Postoperative Serotonin Syndrome: A Case Report Highlighting Dexmedetomidine for Refractory Symptoms

Serotonin syndrome (SS) is a life-threatening condition caused by excessive serotonin, typically due to drugs such as selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), and certain opioids. It often results from combining two serotonin-affecting drugs or excessive use of one. SS is diagnosed clinically, presenting with neuromuscular hyperactivity, autonomic instability, and altered mental status, with clonus as a key distinguishing feature. The Hunter Criteria aids diagnosis but should not be used to rule out SS. Treatment starts with discontinuing the offending agent, followed by supportive care, including airway management and stabilization of vital signs. Benzodiazepines can help control seizures and agitation, while cyproheptadine may be used in moderate to severe cases. Benzodiazepines have many side effects and cyproheptadine is only available in oral formulations, which adds complexity to effective treatment. In rare instances, SS can be refractory and may require intubation and neuromuscular paralytics. In this case, we present a case of a 42-year-old female who developed confusion, tachycardia, muscle rigidity, and hypertension after outpatient ankle surgery, where she received midazolam, fentanyl, propofol, toradol, ondansetron, meperidine, and dexamethasone perioperatively. Her daily medication also included fluoxetine, dextroamphetamine-amphetamine, and trazodone. The patient required intubation for continued diazepam administration and was admitted to the ICU. Despite improving vital signs, she remained altered with diffuse muscle rigidity. After three days of refractory SS, dexmedetomidine, an alpha-2 antagonist, was administered. The patient showed clinical improvement over the next four days and was stable enough for extubation and discontinuation of dexmedetomidine. The patient made significant clinical progress and was discharged to follow up with her primary care provider. This case highlights the importance of early detection through clinical context and not relying solely on the Hunter criteria and the potential use of dexmedetomidine as an adjuvant to benzodiazepine therapy.