Anatomical Variations of Paranasal Sinuses – A MDCT Based Study

ABSTRACT

Background: Pneumatisation of various bones around the nasal cavity results in the formation of paranasal sinuses. Varying degrees of pneumatisation result in multiple variations of paranasal sinuses some of which are important from clinical, pathological and surgical perspective. Objective: Determining the prevalence of various sinonasal anatomical variations on multi-detector computed tomography. Materials and methods: 852 patients with various symptoms of active rhinosinusitis were subjected to non-contrast enhanced CT examinations of the paranasal sinuses and nasal cavity. Multi-planar reconstructions were done in axial, coronal and sagittal plane and the reconstructed CT images were evaluated for the presence of anatomic variants of the sinonasal cavities and the prevalence of each variant was calculated. Results: Deviated nasal septum (DNS) was the most common anatomic variant of the paranasal sinuses and nasal cavity seen in 724 patients (85%), if minimal septal deviation (<1 mm) was also taken into account. The second most common variant was prominent ethmoid bulla which was present in 392 of 852 patients (46%). Dehiscent lamina papyracea (0.9%) and pneumatised crista galli (11.7%) were the least commonly seen sinonasal anatomic variants. Conclusion: Sinonasal anatomic variants are a rule rather than an exception, being present in a majority of population. These variations should be diagnosed and documented on CT examinations of paranasal sinuses to avoid any unforeseen complication during functional endoscopic sinus surgery and other skull base surgeries.