The Application of the Posterior Atlanto-Occipital Membrane Tension Release Technique for Surgical Exposure of the Horizontal Part of the Vertebral Artery's Third Segment: An Anatomical and Clinical Investigation

Objective

This study aims to elucidate the anatomical principles governing the surrounding venous structures (VS) of the horizontal part of the third segment of the vertebral artery (V3h) and develop a safe and bloodless surgical technique for exposing V3h.

Methods

This study used 10 formalin-infused cadaveric head specimens. The dissections were performed stepwise to simulate the far lateral approach process, exposing the V3h with a novel technique. Additionally, we applied this technique to 10 patients undergoing far or extreme lateral approaches.

Results

The VS surrounding V3h is divided into 3 components: the vertebral venous plexus, suboccipital cavernous sinus, and the anastomotic vein. The posterior atlanto-occipital membrane (PAOM), a resilient fascial layer in the craniovertebral junction, extends from the periosteum of the occipital squama to the posterior arch of the atlas. It adheres ventrally to the VS within the suboccipital triangle (SOT), forming a tent-like structure that maintains tension and ensures fullness of the VS around V3h. We discovered that by releasing tension in this membrane and reducing strain on this tent-like structure, the collapse of the venous sinus within the SOT can be achieved, resulting in reduced intraoperative bleeding and improved surgical efficiency. Additionally, we successfully managed 10 clinical cases employing the PAOM tension release technique in clinical cases, with no reported incidents of intraoperative vertebral artery injury.

Conclusions

The application of the PAOM tension release technique effectively collapses the tent-like structure within the SOT, significantly reducing bleeding during V3h exposure in craniovertebral junction.