Rare Anatomical Variants of the Sphenoid and Ethmoid Sinuses. A Case Series

Abstract

There are many established variants of the paranasal sinuses. An in-depth knowledge of the anatomy of the paranasal sinuses and their anatomical variants is crucial in the context of endoscopic endonasal transsphenoidal operations. The sphenoid sinus and body in particular are the focus of this case series. A range of rare anatomical variations of the sphenoid and ethmoid sinuses are discussed, namely, a rare position of the Onodi air cell, a dominant Onodi air cell with an intra-Onodi air cell accessory sphenoid septation, and a case that demonstrates protrusion of the sphenoid body into the right sphenoid sinus.

Contributions: This case series aims to add to the normal anatomical variants of the sphenoethmoidal sinuses and to increase awareness of the existence of these variations in anatomy. To the authors’ knowledge, there are no reported cases of these variants in the English literature, with the exception of the central Onodi air cell, where one previous case was reported, making it a rare case presentation.