Variations in sphenoid sinus anatomy with special emphasis on pneumatization and endoscopic anatomic distances

OBJECTIVE: The purpose of this study was to present the morphometry and pneumatization of the sphenoid sinus in detail for the neurosurgeon for transnasal approach to the hypophyseal tumors and especially for functional endoscopic sinus surgery.

METHODS: One hundred and eighty midsagittal magnetic resonance images, 48 bones and 29 hemi-sectioned cadaveric heads obtained from Ege University, Faculty of Medicine, Departments of Anatomy and Radiology were used in 2003. The sphenoid sinuses were classified into sellar, pre-sellar, conchal and post-sellar types according to the extent of their posterior limits. Different measurements based on the surgical approach and sinus size were performed.

RESULTS: Conchal type sinus was observed in 1.9%, pre-sellar type 9%, sellar type 52.9% and post-sellar type 36.2% of the specimens. Conchal type sphenoid sinus was not observed in males, but in 1.7% of females. Pre-sellar type was observed in 5.6% of males and 2.8% of females. Sellar type was found in 24.4% of males and 23.9% females, and post-sellar type in 19.5% of males and 22.2% of females. The sphenoid sinus length at the upper and lower parts was 13.51+/-3.25mm and 24.57+/-6.65mm. The sphenoid sinus height at the anterior and posterior parts was 21.27+/-4.25mm and 14.5+/-4.07mm. Distance from the ostium to limen was 56.6+/-5.6mm and from ostium to sill was 64.6+/-6.11mm in cadaveric specimens. In MR images, distance from the ostium to the sill was 68.7+/-5.9mm and from sella to sill 82.8+/-6.2mm.

CONCLUSION: Sphenoid sinus variations observed in pneumatization, size, localization and shape are important in providing a better surgical approach and avoiding surgical complications.