Sphenoid Sinus: Anatomic Variations and Their Importance in Trans-sphenoid Surgery

Background: Over the past decades, instruments and techniques of the transsphenoidal approach have improved greatly. All of these procedures, whether microscopic or endoscopic, must pass through the sphenoid sinus to reach the lesions. The sphenoid sinus is surrounded by several vital anatomical structures. Knowing the details of the anatomy of the sphenoid sinus and the extent of pneumatization can guide the surgeon through difficult corners of this approach. Purpose: This work aimed to determine the incidence of the different anatomical variations of the sphenoid sinus in Iranian patients with pituitary adenomas as detected by preoperative MRI and CT scans. Methods: Preoperative CT scan and MRI of 64 adult patients with pituitary adenomas were retrospectively reviewed regarding degree of pneumatization and septation of the sphenoid sinus. Results: Regarding the degree of pneumatization, there were 34 cases with sellar type (59.4%), 10 patients with presellar type (15.6%), and 16 cases with conchal type (25%). Regarding degree of septation, no absence of septum observed in any of our cases. A single intersphenoid septum observed in 18 of cases (28.1%), and 46 of cases had more than one intersphenoid septum (71.9%). Also, one onodi cell was identified. Conclusion: Enrichment of the knowledge of the sphenoid sinus anatomic variation would aid in reducing complications. Surgeons must meticulously study the preoperative imaging to become familiar with the nuances and variations unique to each case and proceed accordingly to decrease the risk of complications.