Endoscopic Endonasal Approach for the Pituitary Adenoma Invading Posterior Compartment of the Cavernous Sinus and Basilar Plexus: Anatomical Consideration and Surgical Strategy for Maximizing Extent of Resection

Objective: Pituitary adenoma (PA) can invade into the cavernous sinus (CS) and the management of this entity is challenging. We studied the surgical anatomy of the posterior compartment of the cavernous sinus (PCCS) and basilar plexus. After the anatomical study, we retrospectively evaluated our treatment outcomes of PA in these areas according to surgical strategies.

Methods: Six cadaveric specimens were prepared for this study to demonstrate the surgical anatomy related to the approach for the PCCS using a neuro-endoscope system and neuro-navigation guidance. From October 2015 to February 2022, pre- and postoperative MRI images of 140 sides of CS from 127 patients were analyzed. The patients were divided into 3 groups according to time periods as follows: A, Microscopic surgery (from October 2015 to December 2017); B, Endoscopic surgery without extensive clival bone resection (from January 2018 to March 2020); C, Endoscopic surgery with partial clival resection (from April 2020 to February 2022)

Results: From period A to period C, in the 140 sides of CS invasion in 127 patients with PA, the PCCS was invaded in 50.0% (70/140) with a gross total resection (GTR) rate of 35.7% (25/70). The basilar plexus was invaded in 30.0% (42/140) with a GTR rate of 26.2% (11/42). After performing the removal of lateral upper and middle clivus through the endonasal endoscopic approach (EEA) with medial wall resection of CS, we could readily identify the neurovascular structures of the PCCS, including the abducens nerve, inferior hypophyseal artery, and the venous channels between PCCS and basilar plexus. The abovementioned surgical procedures could secure the endoscopic surgical view of PCCS and basilar plexus and make sufficient space for surgical manipulation. Based on the cadaveric study, we performed these surgical procedures for patients with PA invading the PCCS and basilar plexus in period C. The GTR rate of PA in PCCS and basilar plexus significantly increased from the microscopic surgery period (period A) to endoscopic surgery (period B and C) (PCCS: 16.1 vs. 51.3%, p = 0.002, basilar plexus; 5.3 vs. 43.5%, p = 0.006). After partial clival resection, the GTR rate of tumors in these areas has significantly increased in period C than in period B (period B vs. period C; PCCS: 36.4% vs. 70.6% p = 0.036, basilar plexus; 9.1% vs. 75.0%, p = 0.002).

Conclusions: We investigated the clinical feasibility of the removal of lateral upper and middle clivus through EEA with medial wall resection of CS for PA invading the PCCS and basilar plexus based on a cadaveric study. This surgical procedure could provide adequate access to the PCCS and basilar plexus and make better clinical results for patients with PA invading these areas.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
05 February 2024