Results of Endoscopic Surgery in Patients with Pituitary Adenomas : Association of Tumor Classification Grades with Resection, Remission, and Complication Rates

OBJECTIVE: The endoscopic endonasal transsphenoidal approach is a widely-used method for the surgical treatment of pituitary adenomas. We aimed to evaluate the results of endoscopic surgery by comparing preoperative classification methods and investigating their relationship with postoperative resection and remission rates and complications. METHODS: We retrospectively reviewed the medical records of 236 patients (118 males) who underwent surgery for pituitary adenomas. Preoperative Knosp classification, tumor size (TS), suprasellar extension (SSE), postoperative resection and remission rates, and complications were evaluated. RESULTS: The follow-up period was 3 months to 6 years. The patients’ ages ranged between 16 and 84 years. Endocrinologically, 114 patients (48.3%) had functional adenoma (FA), and 122 patients (51.7%) had non-functional adenoma (NFA). Among the FA group, 92 (80.7%) showed remission. A statistically significant difference was found between patients with and without remission in terms of the Knosp, TS, and SSE classifications (p<0.01). Knosp, TS, and SSE classification grades were found to be correlated with the resection rates (p<0.01). Meningitis was seen in seven patients (3.0%), diabetes insipidus in 16 (6.9%; permanently in two [0.9%]), and rhinorrhea in 19 (8.1%). Thirty-six patients (15.3%) developed pituitary insufficiency and received hormone replacement therapy. CONCLUSION: The resection categories and remission rates of FAs were directly proportional to the adenoma sizes and Knosp grades, while the degree of suprasellar growth further complicated resection and remission rates. Adenoma sizes less than 2 cm and SSEs less than 1 cm are associated with favorable remission and resection rates.