Anomalous Right Vertebral Artery Originating from the Aortic Arch Distal to the Left Subclavian Artery: a Case Report and Review of the Literature

Objective—Present a case report of an anomalous origin of the right vertebral artery originating from the aortic arch distal to the left subclavian along with a review of cases reported to date in the literature. Methods—Provide background information on this rare anomaly, present the case report, review the literature using PubMed, summarize previously reported cases to date, and discuss the underlying embryologic development of this anomaly along with its significance. Results—We report a 54-year-old man presenting with a subarachnoid hemorrhage referred for diagnostic cerebral arteriography who was found to have an anomalous origin of the right vertebral artery originating from the aortic arch distal to the left subclavian artery in conjunction with a bovine arch. We also report 13 previously reported cases along with their other associated variant anatomy. Conclusions—Based upon our present case and previously documented cases to date, this anomaly is a rare finding. An understanding of aberrant anatomy and its embryologic basis is paramount to avoiding inadvertent vascular injury during diagnostic cerebral angiography. Therefore, this abnormality must be considered if selective vertebral artery catheterization is difficult or unsuccessful.