Anatomic Sphenoid Cell Variants: Introduction of the Retrosphenoid Cell and Relevance in the Presentation and Management of Sinus Disease.

Abstract

Background Despite the well-appreciated variability in sphenoid sinus anatomy, there are no documented cases of retrosphenoid cells in the literature to date. Objective This study defines and determines the prevalence of retrosphenoid cells as identified on computed tomography (CT) imaging and intraoperative endoscopy and reviews the prevalence of other related anatomical variants of the sphenoid sinus. Methods Retrospective study of 300 random noncontrast sinus CT scans of patients with chronic rhinosinusitis presenting to a tertiary rhinology center. All identifiable anatomic variations and any presence of retrosphenoid cells and their pneumatization patterns were recorded. The prevalence of various anatomic variations of the sphenoid sinus was also calculated. Results A total of 300 sinus CT scans were included in the study. Protrusion of both the internal carotid artery (42.6%) and optic nerve (19.7%) into the sinus was more prevalent than the dehiscence of either one. A retrosphenoid cell was identified in 2% of CT scans. Other anatomic variants were less prevalent. Conclusion Meticulous review of preoperative imaging is key in identifying rare and complex sphenoid cell variations in planning surgical approaches and potential treatment strategies for the unusually pneumatized sphenoid air cells. Various manifestations of sinus disease can be localized to this area, and suspicion of a retrosphenoid cell should be raised in patients presenting with recalcitrant headache.