Computed tomographic analysis of the prevalence of International Frontal Sinus Anatomy Classification cells and their association with frontal sinusitis

A Prospective Study on the Anatomical Variations of the Frontal Recess and its Association with Computer Tomographic Signs of Sinusitis

The frontal recess region has a complex anatomy and HRCT scans of the paranasal sinuses (PNS) are the gold standard in evaluating it. Classification systems have been established to identify the frontal recess cells. The objectives of this study are to describe the incidence of anatomical variations, classify the anatomy of the frontal recess using the IFAC & Kuhn's classification systems, find the association between the anatomical variations and the incidence of CT signs of sinusitis. A prospective study of patients undergoing HRCT-PNS was carried out. The frontal recess region was evaluated and classified as per both classification systems. The prevalence of each frontal cell was identified; presence of CT signs of sinusitis was noted and the correlation between the two was evaluated. 272 sides of HRCT scans were evaluated. Prevalence of cells as per IFAC classification showed ANC - 98.2%, SAC-43.4%, SBC-33.1%, SAFC- 28.3%, FSC -25%, SBFC- 3.7% and SOEC- 2.2%. Prevalence of cells as per Kuhn's classification showed ANC - 98.2%, Type 1- 38.2%, SBC-32.7%, FSC -24.3%, Type 3- 16.9%, Type 2- 12.9%, Type 4- 4.8%, FBC- 2.6% and SOEC-2.2%. Sinusitis was seen in 27.2% cases. A significant association was noted between the presence of SOEC, FSC and sinusitis as per both classification systems. (P=0.049 and P<0.001 respectively). In conclusion the cells which lead to an anteriorly based drainage pathway are more common, but the presence of posteriorly based SOEC and medially based FSC have a higher association with sinusitis.

Does Frontal Recess Cell Variation Associate with the Development of Frontal Sinusitis? A Narrative Review

Chronic rhinosinusitis (CRS) can have a significant impact on quality of life. With persistent symptoms and the failure of initial medical treatments, surgical management is indicated. Despite the excellent results of endoscopic sinus surgery for persistent CRS, it is quite a challenging procedure for frontal sinusitis given the complex anatomy and location of the frontal sinus. Frontal recess cells significantly contribute to the complexity of the frontal sinus, and numerous studies have sought to establish their association with sinusitis. This review offers a comprehensive understanding of frontal recess cells, their different classifications, their prevalence among different populations, and their relationship to sinusitis. After an extensive review of the current literature, the International Frontal Sinus Anatomy Classification (IFAC) is the most recent classification method and a preferred practical preoperative assessment tool. Although the agger nasi cell is the most prevalent cell among all reported populations, ethnic variations are still influencing the other cells' distribution. Studies are inconsistent in reporting a relationship between frontal recess cells and sinusitis, and that is mainly because of the differences in the classification methods used. More research using a standardized classification method is needed to understand the association between frontal recess cells and sinusitis.

International Frontal Sinus Anatomy Classification (IFAC): evaluation of frontoethmoidal cells prevalence in a Brazilian population

OBJECTIVES

The aim of this study was to evaluate the prevalence of the frontal cell variants according to International Frontal Sinus Anatomy Classification (IFAC), in the population of a Brazilian tertiary hospital, and analyze the reliability of the classification between observers.

METHODS

A cross-sectional study in the Hospital de Clínicas of the State University of Campinas, Brazil. One hundred and three Computed Tomography's (CTs) were evaluated by radiologists and otorhinolaryngologist to estimate the prevalence of frontoethmoidal cells according to the IFAC. Intraclass Correlation Coefficient (ICC) among examinators was used to evaluate reliability of this findings.

RESULTS

103 CT scans, totaling 206 sides, were evaluated independently. The agger nasi cell was the most prevalent, present in 95.63% of cases, 37.86% of the exams contained supra agger cells, frontal supra agger cell showed prevalence 37.37%; suprabular cell was present in 77.18% of the sides. As for the frontal suprabular cell, the prevalence was 30.09%, the supraorbital ethmoid cell was present in 32.03%, and frontal septal cell had a 33.49% prevalence. The ICC among the evaluators was classified as "good reliability" or "excellent reliability" for all cells.

