Partial Anterior Petrosectomies for Upper Basilar Artery Trunk Aneurysms: A Cadaveric and Clinical Study

Abstract

Surgical clipping for upper basilar artery (BA) trunk aneurysms has become less common since the popularization of endovascular therapy. However, when endovascular therapy is not feasible, direct open surgery is still the treatment of choice. The anterior transpetrosal approach (ATP) is most often used to safely treat these aneurysms. We evaluate the feasibility of a modified partial anterior transpetrosal approach for the treatment of upper BA trunk aneurysms. Using 5 preserved cadaveric heads (10 sides), a modified partial anterior transpetrosal approach (P-ATP) was performed and maneuverability of the upper BA trunk was assessed. The conventional ATP was modified for maximum exposure of the upper BA trunk region with minimal bone removal. The exposure provided by the P-ATP was comparatively assessed with other skull base approaches. The P-ATP was performed on a clinical upper BA trunk aneurysm that required surgical clipping. Drilling only the anterior half of the conventional ATP was sufficient to manipulate the upper BA trunk. This approach provided better surgical maneuverability than the conventional subtemporal approach and shorter distance than the more challenging transcavernous approaches. A stepwise procedure that accounted for the optimal direction of the microscope, relevant surgical landmarks, and increased structural and functional preservation helped to avoid intraoperative complications. The P-ATP was successfully applied without complication to a clinical case of a ruptured BA trunk aneurysm. Modification and minimization of the conventional ATP provided sufficient exposure for the treatment of upper BA trunk aneurysms. Detailed anatomical knowledge obtained though cadaveric dissection facilitated development of this effective and less invasive approach.