Functional brain imaging, clinical and neurophysiological outcome of visual rehabilitation in a chronic stroke patient

Article type: Research Article

Authors: Julkunen, Laura^{; ;} | Tenovuo, Olli | Vorobyev, Victor | Hiltunen, Jaana | Teräs, Mika | Jääskeläinen, Satu K. | Hämäläinen, Heikki^;

Affiliations: Centre for Cognitive Neuroscience, University of Turku, Turku, Finland | Department of Psychology, University of Turku, Turku, Finland | Department of Neurology, Turku University Central Hospital, Turku, Finland | Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland | Turku PET Centre, University of Turku, Turku, Finland | Department of Clinical Neurophysiology, Turku University Central Hospital, Turku, Finland

Note: [] Corresponding author: Laura Julkunen, Department of Psychology, 20014 University of Turku, Finland. Tel.: +358 2 333 6984; Fax: +358 2 333 5060; E-mail: [email protected]

Abstract: Purpose: To study rehabilitation outcome in a chronic visual field defect patient using positron emission tomography (PET) imaging, clinical, and neurophysiological measures. Methods: A patient with chronic visual field defect was rehabilitated using a computer program over a three-month period. Evaluations of rehabilitation effects were done before and after training, and after a three-month follow-up with perimetry, visual evoked potentials (VEP), subjective questionnaire, and PET activation studies of regional cerebral blood flow (rCBF). Results: In perimetry, the visual field increased during the training, and the patient also experienced subjective improvement. In VEP, a previously absent P100 component was identified after the training. In PET, increases in rCBF were diffuse immediately after the training, and more occipital after the late follow-up. A significant positive correlation between the increase in rCBF and improvement in clinical measures was found in the lingual gyrus in the contralesional hemisphere. Conclusions: All clinical measures showed improvement after rehabilitation, and this was maintained during the follow-up. In PET, a more generalized effect, found at the beginning, later concentrated in the occipital cortex. The results suggest that visual training may cause plastic changes in the brain, and that these changes can be detected both with clinical measures and with functional imaging.

Keywords: Visual field defect – chronic, stroke, rehabilitation, computer-assisted training, positron emission tomography, visual evoked potential, perimetry

Journal: Restorative Neurology and Neuroscience, vol. 24, no. 2, pp. 123-132, 2006