Objective: Pituitary macroadenomas extend into the extrasellar space, such as the sphenoid sinus, cavernous sinuses, and suprasellar region. However, factors that regulate the direction of their extensions into the surrounding anatomical structures remain unknown.
Methods: This retrospective study included 162 patients who were treated for pituitary adenomas that had maximum diameters greater than 20 mm. According to the direction of adenoma extension, patients were divided into 4 groups: group A, inferior into the sphenoid sinus; group B, lateral into the cavernous sinus; group C, suprasellar region with enlarged sella turcica; and group D, supraellar region without enlarged sella turcica. Several anatomical structures surrounding the sella turcica were evaluated statistically, and multivariate logistic regression analysis was performed if the structures met the determining factors of adenomas extensions.
Results: The maximum diameter of adenomas was significantly larger in groups A and D. The maximum diameter of the diaphragmatic foramen was largest in group C (19.3 mm) and was significantly narrower in groups B (12.7 mm) and D (12.5 mm). Intrasphenoid septation, attached on the midline of the sella turcica, was observed most frequently in group D (78.6%) and was not detectable in group A (0%). Extension into the cavernous sinus, classified as dural discontinuity, was highly prevalent in group B (80.0%) and was uncommon in group C (12.3%). Erosion of the posterior clinoid process was most apparent in group B (92.0%).
Conclusions: The integrity of the sella dura and the intrasphenoid septation can regulate adenoma extension by encouraging their growth towards paths of least resistance.
Keywords: Dura; Extension; Pituitary adenoma; Regulation; Sphenoid sinus.
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