The Role of Resecting the Medial Wall of the Cavernous Sinus Wall in Optimizing Hormonal Outcomes Functioning Pituitary Adenomas

Introduction: Microscopic invasion of the medial cavernous sinus wall (MCW) by functional pituitary adenomas (FPA) significantly impedes achieving hormonal remission postsurgery. The modified Knosp grading system (KS) for cavernous sinus (CS) invasion, based on MR imaging, may not accurately assess the extent of CS involvement in FPA.[1] A detailed anatomical description and technique for MCW resection have been recently introduced.[2] This retrospective study evaluates the surgical outcomes of MCW resection in FPA patients.

Methods: A retrospective analysis was conducted on FPA cases with MCW resection by the endoscopic endonasal approach (EEA) performed between January 2021 and December 2023. Preoperative CS involvement was assessed using the KS. MCW resection was performed when it appeared infiltrated by FPA on direct endoscopic inspection. Resected MCW samples were evaluated for microscopic tumor infiltration, and histopathological findings were compared with direct endoscopic assessment and KS to predict CS involvement. Statistical analysis was performed to assess the accuracy of MCW involvement by direct endoscopic inspection compared to KS.

Results EEA was performed in 223 patients for pituitary tumors; 40 patients had FPA. MCW resection was performed in 25 patients with suspected CS involvement based on endoscopic inspection. GH-secreting tumors were the most common (48%), followed by ACTH (36%) and PRL-secreting tumors (4%). The overall hormonal remission rate postsurgery was 80%, with remission rates of 88.9% for first-time surgeries and 57.1% for repeat surgeries. Transient lateral rectus palsy occurred in two patients. A CSF leak occurred in one patient, managed by endoscopic repair and lumbar drainage. There were no cases of ICA injury or mortality. The mean surgical time was 224 minutes. The distribution of KS among patients was KS 0 (4%), KS 1 (8%), KS 2 (32%), KS 3A (36%), KS 3B (8%), and KS 4 (12%). Microscopic tumor infiltration was seen in 19 of 25 (76%) MCW samples. When the positive MCW was compared to the KS, we found that MCW involvement was seen in KS 1 (50%), KS 2 (75%), KS 3A (88.8%), KS 3B (100%), and KS 4 (100%). The sensitivity and specificity of direct endoscopic inspection for MCW invasion were 95 and 75%, respectively. ROC curve analysis demonstrated that direct endoscopic visualization is a significantly better predictor of CS involvement than KS, with an AUC of 0.850 indicating good discriminative ability. These findings suggest that KS is unreliable for detecting CS involvement in KS 1 and 2, though a larger study is needed to confirm these results ([Figs. 1] [2] [3]).

Conclusion: MCW resection in FPA cases with suspected CS involvement yields higher hormonal remission rates. Knosp grading underestimates CS invasion, while endoscopic inspection provides greater accuracy in predicting MCW invasion by the tumor.

Publikationsverlauf

Artikel online veröffentlicht:
07. Februar 2025

• References

• 1 Micko AS, Wöhrer A, Wolfsberger S, Knosp E. Invasion of the cavernous sinus space in pituitary adenomas: endoscopic verification and its correlation with an MRI-based classification. J Neurosurg 2015; 122 (04) 803-811
• 2 Truong HQ, Lieber S, Najera E, Alves-Belo JT, Gardner PA, Fernandez-Miranda JC. The medial wall of the cavernous sinus. Part 1: Surgical anatomy, ligaments, and surgical technique for its mobilization and/or resection. J Neurosurg 2019; 131 (01) 122-130