[Case of dementia with Lewy bodies showing cervical dystonia after donepezil administration].

We reported a patient with probable dementia with Lewy bodies (DLB) showing cervical dystonia during treatment with donepezil. A 78-year-old female had been treated with donepezil 5 mg/day for 18 months. The patient admitted to our hospital because of severe antecollis. Antecollis disappeard three weeks after discontinuation of donepezil. Five months later the patient received donepezil 3-5 mg/day for disease progression. The patient showed laterocollis again after a month-treatment with donepezil. Physical examination and labolatory tests were nomal. Magnetic resonance imaging of the neck showed no abnormal finding, but electromyography revealed dystonic changes in the neck muscles. Three weeks after discontinuation of donepezil, laterocollis disappeared. These findings suggest that treatment with donepezil induced cervical dystona in a patient with DLB.