Aberrant Origin of the Right Vertebral Artery From the Common Carotid: Literature-Based Case Review

The vertebral arteries normally arise from the first part of the subclavian arteries and ascend through the transverse foramina of the lower cervical vertebrae before joining as the basilar trunk to supply the posterior circulation.³ Large CTA- and angiography-based series confirm that this classic pattern predominates, but a wide spectrum of origin and course variants has been documented, including aortic arch origin, brachiocephalic trunk origin and carotid-origin vertebral arteries.^{1, 12}

Aberrant origin of the right vertebral artery (RVA) from the right common carotid artery (RCCA) is one of the rarest of these patterns. It has been described mostly in single-patient reports or small series and is often associated with complex aortic arch branching such as aberrant right subclavian artery (ARSCA) and bicarotid trunk.^{5, 10} Although most patients are asymptomatic and the anomaly is detected incidentally on imaging, the variant alters the geometry of the cervical collateral network and may increase the risk of iatrogenic injury during interventions involving the carotid system, subclavian arteries or anterior cervical approaches.

This article provides a purely literature-based case review of all reported RVA-from-RCCA configurations, anchored to systematic and meta-analytic data on vertebral artery origin prevalence and transverse foramen entry levels. The aim is to translate scattered case reports into a coherent, data-driven understanding of how rare this variant is, which aortic arch patterns it clusters with, and which operative and endovascular scenarios are most vulnerable to unrecognised carotid-origin vertebral arteries.^{1, 3}

This review followed the methodological principles of evidence-based anatomy applied to vascular variants.¹² We searched PubMed, Scopus and Web of Science (1950–December 2025) using combinations of the terms “vertebral artery”, “origin variation”, “right vertebral artery”, “common carotid artery”, “aberrant right subclavian artery” and “CT angiography vertebral artery”. Reference lists of key systematic reviews and meta-analyses on vertebral artery origin and course were also screened for additional case reports.^{1, 3}

Three groups of sources were included: (1) broad systematic or narrative reviews of aberrant vertebral artery origins, providing context and pooled prevalence estimates;^{1, 12} (2) meta-analytic data sets evaluating vertebral artery origin and transverse foramen entry levels in large imaging and cadaveric cohorts;³ and (3) individual case reports or small series in which the RVA was clearly documented as arising from the ipsilateral RCCA on CTA, MR angiography, digital subtraction angiography or high-resolution MR, including reports with and without associated ARSCA or other arch variants.^{4, 5}

Data extracted from case reports and small series included laterality, exact origin site on the RCCA, presence or absence of ARSCA, presence of bicarotid trunk or absent brachiocephalic trunk, vertebral transverse foramen entry level (C3–C7) and any reported clinical or procedural complications. For prevalence, we relied on the denominators and pooled estimates provided by Lazaridis et al. for origin variants and by Tudose et al. for transverse foramen entry levels, rather than attempting to recalculate new meta-analyses from case-level data.^{3, 12}

The most robust prevalence estimate for RCCA-origin RVAs comes from the systematic classification by Lazaridis et al., who aggregated imaging and cadaveric data on vertebral artery origin from the aortic arch and its branches.¹² In that data set, left vertebral arteries arising directly from the aortic arch accounted for 3.6% of all vertebral arteries, whereas RVAs originating from the RCCA represented only 0.14%, making this pattern one of the rarest but still reproducible variants (Figure 1).¹²

The same classification noted 18 cases with aberrant right subclavian artery (ARSCA); among these, the RVA originated from the RCCA in 94.4% of cases and from the right subclavian artery in only 5.6%, indicating that when ARSCA is present, RCCA origin is the dominant aberrant RVA configuration rather than an idiosyncratic curiosity.¹² These pooled data place carotid-origin RVAs quantitatively in the “rare variant” band while emphasising that they arise through consistent embryological pathways.

Yuan’s comprehensive review of 1286 aberrant vertebral arteries (955 patients and 331 cadavers) similarly concluded that carotid-origin vertebral arteries occupy a small fraction of aberrant origins overall but should be actively searched for in patients undergoing arch or neck interventions, given the potential for unanticipated haemodynamic patterns and route changes for endovascular access.¹

Ali et al. reviewed the published literature on RCCA-origin RVAs and identified approximately 31 cases up to 2018, nearly all discovered incidentally during angiographic evaluation for headache, cerebrovascular workup or unrelated pathology.⁵ In that series and in earlier Korean and Japanese reports, the anomalous RVA almost invariably coexisted with ARSCA or other supra-aortic arch variants, and was usually asymptomatic from a neurological standpoint.^{5, 10}

Subsequent case reports have broadened the morphologic spectrum. Elnaggar et al. described an RCCA-origin RVA in the setting of absent brachiocephalic trunk, with the right subclavian artery arising directly from the arch as the first branch, followed by the RCCA and left-sided supra-aortic vessels.⁴ Vitošević et al. and Omotoso et al. reported RCCA-origin RVAs in which the brachiocephalic trunk was completely absent or replaced by a bicarotid trunk, again reinforcing the tight coupling between RCCA origin and non-standard arch branching patterns.^{7, 11}

