Bilateral internal carotid absence: a case report of a rare congenital anomaly

Background: Bilateral internal carotid artery agenesis (ICAA) is a rare developmental anomaly of unknown etiology that is often associated with disruption of adequate perfusion to the central nervous system. Nevertheless, some patients remain asymptomatic due to collateral circulation involving the communicating arteries of the Circle of Willis. Secondary to the hemodynamical stress through the collateral circulation, affected patients are at an increased risk of developing subarachnoid hemorrhage and intracranial aneurysms. Methods and results: We report an unusual case of a 62-year-old man with bilateral ICAA who expired following two asystolic events during minor surgery. Conclusion: This case emphasizes the plasticity of the cerebral collateral circulation during development, to the point of normal cerebral perfusion throughout life with no ischemic complications.