Intradural Endoscope-Assisted Anterior Clinoidectomy: A Cadaveric Study

Introduction: The anterior clinoid process (ACP) is critically related to the clinoidal portion of the internal carotid artery (ICA). The deep location of the ACP makes treatment of vascular and neoplastic lesions related to the ACP challenging. Removal of the ACP is advocated to facilitate treatment of such lesions. However, injury to the clinoidal ICA remains a potential and dreadful complication of ACP removal.

Purpose: The aim of this study was to demonstrate an endoscopic-assisted technique to perform intradural removal of the ACP via a pterional approach with continuous visualization of the clinoidal ICA.

Methods: Sixteen bilateral pterional dissections were performed in eight glutaraldehyde-embalmed, colored silicone-injected, adult cadaveric heads. Using a standard pterional approach, we performed drilling of the ACP in two stages. Stage 1 consisted of extradural microscopic removal of the sphenoid ridge to gain access to the origin of the ACP. Stage 2, the endoscopic stage, consisted of intradural endoscopic removal of the ACP and mobilization of the clinoidal segment of the ICA. We used 2.7 mm, 0°, and 30° angled endoscopes.

Results: In all the specimens, we were able to remove the ACP while at the same time continuously visualizing the clinoidal ICA. The exposure of the clinoidal ICA and of adjoining neurovascular structures was excellent and was accomplished with minimal frontal lobe retraction. Mobilization of the clinoidal ICA led to unhindered exposure of the parasellar region.

Conclusions: Endoscopic-assisted ACP removal with continuous ICA visualization was feasible in our model. Continuous visualization of the clinoidal ICA should theoretically decrease the risk of inadvertent ICA injuries. Clinical studies to validate this laboratory study are necessary.