Serotonin syndrome

Serotonin syndrome is diagnosed on the basis of clinical findings. Hunter Toxicity Criteria Decision Rules (sensitivity 84%, specificity 97%) must have the presence of a serotonergic agent and meet one of the following conditions:

• Spontaneous clonus
• Inducible clonus plus agitation or diaphoresis
• Ocular clonus plus agitation or diaphoresis
• Tremor plus hyperreflexia
• Hypertonia plus temperature above 38ºC PLUS ocular clonus or inducible clonus

Medications contributing to serotonin syndrome:

• Amphetamines and derivatives
• Analgesics (cyclobenzaprine, fentanyl, meperidine, tramadol)
• Antidepressants/ mood stabilizers (buspirone, lithium, MOA-I, SSRIs, SNRIs, serotonin 2A-R blockers, St. John’s wort, TCAs)
• Antiemetics (metoclopramide, ondansetron)
• Antimigraine med (carbamazepine, ergots, triptans, valproic acid)
• Miscellaneous (cocaine, dextromethorphan, linezolid, L- tryptophan, 5-hydroxytryptophan)

Treatment:

• Removal of offending agent
• Usually supportive (benzodiazepines), although can give cyproheptadine (serotonin 2A antagonist)