Evaluation of sphenoid sinus variations and adjacent neurovascular structures with cone-beam computed tomography

The sphenoid sinus is adjacent with the anterior cranial fossa, pituitary gland, brainstem, optic nerve (ON), internal carotid artery (ICA), maxillary nerve (MN), vidian canal (VC) and cavernous sinuses. Knowledge of the development of the sphenoid sinus, such as internal structure, anatomical variations, direction and degree of pneumatization, and a comprehensive understanding of the surrounding anatomy is important. This is necessary both to avoid iatrogenic lesions and to understand and manage the pathogenesis of processes that may occur in the sinus cavity and adjacent structures. Cone-beam computed tomography (CBCT) provides low-dose and detailed examination of the sphenoid sinus anatomy and variations, and surrounding neurovascular structures. The aim of this study is to evaluate the frequency of sphenoid sinus variations and surrounding neurovascular structures such as ON, ICA, MN and VC and the relationship of these structures with each other on CBCT. A total of 500 patients (1000 sinuses) 250 (50%) male, 250 (50%) female patients aged between 18-81 years who applied to Gaziantep University Faculty of Dentistry Department of Oral and Maxillofacial Radiology for various reasons between 2017 and 2019 images in the CBCT archive form the study group. 1.0% of the cases were conchal, 2.6% presellar, 56.4% sellar and 40.0% postsellar pneumatization. When ON, ICA, MN and VC configurations were examined, type 2 was the most common in all of these structures in total cases and it was observed as 81.0%, 60.6%, 49.8% and 56.2%, respectively. In our study, a significant relationship was detected between the main types of pneumatization and ON, ICA, MN and VC on both sides. The relationship between ON, ICA, MN and VC and clival, sellar and lateral subtypes on both sides was found significant. In addition, the relationship between these neurovascular structures with each other has been found significant on both sides. In conclusion, CBCT is an effective method in evaluating the sphenoid sinus variations and their relationship with surrounding neurovascular structures.