Imaging and Demographic Characteristics Associated with Invasion of the Medial Wall of the Cavernous Sinus in Patients with Invasive Pituitary Adenomas

Introduction: Resection of the medial wall of the cavernous sinus (MWCS) may be indicated to achieve a gross-total resection in invasive pituitary adenomas. Because of the intrinsic risk to this surgical maneuver, appropriate patient selection is critical to assess who will benefit from the intervention. The purpose of this study is to describe patient and tumor characteristics associated with pathological invasion of the MWCS during an endonasal endoscopic approaches (EEA).

Methods: A retrospective review was conducted to identify pituitary adenoma cases who underwent an EEA with selective resection of the MWCS based on intraoperative suspicion between 2012 and 2017. Pathologic confirmation of pituitary adenoma invasion to the MWCS was used to separate the patient cohorts into positive and negative cases. These two cohorts were then analyzed in terms of demographics and tumor characteristics. Adenomas with CS invasion beyond the medial wall (Knosp 4) were excluded.

Results: Fifty patients were identified and medial wall invasion was histologically confirmed in 43 specimens (86%) (93% of nonfunctional adenomas and 83% of functional adenomas). Tumor size (OR: 1.2; 95% CI: 1.0–1.4 mm) and Knosp grade (OR: 3.5; 95% CI: 1.0–12.6 [per Knosp unit]) were associated with MWCS invasion. Gender and age had no effect. The positive predictive value for a tumor larger than 25 mm in which medial wall invasion was suspected was 100%.

Conclusion: The medial wall of the CS is frequently pathologically invaded when the intraoperative suspicion is high. Larger tumor size and higher Knosp scores predict pathological invasion of the MWCS.

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