Poststroke Illusions and Hallucinations

Abstract

Illusions are misperceptions or perceptual distortions of an existing external stimulus, and hallucination is a perception in the absence of a stimulus. Both phenomena can occur in the course of a large number of cerebrovascular pathological processes, and they may develop in either isolated or combined modalities. Isolated auditory, olfactory, and tactile hallucinations are a rare event and have been associated with a number of stroke subtypes. Charles-Bonnet syndrome is characterized by the occurrence of visual hallucinations that are formed, complex, persistent or repetitive, and stereotyped; fully or partially retained insight; and absent delusions. Peduncular hallucinosis may develop following rostral brainstem lesion and characterized by seeing animals of bizarre appearance, transformation of the animals into human figures, mobile and multiple-colored images, and visuotactile associations. Isolated or combination of visual and auditory hallucinations following multi-infarct dementia with lesions involving occipitotemporal regions may occasionally occur. In most of the patients, auditory hallucinations were observed mostly after ischemic and hemorrhagic stroke involving posterior parts of the cerebral hemisphere and more frequently in the right than in the left. Patients with syncope and transient cerebral hypoxia may experience visual and auditory hallucinations such as gray haze, colored patches, or bright lights consisting of rushing or roaring noises, screaming, or voices. (PsycINFO Database Record (c) 2016 APA, all rights reserved)