Late-Onset Dystonia With Low-Dose Olanzapine in an Older Person: A Case Report

Drug-induced dystonias are rare but can occur with second-generation antipsychotics. They are usually dose-related and occur soon after dose initiation. This case describes the development of dystonia after two years of olanzapine 5 mg daily in an older person with Alzheimer's dementia. The dystonia resolved after diphenhydramine treatment on day two of hospitalization, but then the patient became delirious, which was treated with lorazepam on day three. Six days after admission, she developed tremors and rigidity that self-resolved. Her dystonia resolved after 11 days. The recurrence of symptoms during the hospitalization may have been a result of the progression of her dementia. This is the first known case of a patient developing dystonia after chronic use of low-dose olanzapine. This was not characterized as tardive dystonia because the dystonia was resolved with anticholinergic medication. This case illustrates the difficulty of using anticholinergics to treat dystonias in older people, which can precipitate delirium. Choosing an alternative antipsychotic with less extrapyramidal symptom risk is challenging as she had previous trials with quetiapine and risperidone. Clozapine was deemed an unfavorable alternative, as laboratory monitoring would be burdensome. Olanzapine-induced dystonias can develop anytime during therapy. Families must balance the desire for mood stabilization with antipsychotics side effects.