Congenital absence of bilateral vertebral arteries with occipital-basilar anastomosis.

In the present case, a patient with symptoms referable to the occipital lobe, selective angiography demonstrated evidence of occlusion of branches of the left posterior cerebral artery with collateral circulation in addition to the congenital anomaly. The congenital absence of both vertebral arteries with a large occipital-basilar anastomosis may be explained by our hypothesis that occlusion occurred at the gestation age of 32-36 days. This case is presented in the hope that it will lead to the recognition of similar anomalies and further support our hypothesis. Selective angiography is the method of choice in the study of cerebrovascular disease and brachiocephalic vessels.