Microscopic versus Endoscopic Transsphenoidal Surgery for Pituitary Adenomas: Comparative Outcomes Analysis during the Transition of Methods of a Single Surgeon

Introduction: The transition from microscopic to a fully endoscopic transsphenoidal surgery requires a surgeon to assess how the change in surgical technique will affect the extent of tumor resection (EOR), neurologic and endocrine outcomes, as well as the perioperative complication rate. We compared a single surgeon’s experience transitioning from one technique to the other, and examined the operative outcomes and EOR between microscopic versus endoscopic transsphenoidal surgery.

Methods: Retrospective data analysis of adult patients who were treated surgically for a pituitary adenoma between August 2005 and May 2015 by a single neurosurgeon that was originally trained and practiced in the microscopic transsphenoidal approach. Patient demographics, perioperative conditions, tumor characteristics, operative times, volumetric EOR, postoperative outcome, and the endoscopic learning curve were evaluated.

Results: A total of 109 patients underwent microscopic transsphenoidal surgery and two hundred seventy-five patients underwent a fully endoscopic approach. The patient characteristics were similar in the two groups. Operative room time was significantly shorter in the endoscopic group than in the microscopic group (180.2 vs. 215.6 min, p < 0.001, Fig. 1). We found that it took 29 endoscopic cases before the operative times of both approaches were similar, and 73 endoscopic cases before the endoscopic cases were significantly shorter than the microscopic approach. The endoscopic and microscopic groups had similar volumetric EOR (85.1 vs. 82.8%, p = 0.371) as well as residual tumor volume (1.06 vs. 1.15 cm³, p = 0.765). The EOR was not compromised during the early stages of learning the endoscopic technique compared with the microscopic approach (Fig. 2). The progression free survival for the two cohorts were found to be similar (p = 0.426, Fig. 3). Postoperative outcomes and complications were similar between the two groups. The mean length of hospital stay was 2.4 days in the endoscopic group and 3.2 days in the microscopic group (p = 0.03, Fig. 4).

Conclusion: During the transition from the microscopic to the endoscopic approach, similar surgical outcomes and EOR were achieved in the two cohorts. In our experience, the endoscopic approach offers the advantage of shorter operative times and lengths of hospital stays after the surgeon has developed more experience with the technique.

Fig. 1 Operative Times for the endoscopic and microscopic approaches over a ten year period shows the endoscopic approach became a significantly shorter operation over the ten year period.

Fig. 2 Extent of Resection for the endoscopic and microscopic approaches over a 10 year period shows similar extent of resection between the two approaches.

Fig. 3 Kaplan Meier Curve for Recurrence of pituitary tumor. Kaplan-Meier curves were generated for recurrence free survival, stratified by the two groups (microscopic versus endoscopic). A hazard-ratio test was performed to determine that there was not a statistically significant difference between the two curves (p = 0.426).

Fig. 4 Length of Hospital Stay following an endonasal transsphenoidal surgery. The endoscopic patients were found to have a significantly shorter hospital stay compared with the microscopic group (p = 0.03).