Pneumatization of the sphenoid sinus is the major factor determining the variations of adjacent vital structures

Background Sphenoid sinus (SS) is an important landmark for endoscopic sinus surgery (ESC) and endoscopic skull base surgery. This study examines the relation of the extent of pneumatization of the sphenoid sinus with adjacent vital structures such as the internal carotid artery, optic canal, and Vidian nerve by using paranasal sinus computed tomography (PNSCT). Methods The study was designed retrospectively. PNSCT images in axial, coronal, and sagittal planes on both sides (right, R; left, L) were examined for sphenoid sinus, Vidian canal (VC), optic canal (OC), and carotid canal (CC) bilaterally. Results The carotid canal did not show identification on the SS wall in females compared to males bilaterally (right, p = 0.002 and left, p = 0.002). The mean age was significantly higher in patients with a presellar type of sphenoid sinus ( p =0.003). The mean age was significantly lower on the right side with a VC completely within the sphenoid sinus ( p =0.005). The mean age of patients with an optic canal protrudation to the SS wall was significantly higher than patients with an optic canal indentation to the SS wall ( p = 0.007). On the left side, cases with an optic canal protruding to the SS wall were older than cases with an optic canal indentation to the SS wall ( p = 0.008). SS variations on the sagittal plane were significantly correlated with RVC, RCC, LVC, and LCC variations. Also, SS variations on the coronal plane were significantly related to types of LVC and RVC. Conclusions Pneumatization of SS significantly affects the development of surrounding vital structures, especially with increasing age.