Fetal variant of circle of the Willis and bilateral symmetrical parietal stroke.

We described a rare case in which a congenital abnormal vascular structure associated with mild hyperhomocysteinemia could have caused an ischemic stroke, with an unusual localization in the border-zone of MCA and PCA. We think that the lack of compensatory flow distribution from the right vertebral artery and the right posterior communicating artery probably determined the bilateral ischemic lesions in a patient, who possibly had hypotensive crisis.