Objective: The sphenoid sinus is a paranasal sinus that is extremely difficult to reach, being located deep in the skull and surrounded by a large number of vital neural and vascular structures. Additional radiological evaluation of the sphenoid sinus and related neurovascular structures is essential before surgery. This study aimed to analyze the anatomical variations associated with the neurovascular structures in and around the sphenoid sinus using multislice computed tomography (CT) and contribute to the literature by comparing the obtained data with previous studies.

Material and Method: A total of 100 patients (50 females, 50 males) who underwent paranasal sinus CT for various rhinologic diseases were included in the study. Sphenoid sinus variations were evaluated as bone tissue anomalies and soft tissue pathologies on CT.

Results: In this study, variations in the neurovascular borders of the sphenoid sinus were the most common findings. The variations related to the Vidian canal were most frequent with an incidence of approximately 73%, followed by those related to the optic nerve 55%, maxillary nerve 53%, and internal carotid artery 52%. Pneumatization of the pterygoid plate was observed in 59% of cases, pneumatization of the anterior clinoid process in 41%, and that of the greater wing of the sphenoid in 13%. Furthermore, 15% of the patients had onodi cells, 46% had multiple septations, 20% had mucosal thickening, 0.4% had polyps, and 0.3% had retention cysts.

Conclusion: The structure of the sphenoid sinus is highly variable, and paranasal sinus CT is important in determining anatomic variations before sinonasal and transsphenoidal surgery and predicting possible complications during surgery. In this study, the variations of the sphenoid sinus were found at a higher rate compared to previous studies, which may be due to the differences in ethnic groups, CT imaging technique, or anatomical evaluation criteria.