Patterns of Pituitary Injury during Endoscopic Transsphenoidal Pituitary Surgery: Correlation of Intra-Operative Videos with Endocrinological Outcomes in 76 Patients

Background: Pituitary gland manipulation and intra-operative injury is thought to be a major cause of hypopituitarism following transsphenoidal surgery. Despite numerous surgical series, the mechanisms of surgical injury to the gland has not been a major focus of study. The objective of the current study was to correlate the occurrence of post-operative hypopituitarism with patterns of intra-operative pituitary gland manipulation.

Methods: In this series, 76 consecutive patients underwent endoscopic transsphenoidal pituitary or Rathke’s cleft cyst resection at the Jewish General Hospital, between November 2011 and July 2016. The position of the normal residual pituitary gland was identified pre-operatively and video recordings for all patients were reviewed. A grading scheme was devised to characterize the extent of forces applied intra-operatively during the resection of the tumor. A visual analogue scale was also used to grade the overall extent of injury to the gland.

Results: Mean age was 54 years old. The overall incidence of new pituitary hormonal axis deficiency was 5.2%. The rate of injury between macro- and micro-adenomas was similar. Potential mechanisms of injury observed included inadvertent incision of the effaced gland during tumor exposure, direct curettage on the gland, partial gland resection and indirect traction on the gland during tumor dissection. In patients who developed pituitary hormonal axis insufficiencies post-operatively, the tumor consistency with either more firm or a tumor capsule adherent to the normal gland was observed, leading to traction forces to the gland when standard curettage techniques were implemented.

Conclusion: In this preliminary abstract, tumor curettage in cases with a firm tumor consistency or tumor capsule adherence to the normal gland was associated with post-operative hypopituitarism. Intra-operative recognition of these patterns may help prevent pituitary injury via more traction free dissection techniques.