CONCLUSION

This study describes the frontal cell prevalence among a population in tertiary Brazilian hospital, using the IFAC. This classification had a high ICC.

LEVEL OF EVIDENCE

Level 2: Individual cross-sectional study with consistently applied reference standard and blinding.

Frontal Sinus Anatomy Variations in Race and Sex Using the International Frontal Sinus Anatomy Classification

Objective: To identify frontal sinus anatomical variations grouped by patient sex, race, and presence of chronic rhinosinusitis with frontal sinus involvement (CRFS) using the International Frontal Sinus Anatomy Classification (IFAC) system. Methods: A retrospective review from 2015 to 2020 was performed of consecutive adult patients with computed tomography sinus imaging. Prevalence of frontal sinus cells using the IFAC system was recorded. Comparisons were made between patient race, sex, and CRFS groups. Results: A total of 184 patients (368 sides) were included, 90 (48.9%) of which had CRFS. The racial distribution was 50 white (27.2%), 50 black (27.2%), 45 Hispanic/Latino (24.5%), and 39 Asian (21.2%) patients. The supra agger cell was most prevalent in the white population (P = 0.009), and supraorbital ethmoid cells were more prevalent in the Asian population (P = 0.017). Patients with frontal sinus disease were more likely to have a supraorbital ethmoid cell (P = 0.024). Overall, CRFS was more prevalent in the Asian population (P = 0.013). Conclusion: Significant differences in frontal sinus anatomy and disease exist between patient race and sex. Supraorbital ethmoid cells are associated with the development of CRFS. These patterns in frontal sinus anatomy should be noted prior to frontal sinus surgery to improve surgical awareness and outcomes.

Radiological anatomical variations of the lateral nasal wall and anterior skull base amongst different populations: A systematic review and meta-analysis

OBJECTIVES

To determine the anatomical variations of the lateral nasal wall and anterior skull base amongst populations in different geographical regions.

DESIGN

Systematic review and meta-analysis.

METHODS

Using PRISMA guidelines, SCOPUS and PUBMED databases were searched from inception until 1 March 2022. The regions and populations identified were from Europe, Asia, Middle East, Australia-New Zealand-Oceania, South America, North America and Africa. Random-effects model was used to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic and Cochran's Q test.

MAIN OUTCOME MEASURES

Anatomical variations of the lateral nasal wall and anterior skull base confirmed by computed tomography scan.

RESULTS

Fifty-six articles were included with a total of 11 805 persons. The most common anatomical variation of the ostiomeatal complex was pneumatization of the agger nasi (84.1%), olfactory fossa was Keros type 2 (53.8%) and ethmoids was asymmetry of the roof (42.8%). Sphenoethmoidal and suprabullar cells have a higher prevalence in North Americans (53.7%, 95% CI: 46.00-61.33) while asymmetry of ethmoid roof more common in Middle Easterns (85.5%, 95% CI: .00-100). Bent uncinate process has greater prevalence in Asians while supraorbital ethmoid cells and Keros type 3 more common in non-Asians. The overall studies have substantial heterogeneity and publication bias.

CONCLUSION

Certain anatomic variants are more common in a specific population. The 'approach of analysis' plays a role in the prevalence estimates and consensus should be made in future studies regarding the most appropriate 'approach of analysis' either by persons or by sides.

Anterior ethmoid and frontal sinus drainage pathways: five patterns formed and defined by their bony walls

PURPOSE

To perform endoscopic sinus surgery safely and effectively, surgeons need to visualize the complex anatomy of the anterior ethmoid and frontal sinus region. Because this anatomy is so variable and individualized, the foundation of understanding lies in identifying, following, and visualizing the drainage pathway patterns and anticipating possible variations.

