Intraoperative unfolding and postoperative pruning of the pituitary gland after transsphenoidal surgery for pituitary adenoma: A volumetric and endocrinological evaluation.

Purpose: To describe the volumetric changes that the pituitary gland (PG) undergoes during and after transsphenoidal surgery (TSS), and to evaluate if unfolding and/or pruning are related to endocrinological outcome measures.
Methods: Retrospective evaluation of data prospectively collected of a cohort of patients undergoing TSS for a pituitary adenoma with the adjunctive use of high field 3 Tesla intraoperative MRI. All patients underwent a full endocrinological workup preoperatively, as well as at 6 weeks and 1 year postoperatively. A decrease in PG volume ≥15% between the intraoperative and 3-month, or between the 3-month and 12-month measurements, was considered early and late pruning, respectively.
Results: The PG unfolds significantly during TSS, and subsequently undergoes pruning up until 1 year postoperatively, in most cases returning to the preoperatively measured PG volume. A smaller baseline PG volume predicts intraoperative unfolding. Early pruning of the PG after surgery was associated with new functional deficits. Baseline pituitary compression also correlated to newly occurring deficits after surgery. A larger 1-year pituitary volume was associated with biochemical remission in secreting adenomas.
Conclusions: The PG shows dynamic change during and after TSS for pituitary adenoma. Small baseline and 3-month PG volumes, as well as early pruning were independently associated with new deficits. Our findings warrant prospective validation in a larger cohort with higher statistical power.