Polypharmacy-induced serotonin syndrome revealing underlying neurocognitive impairment and cervical myelopathy.

Serotonin syndrome is a life-threatening condition characterized by neuromuscular hyperactivity, autonomic dysregulation and altered mental status. Polypharmacy in older adults with multiple comorbidities is associated with increased risk of serotonin syndrome. We report a woman in her 50s with diabetes, hypertension and chronic kidney disease recently misdiagnosed with Parkinsonism. She presented with confusion, hyperreflexia, myoclonus and autonomic instability. Her medications included supratherapeutic paroxetine (40mg two times per day), aripiprazole and benztropine. Symptoms improved with cyproheptadine and cessation of serotonergic agents. However, persistent motor findings prompted further evaluation. Cervical spine MRI showed C4-C5 disc protrusion with ventral cord compression, while brain imaging revealed cerebral atrophy. Cautious administration of haloperidol did not worsen symptoms, suggesting drug-induced or structural Parkinsonism. This case highlights the risk of uncoordinated pharmacotherapy and premature diagnostic closure. The presentation of serotonin syndrome may obscure underlying neurologic pathology, making thorough medication review and multidisciplinary evaluation essential in complex geriatric presentations.