Extradural Endoscope-Assisted Subtemporal Posterior Clinoidectomy

Surgical treatment of distal basilar artery aneurysms is challenging because of the narrow surgical corridor, presence of vital perforating vessels, deep location, and difficulty in obtaining proximal control.To investigate using a cadaver model the feasibility of performing a transcranial extradural posterior clinoidectomy via a subtemporal route between V2 and V3 using an endoscope-microscope combination.Fourteen dissections were performed in 14 fresh cadaver heads. A standard pterional approach with removal of the zygomatic arch was followed by a 2-stage dissection to remove the posterior clinoid process. In stage 1 (microscopic stage), the area between the second and third trigeminal divisions (V2 and V3) was exposed and the anterior half of the bone between them was drilled to the sphenoid sinus cavity inferior to the carotid sulcus. In stage 2 (endoscopic stage), the drilling was continued to the carotid sulcus. Next, the endosteal layer of the dura lining the carotid sulcus was dissected from the bone that was then removed. At the end of this stage, the dura reflection that forms the posterior part of the pituitary capsule was exposed and the base of the posterior clinoid process was removed using a high-speed drill and curet. Finally, the dura was opened to confirm the removal of the posterior clinoid process.It was possible to remove the posterior clinoid process in every specimen without any obvious anatomic injury to the surrounding structures.This study demonstrated the feasibility of the resection of the posterior clinoid process extradurally. This maneuver could be incorporated in multiple cranial base approaches to the retrosellar area and interpeduncular cistern region.