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Serotonin Syndrome - What is It?
- Potentially life-threatening condition associated with increased serotonergic activity in the CNS.
- Selective serotonin reuptake inhibitors (SSRIs) are the most commonly implicated class of medications. However, other medications can also be involved.
- It is a clinical diagnosis!
- Classic triad: mental status change, autonomic hyperactivity, and neuromuscular abnormalities
- Mental status change - anxiety, agitation, restlessness, disorientation
- Autonomic hyperactivity - diaphoresis, tachycardia, hypertension, hyperthermia, nausea, vomiting, diarrhea
- Neuromuscular abnormalities - tremor, muscle rigidity, myoclonus, hyperreflexia, clonus, Babinski sign (abnormal plantar reflex)
- Hunter Criteria is the most accurate diagnostic rule:
- Serotonergic agent + one of the following:
- Spontaneous clonus
- Inducible clonus + agitation or diaphoresis
- Ocular clonus + agitation or diaphoresis
- Tremor + hyperreflexia
- Hypertonia + temperature above 38C + ocular clonus or inducible clonus
- Serotonergic agent + one of the following:
- Majority of cases present within 24 hours, most within 6 hours, of a change in dose or initiation of a medication.
** Stay tuned for part 2 on what causes serotonin syndrome **
References
- Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med. 2005;352:1112-1120.
- Dunkley EJ, Isbister GK, Sibbritt D, Dawson AH, Whyte IM. The Hunter Serotonin Toxicity Criteria: simple and accurate diagnostic decision rules for serotonin toxicity. QJM. 2003;96(9):635.
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