title: Lateral geniculate atrophy in Parkinson's with visual hallucination: A trans-synaptic degeneration?
abstract: BACKGROUND
  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.
authors: Department of Neurology, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.|College of Medicine, Seoul National University, Seoul, Republic of Korea.
authors: Jee-Young
authors: JY
authors: Lee
authors: Department of Nuclear Medicine, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.
authors: Eun Jin
authors: EJ
authors: Yoon
authors: Department of Neurology, Eulji General Hospital, Seoul, Republic of Korea.
authors: Woong Woo
authors: WW
authors: Lee
authors: Department of Nuclear Medicine, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.|College of Medicine, Seoul National University, Seoul, Republic of Korea.
authors: Yu Kyeong
authors: YK
authors: Kim
authors: Department of Psychiatry, Seoul National University-Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.|College of Medicine, Seoul National University, Seoul, Republic of Korea.
authors: Jun-Young
authors: JY
authors: Lee
authors: Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea.|College of Medicine, Seoul National University, Seoul, Republic of Korea.
authors: Beomseok
authors: B
authors: Jeon
mesh_terms: D000368:Aged; D001284:Atrophy / Q000473:pathology; D005260:Female; D005829:Geniculate Bodies / Q000473:pathology*; D006212:Hallucinations / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D013569:Synapses / Q000473:pathology*; D014795:Visual Pathways / Q000473:pathology*; D014796:Visual Perception / Q000502:physiology*
keywords: Parkinson's disease; diffusion tensor analysis; visual hallucination; visual pathway; volumetric analysis