Posterior identification and exposure of the V3 segment of the vertebral artery.

Objective: The purpose of this study was to define the anatomy of the V3 segment of the vertebral artery (VA) from the posterior approach.

Methods: Ten formalin-fixed cadavers were carefully dissected bilaterally using landmark features to identify and safely expose the VA from the posterior. Measurements regarding morphometric characteristics of landmark features and feasible resection quantifications were obtained and analyzed. The C2 pars was resected completely in all cadavers, averaging 15.03 ± 1.06 mm in thickness.

Results: The average diameter of the VA at the midline of C2 on the right side was 4.66 ± 0.51 mm compared to the left 5.2 ± 0.49 mm ( P = 0.002). The distance of the VA from the midline increased from caudal to rostral. The distance between the VA to the lateral edge of the dura in the middle of the window of approach was 9.67 ± 0.81 mm. The rostral-caudal length of the window of approach was 21.94 ± 1.60 mm. The percentage of C2 body removal was 28.04% ± 6.09% through each side (249.55 ± 55.5/898.2 ± 146.17 mm2 ). While carefully exposing the VA, a posterior approach can be feasible in cases of injury during C1-C2 instrumentation or during resection of tumors of the C2 pars with or without extension into the C2 body.

Discussion: The posterior approach for a C2 partial corpectomy can also be used as an adjunct to anterior approaches when necessary to widen the extent of bone resection.

Conclusion: Exposure of the V3 segment of the vertebral artery was defined as well as the extent of C2 corpectomy through the posterior approach.