Effect of Sphenoid Sinus Pneumatization on the Surgical Windows for Extended Endoscopic Endonasal Transsphenoidal Surgery

BACKGROUND: Little is known on the impact of the pattern and extent of pneumatization of the sphenoid sinus (SS) on the dimensions of the surgical windows used in extended endoscopic endonasal transsphenoidal approaches. We therefore investigated whether the distances between the 2 optic canals and between the paired para-clival carotid arteries are influenced by the pattern and extent of pneumatization of the SS. METHODS: One hundred high-resolution computed tomography scans from 47 adult female and 53 adult male patients were analyzed. The pattern of SS pneumatization was classified into conchal, presellar, and sellar types. Sellar-type sinuses were then classified according to a newer detailed classification system. Maximal anteroposterior (AP), transverse (TR), and craniocaudal diameters of the SS, interoptic distance at the limbus sphenoidale (IODL) and at the entrance of the optic canal (IODE) and the intercarotid distance between the paraclival carotids (ICD) were measured. A 2-tailed Mann-Whitney U test and Pearson correlation coefficient (R) were used for statistical analysis. A P value <0.05 was considered statistically significant. RESULTS: Positive correlation was found between IODL and both AP and TR diameters of the SS; between IODE and both AP and TR diameters of the SS; and between ICD and all diameters of the SS. The highest correlation for each of the IODL, IODE, and ICD was noted with the TR diameter of the SS. CONCLUSIONS: During the development of the SS, pneumatization progress likely exerts quantitative and direction-specific forces, which gradually increase the interoptic and intercarotid distances.