Evaluation of Anatomical Variations on Paranasal Sinus CT

OBJECTIVES:  The purpose of this study is to analyze and assess the frequency of anatomical variants of paranasal sinuses scanned by multidetector computed tomography (MDCT). METHODS: A total number of 225 patients (122 males, 103 females) with a median age of 28 (15-77) years were included in this retrospective study. We analyzed the presence of the nasal septal deviation (NSD), variations of the nasal turbinates, ethmoidal air cells, paranasal sinus pneumatization, accessory pneumatization of the paranasal complex, variations of the sphenoid sinus related structures and the optic nerve and vidian canal classification in the paranasal computed tomography (CT) of the selected patients. RESULTS: NSD was present in 124 (55.1%) patients, superior concha pneumatization in 30 (13.3%), middle concha pneumatization in 100 (44.4%),  agger nasi cells (ANC) in 192 (85.3%), Haller cells in 47 (20.9%), Onodi cells in 44 (19.6%), maxillary sinus hypoplasia in 6 (2.6%), frontal sinus hypoplasia in 29 (12.9%), frontal sinus aplasia in 7 (3.1%), sphenoid sinus hypoplasia in 7 (3.1%), uncinate process pneumatization in 12 (5.3%), anterior clinoid process (ACP) pneumatization in 60 (26.7%) and pterygoid process (PP) pneumatization in 75 (33.3%) patients.  Optic nerve Type 1 was detected in 122 (54.2%) patients, Type 2 in 29 (12.9%), Type 3 in 36 (16%) and Type 4 in 38 (16.9%) patients. Vidian canal Type 1 was observed in 37 (16.4%), Type 2 in 95 (42.2%) and Type 3 in 93 (41.3%) patients. CONCLUSION:  The analysis of the paranasal CT is crucial in diagnosis of miscellaneous diseases of the paranasal sinuses.  The anatomical variations of the sinuses are prevalent among the population, so otolaryngologists should be aware of these variations for precise diagnosis and to avoid surgical complications.