Detailed anatomical analysis of the sphenoidal sinus and ostium of sphenoidal sinus by the cone-beam computed tomography

Purpose: Sphenoid sinuses are located in corpus of sphenoid bone and neighborhood with many important structures. This sinus opens sphenoethmoidal recess by ostium sinus sphenoidalis which is located in the upper part of front wall through the sphenoid sinus. In transsphenoidal surgery, the sphenoidal sinus is entered through ostium sinus sphenoidalis. Therefore, opening of sphenoidal sinus and anatomical differences between individuals are important in terms of the surgical approach. The aim of this study is to evaluate the anatomical structure of the ostium sinus sphenoidalis used as a reference point in transsphenoidal surgery by using cone-beam computed tomography. Material and Method: Our study was performed using the cone-beam computed tomography images of 16-82 years old 200 (112 female, 88 male) patients (Newton 5G, Verona Italy). Septum deviation of sphenoidal sinus and the distance between two ostiums were evaluated by coronal and axial sections, respectively. Pneumatization degree of sphenoidal sinus, diameter of ostium sinus sphenoidalis and distance lower edge of concha nasalis superior to ostium sinus sphenoidalis were measured by using sagittal sections. Results: The sellar type was the most common pneumatization type of sphenoid sinus in our study. Presellar and conchal type sinus pneumatization was observed to be equal. While C type septum deviation was observed as the most common, T type deviation was the least type in sphenoid sinus. Ostium sinus sphenoidalis was bilaterally in 71.5% of individuals, and it was not found in 10% of individuals included the study. No statistical differences were determined in women and men patients in terms of right and left diameter of ostium sinus sphenoidalis. When evaluated diameter of ostium sinus sphenoidalis according to age groups, a significant decrease was determined in diameter of the left ostium sinus sphenoidalis with aging. The distances between two ostium sinus sphenoidalis were 7.30±2.77 mm for women and 6.09±2.58 mm for men, respectively and no significant differences were observed. No statistical differences were found in women and men patients in terms of distances between the lower edge of the right and left concha nasalis superior and ostium sinus sphenoidalis in their sides. Conclusion: Cone-beam computed tomography with less radiation and cost compared to classic CT, can be used in situations that should be evaluated sphenoid sinus and ostium sinus sphenoidalis. Keywords: Ostium sinus sphenoidalis, Cone-beam computed tomography, Transsphenoidal surgery