Neuroleptic malignant syndrome variant in a patient receiving donepezil and olanzapine.

BACKGROUND: A 78-year-old man with a 22-year history of schizoaffective disorder and a 5-year history of dementia presented to the emergency department with a 5-day history of fatigue, progressive weakness, confusion and lethargy, and a 1-day history of severe muscle stiffness. For the past 10 years the patient had been treated with olanzapine for an unspecified psychiatric illness, without adverse effects. One week before presentation the patient was started on donepezil to treat mild dementia. INVESTIGATIONS: Physical examination, serum and urine laboratory evaluation, lumbar puncture, brain CT scan, brain MRI, electroencephalogram, chest X-ray, and electrocardiogram. DIAGNOSIS: A variant of neuroleptic malignant syndrome secondary to drug interaction. MANAGEMENT: Discontinuation of donepezil and olanzapine, aggressive intravenous hydration, intravenous dantrolene, and bromocriptine via a nasogastric tube. The patient was also administered intravenous antibiotics for aspiration pneumonia, and carbidopa-levodopa for residual parkinsonian features.