METHODS

We studied 100 sides (50 cases: 22 male, 28 female, aged 12-86, average age 46.5 years, ± 19.5) using computed tomography (CT) and multiplanar reconstruction (MPR) to identify and classify the drainage pathways leading to the frontal sinus and anterior ethmoidal cells.

RESULTS

Analysis revealed five patterns of drainage pathways defined by their bony walls: between the uncinate process and the lamina papyracea [UP-LP]; between the uncinate process and the middle turbinate [UP-MT]; between the uncinate process and the accessory uncinate process [UP-UPa]; between the uncinate process and the basal lamella of the ethmoidal bulla [UP-BLEB]; and between the basal lamella of the ethmoidal bulla and the basal lamella of the middle turbinate [BLEB-BLMT]. In most cases, BLEB formed the posterior wall of the drainage pathway of the frontal sinus, indicating BLEB could be one of the most important landmarks for approaching the frontal sinus.

CONCLUSIONS

As endoscopic sinus surgery depends on an understanding of this anatomy, this study may help surgeons to identify and follow the drainage pathways more accurately and safely through the anterior ethmoid to the frontal sinus.

Three-Dimensional Volumetric Analysis of Frontal Ethmoidal Cells and Evaluation of Influential Factors: A Helical Computed Tomography Study

In the present study, we aimed to assess frontal ethmoidal cells by using segmentation 3D software to establish a possible correlation between volume variation and both gender and age, as well as a relationship with Keros classification. Helical computed tomography images were obtained from 71 patients for analysis, in which the agger nasi cell, supra agger cell, supra agger frontal cell, supra bulla frontal cell, supraorbital ethmoidal cell, supra bulla cell, and frontal septal cell were identified and segmented to obtain their volume. Significant differences in volume were found for age and gender regarding agger nasi cells (p-value = 0.017), supra agger cells (p-value < 0.001), and frontal septal cells (p-value = 0.049). In the frontal septal cells, an increase of one year in age reduced the volume by 0.309, on average. According to Keros classification, the mean volumes were 10.07 and 25.64, respectively, for types II and III, both being greater than that of type I. Extracting volumetric data by using segmentation software in agger nasi cells, supra agger cells, and frontal septal cells may be useful for obtaining additional information related to age, in addition to possibly contributing to elucidating the anatomical variations in the region and an identification forensic tool.

The prevalence of frontal cell variants according to the International Frontal Sinus Anatomy Classification and their associations with frontal sinusitis

BACKGROUND

The International Frontal Sinus Anatomy Classification (IFAC) is introduced to simplify the classification of different frontal cell variants based on their topographical structures. The objectives of our study were to determine the prevalence of the frontal cell variants according to IFAC and their association with the development of frontal sinusitis.

METHODOLOGY

A retrospective chart review on computed tomography paranasal sinus (CTPNS) was conducted. A total of 200 patients who had clinical and endoscopic findings of chronic rhinosinusitis (CRS) and undergone CTPNS were reviewed. The CTPNS was evaluated for the presence of frontal cell variants according to IFAC and mucosal changes consistent with frontal sinus involvement.

RESULT

A total of 400 sides of the CTPNS were analyzed. The agger nasi cells (ANCs) were the most common (95.5%) followed by supra bulla cells (SBCs) (60.8%), supra bulla frontal cells (SBFCs) (53.0%), supra agger cells (SACs) (50.0%), supra agger frontal cells (SAFCs) (36.0%), frontal septal cells (FSCs) (8.3%), and supraorbital ethmoidal cells SOECs (5.5%). There was significant association between SOEC (p = 0.001) and FSC (p = 0.044) with the development of frontal sinusitis.

CONCLUSIONS

Apart from ANCs, the posterior-based cells (SBCs and SBFCs) have higher prevalence than the anterior-based cells (SACs and SAFCs). Despite being the least, both SOECs and FSCs are significantly associated with frontal sinusitis.