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

Abstract

The aim of this study is the evaluation of the anatomical structures of sphenoid sinus ostium used as a reference point for transsphenoidal surgery by cone beam computed tomography. The authors’ study was performed using the cone-beam computed tomography images of 16 to 82-year old 200 (112 female, 88 male) patients (Newton 5G, Verona, Italy). Septum deviation of sphenoid sinus and the distance between 2 ostia were evaluated by coronal and axial sections, respectively. Pneumatization degree of sphenoid sinus, diameter of sphenoid sinus ostium, and distance lower edge of superior turbinate to sphenoid sinus ostium were measured by using sagittal sections. The sellar type was the most common pneumatization type of sphenoid sinus in authors’ study. While the C-type septum deviation was observed as the most common, T-type deviation was the least type. Sphenoid sinus ostium was bilaterally in 71.5% of individuals, and it was not found in 10% of individuals included in the study. A significant decrease was determined in diameter of the left sphenoid sinus ostium with aging. The distances between 2 sphenoid sinus ostia were 7.30 2.77 mm for women and 6.09 2.58 mm for men, respectively. No statistical differences were found in women and men in terms of distances between the lower edge of the right and left superior turbinate and sphenoid sinus ostium on their sides. Consequently, making detailed preoperative radiological evaluation of anatomic variations of sphenoid sinus and sphenoid sinus ostium is important in terms of guiding the surgeon in the process of a successful transsphenoidal surgery. Key Words: Cone-beam computed tomography, sphenoid sinus, sphenoid sinus ostium, transsphenoidal surgery The sphenoid sinus is a double sinus located within the body of the sphenoid bone. Sizes, shapes, and pneumatization type vary from person to person. The bony septum that is located in the midline separates the 2 sinuses from each other.1 The sinus was surrounded with many important anatomical structures, neighborhoods internal carotid artery in the lateral wall, optic nerve at the superolateral and pterygoid nerve (The Vidian Nerve) at the base of the spheoid sinus.2 This sinus opens sphenoethmoidal recess by sphenoid sinus ostium that is located in the upper part of the front wall through the sphenoid sinus.3 The diameter of sphenoid sinus ostium is 2 to 3 mm, it is situated 11 to 14 mm above the base level of the sinus, 4 to 5 mm in lateral of nasal septum, 30 degrees above the base of the nose.4–6 The opening of sphenoid sinus ostium is one of the most important points in transsphenoidal surgery for surgeons. The surgical procedure is done by extending this opening. Closed or being in different positions of this opening can cause difficulty during surgical procedures.7 During the endoscopic and surgical transsphenoidal approaches, finding the ostium is not always easy. So the detection of detailed anatomical analysis this natural way and adjacent structures prior to transsphenoidal surgery may reduce complication incidence. The aim of this study is the evaluation of the anatomical structures of sphenoid sinus ostium used as a reference point for transsphenoidal surgery by cone beam computed tomography. At the same time, the anatomical variations and the pneumatization status of the sphenoid sinus were examined using the same method.