Serotonin Syndrome What is it? Potentially life threatening adverse drug reaction resulting from excess serotonergic agonism of CNS receptors. Serotonin syndrome is described as a clinical triad of AMS, autonomic hyperactivity and neuromuscular abnormalities. How often does it happen? In 2002, 26,7333 reported cases with significant toxic effects in 7349 and 93 deaths. It has been identified in patients of all ages, including elderly, children and infants. Why? Serotonergic neurons primarily in the midline raphe nuclei located in the brain stem from the midbrain to the medulla. Assists with regulation of wakefulness, affective behavior, food intake, thermoregulation, migraines, emesis, sexual behavior, nociception and motor tone. Peripherally the serotonin system assists with the regulation of vascular tone and gastrointestinal motility. When? Onset of symptoms rapid with clinical findings often occurring within minutes to 6 hours after medication or self poisoning. A large number of drugs and drug combinations can cause serotonin syndrome and a single therapeutic dose has been enough. MAOIs have a strong association with severe cases of the syndrome esp in combination with meperidine, dextromethorphan, SSRI, or ecstasy. What are the symptoms? Clinical signs is a range of clinical symptoms. Mild cases may have tachycardia and autonomic findings such as shivering, diaphoresis, or mydriasis. Also may have intermittent myoclonus or tremor. Moderate cases may have tachycardia, HTN, hyperthermia (muscle hyperactivity). Symptoms may include mydriasis, hyperactive bowel sounds, diaphoresis, normal skin color, hyperreflexia, clonus, and agitation. Severe cases may have severe hypertension and tachycardia with may deteriorate to shock. Pt will likely have muscular rigidity and hypertonicity. How to treat? Removal of precipitating drugs. Many cases serotonin syndrome resolve within 24 hours after the initiation of therapy and discontinuation of serotonergic drugs. Mild cases can be managed with supportive care and treatment of benzodiazepines to control agitation. Moderate cases should have all cardiorespiratory and thermal abnormalities aggressively corrected. Pt may benefit from 5- HT2A antagonist, cyproheptadine. Severe cases should additionally have immediately sedation, neuromuscular paralysis and intubation. How not to treat? Propranolol, bromocriptine, and dantrolene not recommended. Propranolol , a 5 HT1A antagonist, has long duration of action and may cause hypotension. Bromocriptine (dopamine agonist and used in neuroleptic malignant syndrome) has been implicated in development of serotonin syndrome. Dantrolene has no effect on survival.