Asymmetry of lateral lamella of the cribriform plate: a software-based analysis of coronal computed tomography and its clinical relevance in endoscopic sinus surgery.

Document Type



Otolaryngology, Head and Neck Surgery



Endoscopic sinus surgery is a known approach for sinonasal pathologies. Due to close proximity of sinuses to orbits and brain, surgeon should be aware of sinonasal anatomy and associated variations. The roof of ethmoid (fovea ethmoidalis) separates the ethmoidal cells from the anterior cranial fossa. Medially the fovea attaches to the lateral lamella of the cribriform plate, which is the thinnest bone of the skull base. Hence, it is at a high risk of getting damaged during surgery.


To ascertain the quantitative analysis of height of lateral lamella according to Keros classification in the computed tomographic (CT) images of patients presenting to our clinic.


It was retrospective review of 77 CT scans using computerized software known as picture archiving and communication system. The height of lateral lamella was examined for both sides and then classified according to Keros classification. Asymmetry between two sides was also reported.


Keros type I was seen in 46 sides (29.8%), type II in 75 sides (48.7%) and type III was seen in 33 (21.4%) sides. Keros type I was seen in 38 sides in males and 8 sides in females. Type II was seen in 46 and 29 sides in males and females, respectively. Type III was seen in 18 sides in males and in 15 sides in females.


Understanding of the anatomy of ethmoid roof with its possible variation is crucial to give the surgeon optimal information about the possible risk that one can face during the surgery. Hence dreadful complications can be avoided.


Surgical and Radiologic Anatomy