Lateral lamella of the cribriform plate, a keystone landmark: proposal for a novel classification system.

BACKGROUND The aim of this study is to propose a classification of the angle formed by the lateral lamella of the cribriform plate (LLCP) and the horizontal plane passing through the cribriform plate. In particular, the angle was classified into class I (over 80 degrees), class II (45 to 80 degrees, and class III (under 45 degrees) METHODOLOGY: A total of 190 computed tomography scans were retrospectively reviewed in order to obtain four sets of measurements. 1) depth of the cribriform, 2) angle, 3) length of the LLCP, 4) width of the fovea ethmoidalis. The relationship among these measurements were analyzed. RESULTS The angle was significantly correlated with the depth of the cribriform and the length of the fovea, while it was negatively correlated with the length of the LLCP. Significant negative correlation was also found between the length of the LLCP and the width of the fovea. CONCLUSIONS This angle classification is based on the theoretical risk of iatrogenic injuries, but it could be helpful also in clinical practice by providing indirect information on the thickness of the anterior skull base. As the angle decreases, in fact, the portion of the anterior skull base composed by the LLCP, increases.