ANTERIOR SKULL BASE MORPHOLOGY ON COMPUTED TOMOGRAPHY: CORRELATION BETWEEN OLFACTORY FOSSA DEPTH AND LATERAL LAMELLA INCLINATION ANGLE
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Abstract
Objectives: To determine the correlation between olfactory fossa depth (Keros classification) and the lateral lamella angle of the cribriform plate (Gera classification) on computed tomography (CT) scans, and to analyze anatomical characteristics related to the risk of iatrogenic skull base injury.
Subjects and Methods: A cross-sectional analytic study was conducted on 298 sinus sides of 149 adult patients undergoing multidetector CT) at Nhan Dan Gia Dinh Hospital from June 2024 to June 2025. Olfactory fossa depth and lateral lamella angle were measured on coronal planes. The relationship between variables was assessed using Pearson correlation coefficient and Chi-square test.
Results: Keros Type 2 (69.5%) and Gera Type B (78.2%) were the most prevalent classifications. A statistically significant positive linear correlation was observed between olfactory fossa depth and lateral lamella angle (r = 0.240; p < 0.001). The mean lateral lamella angle increased with olfactory fossa depth: lowest in the Keros Type 1 group (56.8° ± 15.2°) and highest in the Keros type 3 group (69.9° ± 10.5°). Notably, the Keros type 1 group (shallow olfactory fossa) had the highest prevalence of the high-risk flat angle (Gera Type C < 45°), accounting for 25.0%, whereas no cases of low-angle variants were observed in the Keros type 3 group.
Conclusion: There is a natural morphological compensation mechanism of the anterior skull base: a shallower olfactory fossa is associated with a flatter lateral lamella, while a deeper fossa is associated with a more vertical orientation. These findings highlight a potential risk of skull base injury in patients with Keros type 1 due to the low approach angle of the lateral lamella, emphasizing the necessity of combined preoperative assessment of both depth and angulation.
Keywords
Lateral lamella of cribriform plate (LLCP), Olfactory fossa, Keros classification, Gera classification, Endoscopic sinus surgery
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References
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