Selective Surgical Resection of the Medial Wall of the Cavernous Sinus for Invasive Pituitary Adenomas: Surgical Technique and Outcomes in 49 Patients

Background Pituitary adenomas often invade the medial wall of the cavernous sinus (CS) without extending into the cavernous sinus compartments. Surgical removal of the medial wall of the CS, while considered important to increase remission rates and decrease tumor recurrence, is generally not recommended secondary to the risk of vascular and cranial nerve injury and massive blood loss.

Objective The purpose of this study is to present a step-by-step surgical technique designed to completely remove the medial wall of the CS, and to report the surgical outcomes in a large series of invasive pituitary adenomas.

Methods A retrospective review was conducted to identify patients who underwent an endoscopic endonasal approach (EEA) for pituitary adenoma with selective resection of the medial wall of the CS since its implementation in 2012. Cases with tumor invasion into cavernous sinus compartments were excluded. Patient complications, resection, and remission rates (using the most up-to-date criteria) were assessed.

Results The key steps of the proposed surgical technique are: (1) wide exposure of the anterior wall of the CS and skeletonization of the internal carotid artery (ICA); (2) removal of all sellar tumor and inspection of the medial wall; (3) opening of the anterior wall to directly access the CS; (4) gentle mobilization of the medial wall starting at the sellar floor; (5) identification of the cavernous ICA and inferior CS ligament; (6) coagulation and transection of the inferior hypophyseal artery; (7) further mobilization of the medial wall in a posterior direction to reach the posterior clinoid, and in a superior direction up to the carotico-clinoidal ligament; and (8) medial, posterior, and superior dural cuts.

Forty-nine patients were eligible for this study, 15 (31%) with nonfunctional adenomas and 34 (69%) with functional adenomas, including 16 GH, 10 PRL, and 8 ACTH secreting adenomas. Five cases (10%) corresponded to reoperations. The average size was 2.29 cm for nonfunctional and 1.29 cm for functional adenomas. Radiographically, 11 patients (22%) were Knosp Grade I, 22 (45%) patients were Knosp Grade II, and 16 (33%) patients were Knosp Grade III. Complete tumor resection, based on intraoperative impression and postoperative MRI, was achieved in all cases. Mean follow-up was 13.3 months (1.8–29.8) for nonfunctional and 25.8 months (1.7–64.1) for functional adenomas. Complete remission in functional adenomas was seen in 33 patients (97%). No imaging recurrences were seen during this period in nonfunctional adenomas. There were neither deaths nor ICA injuries, and the average blood loss was 378 mL. Four patients (8%) developed a new CN palsy that resolved completely at 3 months of follow-up in all of them, with two requiring early postoperative clot or fat graft evacuation.

Conclusion The surgical technique described here is based on an accurate understanding of the dural layers, CS ligaments, venous channels, and cavernous ICA trajectory and branches. The medial wall of the CS can be removed safely and effectively, with minimal morbidity and excellent resection and remission rates. Further follow-up is needed to determine the long-term results of this technique.