Location of the Sphenoid Sinus Ostium in Relation to Adjacent Anatomical Landmarks

Purpose: The variability of sphenoid pneumatization and its relationship with the surrounding structures has been suggested. The aim of this study was to examine the effect of the surrounding bony structures on the position of the sphenoid ostium (SO). Methods: A prospective radiological review of computed tomography images of paranasal sinuses of 150 patients (300 sides) was conducted. Parameters investigated included the presence of Onodi cells, sphenoid rostrum pneumatization, and the type of sphenoid pneumatization on the coronal and sagittal planes. Their effect was studied on the vertical and horizontal plane using lines of measurement 1 through 5. Results: The most common location of the SO on the horizontal plane was found to be in the middle third and was significantly affected by the rostrum pneumatization (P value <.001) and sphenoid pneumatization on the coronal plane (P value = .018). The location of the SO on the vertical plane was most commonly in the middle third. It was significantly affected by Onodi cell pneumatization (P value = .021) as well as the sphenoid height (P value <.001). Conclusions: Pneumatization of the sphenoid sinus and adjacent bony structures can affect the location of the SO. Presence of rostrum pneumatization and lateral sphenoid pneumatization shift the SO laterally. Presence of Onodi cell and low sphenoid roof shift the SO inferiorly. These variations need to be studied carefully before surgery in order to avoid operative complications.