Utility of Biting Clinoidectomy for Internal Carotid Artery Paraclinoid Aneurysm Clipping-A Variation of Anterior Clinoidectomy.

Abstract

Anterior clinoidectomy (ACD) is an essential skull base surgical technique for internal carotid artery paraclinoid aneurysm (ICPA) clipping. However, ACD has risks of injuries to aneurysm and surrounding structures, such as the internal carotid artery (IC) and the optic nerve (ON). We have been practicing a modified ACD technique (biting clinoidectomy) to reduce the aforementioned risks, and introduce it. In biting clinoidectomy, drilling begins with the optic canal unroofing, proceeds toward the supraorbital fissure, but is confined to the cancellous bone of the anterior clinoid process (ACP) with the avoidance of further and deeper drilling for the removal of the optic strut and the medial lesser wing of the sphenoid bone near the ON and IC to detach the ACP from them. Then, the ACP is made to egg-shell-like cortical bone, and this is rongeured off in pieces using the osteotrite forceps (biting clinoidectomy). In this method, manipulations are confined to the ACP cavity. Moreover, grasping and shaking of the ACP for its removal are not required. Therefore, risk of thermal injury to the ON and the IC with drilling, and external force to the aneurysm, could be decreased. We have performed ICPA clipping for 6 cases using biting clinoidectomy, and experienced no intraprocedural premature rupture or injuries of the IC or ON. In addition, we experienced no insufficient removal of the ACP for clipping. Biting clinoidectomy is a useful and less risky variation of the ACD than conventional ACD.