Abstract Anomalous origins of the vertebral arteries are uncommon and typically associated with other abnormalities of the great vessels. We present a case of an isolated origin of the right vertebral artery from the ipsilateral common carotid artery detected using magnetic resonance angiography. Such variants can significantly affect endovascular and surgical planning. Vertebral artery , Variant anatomy , Magnetic resonance angiography INTRODUCTION Anomalous origins of the vertebral artery (VA) from the common carotid artery (VA-CC) are uncommon and can be traced to developmental abnormalities based on laterality. Previously, anomalous origins of the right VA have been invariably described in association with aberrant subclavian arteries, occasionally in conjunction with a right-sided aorta. Herein, we present the case of a patient with conventional aortic and subclavian anatomy with an isolated right VA-CC. CASE REPORT A 49-year-old woman with diabetes and hypertension presented to the emergency department with chronic headaches, vertigo, blurred vision and disorientation, worsened by standing. Magnetic resonance angiography of the brain/neck was ordered due to the VA asymmetry on a previous magnetic resonance imaging (MRI), which demonstrated no perfusion abnormalities. The posterior cerebral artery was hypoplastic within the P1 segment with well-formed bilateral posterior communicating arteries. The diminutive right VA arose aberrantly from the proximal ipsilateral common carotid (Fig. 1). The aorta, brachiocephalic trunk, left common carotid, left subclavian and left VA demonstrated conventional anatomy. Figure 1: View largeDownload slide Magnetic resonance angiography of the neck showing the right vertebral artery arising from the ipsilateral common carotid artery (A), coursing superiorly to form the basilar artery (B). Figure 1: View largeDownload slide Magnetic resonance angiography of the neck showing the right vertebral artery arising from the ipsilateral common carotid artery (A), coursing superiorly to form the basilar artery (B). DISCUSSION Anomalous VA origins are usually found incidentally during workups for intracranial vascular abnormalities (i.e. aneurysms, infarcts and venous sinus thromboses) . In the conventional configuration, the VA arises as the 1st branch of the ipsilateral subclavian arteries. Although the most common variant of cervicothoracic anatomy is the erroneously named ‘bovine arch’, variants of the VA origins are also well described in the literature . The most common variant is the left VA arising from the left-sided aortic arch between the common carotid and subclavian arteries, with a prevalence of 2.4–5.8% [1, 3]. The incidence of the right VA-CC and aberrant right subclavian artery is 0.18% . To our knowledge, a right VA-CC with conventional aortic and subclavian anatomy has not been described . Embryologically, the subclavian and vertebral arteries result from the development and degeneration of the 7 cervical intersegmental arteries arising from the dorsal aorta. The 1st to 6th intersegmental arteries degenerate at the 14–17-mm stage, whereas the 7th intersegmental artery develops into both the vertebral and subclavian arteries [1, 3]. The right dorsal aorta normally degenerates below the 7th intersegmental artery. If the right dorsal aorta degenerates above the 7th intersegmental artery, the right subclavian arterial origin moves left and becomes aberrant. Anomalies can also occur if the 1st to 6th intersegmental arteries fail to regress. If the 1st or 2nd intersegmental artery persists, an abnormal origin of the VA from the internal or external carotid results; if the persistent artery occurs from the 3rd to the 6th intersegmental artery, a VA-CC or VA arising from the aorta occurs. In our case, isolated persistence of the right 4th or, less likely, 3rd intersegmental artery with proper involution of the right 1st to 3rd (or 4th), 5th and 6th intersegmental arteries, combined with aberrant regression or failure of formation of the longitudinal intersegmental anastomosis below the 4th intersegmental artery, could have resulted in the observed finding of an isolated VA-CC (Fig. 2). Figure 2: View largeDownload slide Hypothesized development of the right vertebral artery from the ipsilateral common carotid. BA: basilar artery; LCCA: left common carotid artery; LECA: left external carotid artery; LICA: left internal carotid artery; LSCA: left subclavian artery; LVA: left vertebral artery; RCCA: right common carotid artery; RECA: right external carotid artery; RICA: right internal carotid artery; RVA: right vertebral artery; RSCA: right subclavian artery. Figure 2: View largeDownload slide Hypothesized development of the right vertebral artery from the ipsilateral common carotid. BA: basilar artery; LCCA: left common carotid artery; LECA: left external carotid artery; LICA: left internal carotid artery; LSCA: left subclavian artery; LVA: left vertebral artery; RCCA: right common carotid artery; RECA: right external carotid artery; RICA: right internal carotid artery; RVA: right vertebral artery; RSCA: right subclavian artery. Though left-sided VA variants are typically asymptomatic, Yuan  theorized that the direct aortic origin of a left VA with its C4 entrance into the transverse foramen could result in ataxia during head rotation. Such anomalies have been associated with arterial dissection likely due to increased shear forces on the longer arteries . Kim et al.  found an association between anomalous origins of the VA and VA hypoplasia. Furthermore, knowledge of the anatomy of the vertebral and subclavian arteries is crucial for the planning of surgical/interventional procedures involving the head and neck, including oncological and reconstructive dissections. Herein, we have reported an isolated right VA-CC without an accompanying aberrant subclavian artery. Although this variant has not been previously described and was not believed to cause symptoms in our patient, whom was ultimately diagnosed with chronic migraines as an outpatient, it fits within the existing theory of development of the aortic arch and its cervicothoracic branches. Such variants are critical in endovascular and surgical planning. Conflict of interest: none declared. REFERENCES 1 Liu YD , Li ZQ , Fu JJ , E YJ. A rare anomalous origin of right vertebral artery with double branch: first case report . Interv Neuroradiol 2018 ; 24 : 225 – 8 . Google Scholar CrossRef Search ADS PubMed 2 Babu CS , Sharma V. Two common trunks arising from arch of aorta: case report and literature review of a very rare variation . J Clin Diagn Res 2015 ; 9 : AD05 – 7 . Google Scholar PubMed 3 Yuan SM. Aberrant origin of vertebral artery and its clinical implications . Braz J Cardiovasc Surg 2016 ; 31 : 52 – 9 . Google Scholar PubMed 4 Palmer FJ. Origin of the right vertebral artery from the right common carotid artery: angiographic demonstration of three cases . Br J Radiol 1977 ; 50 : 185 – 7 . Google Scholar CrossRef Search ADS PubMed 5 Kim C , Sohn JH , Choi HC. Are the anomalous vertebral arteries more hypoplastic?: retrospective linear mixed model approach . BMC Neurol 2017 ; 17 : 168. Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Interactive CardioVascular and Thoracic Surgery – Oxford University Press
Published: Apr 18, 2018
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