Extension Pathways of Pituitary Adenomas with Cavernous Sinus Involvement and Its Surgical Approaches

BACKGROUND: Resection and remission rates are low in pituitary adenomas that invade the cavernous sinus (CS) because of the complexity of the region. In this study, the authors describe the invasion patterns and surgical approaches for these corridors. METHODS: Endoscopic transsphenoidal surgery was performed in 1849 patients between August 1997 and 2017; 381 of these patients were included in the study because of the presence of CS invasion. CS invasion pathways and CS compartments were defined, and these patients were divided into 3 groups according to their invasion corridors. The cases were also categorized according to the Knosp classification. RESULTS: A total of 381 patients were included, 199 of whom were men. The mean follow-up duration was 34 months. In preoperative magnetic resonance imaging measurements, 2 of 381 patients had microadenoma, 350 of 381 had macroadenoma, and 29 of 381 had giant adenoma. When the early postoperative magnetic resonance images were compared with the preoperative images, 91 of 381 (23.9%) patients had subtotal tumor resection, 83 of 381 (21.8%) had near-total tumor resection, and 207 of 381 (54.3%) had gross total tumor resection. Considering the invasion classification with endoscopic confirmation, there were 168 of 381 (44.1%) cases of isolated medial corridor involvement, 74 of 381 (19.4%) cases of isolated lateral corridor involvement, and 139 of 381 (36.5%) cases of total involvement cases. CONCLUSIONS: Medial wall defect has no importance in the invasion. Similarly, seeing the existence of pitholes is not an invasion criterion. Pituitary adenomas invade 4 compartments: the superior, anteroinferior, posterior, and lateral compartments of the CS via 2 corridors. Increased experience, novel approaches, and endoscopic developments have contributed immensely to this field.