More recently, Uchino and co-workers described RCCA-origin RVA without any associated ARSCA, emphasising that isolated carotid origin can occur in an otherwise normal arch. In their case, the RVA entered the transverse foramen at C3, well above the usual C6 level.⁶ Chen et al. reported two patients whose RVA originated from the RCCA in conjunction with an RSCA arising separately from the aortic arch, illustrating yet another reproducible supra-aortic pattern in which carotid-origin RVA appears as part of a broader reconfiguration of the arch tree.¹³

Across these reports, several features are consistent: the anomaly is typically unilateral; the contralateral vertebral artery has a standard subclavian origin; and the carotid-origin RVA is discovered incidentally rather than because of specific posterior circulation symptoms. Clinical relevance arises mainly in the context of surgery or intervention on the arterial tree rather than from the variant itself.

Literature-based data position RCCA-origin RVA as a quantitatively rare but reproducible pattern within the broader landscape of vertebral artery variability. Lazaridis et al. showed that among all vertebral arteries surveyed, RVA origin from the RCCA accounts for roughly 0.14%, while left VA origin from the aortic arch is more frequent at 3.6%.¹² When ARSCA is present, RCCA-origin RVA overwhelmingly dominates as the aberrant configuration (94.4% of ARSCA cases), implying that carotid-origin RVAs are not random but reflect consistent embryological remodelling of the aortic arch and intersegmental arteries.¹²

From an embryological standpoint, these patterns can be explained by persistence of upper cervical intersegmental arteries and altered regression of the right dorsal aorta segments that ordinarily participate in forming the subclavian artery and proximal RVA. When the segment destined to join the subclavian regresses and a more cranial channel connected to the third aortic arch (future RCCA) persists, the vertebral artery can appear to “migrate” onto the RCCA. Coexisting ARSCA, bicarotid trunk or absent brachiocephalic trunk represent different solutions to the same underlying remodelling problem.^{1, 12}

Clinically, the importance of RCCA-origin RVA lies less in spontaneous symptom production and more in its implications for intervention. For carotid endarterectomy and stenting, a vertebral artery originating from the posterior or posterolateral wall of the RCCA may be jeopardised by clamps, shunts or stent deployment, particularly when the contralateral VA is hypoplastic or when the anomalous RVA is dominant.^{5, 10} Failure to recognise a carotid-origin RVA risks unexpected posterior circulation compromise if the vessel is inadvertently narrowed or occluded.

For anterior cervical discectomy and fusion or corpectomy, the global meta-analysis of vertebral artery entry levels by Tudose et al. shows that although C6 is the dominant entry level (about 92%), approximately 5–6% of vertebral arteries enter at C5 and a smaller proportion at C4 or C7.³ RCCA-origin RVA case reports highlight exactly such atypical, higher entry levels, including C3 and C4, bringing the vessel closer to standard dissection planes and increasing the risk that screws, retractors or needles will intersect the artery.^{6, 13}

In endovascular practice, carotid-origin RVAs alter catheterisation strategy. Instead of being approached via the subclavian artery, the RVA must be accessed through the carotid axis, changing wire angles, support characteristics and the risk of plaque mobilisation if atherosclerotic disease is present. Case reports describe prolonged procedure times and increased technical complexity when the variant is not anticipated, even when no frank complication occurs.^{4, 21}

Taken together, these findings argue that vertebral artery origin and transverse foramen entry level should be treated as routine checklist items on pre-operative and pre-interventional CT or MR angiography, particularly in patients scheduled for carotid, cervical spine or aortic arch procedures. RCCA-origin RVA remains rare in absolute terms but common enough in large vascular units that ignorance of the pattern is no longer defensible.

A right vertebral artery arising from the right common carotid artery is a genuinely rare but increasingly well-characterised anatomical variant. High-quality systematic data place its prevalence at around 0.14% of vertebral arteries, with a strong clustering in patients who also harbour aberrant right subclavian artery or other non-standard supra-aortic branching patterns.^{1, 12} Case reports demonstrate that most individuals are asymptomatic and that the variant is usually detected incidentally, yet the configuration has meaningful consequences for carotid surgery, cervical spine approaches and posterior circulation endovascular procedures.

For anatomists and radiologists, RCCA-origin RVAs exemplify how case-level observations, when collated through systematic review and meta-analysis, can be converted into quantitative risk estimates and practical checklists. For surgeons and interventionalists, the message is straightforward: vertebral artery origin and transverse foramen entry level should be explicitly assessed on preoperative imaging. When the RVA arises from the common carotid artery or enters the transverse foramen above C6, operative strategy and consent should reflect that data-driven departure from textbook anatomy.