Authors: Andrew Scott Little, MD, FAANS; TRANSSPHER Study Group (Phoenix, AZ)

Introduction: Many surgeons have adopted fully endoscopic over microscopic transsphenoidal surgery for pituitary tumors, although no high-quality evidence demonstrates superior patient outcomes with endoscopic surgery. Previously, we presented an analysis of extent of tumor resection from a multicenter prospective study, which demonstrated that these techniques yielded similar gross total tumor resection rates. In this abstract, we present the comparative pituitary gland endocrine outcomes. Methods: Adrenal, thyroid, gonadal, and posterior gland function were evaluated before and 6 months after surgery using standard endocrine laboratory testing. Results were centrally adjudicated. Results: Seven pituitary centers and 15 surgeons participated. 260 patients were enrolled (82 with microscopic procedures, 177 with endoscopic procedures, 1 cancelled surgery). Baseline patient tumor characteristics were similar between groups. A new deficiency of at least one hormone axis was noted in 19 of 67 patients (28.4%) in the microscopic cohort and 14 of 145 patients (9.7%) in the endoscopic cohort ( P <0.001; OR, 3.7; 95% CI, 1.7-7.7). Improvement in at least one hormone axis was noted in 12 of 50 patients (24.0%) in the microscopic group and 20 of 93 patients (21.5%) in the endoscopic group ( P =0.83; OR, 1.2; 95% CI, 0.5-2.7). Increased rates of new adrenal insufficiency (11 of 59 patients [18.6%] vs. 4 of 135 patients [3.0%]; P <0.001; OR, 7.5; 95% CI, 2.5-22.1) and diabetes insipidus (7 of 79 patients [8.9%] vs. 4 of 166 patients [2.4%]; P =0.04; OR, 3.9; 95% CI, 1.2-12.2) were observed in the microscopic cohort compared with the endoscopic cohort. Rates of individual hormone axis recovery were similar between groups ( P >0.30) for all evaluated pituitary hormone axes. Individual surgeon effects will be presented. Conclusion: The endoscopic technique was associated with lower rates of new postoperative adrenal insufficiency and diabetes insipidus. We hypothesize that the superior view provided by the endoscopic technique facilitates gland preservation.