August 2008
Poewe W
Visual hallucinations are a typical feature of Lewy body parkinsonism
and occur in some 40% of patients with Parkinson’s disease.
Age and
cognitive decline are the most important intrinsic risk factors, but
hallucinosis is often triggered by comorbid conditions such as infection
and dehydration. The single most important trigger, however, is
exposure to CNS drugs, in particular antiparkinsonian agents. While
hallucinosis and psychosis can be triggered by amantadine and
anticholinergics, they are more commonly experienced after changes in
dopaminergic medication. Dopamine agonists have greater potential to
induce hallucinosis compared with L-dopa.
Attempting to reduce
antiparkinsonian drugs is an important part in the management of these
patients, but atypical neuroleptics like clozapine or quetiapine are
frequently necessary. Visual hallucinations in Parkinson’s disease
patients with dementia can also be improved by treatment with the
cholinesterase inhibitor rivastigmine.
