Surgical and Endocrine Outcomes of Medial Cavernous Sinus Wall Resection in Functioning Pituitary Tumors

BACKGROUND AND OBJECTIVES: To evaluate the role of medial cavernous sinus wall (MCW) resection in achieving hormonal remission in functioning pituitary tumors and assess the diagnostic accuracy of intraoperative endoscopic inspection vs preoperative Knosp score (KS) grading for MCW invasion. METHODS: A retrospective analysis of 223 patients who underwent endoscopic endonasal approach for pituitary adenomas between January 2021 and December 2023 was performed. MCW resection was performed in 25 patients based on intraoperative endoscopic assessment. Histopathological confirmation of MCW infiltration was obtained in all cases. Preoperative MRI was used to determine Knosp classification, and postoperative hormonal remission was assessed at regular intervals. Statistical analysis included sensitivity, specificity, and receiver operating characteristic curve analysis to compare intraoperative findings with KS-based assessment. RESULTS: MCW invasion was confirmed histopathologically in 80% (20/25) of cases. The overall hormonal remission rate was 80%, with higher remission in first-time surgeries (89%) compared with reoperations (57%). Direct endoscopic inspection had a sensitivity of 95% and specificity of 75% for detecting MCW invasion. Receiver operating characteristic analysis demonstrated superior predictive ability of intraoperative visualization (area under the curve 0.850) compared with KS grading (area under the curve 0.300). Larger tumors (>2.15 cm) were significantly associated with MCW invasion ( P = .020). Complications included 1 case of cerebrospinal fluid rhinorrhea, 2 transient abducens nerve palsies, and 1 deep venous thrombosis. CONCLUSION: MCW resection improves hormonal remission, particularly in primary surgeries. MRI-based KS underestimates MCW invasion, whereas intraoperative endoscopic inspection provides a more reliable assessment. A precise surgical technique is essential for safe and effective MCW resection.