A potential case of peduncular hallucinosis treated successfully with olanzapine

Visual hallucinations have a differential diagnosis, both psychiatric and nonpsychiatric in nature. Described first by Lhermitte, peduncular hallucinosis is an uncommon etiology of visual hallucinations (VH). Typically, the offending lesion is vascular in origin and occurs at the level of the midbrain, thalamus, or rostral brainstem. Interestingly, the origin of the VH in our patient's case could have been either/both from an ischemic insult at the midbrain or compression of the brainstem due to aneurism. While evidence for treatment is scarce, we present a posited case of peduncular hallucinosis treated successfully with olanzapine.