Real-Time Intraoperative Ultrasound Imaging of the Posterior Pituitary Gland during Endoscopic Endonasal Skull Base Surgery

Background and Objectives: Pituitary adenomas are amongst the most common benign central nervous system tumors, occurring in 10% of the population. Despite their benign nature, these lesions may require resection via an endoscopic endonasal approach (EEA) if they become large enough to cause visual compromise, or are biochemically active. Two of the most common complications associated with surgical resection are central diabetes insipidus (DI) and syndrome of inappropriate antidiuretic hormone secretion (SIADH). Both are thought to be caused by manipulation of, or injury to, the posterior pituitary gland (PPG) during surgery, making intraoperative visualization and preservation of this structure critical. Intraoperative endoscopic endonasal ultrasound (IEUS) may present an optimal tool for this purpose. However, no studies to date have described the IEUS imaging characteristics of the PPG. This study aims to describe the appearance and morphology of the PPG on IEUS, along with the relationship of the PPG to the lesion and anterior pituitary gland, among patients being treated for pituitary adenomas.

Methods: This study includes all pituitary adenoma surgeries during which IEUS was utilized and the PPG was visualized between January 1, 2022, and December 31, 2023. Demographic, clinical, pathological, and radiological data were retrospectively collected from the electronic medical record of each patient. The PPG was described as hypoechoic, isoechoic, or hyperechoic as compared to the anterior pituitary gland and adenoma on each IEUS image. The morphology of the PPG was then further classified as ellipse or crescent shaped. Due to the descriptive nature of the study, no formal statistical analysis was conducted.

Results: Forty-three patients were included in our final cohort, the majority of which were female (67.4%) with an average age of 49.1 years (±15.9). On IEUS imaging, the PPG was hypoechoic compared to the anterior pituitary gland and adenoma in 41 cases (95.3%), and isoechoic in 2 cases (4.65%). Morphologically, the PPG appeared elliptical in 27 cases (62.8%), and crescent shaped in 16 cases (37.2%). An ellipse was the predominant morphology in both microadenomas (10/13, 76.9%) (Fig. 3) and macroadenomas (17/30, 56.7%) ([Fig. 2]), but the crescent shape was more often noted in macroadenomas (13/30, 43.3%, vs. 3/13, 23.1%).

Conclusion: Intraoperative endoscopic endonasal ultrasound is a tool for identification of the posterior pituitary gland during pituitary adenoma resection. On imaging, the posterior gland can typically be visualized as a hypoechoic structure immediately anterior to the posterior wall of the sella turcica. The morphology of the PPG can generally be described as either an ellipse or crescent shape, with elliptical being more common. These imaging characteristics can be used by the skull base surgeon to more confidently identify the position and morphology of the PPG intraoperatively for preservation.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
07 February 2025