Clinically significant anatomical variants of the paranasal sinuses.

OBJECTIVE Anatomic structural variations of the paranasal sinuses have a practical significance during surgical procedures conducted on the sinuses by otolaryngologists. This study aims to evaluate the prevalence of clinically significant anatomical variations of the paranasal sinuses. METHODS A prospective analysis of 435 computed tomography (CT) examinations of adult Omani patients was conducted to determine the prevalence of clinically significant anatomical variations of the paranasal sinuses. A total of 360 CT scans were included from January 2009 to January 2010. RESULTS The findings showed abnormal Agger nasi cells in 49% of cases (95% CI: 44-54%), concha bullosa in 49% (95% CI: 44-54%), Haller cells in 24% (95% CI: 18-31%), asymmetry in anterior ethmoidal roof 32% (CI: 29-37%), Onodi cells in 8% (CI: 5%-10%). The type of skull base were as follows; Type 1 was 30% (n=107; 95% CI: 25-35%), Type 2 was 34% (n=123; 95% CI: 29-39), and Type 3 was 36% (n=130; 95% CI: 31-41%). Many other surgically significant anatomical variations in small numbers (1-3) were incidentally identified. CONCLUSION Knowledge of the presence of anatomical variations of the sinuses has a clinical significance as it minimizes the potential for surgical complications. There is an ethnical difference in the prevalence of anatomical variations. Further studies of anatomical variations with clinical disease correlations are needed.