Agenesis of the Left Internal Carotid Artery in the Right Aortic Arch with Isolation of the Left Innominate Artery Associated with Ruptured Cerebral Aneurysm: Case Report.

As we occasionally encounter congenital blood vessel abnormalities, their variety, embryology, and associated clinical problems must be understood. We report a case of a 50-year-old man with subarachnoid hemorrhage due to a ruptured cerebral aneurysm at the internal carotid-anterior choroidal artery bifurcation who manifested extremely rare congenital anomalies, i.e., a right aortic arch, isolated left innominate artery, agenesis of the left internal carotid artery, and dysplasia of the basilar artery to the posterior cerebral arteries. This complex anomaly, to the best of our knowledge, has not been previously reported.