Sphenoid Sinus:Anatomic Variations and Their Importance in Trans-sphenoidSurgery

B a c k ground: 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.