Bilateral Fetal-Type Posterior Cerebral Arteries with Vertebrobasilar Hypoplasia: A Rare Vascular Variant Presenting as Recurrent Posterior Circulation Stroke

Abstract Background: Bilateral fetal-type posterior cerebral artery (fPCA) is a rare anatomic variant of the circle of Willis. Its clinical significance, particularly when associated with vertebrobasilar hypoplasia, is poorly understood. Case presentation: We report a 58-year-old man with recurrent posterior circulation ischemic events. His first episode was characterized by left-sided ataxia, followed six months later by right-sided sensory loss. MRI revealed multiple chronic lacunar infarcts, small vessel ischemic changes, and cortical atrophy. MR angiography demonstrated bilateral fPCA with vertebrobasilar hypoplasia, and MR venography revealed hypoplastic left transverse and sigmoid sinuses. Conclusion: This case illustrates the rare coexistence of bilateral fPCA and vertebrobasilar hypoplasia as a potential mechanism for recurrent posterior circulation ischemia. Recognition of such variants may help refine prognosis and guide preventive strategies.