Serotonin Syndrome and Neuroleptic Malignant Syndrome: A Mixed Case Following Antidepressant/Antipsychotic Overdose

Abstract

Background: Serotonin Syndrome (SS) and Neuroleptic Malignant Syndrome (NMS) are life-threatening conditions with overlapping features, including altered mental status, autonomic instability, and hyperthermia. Despite clinical similarities, their pathophysiology differs: SS arises from excessive central serotonergic activity, while NMS results from dopamine receptor blockade, typically due to antipsychotic use.

Case History: A 71-year-old male with a history of depression and benign prostatic hyperplasia presented with restlessness, insomnia, and confusion. Medication adjustments two weeks prior included an increase in escitalopram (20 mg to 40 mg/day), initiation of olanzapine (2.5 mg/day), and continuation of clomipramine (75 mg/day) and alprazolam. Brain CT and angiography were normal. The subacute symptom onset, medication profile, and clinical picture suggested a mixed SS/NMS. All psychotropic drugs were discontinued. The patient was treated with short-acting benzodiazepines and antihypertensives (e.g., esmolol), without specific antidotes.