Case report of anomalous vertebral artery from common carotid artery with C4 entry and aberrant right subclavian artery

Abstract

Introduction and importance:

Anomalous origin of the vertebral artery from the common carotid artery (VA-CCA), particularly when combined with an aberrant right subclavian artery (ARSA) and a high (C4) transverse foramen entry, represents an exceptionally rare congenital vascular variant. This complex anatomy poses significant risks of iatrogenic injury during endovascular interventions and anterior cervical spine surgery.

Case presentation:

A 62-year-old male presented with persistent dizziness. Comprehensive computed tomography angiography (CTA) and digital subtraction angiography (DSA) revealed a unique combination of anomalies: the right vertebral artery originating from the right common carotid artery, entering the transverse foramen at the C4 level, and a retroesophageal ARSA. The patient was managed conservatively with symptomatic resolution and received extensive counseling regarding his anatomy.

Clinical discussion:

The incidence of VA-CCA is approximately 0.18%. Its association with ARSA and a high cervical entry point creates an elongated, mobile cervical segment with an acute origin angle. This increases the risk of vascular injury during catheterization and anterior surgical approaches to the C4-C6 levels. Pre-procedural recognition via advanced vascular imaging, such as CTA with 3D reconstruction, is crucial for preventing catastrophic complications.

Conclusion:

This case underscores the critical importance of recognizing this rare vertebral artery anomaly complex. Accurate pre-operative imaging diagnosis and thorough patient counseling are essential for procedural safety planning in patients undergoing neck interventions.

Introduction

Vertebral artery anomalies are uncommon but clinically significant variations that can lead to catastrophic complications during routine procedures. The normal vertebral artery typically originates from the subclavian artery and enters the transverse foramen at the C6 level. However, anatomical variations can occur, with the vertebral artery occasionally originating from alternative locations such as the common carotid artery.

HIGHLIGHTS

• First case of VA from CCA with C4 entry plus retroesophageal right subclavian.

• Extremely rare vascular anomaly with incidence of only 0.18% in population.

• High-quality CTA and DSA imaging documenting exceptional vascular anatomy.

• Critical procedural risks for endovascular and cervical spine surgery

• Essential recognition for patient safety and procedural planning.

The incidence of vertebral artery origin from the common carotid artery (VA-CCA) is approximately 0.18%, making it an exceptionally rare finding^[1^]. This anomaly is almost invariably associated with an aberrant right subclavian artery, reflecting complex developmental abnormalities^[2^]. The literature contains only about 31 reported cases of VA-CCA, with even fewer describing C4 transverse foramen entry^[3^].

The combination of VA-CCA with C4 entry level represents one of the rarest vascular patterns reported. Understanding this anatomy is essential for safe clinical practice, particularly as endovascular interventions become increasingly common. The European Society of Neuroradiology and the Society of Interventional Radiology have established protocols emphasizing comprehensive pre-procedural vascular imaging assessment.

In this study, we report the case of a patient who presented with this extremely rare combination of vascular anomalies, providing high-quality multimodal imaging documentation and discussing the clinical implications for procedural planning.

Case report

We present the case of a 62-year-old Han Chinese male patient. This case has been reported in line with the SCARE criteria^[4^].

The patient was retired and was admitted to our neurology department for evaluation of persistent dizziness lasting 1 month.

The patient had been experiencing non-rotatory dizziness without associated headaches, syncope, vertigo, or focal neurological symptoms. There was no history of trauma, medication changes, or other precipitating factors. Past medical history was unremarkable with no prior hospitalizations or surgical procedures. The patient was taking no regular medications and reported no known drug allergies.

Family and social history: No significant family history of cardiovascular or neurological conditions. Smoking history: 10 pack-years (1 pack/day × 10 years), quit 20 years ago. Occasional alcohol use. Lives independently.

Physical examination revealed normal vital signs with blood pressure 120/80 mm Hg, heart rate 72 bpm, and temperature 36.8 °C. Neurological examination was unremarkable without focal deficits, nystagmus, or cerebellar signs. Cardiovascular examination showed regular heart rhythm with no murmurs, and peripheral pulses were palpable and symmetric bilaterally.

Comprehensive vascular imaging was performed to exclude cerebrovascular pathology. Computed tomography angiography (CTA) was performed on 23 June 2025, demonstrated multiple congenital vascular variants (Fig. 1). The aortic arch exhibited an aberrant four-vessel branching pattern with sequential origins of the right common carotid artery, left common carotid artery, left subclavian artery, and aberrant right subclavian artery, the latter following a retroesophageal course. Additional vertebral artery anomalies were identified, including anomalous origin of the right vertebral artery from the right common carotid artery approximately 8 cm below the carotid bifurcation, with subsequent entry into the transverse foramen at the C4 level rather than the typical C6 entry point. This configuration resulted in an elongated pre-foraminal cervical segment with a predominantly vertical trajectory. Intracranial evaluation revealed an intact Circle of Willis with a variant anatomy consisting of a common trunk giving rise to both anterior cerebral arteries from the left internal carotid artery. Dynamic vascular assessment with digital subtraction angiography was subsequently performed on 27 June 2025 (Fig. 2 and Supplemental Digital Content Videos 1, available at: http://links.lww.com/IJSCR/A22; Supplemental Digital Content Videos 1, available at: http://links.lww.com/IJSCR/A23) to provide confirmatory hemodynamic evaluation. The study verified anomalous right vertebral artery origin from the right common carotid artery with normal flow dynamics, confirmed the retroesophageal course of the aberrant right subclavian artery, and revealed no significant stenosis or flow-limiting lesions.

Figure 1.

