Serotonin syndrome

Diagnosis

Hunter Criteria

• Must have a serotonergic exposure
• The diagnosis is made in any of the following situations:
  • Spontaneous clonus
  • Either ocular clonus or inducible clonus, plus either agitation or diaphoresis
  • Tremor plus hyperreflexia
  • Hypertonia, plus temperature over 38C, plus either ocular clonus or inducible clonus

• Sensitivity 84% and specificity 97%

Sternbach Criteria

• Recent addition or increase in a known serotonergic agent
• Absence of other possible etiologies such as infection, substance abuse
• No recent addition or increase of a neuroleptic agent
• At least three of the following:
  • Mental status changes such as confusion or hypomania
  • Agitation
  • Myoclonus
  • Hyperreflexia
  • Diaphoresis
  • Shivering
  • Tremor
  • Diarrhea
  • Incoordination or ataxia
  • Fever
• False positives are common

Clinical Manifestations

• Fever, rigidity, clonus, diaphoresis, tremor, and agitation
• Compared to NMS, SS is more likely to have:
  • Acute onset
  • Sialorrhea, hyperactive bowel sounds
  • Hyperreflexia and clonus
  • Mydriasis

Management

• Stop all serotonergic drugs
• Supportive therapy
  • Aggressive cooling
• Sometimes can use
  • Cyproheptadine but is PO and takes 24-48h
  • Olanzapine 10mg IV BID