Complex anomalies of type 1 proatlantal intersegmental artery and aortic arch variations.

PURPOSE: We report a case of type 1 proatlantal intersegmental artery (PIA) associated with multiple anomalies of the aortic arch, and discuss the possible embryonic mechanism and clinical importance of the multiple cerebrovascular variants in this patient.

METHODS: A 65-year-old woman with dizziness underwent cerebral magnetic resonance (MR) imaging and head and neck MR angiography using a 3-tesla scanner and computed tomography (CT) angiography using a 64-slice multidetector CT scanner.

RESULTS: MR and CT angiography demonstrated an aneurysm of the distal end of the azygos anterior cerebral arteries and hypoplasia of the proximal right vertebral artery (VA) with an anastomotic artery, between the right internal carotid artery (ICA) and distal right VA that passed through the foramen magnum, indicating a type 1 PIA. She also demonstrated an aberrant right subclavian artery (ARSA) with hypoplasia of the right VA, and the left VA arose directly from the aortic arch.

CONCLUSION: To our knowledge, this is the first report of a type 1 PIA associated with multiple vascular anomalies of the aortic arch, such as ARSA and origin of the left VA from the arch. In cases of persistent anastomoses between the carotid and vertebrobasilar arteries, such as PIAs, imaging examination should include the aortic arch to identify associated vascular variations.