Classification of Vertebral Artery Course Variations in the Atlantoaxial Region and Their Anatomic Considerations for Surgical Planning: A CTA Imaging Analysis of 511 Patients.
TL;DR
Different vertebral artery course variation types carry distinct and predictable potential surgical implications for surgical planning and each carries distinct anatomic considerations for screw placement, exposure, and surgical approach selection.
Abstract
Background
Vertebral artery (VA) course variations in the atlantoaxial region pose significant risks during posterior C1-C2 fixation. This study aimed to classify these variations on CT angiography (CTA) and assess their anatomic implications for surgical planning.
Methods
A retrospective analysis was conducted on 511 patients (1,022 vertebral arteries) who underwent cervical CTA at Beijing Tongren Hospital between January 2019 and December 2024. Vertebral artery course variations were classified by two independent senior radiologists. Interobserver agreement was assessed using Cohen's kappa coefficient. Associations between variation types and gender/side were analyzed using chi-square tests with adjusted standardized residuals. potential surgical implications were assessed based on anatomical relationships and literature review Results: Seven types were identified: normal type (712 arteries, 70%), high-riding type (243, 24%), posterior arch bridge type (26, 2.5%), protruding type (14, 1.4%), segmental artery type (13, 1.2%), fenestration type (9, 0.9%), and combined type (5, 0.5%). Interobserver agreement was substantial (κ = 0.795). Each type carries distinct anatomic considerations for screw placement, exposure, and surgical approach selection.
Conclusions
Different vertebral artery course variation types carry distinct and predictable potential surgical implications. Detailed preoperative CTA assessment with three-dimensional reconstruction is essential for identifying these variations and minimizing the risk of iatrogenic vertebral artery injury during posterior atlantoaxial surgery.