Quiz: Serotonin Syndrome - Medscape - Jun 04, 2021.

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