A systematic classification of the vertebral artery variable origin: clinical and surgical implications.

Several congenital anomalies regarding the right (RVA) and left (LVA) vertebral artery have been described. The current paper aims to perform a systematic literature review of the variable vertebral artery (VA) origin from the aortic arch (AOA) and its branches. The incidence of these variants and the ensuing AOA branching pattern are highlighted. Atypical origin cases were found more commonly unilaterally, while LVA presented the majority of the aberrancies. The LVA emersion from the AOA (3.6%) and the RVA from the right common carotid artery (RCCA) (0.14%) were the commonest origin variations. Aberrant RVA origin as last branch of the AOA is very rare. Eighteen cases (0.12%) with an aberrant right subclavian artery (ARSCA) were found. Among them, the RVA originated from the RCCA and right subclavian artery in 94.4 and 5.6%, respectively. Sporadic cases had an AOA origin bilaterally; RVA and LVA had a double origin in 0.027 and 0.11%, respectively. A dual origin was detected in 0.0069%, bilaterally. The atypical VA origin may coexist with: (i) an ARSCA, (ii) a common origin of brachiocephalic artery and left common carotid artery (the misnomer bovine arch) and (iii) a bicarotid trunk. The aberrant VA origin favors hemodynamic alterations, predisposing to cerebrovascular disorders and intracranial aneurysm formation. Detailed information of VA variants is crucial for both endovascular interventionists and diagnostic radiologists involved in the treatment of patients with cerebrovascular disease. Such information may prove useful to minimize the risk of VA injury in several procedures.