Evaluation of the Keros Classification of Olfactory Fossa by CT Scan in Qassim Region

Abstract

Endoscopic sinus surgery (ESS) is now the most often utilized surgical procedure for treating chronic sinonasal disorders. Therefore, anatomical knowledge of its variations is required to avoid serious postoperative complications. Thus, careful preoperative examination for patients with a paranasal sinus CT scan is necessary. Our study aims to evaluate Keros types and their incidence by evaluating the olfactory fossa (OF) depth according to the Keros classification on paranasal sinus CT scans in the Qassim region. MethodsA cross-sectional study was conducted between January 2018 and January 2021 on 148 patients with an average age of 32.59 ± 6.1 who had a non-enhanced paranasal sinus CT scan evaluated by a consultant radiologist using the PACS (picture archiving and communication system) software. Statistical analysis was performed using the statistical software package SPSS version 25 (IBM Corp., Armonk, NY). The chi-square test was used to analyze the relationship between findings and patient characteristics. Also, a p-value of < 0.05 was kept in mind to indicate statistical significance. ResultsThe average depth of the right olfactory fossa (OF) was 5.1 mm with a standard deviation of 1.756 while it was 5.28 on the left side with a standard deviation of 1.66. According to the Keros classification, out of a total of 296 OF, type 1 was found in 84 (28.4%), type 2 in 188 (63.5%), and type 3 in 24 (8.1%). Consequently, the majority of cases were of type 2. Also, we found that type 2 was the most common on both sides in males, whereas, in females, type 2 was the most common on the left side and type 1 on the right side. ConclusionThe study of the Keros classification is significantly important to evaluate the anatomy of the anterior skull base and give the surgeon knowledge about the depth of the olfactory fossa. Thus, a preoperative CT scan of the paranasal sinus is critical to ensure that the surgical approach is properly planned and possible surgical complications related to the anatomy of this area can be prevented. Our study showed that Keros type II is the most common, followed by type I and then type III.

Study of frontal and ethmoid sinus of sinonasal complex along with olfactory fossa: anatomical considerations for endoscopic sinus surgery

“…The OF of Keros III was described in 0.5% of the population, versus 9.5% in our study. Almushayti et al [ 4 ] also found the type II category as the most common followed by type I then type III. Few authors reported that type one was the most common followed by type two then type three [ 7 , 10 , 11 ].…”

“…The olfactory fossa (OF) is located along the superior aspect of cribriform plate which varies in shape and depth. This variable measurement of the depth of OF or the height of ethmoid roof is mostly responsible for a greater risk of intracranial infiltration during endoscopic procedures in and around the nasal cavity [ 3 - 5 ]. Previous authors and Kero’s described high risk cases where the depth of OF was between 7–16 mm and categorized them as type III category on paranasal sinus CT scans.…”

“…Clinically the ES are categorized into anterior and posterior groups on each side by a tortuous barrier [ 9 ]. Although, there is continuous progress in three-dimensional imaging techniques during past two decades but with lack of necessary depth of perception [ 3 - 6 ]. This cadaveric study is planned to improve the ability of the otolaryngologist, radiologist, and anatomist to understand the possible morphological variations and plan steps of less invasive “precision surgery” to have a safe and complication free procedures and communicate these complexities when teaching or reporting outcomes.…”

Exploring the Ovine Anatomy: A Comprehensive Study of the Sheep’s Head for Basic Training in Functional Endoscopic Sinus Surgery

“…Regarding the ethmoidal roof, type 3 identified in the studied ovine model, is particularly critical in endoscopic sinus surgery due to its thin cribriform plate, making it the most challenging and significant type. According to the Keros classification, the depth of the olfactory fossa can be categorized into three types: type 1 (1-3 mm), type 2 (4-7 mm), and type 3 (8-16 mm) [ 14 ].…”

Diagnostic accuracy of CT scans in allergic fungal sinusitis: A cross sectional study

“…Keros type-II is the most common type, followed by type-I and type-III. Patients with Keros type-III, where the olfactory fossa is deepest, are more prone to iatrogenic injury at cribriform plate or lateral lamella of cribriformplate [27]. Since, the base of skull has a slopping shape, it limits the utilization of Keros classification.…”