Evolution of Endoscopic Endonasal Posterior Clinoidectomy Technique: From Extradural, Transcavernous to Extended Transcavernous Posterior Clinoidectomy

Objective: Posterior clinoidectomy is of utmost importance for the neurosurgeon specializing in endonasal endoscopic approaches, as the posterior clinoid processes (PCP) are commonly involved in chondroid tumors. Two main techniques have been developed: extradural posterior clinoidectomy and transcavernous interdural posterior clinoidectomy. Here we introduce a novel technical variant, termed “extended transcavernous posterior clinoidectomy” and we elaborate on its clinical application based on anatomical dissections and radiological studies.

Methods: Computed tomography angiography images and 3D reconstruction of PCP in 50 adults were reviewed, and the ossified ligamental attachment to PCP and the height of PCP were analyzed. Twelve lightly embalmed postmortem human heads (24 hemispheres) underwent endoscopic endonasal posterior clinoidectomy. Three techniques including extradural, transcavernous and extended transcavernous posterior clinoidectomy were performed sequentially, and anatomic landmarks and exposed areas with each technique were investigated and compared. The extended version of the transcavernous posterior clinoidectomy requires transection of the carotico-clinoidal ligament to connect the transcavernous route with the dorsal clinoidal space.

Results: The radiologic study classified the PCP into 2 types: (1) normal-type, defined as height less than 8mm and no ossified ligamental attachment to PCP ([Fig. 2A–C]) and (2) complicated-type, defined as height more than 8mm or ossified ligamental attachment to PCP ([Fig. 2D–F]). Compared with extradural (exposed height of PCP is 4.7 ± 0.7 mm) and transcavernous (exposed height of PCP is 7.3 ± 1.0 mm), the extended transcavernous posterior clinoidectomy provided the maximally exposed height of PCP with 9.5± 0.4 mm (p < 0.0001, [Fig. 1]).

Conclusion: This study details the extended transcavernous posterior clinoidectomy as a novel technical variant for maximal exposure of the PCP in endoscopic endonasal surgery. It also establishes the utility for the radiologic assessment of PCP with the connection of the preoperative plan for the surgical approach.

Fig. 1 Comparison among extradural, transcavernous to extended transcavernous posterior clinoidectomy.

Fig. 2 Morphologic classification of posterior clinoid process.

Publication History

Article published online:
01 February 2023