Altered patterns of blood flow response during visual stimulation in carotid artery occlusive disease

With visual stimulation, CBF in the primary visual cortex significantly increased in all patients, while in the surrounding region, CBF showed variable changes, including decreases in some patients. In 9 patients with unilateral ICA lesions, the CBF change in the surrounding region ipsilateral to the ICA lesion was significantly decreased compared with the value in the contralateral hemisphere, while the CBF change in the primary visual cortex showed no hemispheric difference. The hemispheric values of oxygen extraction fraction in the ICA distribution and the amount of CBF increase in the visual cortex were independently and negatively correlated with the CBF change in the surrounding region. We conclude that the pattern of CBF response during visual stimulation may change in ICA occlusive disease. We suggest that the redistribution of CBF during visual stimulation may be a contributing mechanism.