A rare origin of the right vertebral artery and its clinical implications in a proximal occlusion to proximal origin to the brachiocephalic trunk

Abstract

The Subclavian Steal Syndrome is a retrograde flow in the vertebral artery as a result of proximal subclavian artery occlusion or severe stenosis. This retrograde flow presupposes that the vertebral artery is of usual origin from the superior surface of its ipsilateral subclavian artery. We present a rare variant of the right vertebral artery originating as part of a trifurcated brachiocephalic trunk in a 76-year-old female cadaver. Our discussion is focused on the clinical implication of this variant should there be a proximal occlusion to the right subclavian artery or such occlusion occurring in the proximal origin of the brachiocephalic trunk off the aortic arch. Even though aberrant vertebral arteries are often asymptomatic, but a good search should be made to locate their aberrant origins. Good knowledge of the anatomic location of the vertebral artery is important to endovascular, and maxillofacial and neurosurgeons engaged in surgical interventions in the head and neck region to assist in the selection of appropriate surgical interventions and to neuroradiologists, in the interpretation of images. The main thrust of our report is focused on a modeled occlusion in the proximal region of the subclavian artery or in the proximal segment of the brachiocephalic trunk and the clinical outcome of retrograde flow in the variant right vertebral artery originating from a bifurcated brachiocephalic trunk in both circumstances. When a retrograde flow is modeled in a hypothetical proximal occlusion to the subclavian artery only, this does not give any vascularization to the subclavian artery since the occlusion is occurring distally to the retrograde flow. However, in the case of occlusion occurring, the proximal origin of the brachiocephalic trunk before trifurcating, and before the trifurcation, a reversed flow from the variant vertebral artery will send blood to vascularize both the right common carotid and the right subclavian arteries, resulting in a hypothesized combined Common Carotid-Subclavian Steal Syndrome (CC-SSS). This emphasizes clinically that varying origins of the vertebral artery would play dissimilar roles in occlusion or stenosis in the proximal segments of the major supra-aortic vessels.