A rare anomalous origin of right vertebral artery with double branch: First case report

Abstract

Vertebral artery origin anomalies are typically incidental findings during angiography. We present an extremely rare variant in which the right vertebral artery has a double origin from the right subclavian artery and right common carotid artery in association with an aberrant right subclavian artery, which has never been reported before.

Introduction

Many variations of the origin and course of the vertebral arteries have already been well described in the literature.^1–4 However, in this case, we report an extremely rare anomaly of a right vertebral artery with double branch originating from the right subclavian artery and right common carotid artery, associated with an aberrant right subclavian artery, and this is followed by a review of literature on the embryological basis of vertebral artery variants and associated anomalies.

Case presentation

A 17-year-old female patient presented with acute unconsciousness and vomiting for 4 hours. She was admitted with a diagnosis of “spontaneous cerebellar hemorrhage breaking into the ventricle”. Noncontrast head computed tomography scan showed cerebellar hemorrhage breaking into the third and fourth ventricle, and posterior decompression with resection of hemorrhage was made for cerebellar hematoma. Follow-up cerebral angiography 18 days after the procedure indicated that the right vertebral artery had an abnormal origin, that is, a double branch originating from the right subclavian artery and the right common carotid artery, respectively, converging at the lower edge of the fourth cervical vertebrae. Additionally, an aberrant right subclavian artery was noted to originate as the last vessel from the aortic arch (Figure 1).

Figure 1.

(a) Right anterior oblique view of the selective right subclavian artery showing the branch of the right vertebral artery originating from the right subclavian artery. (b) DSA with right vertebral injection showing anomalous origin of right vertebral artery with double branch. (c), (d) DSA right common carotid artery lateral view projection showing the fusion of two branches (arrow). (e), (f) Enhanced anteroposterior and posteroanterior multiplanar reconstruction CT image demonstrates an aberrant right subclavian artery originating from the aortic arch distal to the left subclavian artery. (g) Enhanced sagittal CT image shows that the branch originating from the right common artery enters the transverse foramen at the level of C4, where fusion occurs (arrow).

Discussion

According to previous literature, the most common anomalous origin of the vertebral artery is the left vertebral artery arising from the aortic arch between the left common carotid artery and the left subclavian artery, with a reported prevalence of 2.4–5.8%. ¹ The second variant is the right vertebral artery originating from the right common carotid artery accompanied by an aberrant right subclavian artery (0.18%). ² Some scholars have divided the anomalous origin of the right vertebral artery into three categories ³ : originating from the aortic arch; originating from the right common carotid artery or the brachiocephalic artery; or repeat origin, for example, both branches originate from the right subclavian artery. ⁴ To our knowledge, a right vertebral artery with double branches originating from aberrant right subclavian artery and right common carotid artery has never been reported before.

In the embryonic period, the development of subclavian arteries and vertebral arteries is mainly attributed to the selective development and degeneration of the seven cervical intersegmental arteries connected to the dorsal aorta. The 7th cervical intersegmental artery develops into a part of the subclavian artery and the dorsal branch of the 1st–6th cervical intersegmental arteries disappears, while the longitudinal anastomosis of the 1st–7th cervical intersegmental arteries eventually develops into the vertebral artery. Normally, the right dorsal aorta is obliterated below the 7th cervical intersegmental artery to the junction with the left dorsal aorta. When obliteration of the right dorsal aorta occurs proximal to the 7th cervical intersegmental artery origin, the right subclavian artery origin is moved to the left. ⁵ Some scholars pointed out that if one of the 3rd–6th cervical intersegmental arteries on one side fails to disappear, the vertebral artery of the same side may originate from the aortic arch or the common carotid artery. ⁶ Some scholars have suggested that when the right vertebral artery originated from the 6th cervical intersegmental artery and the longitudinal anastomosis between the 6th and 7th cervical intersegmental arteries did not develop, the right vertebral artery may originate from the right common carotid artery. ⁵ In this case, the double origin of the right vertebral artery could be attributed to the right side of the 4th cervical intersegmental artery without degeneration, which ultimately developed into the branch of the right carotid artery, while the longitudinal anastomosis between the 4th and 7th cervical intersegmental arteries developed into the subclavian branch, and subsequently obliteration of the right dorsal aorta occurred proximal to the origin of the 7th cervical intersegmental artery. We modified a figure from Meila et al. ⁴ showing the likely developmental origin of this anomaly (Figure 2).

Figure 2.

Schematic diagram. Developmental schema shows the developmental origin of an aberrant right subclavian artery in combination with the double origin of the right vertebral artery from the right common carotid artery and right subclavian artery. Modified from Meila et al. (2012). ⁴

ECAL: left external carotid artery; ECAR: right external carotid artery; ICAL: left internal carotid artery; ICAR: right internal carotid artery; SCAL: left subclavian artery; SCAR: right subclavian artery; VAL: left vertebral artery; VAR: right vertebral artery.

It is important to understand the variations in the origin of the vertebral artery, especially for formulation of surgical procedures in the related region. When performing angiography, endovascular treatment, head and neck surgery, and even thyroid puncture, more attention should be paid to the possibility of abnormal origin of the vertebral artery. This case is an incidental finding in diagnostic cerebral angiography. Studies showed that anomalous origin of vertebral artery, due to hemodynamic changes, could increase the incidence of arteriovenous malformations and cerebral aneurysms,^7,8 and Yuan ⁹ suggested that patients with neurological symptoms and those awaiting neck and chest operations and interventions should be carefully screened for the possibility of an aberrant origin of the vertebral artery, while some other scholars hold the opposite idea.^10,11 In this case, no correlation could be found between the double origin of the right vertebral artery and the cerebellar hemorrhage. With the popularization of various vascular examinations, and especially with the advent of minimally invasive and noninvasive vascular examination methods, more and more anomalous cerebrovascular variability will be reported, and the correlation between the variation itself and its clinical significance will be gradually revealed.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.