Introduction: The comparative efficacy of microscopic and fully endoscopic transsphenoidal surgery for pituitary adenomas has not been well studied despite the adoption of fully endoscopic surgery by many pituitary centers. We compared the extent of tumor resection (EOR) and the endocrine outcomes of one very experienced surgeon performing a microscopic-transsphenoidal surgery technique (1800 independent cases) with those of a less experienced surgeon using a fully endoscopic-transsphenoidal surgery technique (100 independent cases) for nonfunctioning pituitary adenomas in a concurrent series of patients.

Methods: Post-hoc analysis was conducted of a cohort of adult patients prospectively enrolled in a pituitary adenoma quality-of-life study between 2011-2014.

Results: Fifty-five patients underwent fully endoscopic transsphenoidal surgery, and 80 patients underwent fully microscopic transsphenoidal surgery. Baseline characteristics of the two treatment groups were well matched. EOR was similar between the endoscopic and microscopic groups, respectively, as estimated by gross total resection rate (78.2% vs 81.3%, p = 0.67), percentage of tumor resected (99.2% vs 98.7%, p = 0.42), and volume of residual tumor (0.12 cm3 vs 0.20 cm3, p = 0.41). Multivariate modeling suggested that preoperative tumor volume was the most important predictor of EOR (p = 0.001). No difference was found in the development of anterior gland dysfunction (p > 0.14), but there was a higher incidence of permanent posterior gland dysfunction in the microscopic group (p = 0.04). Combined rates of major complications and unplanned readmissions were lower in the endoscopic group (p = 0.007), but individual complications were not different.

Conclusions: A less experienced surgeon using a fully endoscopic technique was able to achieve similar outcomes compared to a very experienced surgeon using a microscopic technique in a cohort of patients with nonfunctioning tumors. This data suggests that certain advantages afforded by the fully endoscopic technique help address the learning curve in pituitary surgery.

Patient Care: Endoscopic resection of nonfunctioning pituitary adenomas may allow a novice surgeon to rapidly achieve the surgical skills necessary to deliver safer and more effective resection of these lesions versus a traditional microscopic approach.

Learning Objectives: - Endoscopic surgery provides improved magnification, superior visualization of the cavernous sinus, suprasellar space, and normal rim of pituitary gland, and improved surgical freedom because of the use of a binostril technique versus the microscopic approach. - Our results raise the provocative question of whether certain advantages of endoscopic surgery may help a less experienced surgeon achieve outcomes similar to those of a very experienced surgeon.

References: 1. Ammirati M, Wei L, Ciric I: Short-term outcome of endoscopic versus microscopic pituitary adenoma surgery: a systematic review and meta-analysis. J Neurol Neurosurg Psychiatry 84:843-849, 2013 2. Dallapiazza R, Bond AE, Grober Y, Louis RG, Payne SC, Oldfield EH, et al: Retrospective analysis of a concurrent series of microscopic versus endoscopic transsphenoidal surgeries for Knosp Grades 0-2 nonfunctioning pituitary macroadenomas at a single institution. J Neurosurg 121:511-517, 2014 3. Messerer M, De Battista JC, Raverot G, Kassis S, Dubourg J, Lapras V, et al: Evidence of improved surgical outcome following endoscopy for nonfunctioning pituitary adenoma removal. Neurosurg Focus 30:E11, 2011