Donepezil-induced cervical dystonia in Alzheimer's disease: a case report and literature review of dystonia due to cholinesterase inhibitors.

We herein report an 81-year-old woman with Alzheimer's disease (AD) in who donepezil, a cholinesterase inhibitor (ChEI), caused cervical dystonia. The patient had a two-year history of progressive memory disturbance fulfilling the NINCDS-ADRDA criteria for probable AD. Mini-Mental State Examination score was 19/30. The remaining examination was normal. After a single administration of donepezil (5 mg/day) for 10 months, she complained of dropped head. Neurological examination and electrophysiological studies supported a diagnosis of cervical dystonia. Antecollis disappeared completely at 6 weeks after cessation of donepezil. Dystonic posture can occur at various timings of ChEI use. Physicians should pay more attention to rapidly progressive cervical dystonia in ChEI-treated AD patients.