Resolution of Visual Hallucinations in Parkinson's Disease After Right Occipitoparietal Subcortical Hemorrhage: A Case Report.

Visual hallucinations are common non-motor symptoms of Parkinson's disease (PD) that substantially impair quality of life, particularly in advanced stages. However, the neural substrates underlying visual hallucinations in PD remain incompletely understood. Here, we report a rare case of a 72-year-old right-handed man with PD whose visual hallucinations completely resolved after a right occipitoparietal subcortical hemorrhage. He developed PD at 58 years of age and later experienced wearing-off, dyskinesia, cognitive decline, visual hallucinations, and a false sense of presence. At 72 years of age, he presented with headache, nausea, and worsening gait. Neuroimaging demonstrated a right occipitoparietal subcortical hemorrhage. After the hemorrhagic event, visual hallucinations disappeared completely, whereas the false sense of presence persisted. Follow-up MRI three months later showed a residual lesion confined to the right precuneus. The patient remained free of visual hallucinations for several months. This case suggests that the right occipitoparietal region, particularly the precuneus, may play an important role in the generation of visual hallucinations in PD, while persistence of non-visual hallucinations supports partially distinct neural substrates. To our knowledge, this is the first reported case of PD in which visual hallucinations resolved following a hemorrhagic event, providing insight into the neuroanatomical mechanisms of hallucinations in PD.