Early diffusion evidence of retrograde transsynaptic degeneration in the human visual system.
We investigated whether diffusion tensor imaging (DTI) indices of white matter integrity would offer early markers of retrograde transsynaptic degeneration (RTD) in the visual system after stroke.



We performed a prospective longitudinal analysis of the sensitivity of DTI markers of optic tract health in 12 patients with postsynaptic visual pathway stroke, 12 stroke controls, and 28 healthy controls. We examined group differences in (1) optic tract fractional anisotropy (FA-asymmetry), (2) perimetric measures of visual impairment, and (3) the relationship between FA-asymmetry and perimetric assessment.



FA-asymmetry was higher in patients with visual pathway lesions than in control groups. These differences were evident 3 months from the time of injury and did not change significantly at 12 months. Perimetric measures showed evidence of impairment in participants with visual pathway stroke but not in control groups. A significant association was observed between FA-asymmetry and perimetric measures at 3 months, which persisted at 12 months.



DTI markers of RTD are apparent 3 months from the time of injury. This represents the earliest noninvasive evidence of RTD in any species. Furthermore, these measures associate with measures of visual impairment. DTI measures offer a reproducible, noninvasive, and sensitive method of investigating RTD and its role in visual impairment.
From the Athinoula A. Martinos Center for Biomedical Imaging (K.R.P.), Massachusetts General Hospital, Boston; Departments of Neurology (L.E.R., N.V.M., G.L.S., M.C.), Radiology (M.C.), and Anatomy and Neurobiology (M.C.), Washington University in St. Louis School of Medicine, MO; and Department of Neuroscience (M.C.), University of Padua, Italy. kpatel40@mgh.harvard.edu.
Kevin R
KR
Patel
From the Athinoula A. Martinos Center for Biomedical Imaging (K.R.P.), Massachusetts General Hospital, Boston; Departments of Neurology (L.E.R., N.V.M., G.L.S., M.C.), Radiology (M.C.), and Anatomy and Neurobiology (M.C.), Washington University in St. Louis School of Medicine, MO; and Department of Neuroscience (M.C.), University of Padua, Italy.
Lenny E
LE
Ramsey
From the Athinoula A. Martinos Center for Biomedical Imaging (K.R.P.), Massachusetts General Hospital, Boston; Departments of Neurology (L.E.R., N.V.M., G.L.S., M.C.), Radiology (M.C.), and Anatomy and Neurobiology (M.C.), Washington University in St. Louis School of Medicine, MO; and Department of Neuroscience (M.C.), University of Padua, Italy.
Nicholas V
NV
Metcalf
From the Athinoula A. Martinos Center for Biomedical Imaging (K.R.P.), Massachusetts General Hospital, Boston; Departments of Neurology (L.E.R., N.V.M., G.L.S., M.C.), Radiology (M.C.), and Anatomy and Neurobiology (M.C.), Washington University in St. Louis School of Medicine, MO; and Department of Neuroscience (M.C.), University of Padua, Italy.
Gordon L
GL
Shulman
From the Athinoula A. Martinos Center for Biomedical Imaging (K.R.P.), Massachusetts General Hospital, Boston; Departments of Neurology (L.E.R., N.V.M., G.L.S., M.C.), Radiology (M.C.), and Anatomy and Neurobiology (M.C.), Washington University in St. Louis School of Medicine, MO; and Department of Neuroscience (M.C.), University of Padua, Italy.
Maurizio
M
Corbetta
D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D011446:Prospective Studies; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D014786:Vision Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D058609:Visual Field Tests; D014795:Visual Pathways / Q000000981:diagnostic imaging* / Q000503:physiopathology; D066127:White Matter / Q000000981:diagnostic imaging* / Q000503:physiopathology