The "Double-Peak" Pattern of Pituitary Adenoma Intrasellar Pressure and Its Effects on the Microvascular Structure.

Objective: The purpose of the present study was to investigate the relationship between the intrasellar pressure (ISP) and the microvascular structure of pituitary adenomas.

Methods: We retrospectively analyzed the ISP in 66 patients with pituitary adenomas. The corresponding microvascular structure was obtained using immunohistochemistry and analyzed for its correlation with the ISP.

Results: The average ISP was 25.89 ± 8.27 mm Hg, and the ISP was not related to the size of the adenoma (Pearson correlation coefficient, 0.103; P = 0.415). The ISPs of adenomas with different Knosp grades were significantly different (P < 0.05). From grade 0 to grade 4, at first, the ISP increased with the Knosp grade and reached the first peak at grade 2. It then decreased at grade 3 and increased again at grade 4, showing a "double-peak" pattern. The minimal diameter and perimeter of the microvessels and the vessel-covered area percentage were positively related to the ISP. When these parameters were compared among the adenomas of different Knosp grades, they also exhibited a "double-peak" pattern.

Conclusions: In the present study, we found that with the increase in pituitary adenoma size and invasion of the surrounding tissues, the ISP of pituitary adenomas showed a "double-peak" pattern. The ISP and certain parameters of the microvascular structure are related, because the microvasculature adaptively changes its structure in response to the changing ISP to ensure a sufficient blood supply to the adenoma. The specific mechanism of this phenomenon requires further study.