Jee-Young Lee1,2, Eun Jin Yoon3, Woong Woo Lee4, Yu Kyeong Kim3,2, Jun-Young Lee5,2, Beomseok Jeon6,2. 1. Department of Neurology, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea. 2. College of Medicine, Seoul National University, Seoul, Republic of Korea. 3. Department of Nuclear Medicine, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea. 4. Department of Neurology, Eulji General Hospital, Seoul, Republic of Korea. 5. Department of Psychiatry, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea. 6. Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea.
Abstract
INTRODUCTION: Defective visual information processing contributes to visual hallucination in PD, for which "top-down" and "bottom-up" impairment are suggested mechanisms. This study was aimed to investigate macro- and microstructural neural changes in afferent visual pathways in relation to visual hallucination in nondemented PD patients. METHODS: This study included 24 nondemented, nondepressed PD patients (10 hallucinating and 14 nonhallucinating) and 15 age-matched healthy controls. We analyzed volumetric and diffusion tensor MRI data by applying region of interest analyses on the visual pathways, including the optic chiasm, bilateral optic nerves, lateral geniculate bodies, optic radiations, and primary visual cortex. RESULTS: Patients' demographic characteristics, daily medication doses, as well as duration and motor severity of PD were similar in the two PD groups. Compared to PD patients without hallucination, those with hallucination had fractional anisotropy decrease in the left optic nerve and showed atrophy of lateral geniculate bodies, especially in the left side. In addition, the PD with hallucination group had diffusivity increase in the left optic radiation compared to that in the PD without hallucination and healthy control groups. There were no differences in the primary visual cortex volume among the study groups. CONCLUSIONS: We found microstructural alterations in visual pathways in nondemented PD patients with hallucination, mainly in first-order neurons and atrophy in the lateral geniculate body where the retinal ganglion cells synapse to second-order neurons. Afferent visual pathway degeneration may occur in a trans-synaptic way in PD. Further studies warrant to be conducted.
INTRODUCTION: Defective visual information processing contributes to visual hallucination in PD, for which "top-down" and "bottom-up" impairment are suggested mechanisms. This study was aimed to investigate macro- and microstructural neural changes in afferent visual pathways in relation to visual hallucination in nondemented PDpatients. METHODS: This study included 24 nondemented, nondepressed PDpatients (10 hallucinating and 14 nonhallucinating) and 15 age-matched healthy controls. We analyzed volumetric and diffusion tensor MRI data by applying region of interest analyses on the visual pathways, including the optic chiasm, bilateral optic nerves, lateral geniculate bodies, optic radiations, and primary visual cortex. RESULTS:Patients' demographic characteristics, daily medication doses, as well as duration and motor severity of PD were similar in the two PD groups. Compared to PDpatients without hallucination, those with hallucination had fractional anisotropy decrease in the left optic nerve and showed atrophy of lateral geniculate bodies, especially in the left side. In addition, the PD with hallucination group had diffusivity increase in the left optic radiation compared to that in the PD without hallucination and healthy control groups. There were no differences in the primary visual cortex volume among the study groups. CONCLUSIONS: We found microstructural alterations in visual pathways in nondemented PDpatients with hallucination, mainly in first-order neurons and atrophy in the lateral geniculate body where the retinal ganglion cells synapse to second-order neurons. Afferent visual pathway degeneration may occur in a trans-synaptic way in PD. Further studies warrant to be conducted.
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