CTA demonstrating multiple vascular anomalies. Panel A shows a three-dimensional reconstruction of the aortic arch with an unusual four-vessel branching pattern. From right to left: right common carotid artery (RCCA), left common carotid artery (LCCA), left subclavian artery (LSCA), and aberrant right subclavian artery (ARSA, arrow) with retroesophageal course (CTA). Panel B demonstrates the anomalous origin of the right vertebral artery (arrow) from the RCCA approximately 8 cm below the carotid bifurcation, with a more vertical course than normal (DSA). Panel C shows an axial image at the C4 level revealing the aberrant right vertebral artery entering the transverse foramen (arrow), rather than at the typical C6 level (CTA). Panel D displays the ARSA (arrow) originating from the medial aspect of the aortic arch, taking a retroesophageal course posterior to the esophagus and trachea (CTA). CTA, computed tomography angiography; DSA, Digital Subtraction Angiography.

Figure 2.

Digital subtraction angiography confirming the vascular anomalies. Panel A shows a selective right common carotid artery angiogram in a right anterior oblique (RAO 30.4°) and slight cranial (2.9°) projection, clearly delineating the anomalous origin of the right vertebral artery (arrow). Panel B shows a left anterior oblique (LAO 43°) projection of an aortic arch angiogram, demonstrating an aberrant right subclavian artery (ARSA, arrow) arising as the last branch of the aortic arch, distal to the origin of the left subclavian artery.

The patient was managed conservatively with comprehensive education regarding his complex vascular anatomy and its clinical implications. Detailed documentation of all vascular anomalies was incorporated into the medical record, and complete imaging studies were provided to the patient for future medical encounters. Extensive counseling was conducted regarding the significantly increased procedural risks associated with endovascular interventions, cervical spine surgery, carotid endarterectomy, and any cervical or thoracic procedures due to the aberrant vascular anatomy. The patient’s presenting symptoms resolved with conservative management, and he was specifically advised to inform all future healthcare providers about these vascular anomalies prior to any interventional procedures involving the neck, chest, or cerebrovascular system to ensure appropriate procedural planning and risk mitigation.

Discussion

The combination of a right vertebral artery originating from the common carotid artery with C4 transverse foramen entry and a retroesophageal right subclavian artery represents an extremely rare vascular anomaly. The incidence of vertebral artery origin from the common carotid artery (VA-CCA) is approximately 0.18%^[5^], and this anomaly is almost invariably associated with an aberrant right subclavian artery^[2^]. The literature contains only about 31 reported cases of VA-CCA^[2^], and even fewer describe the level of transverse foramen entry at the C4.

The developmental mechanism involves abnormal persistence of cervical intersegmental arteries and failure of normal longitudinal anastomoses. When the 3rd to 6th cervical intersegmental arteries fail to regress and the longitudinal anastomosis below this level fails to form, the vertebral artery will originate from the common carotid artery^[3^]. The C4 entry level in our case suggests persistence of the 4th cervical intersegmental artery. The association with aberrant right subclavian artery reflects abnormal regression of the right dorsal aorta proximal to the 7th intersegmental artery^[6^].

This rare vascular anomaly has several notable clinical implications. The elongated free cervical segment and acute angle of origin increase technical difficulty and the risk of vascular injury during catheterization, often making standard vertebral artery catheters insufficient^[5^]. In anterior cervical spine surgery at the C4–C6 levels, the vertebral artery’s atypical course – lying free rather than within the transverse foramen – raises the risk of iatrogenic injury^[7^]. Moreover, the mobile, elongated segment may be more prone to trauma and spontaneous dissection due to increased shear stress^[8^]. Diagnostic errors may also occur, as routine imaging can misinterpret the vertebral artery’s absence in the C6 transverse foramen as congenital aplasia^[5^].

Our case adds to the limited literature by providing high-quality CTA and DSA imaging demonstrating this rare combination of anomalies. The clear visualization of the C4 transverse foramen entry level helps support the embryological theory of different levels of intersegmental artery persistence.

Conclusion

In conclusion, recognition of this rare vascular anomaly is essential for safe performance of endovascular and surgical procedures in the neck. CTA with 3D reconstruction provides excellent anatomical detail for diagnosis and treatment planning. Patients with this anomaly should be counseled about the increased risk of vascular injury and the importance of informing healthcare providers about their vascular anatomy before any neck procedures.

Ethical approval

The research followed the ethical standards established by the national research committee and the 1964 Helsinki Declaration and its later revisions, or similar ethical standards. The study does not influence patient care or their clinical experience in any manner. The data analysis does not risk the participants’ privacy or safety. The study complies with all national data protection and privacy regulations.

Consent

The study was approved by the institutional review board of Guangdong Second Provincial General Hospital (2023-KY-KZ-306-03). Consent for publication was obtained from the patient, and all data were anonymized and the submitted image does not contain any identifying features.

Author contributions

Y.Z. and S.S.: image analysis, radiological interpretation; B.Z. and J.F.: data acquisition, analysis, initial draft; J.F.: imaging acquisition, technical analysis; Y.Z. and Z.X.H.: clinical assessment, vascular interpretation; Y.H.: data analysis, literature review; Z.X.H.: study conception, DSA procedure, supervision, critical revision. All authors critically revised the manuscript, approved the final version, and agree to be accountable for all aspects of the work.

Sources of funding

Supported by the Guangzhou Municipal Science and Technology Bureau Key Research and Development Program (2024B03J0436).

Conflicts of interest disclosure

The authors report no relevant disclosures.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Zhi-Xin Huang is the guarantor of this study and accepts full responsibility for the integrity of the work.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability statement

No datasets were generated or analyzed during the current study.

Acknowledgements

The authors thank the patient for providing clinical information for this report.