Visual recovery demonstrated by functional MRI and diffusion tensor tractography in bilateral occipital lobe infarction

We report on a patient who showed visual recovery following bilateral occipital lobe infarct, as evaluated by follow up functional magnetic resonance imaging (fMRI) and diffusion tensor tractography (DTT). A 56-year-old female patient exhibited severe visual impairment since onset of the cerebral infarct in the bilateral occipital lobes. The patient complained that she could not see anything, although the central part of the visual field remained dimly at 1 week after onset. However, her visual function has shown improvement with time. As a result, at 5 weeks after onset, she notified that her visual field and visual acuity had improved. fMRI and DTT were acquired at 1 week and 4 weeks after onset, using a 1.5-T Philips Gyroscan Intera. The fiber number of left optic radiation (OR) increased from 257 (1-week) to 353 (4-week), although the fiber numbers for right OR were similar. No activation in the occipital lobe was observed on 1-week fMRI. By contrast, activation of the visual cortex, including the bilateral primary visual cortex, was observed on 4-week fMRI. We demonstrated visual recovery in this patient in terms of the changes observed on DTT and fMRI. It appears that the recovery of the left OR was attributed more to resolution of local factors, such as peri-infarct edema, than brain plasticity.