Impact of Selective Pituitary Gland Resection or Incision on Hormonal Function in Endonasal Tumor or Cyst Removal

Objective: With the resection of pituitary adenomas or Rathke cleft cysts (RCC), the anterior pituitary gland often partially or completely obstructs transsphenoidal access to the lesion. In such cases, a gland incision and/or partial gland resection may be required to obtain adequate tumor/cyst exposure. We investigated the frequency with which this technique was performed in our practice and determined the associated risk of postoperative hypopituitarism.

Methods: All patients who underwent endoscopic-assisted or fully endoscopic removal of a pituitary adenoma or RCC between July 2007 and January 2013 (minimum 3-month follow-up) and had a gland incision or resection performed were identified. Each patient's routine pre- and postoperative hormonal testing was then retrospectively evaluated to determine the overall impact on pituitary gland function. Total hypophysectomy patients were excluded from outcome analysis.

Results: Of 372 total operations over this period, an anterior pituitary gland incision or partial gland resection was performed in 80 cases (21.5%). In 53 operations, a vertical or horizontal gland incision was made only while the remaining 27 cases involved some degree of gland resection including 12 partial hemihypophysectomies and 14 resections of thinned/attenuated anterior gland draped over a large macroadenoma. There was only one patient with complete hypophysectomy. Diagnoses included 65 pituitary adenomas (17 endocrine-inactive, 29 Cushing, 13 prolactinomas, and 6 acromegaly) and 15 RCCs. New permanent hypopituitarism occurred in four patients (5.1%): two with macroadenomas (3.2 and 3.5 cm) and two with RCCs (2.7 and 1.2 cm). Of these four patients, one macroadenoma patient had apoplexy and one RCC patient had preoperative hypopituitarism. All four patients developed permanent DI and one macroadenoma patient developed growth hormone deficiency. Four additional patients had transient postoperative hyponatremia.

Compared with a control cohort, there was a significantly lower incidence of transient DI (0 vs. 11.1%) but a slightly higher incidence of permanent DI (5.1 vs. 4.0%) in the gland incision group (p = 0.009). In patients with normal preoperative endocrine function, there was no significant difference in postoperative dysfunction (9.8 vs. 8.5%). In patients with preoperative pituitary dysfunction, there was a small, but nonsignificant advantage for the gland incision group for further gland dysfunction (0 vs. 8.6%, p = 0.2) and no significant difference in gain of function (38.1 vs. 32.8%, p = 0.43).

Discussion: Selective gland incisions and gland resections which were performed in over 20% of our cases, appear to minimize traction on compressed normal pituitary gland during removal of large tumors or cysts and facilitates better visualization and removal of both microadenomas and macroadenomas. Despite this, there is a slight shift from transient to permanent DI in this cohort of patients.