J Neurol Surg B Skull Base 2023; 84(S 01): S1-S344
DOI: 10.1055/s-0043-1762055
Presentation Abstracts
Oral Abstracts

Endoscopic Endonasal Posterior Clinoidectomy: Surgical Anatomy and Operative Technique

Muhammad Salman Ali
1   University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Georgios Zenonos
1   University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Carl Snydermann
1   University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Eric Wang
1   University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Paul Gardner
1   University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
› Author Affiliations
› Further Information
 

Introduction: Posterior clinoidectomy (PC) is an integral part of the endoscopic endonasal approach (EEA) to the upper clivus and can be used for many different pathologies. No well-defined osteotomies have been described for efficient removal of the PC. This study reviews surgical anatomy of the PC and describes 3 osteotomies for removal of the PC through EEA.

Methods: Three cadaveric head specimens were used to study the anatomy of PC and necessary osteotomies to detach the PC endonasally. The previously defined transcavernous approach to remove the PC was then performed once it was disconnected from its bony attachments. A clinical case demonstrating the technique is presented as well for removal of a dorsum sella meningioma.

Results: The PC could be removed in all 6 sides by drilling 3 bony attachments: caudally the clivus, medially the dorsum sella (DS), and laterally the paraclival carotid canal. Disconnecting the DS is critical to avoid manipulating both PCs at the same time. The pituitary gland is elevated extradurally to disconnect the DS using Kerrison rongeur or drill. After the parasellar carotid is exposed, the bone over the upper paraclival ICA must be drilled to disconnect it. The medial cavernous sinus is then opened (embolized using flowable gel foam in patients). Intra-cavernous sinus ligaments (inferior parasellar and carotico-clinoidal) were present in all cadavers and were cut. This allowed the most rostral extent of PC to be exposed and dissected instead of blind extradural dissection and removal. None of the cadavers had any calcified ligaments or atypical bony attachments with the middle clinoid, though these may be present and should be evaluated.

Conclusion: Removing the posterior clinoid process is a critical step in endonasal endoscopic approach for various skull base pathologies. Understanding the anatomy and making 3 well defined osteotomies allows for efficient removal of posterior clinoid in a controlled fashion. Removing the PC extradurally blindly or without proper bony release may predispose to unwarranted neurovascular injury or partial resection of PC.

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Fig. 1 Endoscopic endonasal view of removal of the right posterior clinoid process in a cadaver. Parasellar carotid is exposed (A), clivus is drilled (B), cavernous sinus is opened (C), inferior hypophyseal artery and inferior parasellar ligaments cut (D), posterior clinoid exposed and removed (E and F).
Zoom Image
Fig. 2 Intra-operative endoscopic endonasal images of left clinoid process removal for a dorsum sella meningioma. Parasellar carotid is exposed (A and B), clivus is drilled and disconnected from dorsum sella (C), cavernous sinus is opened (D), inferior hypophyseal artery coagulated and cut (E), inferior parasellar ligament cut (F), right and left posterior clinoid processes are disconnected (G and H) and finally posterior clinoid is exposed and removed (I).


Publication History

Article published online:
01 February 2023

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