Variations in the Origin and Course of the Extracranial Vertebral Artery on Multidetector Computed Tomography Angiography

Abstract

Background: Variations in the origin of vertebral arteries (VA) and its entrance level into the transverse foramen are common and important when planning neck and cervical spine interventions. Objectives: The aim of this study was to investigate the prevalence of anatomical variations in the origin of vertebral arteries, and anomalous course of the extracranial vertebral artery using dual energy CT angiography. Methods: Retrospectively, we reviewed head and neck dual energy computed tomography (DECT) angiographies of 1218 consecutive patients during 2010 -2014. The images were evaluated with exceptional attention to the origin of VA and its level of entrance into and exit out of the transverse foramen of the cervical spine, specific variations of VA including fenestration and intradural course of C1 -C2 VA. Results: We found a rare case of double origin of left VA with bifid origins (one from the aortic arch and the other from the left subclavian artery) and entering the transverse foramen at C6 and C5 levels. The majority of left VA (1173/1219, 96.2%) originated from the left subclavian artery. Most of them (1159/1173, 98.8%) entered the C6 transverse foramen. Forty -six of left VA (46/1219, 3.8 %) originated from the aortic arch and thirty -seven (80.4%) of them entered the C5 transverse foramen. When the left VA arose from the aorta, there was a significant higher rate of anomalous entrance level (C4 or C5) to normal C6 entrance level (P < 0.001). The majority of right VA (1209/1218, 99.3%) originated from the right subclavian artery. Eight (0.7 %) of right VA arose from the aberrant right subclavian artery (ARSA). One rare case of right VA from right common carotid artery (CCA) entered the transverse foramen at C4 level with coexisting ARSA. Five cases had atlanto -axial fenestration of the VAs and five cases had intradural course of left C1 -C2 VAs. Conclusions:The study showed anatomical variations of the VA in its origin and extracranial course. A pre -operative CT angiography is useful to identify the anomalous extracranial VA course. It reduces the risk of intra -procedure VA injury.

Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings

“…However, their view caused contradictory when taking our ndings into consideration. Interestingly, our nding revealed that 50% of patients with anomalous LVA origin was observed the correlated anomalous entry level into the transverse foramen, while the rest 50% of them was found with normal entry level; whereas Lin et al 15 showed that 4.34% of patients with anomalous LVA origin was observed with normal entry level. The large difference in proportion between our study and theirs has aroused our interest in the investigation of embryonic development.…”

“…The proportion of higher entrance level (C3,4,5) were statistically increased in abnormal origin subjects when comparing to normal origin subjects, which was consistent with the Japanese nding that anomalous origin and anomalous entry level into the transverse foramen correlated strongly. 14 Similarly, Lin et al 15 reported that there was a signi cantly higher rate of anomalous entrance level (C4 or C5) to normal C6 entrance level of the patient with abnormal VA origin. Meila et al 16 claimed that LVA originating from the aortic arch would never enter the transverse foramen at the level of C6, which turned out to enter at a higher level at C4 or C5 with an aortic arch origin proximal to the subclavian artery, or at C7 with an aortic arch origin distal to the subclavian artery respectively.…”

“…The difference of the level of vertebral artery entrance is associated with the dominance of the ascending or deep cervical artery anastomosis. 21 In order to better understand the origin and variation of the vertebral artery, we speculated the development pattern based on the ndings of CY Lin 15 . RVA was normally generated from the rst part of the subclavian artery, and owed into the transverse foramina in the sixth cervical vertebra C6, then passed through the transverse process of C6 to the rst cervical vertebra C1, and eventually extended from C1 to the intracranial segment via foramen magnum.…”

Incidental identification of the aberrant origin of left vertebral artery using magnetic resonance angiography: A case report

“…Many publications have reported abnormal VAs with different genesis including trunk of thyrocervical artery, brachiocephalic artery, common carotid artery, and the aorta [9][10][11][12]. However, there are less than 5 studies which reported that VA originates from external carotid artery [8,[13][14][15]. Elevated risk for cerebrovascular accidents including ath-for cerebrovascular accidents including ath-for cerebrovascular accidents including atherosclerosis, intracranial vascular deformities, arterial cutting up and resulting intracranial complexities due to confusion of the blood flow proceeding from aberrant origin of the VAs have been illustrated in many studies [8][9][10][11][12][13][14][15][16].…”

“…However, there are less than 5 studies which reported that VA originates from external carotid artery [8,[13][14][15]. Elevated risk for cerebrovascular accidents including ath-for cerebrovascular accidents including ath-for cerebrovascular accidents including atherosclerosis, intracranial vascular deformities, arterial cutting up and resulting intracranial complexities due to confusion of the blood flow proceeding from aberrant origin of the VAs have been illustrated in many studies [8][9][10][11][12][13][14][15][16]. The extra-cranial section of the VA is often affected by atherosclerosis leading to a restriction notably in its root [17].…”