Evaluation of Anatomical Variation of the Crista Galli Using Computed Tomography

Background and Aim: Pneumatization of the crista galli (CG) is a recognized incidental finding on computed tomography (CT) images, usually with little relevance to the clinical picture. There are, however, notable exceptions: Congenital midline nasal defects including nasal dermoids have been seen to track through or near the CG, and mucocele development has also been seen. The aim of this study was to evaluate the variation in CG morphology and pneumatization and assess whether specific morphologies existed.

Material and Method: A retrospective observational study was undertaken between November 2007 and January 2008. Head and paranasal sinus images were evaluated using coronal and axial reconstructed CT views. The CG variations were classified according to the relative position of CG to the skull base and to the degree of pneumatization. Computed tomography findings of CG morphology in 103 patients were reviewed, and a classification system derived.

Results: Three base variations of CG position were defined. In 31.1% of the films, CG did not extend below the skull base. In 61.2%, CG extended less than 50% of its size below skull base, and in 7.7% CG extended more than 50% of its size below skull base. Pneumatization was noticed in 13.6% of the scans.

Conclusion: Variation in the morphology and pneumatization of the CG does exist. As involvement of the CG in various conditions has been documented, knowledge of these anatomical variations might be of help in preoperative planning of the surgical approach, especially if endonasal/combined approaches are considered.