Anatomic and Ergonomic Impact of C1 Transversectomy on the Anterolateral OA–V3 Bypass Corridor: A Cadaveric Study

BACKGROUND AND OBJECTIVES: The occipital artery–vertebral artery (OA–VA) bypass of the V3 segment has been described as a possible feasible revascularization strategy through the anterolateral approach. However, the impact of C1 transverse process removal on surgical corridor expansion, VA mobility, and microsurgical ergonomics has not been evaluated. In this cadaveric study, we assessed the anatomic and ergonomic effect of C1 transversectomy for OA–V3 bypass. METHODS: Five injected cadaveric specimens (10 sides) were subjected to paired analysis comparing standard anterolateral exposure (baseline) vs the same approach with C1 transversectomy and VA skeletonization. Quantitative end points included surgical working area, exposed VA length, working depth, and instrument divergence angle. Paired statistical analysis was calculated. RESULTS: C1 transversectomy resulted in a significant improvement in all major parameters of surgical exposure. The working area increased by 130% (from 226.1 to 519.1 mm 2 , P < .001), whereas the exposed VA length increased by 84% (from 12.7 to 23.4 mm, P = .002). VA mobility demonstrated the greatest relative gain, increasing by 207% (from 1.5 to 4.6 mm, P < .001). The instrument divergence angle also significantly improved, increasing by 109% (from 18.2° to 38.1°, P < .001). No statistically significant changes were observed in working depth. CONCLUSION: C1 transversectomy markedly enhances exposure, mobility, and operative ergonomics within the anterolateral OA–V3 corridor. These findings provide quantitative anatomic validation of a technical refinement that may improve reproducibility and safety of OA–VA bypass in selected clinical scenarios.