Ischemia in the territory of a hypoplastic vertebrobasilar system

Background: Congenital variations in the configuration and size of the cerebral vessels may predispose to ischemic stroke. Objectives/Methods: To illustrate that a hypoplastic basilar artery may lead to posterior circulation ischemia in adults, eight cases are reported from two university medical centers. Results: Five men and three women with a mean age of 49.8 years are reported. Four of the patients had other conventional stroke risk factors. Two patients had brainstem strokes, and six had TIA. All patients had hypoplastic basilar arteries. Seven patients had at least one hypoplastic vertebral artery (bilateral in five cases), and six patients had both posterior cerebral arteries originating from the internal carotid arteries. Conclusions: A hypoplastic basilar artery is frequently accompanied by vertebral artery hypoplasia, and this can predispose adults to posterior circulation ischemia. This entity can be suspected on the basis of MR angiogram, but conventional angiography will provide definitive diagnosis. Optimal medical and surgical treatment of this condition is unresolved.