Horizontal lateral lamella as a risk factor for iatrogenic cerebrospinal fluid leak. Clinical retrospective evaluation of 24 cases

Abstract

Background: Several authors highlighted the limitations of the Keros classification system in predicting intracranial entry risk. Recently, our group proposed a new classification system based on the angle formed between the lateral lamella of the cribriform plate (LLCP) and the continuation of an horizontal plane passing through the cribriform plate (Gera classification). The aim of this study was to analyze whether the risk of iatrogenic cerebrospinal fluid leak (CSF-L) was better predicted by Keros or Gera classification. Methodology: The pre-operative CT scans of 24 patients (CSF-L group) who suffered from iatrogenic CSF-L during endoscopic sinus surgery (ESS) were compared to those obtained from a group of 100 patients who underwent uneventful ESS (control group). The skull base measurements as well as the distribution of Keros and Gera classes in the 2 groups were analyzed. Results: No difference in the distribution of Keros classes or in the depth of the cribriform plate between CSF-L and control group were demonstrated. On the contrary, significant differences in the distribution of Gera classes and in the degree of the angle formed by the LLCP and the continuation of the horizontal plane passing through the cribriform plate were found. In particular, according to Gera classification system, 19 out of 24 patients in the CSF-L group were considered at risk for iatrogenic CSF-L. Conclusions: Gera classification system might be more sensitive to anatomical variations associated with CSF-L than the Keros' one, further suggesting the application of the former during the preoperative CT scan evaluation.

A new radiological classification for the risk assessment of anterior skull base injury in endoscopic sinus surgery

“…Subsequently, the Gera classification 9 was proposed to consider the sloping level of ethmoidal roof (ER) relative to CP. By measuring the angle formed by the lateral lamella of CP and the continuation of the horizontal plane passing through CP, the risk of intracranial entry was divided into 3 classes; class I (>80 degrees, low risk), class II (45 to 80 degrees, medium risk) and class III (<45 degrees, high risk) 9,10 .…”

Anatomic Variations of Ethmoid Roof and Risk of Skull Base Injury in Endoscopic Sinus Surgery: Statistical Correlations

“…Understanding the anatomic variations of the ethmoid roof (ER) and skull base (SB) using computed tomography (CT) is essential to reduce the risk of major complications during endoscopic sinus surgery (ESS), eg cerebrospinal fluid leak (CFL), orbital and intracranial injury, or anterior ethmoidal artery (AEA) injury. 1,2 The lateral lamella of the cribriform plate (LLCP) extends laterally to the cribriform plate (CP) delimiting the olfactory fossa (OF). The LLCP is the thinnest (0.05-0.2 mm) and most vulnerable bone of the anterior SB, is frequently the site of intracranial injuries, [3][4][5][6] and may be dehiscent in up to 14% of patients.…”

“…7 In 1962, Keros described a classification based on the depth of the OF in relation to the ER. 8 More recently, to evaluate the slope of the ER, Gera et al 1 proposed a new classification based on the angle between the LLCP and the lateral extension of a horizontal plane passing through the CP. Patients with Keros Type III and patients with Gera Class III are more susceptible to SB iatrogenic injuries with increasing depth of the OF, and slope of the ER.…”

Adult and Pediatric Lateral Lamella Cribriform Plate Height: In Need for a Comparative Study

“…Class 1 angle >80° is low risk, class 2 angle 45° to 80° is medium risk, and class 3 angle <45° is high risk. 8…”

“…Class 1 angle >80 is low risk, class 2 angle 45 to 80 is medium risk, and class 3 angle <45 is high risk. 8 With all the precautions in place and the understanding of the differences in the anatomy between adult and pediatric, ESS can be a relatively a safe procedure. According to Elsisi, ESS is a safe and effective procedure in children, provided a proper preoperative selection of patients made mandatory.…”