Evaluation of anatomical variation of the crista galli using computed tomography

Pneumatization of the crista galli is a recognized incidental finding on computed tomography (CT), 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 crista galli. Mucocele development has also been seen. This study aimed to evaluate the variation in crista galli morphology and pneumatization and assess whether specific morphologies occur. A retrospective observational study was undertaken between November 2007 and January 2008. Using coronal and axial reconstructed CT views, images of the head in the region of the paranasal sinuses were assessed. Variations in the crista galli were classified according to their position relative to the cribriform plate and to the degree of pneumatization. Computed tomography findings of the morphology of the crista galli in 99 patients were reviewed and a classification system derived from the findings. Three variations of the position of the base of the crista galli were defined. In 28.3% of subjects the base of the crista galli did not extend below the level of the cribriform plate. In 63.6%, the crista galli extended less than 50% of its height below the cribriform plate and in 8.1% of the scans the crista galli extended more than 50% of its height below the cribriform plate. Pneumatization was noticed in 14.1% of the scans. Our results demonstrate the variation that occurs in the morphology and pneumatization of the crista galli. We hope this knowledge might be of help in preoperative planning of surgical approaches to sites of disease involving the crista galli.