Antidepressant and antiobesity drug-induced serotonin syndrome complicated by multiple organ injury A case report

Rationale: Serotonin syndrome (SS), also referred to as serotonin toxicity, is a potentially life-threatening condition associated with increased serotonergic activity in the central nervous system, but often underdiagnosed due to its variable presentation. Patient concerns: A 46-year-old woman presented to the emergency department with complaints of fever, confused mental status with slurred speech, agitation. The patient also exhibited lower extremities weakness with spontaneous clonus. The physical examination revealed tachycardia and tachypnea. The patient was taking fluoxetine for depression disorder and anti-obesity medications including topiramate and phentermine. Initial laboratory finding demonstrated severe hypoxemia and rhabdomyolysis with renal dysfunction. Diagnoses: Spinal tap and brain magnetic resonance imaging showed no clues that could explain the patient’s neuromuscular symptoms. Based on the patient’s overall presentation and use of medications, a diagnosis of SS was made. However, the patient’s inpatient treatment was complicated by pulmonary thromboembolism (PTE) and stress-induced cardiomyopathy (SCM). Interventions: The patient was intubated and admitted to the intensive care unit for supportive care, including mechanical ventilation and hemodialysis. The patient received an intravenous benzodiazepine and vecuronium for controlling autonomic dysfunction and neuromuscular symptoms. Anticoagulation was also initiated promptly following the diagnosis of PTE. Outcomes: After intensive supportive care, she was discharged 1 month after admission with normalized left ventricular motion and systolic function. Lessons: This case highlights that SS should be considered as an etiology of unexplained episodes of altered mental status and neuromuscular abnormalities. Rarely, this condition can be complicated by multiple organ injury, involving conditions such as rhabdomyolysis, renal failure, SCM and PTE. Thus, physicians must be aware of the various and atypical manifestations of serotonin syndrome in order to avoid missing the diagnosis of a potentially fatal condition.