Pimozide Overdose-induced Extrapyramidal Symptoms Mimicking Neuroleptic Malignant Syndrome: A Case Report with Literature Review.

Pimozide overdose is uncommon, with limited published cases worldwide. Its long elimination half-life predisposes to delayed and prolonged toxicity, including extrapyramidal symptoms (EPS) that may mimic neuroleptic malignant syndrome (NMS). Herein, we report a case of a 33-year-old female with dysthymic disorder, recurrent depression, and obsessive-compulsive disorder who presented with rigidity, mutism, psychomotor retardation, and reduced responsiveness for 4 days. She had intentionally ingested around 20-30 pimozide tablets 4 days prior. Initial suspicion of catatonia was revised after the patient disclosed overdose. She developed fever (100°F), worsening rigidity, tremors, and ankle clonus. Creatine phosphokinase (CPK) was mildly elevated at 523 U/L, which argued against NMS. Fever resolved with antibiotics, and EPS improved with supportive care and levodopa-carbidopa. However, the patient developed aspiration pneumonia and succumbed. Thus, pimozide overdose can cause severe EPS mimicking NMS. Differentiation relies on CPK levels and fever response. Supportive care and prolonged observation are critical for favorable outcomes.