title: Abnormal white matter tractography of visual pathways detected by high-angular-resolution diffusion imaging (HARDI) corresponds to visual dysfunction in cortical/cerebral visual impairment.
abstract: Cortical (cerebral) visual impairment (CVI) is characterized by visual dysfunction associated with damage to the optic radiations and/or visual cortex. Typically it results from pre- or perinatal hypoxic damage to postchiasmal visual structures and pathways. The neuroanatomical basis of this condition remains poorly understood, particularly with regard to how the resulting maldevelopment of visual processing pathways relates to observations in the clinical setting. We report our investigation of 2 young adults diagnosed with CVI and visual dysfunction characterized by difficulties related to visually guided attention and visuospatial processing. Using high-angular-resolution diffusion imaging (HARDI), we characterized and compared their individual white matter projections of the extrageniculo-striate visual system with a normal-sighted control. Compared to a sighted control, both CVI cases revealed a striking reduction in association fibers, including the inferior frontal-occipital fasciculus as well as superior and inferior longitudinal fasciculi. This reduction in fibers associated with the major pathways implicated in visual processing may provide a neuroanatomical basis for the visual dysfunctions observed in these patients.
authors.affiliation: The Laboratory for Visual Neuroplasticity, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
authors.forename: Corinna M
authors.initials: CM
authors.lastname: Bauer
authors.affiliation: Pediatric Neuro-Ophthalmology Service, Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston.
authors.forename: Gena
authors.initials: G
authors.lastname: Heidary
authors.affiliation: Center for Biomedical Imaging, Boston University School of Medicine, Boston.
authors.forename: Bang-Bon
authors.initials: BB
authors.lastname: Koo
authors.affiliation: Center for Biomedical Imaging, Boston University School of Medicine, Boston.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Killiany
authors.affiliation: Department of Ophthalmology, Massachusetts Eye and Ear Infirmary-Schepens Eye Research Institute, Harvard Medical School, Boston.
authors.forename: Peter
authors.initials: P
authors.lastname: Bex
authors.affiliation: The Laboratory for Visual Neuroplasticity, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts. Electronic address: lotfi_merabet@meei.harvard.edu.
authors.forename: Lotfi B
authors.initials: LB
authors.lastname: Merabet
mesh_terms: D000293:Adolescent; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009778:Occipital Lobe / Q000473:pathology; D010468:Perceptual Disorders / Q000175:diagnosis*; D014786:Vision Disorders / Q000175:diagnosis*; D014792:Visual Acuity; D014795:Visual Pathways / Q000473:pathology*; D066127:White Matter / Q000473:pathology*; D055815:Young Adult
references.citation: J Neurol Neurosurg Psychiatry. 2010 Nov;81(11):1280-7
references.pmid: 20972204
references.citation: Dev Med Child Neurol. 2012 Jan;54(1):38-43
references.pmid: 22171928
references.citation: Magn Reson Med. 2002 Oct;48(4):577-82
references.pmid: 12353272
references.citation: Radiographics. 2006 Oct;26 Suppl 1:S205-23
references.pmid: 17050517
references.citation: Cortex. 2008 Sep;44(8):936-52
references.pmid: 18635164