Serotonin syndrome
Background
- Can be produced by any serotonergic medication
- Vast majority of cases occur with therapeutic dosages
- Most common cause of death is severe hyperthermia
Causative Agents
- SSRIs
- MAOIs
- TCAs
- Drugs of Abuse: Cocaine, Ecstasy, Marijuana
- Analgesics: Demerol, fentanyl
- Antiemetics
- Triptans
- Bromocriptine
- OTC: Cough meds, herbal products, St John’s Wort
Clinical Features
- Altered mental status: Agitated delirium
- Autonomic Instability: Hyperthermia, Tachycardia, hypertension, diaphoresis [1]
- Often labile blood pressure, HR
- Neuromuscular Abnormalities: Myoclonus, ocular clonus, rigidity, hyperreflexia, tremor
- More pronounced in the lower extremities
- Myoclonus: most common finding
- Important to identify because it does not occur in other conditions that mimic serotonin syndrome
Differential Diagnosis
Altered mental status and fever
- Infectious
- Sepsis
- Meningitis
- Encephalitis
- Cerebral malaria
- Brain abscess
- Other
Diagnosis
Hunter Toxicity Criteria Decision Rules
Serotonergic agent plus 1 of the following:
- Spontaneous clonus
- Inducible clonus AND (agitation or diaphoresis)
- Ocular Clonus AND (agitation or diaphoresis)
- Tremor AND hyperreflexia
- Hypertonia AND temp >38 AND (ocular clonus or inducible clonus)
84% Sn, 97% Sp
Treatment
- Discontinue all serotonergic drugs
- Benzos
- Goal is to eliminate agitation, neuromuscular abnormalities, elevations in HR/BP
- Cyproheptadine
- Give if benzos and supportive care fail to improve agitation and abnormal vitals
- Serotonin antagonist
- Give 12mg PO/NG; repeat with 2mg q2hr until clinical response is seen (max 32mg/d)
- Give 4mg q6hr x48hr if pt is responsive to initial dose
- Treat hyperthermia
- Hyperthermia due to increase in muscular activity, not change in set point
- Intubate and paralyze
- Standard cooling measures
Disposition
See Also
References
- ↑ Boyer, E. W. and Shannon, M. (2005) ‘The Serotonin Syndrome’, New England Journal of Medicine, 352(11), pp. 1112–1120. doi: 10.1056/nejmra041867