Korean J Otorhinolaryngol-Head Neck Surg.  2024 Feb;67(2):87-91. 10.3342/kjorl-hns.2023.00241.

A Study of Skull Base According to Gera Classification in a Korean Population

• Son SJ
• Koo HB
• Lee JH

• KMID: 2552827
• DOI: http://doi.org/10.3342/kjorl-hns.2023.00241

Abstract

Background and Objectives
The leakage of cerebrospinal fluid due to damage to the ethmoid roof and cribriform plate (CP) is one of the most serious complications of endoscopic sinus surgery (ESS). For the risk of skull base injury during ESS, the Keros classification has been widely used, but recently the Gera classification has been introduced as a tool for risk assessment. This study evaluated the risk of skull base damage using the Gera classification in Koreans.
Subjects and Method
We analyzed 592 left and right sides of 296 paranasal sinus CTs, and measure the angle between the lateral lamella of CP and the lateral extension of the horizontal plane passing through CP, namely the Gera angle. The angles were classified into three categories: the type I (>80°, low risk), type II (45° to 80°, medium risk), and type III (<45°, high risk).
Results
The type III, which is vulnerable to skull base damage, accounted for 11.7% of the study subjects. The Gera angle in females (64.0°±12.3°) was greater than that in males (61.3°± 14.0°), showing a significant gender difference (p=0.015). Although there was no difference between the left and the right side of the Gera angle (p=0.155), there was a significant difference between the left and the right side in the Gera classification (p<0.001). Age and the Gera angle showed a negative correlation (r=-0.116, p=0.005).
Conclusion
The type III of the Gera classification was observed in 11.7% of the total study group. For the type III, extra care is required during ESS.

Keyword

Cerebrospinal fluid leakage; Gera angle; Gera classification; Sinus surgery; Skull base