A Relationship between Sphenoid Sinus Anatomy and Suprasellar Extension of Pituitary Tumors?

Introduction: Tumors are generally known to follow a path of least resistance. Pituitary macroadenomas commonly extend into the suprasellar region as they enlarge. The sphenoid sinus is known to have a variable pneumatization pattern, and we hypothesize that midline insertion of the sphenoid intersinus septum may act as a structural buttress to resist tumor expansion into the sphenoid sinus, thereby directing tumor growth into the suprasellar space. The aim of this study is to determine if midline insertion of a sphenoid intersinus septum is associated with suprasellar extension of pituitary tumors.

Methods: A retrospective analysis was conducted of 106 consecutive surgical cases of pituitary macroadenoma. The presence or absence of suprasellar tumor extension and the location of insertion of the intersinus septum were recorded on radiographic review. Pearson's chi-squared test of independence was used to examine statistical association between these findings.

Results: Of the 106 cases, 69 patients had a midline insertion of the intersinus septum (65.1%). Forty-nine of these 69 patients had suprasellar extension of their pituitary tumors (71.0%), whereas 22 of the 37 patients without midline insertion of an intersinus septum were found to have suprasellar extension of their tumors (59.4%) (P = 0.23). Fifteen of the 106 patients had more than intersinus septation (14.2%).

Conclusions: The possible function of the sphenoid intersinus septum as a buttress to resist pituitary tumor growth cannot be asserted. Growth of pituitary macroadenomas may extend in a suprasellar direction or into the sphenoid sinus regardless of the sphenoid sinus anatomy.