Introduction & Objective: Because of widespread use of Functional Endoscopic Sinus Surgery (FESS) technique and basic role of coronal CT- Scan in understanding of normal drainage route of Para-nasal sinuses, identifying the major patterns of inflammatory sinonasal disease and accompanied anatomical variations is crucial for appropriate preoperative surgical planning. The purpose of this study was to determine the incidence of major inflammatory patterns and accompanied anatomical variations in patients with chronic inflammatory sinonasal disease that underwent FESS in different hospitals of Hamadan during 2000- 2004.

Materials & Methods: This prospective descriptive study was carried out on coronal CT- Scans of 385 patients with chronic inflammatory sinonasal disease that underwent FESS. Patients with clinical signs of chromic rhinosinusitis were diagnosed by otolaryngologist and after 3- 6 weeks of medical therapy if appropriate clinical response were not achieved, coronal and if needed axial CT-Scan were taken from them. CT-Scans were taken mainly in bone and intermediate windows and if soft tissue masses except than polyposis were suspected soft tissue windows were taken too. CT-Scans were reported by radiologist and inflammatory patterns and accompanied anatomical variations with clinical and demographic information were analyzed.

Results: In 385 cases major inflammatory pattern included: infundibular 11.1%, osteomeatal unit 37.6%, sphenoethmidal recess 21.2%, sinonasal polyposis 18.9% and sporadic 24.4% . These patterns were seen solely or as a combinations and so total percent was more than 100%. Three major obstructive patterns were seen in 70.1% of cases. In 73.2% of cases accompanied anatomical variation including septal deviation (50.6%), concha bullosa (28.5%), extensive pneumatization of sphenoid sinus (17.9%), paradoxic middle turbinate (16.1%), Haller cell (15.5%), giant bulla ethmoidalis (10.3%), athelectatic uncinate process (8.8%), Agger nasi cell (8.3%) and Onodi cell (3.1%) were seen. Conclusion: Because of study on surgical cases, higher incidence of more severe patterns and anatomical variations in our study was predictable, but some delay in patient's presentation due to socioeconomic problems in our society should be considered too.