ANATOMICAL VARIATIONS OF THE SPHENOID SINUS ASSESSED WITH MDCT

Background The aim of this study was to assess the incidence of the anatomical variations of the sphenoid sinus in 293 patients studied by multidetector computed tomography (MDCT). Materials and Methods The MDCT (64 rows) studies of the paranasal sinuses of 293 patients, performed in 2006-2009, were reviewed to assess anatomical variations of the sphenoid sinus and related neurovascular structures. Anatomical variations were evaluated on 1 mm thick MPR reformations, displayed on a high resolution workstation screen. Pneumatization of the anterior clinoid process (ACP), pterygoid recess (PR), protrusion of the internal carotid artery (ICA), optic nerve (ON), maxillary and vidian nerve into the sphenoid sinus, as well as insertion of sphenoid sinus septa on neurovascular canals were assessed. Onodi cells were also recorded. Results MDCT findings were: pneumatization of the ACP with ON protrusion in 78 patients (26.6%); Onodi cells in 107 patients (36.5%); PR in 83 patients (28%); protrusion of ICA in 107 patients (36%); protrusion of maxillary nerve in 120 patients (40%); protrusion of vidian nerve in 120 patients (40%); sphenoid sinus septa in 34 patients (11.6%); insertion of sphenoid sinus septa on neurovascular canals in 33 patients (11.25%), of whom on optic canal in 2 patients, on carotid canal in 30 patients, on vidian canal in 1 patient; in 1 patient (0.3%) maxillary and vidian nerves protruded in a right Onodi cell that formed a pterygoid recess. Conclusions Preoperative recognition of the anatomical variations by computed tomography is mandatory before FESS, to prevent surgical complications.