Chronic sinusitis, also known as chronic rhinosinusitis (CRS), is defined as inflammation of the paranasal sinuses persisting for more than 12 weeks despite medical treatment. It significantly impacts quality of life due to symptoms such as nasal obstruction, facial pain, and purulent nasal discharge [1,2]. Computed Tomography (CT) is the gold standard imaging modality for assessing chronic sinusitis, providing detailed views of both the sinus cavities and adjacent anatomical structures. It plays a critical role in identifying anatomical variations such as Concha Bullosa, Agger Nasi cells, Haller cells, Onodi cells, and deviations of the nasal septum, which can predispose patients to chronic sinus disease by impairing sinus drainage pathways [3,4]. Previous studies have highlighted the significance of these anatomical variations in sinus pathology. Concha Bullosa, a pneumatized middle turbinate, is present in 14–53% of patients and may contribute to sinus ostial obstruction [5]. Agger Nasi cells, the most anterior ethmoidal air cells, can impact frontal recess drainage [6]. Haller cells, infraorbital ethmoidal cells, may narrow the infundibulum and lead to recurrent sinusitis [7]. Onodi cells, posterior ethmoidal air cells located near the optic nerve, are clinically significant due to potential surgical risks [8]. Furthermore, a deviated nasal septum is a common finding in chronic sinusitis and has been reported in up to 26–45% of cases, contributing to unilateral obstruction and drainage impairment [9]. The maxillary sinus is typically the most frequently involved sinus in chronic sinusitis due to its anatomical position and drainage characteristics [10]. Despite numerous studies, the correlation of specific anatomical variations with chronic sinusitis remains inconsistent, warranting further research to improve diagnostic accuracy and therapeutic interventions [1,2]. This study aims to analyze CT findings in chronic sinusitis patients to identify the prevalence of sinus involvement and common anatomical variations, aiding in personalized management strategies.

Study Design: A cross-sectional observational study was conducted. Study Population: Fifty patients clinically diagnosed with chronic sinusitis, attending the Radiology Department for CT Paranasal Sinus evaluation. Inclusion Criteria: • Patients above 18 years with clinical symptoms of chronic sinusitis persisting for more than 12 weeks (nasal obstruction, facial pain/pressure, nasal discharge). Exclusion Criteria: • Patients with acute sinusitis, history of sinus surgery, sinonasal tumors, or trauma. CT Imaging Protocol: All patients underwent non-contrast computed tomography (CT) of the paranasal sinuses using a multidetector CT scanner. Thin axial and coronal sections of 1-3 mm slice thickness were obtained. Data Collection: CT images were assessed for the following: 1. Involved sinuses (Maxillary, Ethmoid, Frontal, Sphenoid). 2. Presence of anatomical variations: • Concha Bullosa • Agger Nasi cells • Haller Cells • Onodi Cells 3. Deviated Nasal Septum: Direction (left or right). Statistical Analysis: Data were entered into Microsoft Excel and analyzed using descriptive statistics. Continuous variables (e.g., age) were expressed as mean ± standard deviation. Categorical variables (e.g., anatomical variations) were expressed as percentages.

A total of 50 patients diagnosed with chronic sinusitis were included in this study. The results are summarized in the following tables: The study population included 31 male patients (62%) and 19 female patients (38%). Table 1 Gender Gender No. of Patients (%) Male 31 (62 %) Female 19 (38 %) Total 50 (100 %) The patients' age ranged across various groups, with a mean age of 37.45 ± 11.32 years. Table 2 Age Age Group No. of Patients (%) Mean Age 37.45 ± 11.32 The maxillary sinus was the most commonly involved sinus in chronic sinusitis, present in 84% of patients. Other sinuses (anterior ethmoid, posterior ethmoid, frontal ethmoid, and sphenoid ethmoid) were each involved in 4% of patients. Table 3 Deceased Sinus Sinus No. of Patients (%) Maxillary 42 (84 %) Anterior Ethmoid 2 (4 %) Posterior Ethmoid 2 (4 %) Frontal Ethmoid 2 (4 %) Sphenoid Ethmoid 2 (4 %) Total 50 (100 %) Deviated nasal septum was present in 34% of patients, with 22% deviated to the right and 12% to the left. Table 4 Deviated Nasal Septum on CT Deviated Nasal Septum No. of Patients (%) Towards Right 11 (22 %) Towards Left 6 (12 %) Total 17 (34 %) Various anatomical variations were identified among the patients: • Concha Bullosa was seen in 18% of cases. • Middle Turbinate Hypertrophy was seen in 6% of cases. • Agger Nasi cells were present in 64% of cases. • Haller cells were present in 14% of cases. • Onodi cells were present in 6% of cases. Table 5 CT Findings Variation No. of Patients (%) Middle Turbinate Concha Bullosa 9 (18 %) Hypertrophy 3 (6 %) Normal 38 (76 %) Agger Nasi Absent 18 (36%) Present 32 (64 %) Haller Cells Absent 43 (86 %) Present 7 (14 %) Onodi Cells Absent 47 (94 %) Present 3 (6 %)

In this study, a total of 50 patients diagnosed with chronic sinusitis underwent CT imaging of the paranasal sinuses to assess sinus involvement and anatomical variations that may predispose to or complicate the disease. The study found a higher proportion of male patients (62%) compared to females (38%), which is consistent with some previous studies that reported a slight male predominance in chronic sinusitis [1]. The mean age of 37.45 ± 11.32 years aligns with data from several studies showing that chronic sinusitis predominantly affects the middle-aged adult population [2,3]. The maxillary sinus was the most commonly involved sinus (84%), followed by anterior, posterior, frontal, and sphenoid ethmoids, each at 4%. This finding is in agreement with the study by Georgalas et al. (2011), which demonstrated that the maxillary sinus is most frequently affected due to its anatomical drainage pathway and proximity to dental infections [4]. Similarly, a study by Brook et al. (2006) reported maxillary sinus involvement in over 80% of chronic sinusitis cases [5]. The relatively low involvement of other sinuses may be due to their anatomical complexity and better drainage compared to the maxillary sinus [6]. Deviated nasal septum (DNS) was present in 34% of patients (22% to the right, 12% to the left). These findings are consistent with earlier studies where DNS was reported in 20–45% of patients with chronic sinusitis [7,8]. Kohli et al. (2017) suggested that septal deviation leads to altered airflow dynamics, contributing to impaired sinus drainage and increased risk of sinusitis [9]. However, some studies have suggested that DNS alone may not be a direct causative factor, but in combination with other anatomical variations, the risk increases significantly [10]. Concha Bullosa was present in 18% of patients in our study, which falls within the range (14–53%) reported by Albayram et al. (2005) [11]. A study by Zinreich et al. (1988) suggested that large Concha Bullosa may obstruct the middle meatus, contributing to chronic sinusitis [12]. Agger Nasi cells were present in 64% of patients, comparable to the study by Lee et al. (2011), which reported a prevalence of 60–70% [13]. Agger Nasi cells are considered significant due to their role in the anatomy of the frontal recess and potential blockage of frontal sinus drainage [14]. Haller cells were present in 14% of patients, which is in line with Vijayakumar et al. (2017), who reported a prevalence range of 10–30% [15]. The presence of Haller cells may narrow the infundibulum, causing impaired drainage of the maxillary sinus, increasing the risk for chronic sinusitis [16]. Onodi cells were found in 6% of patients, matching findings by Lebowitz et al. (2005), which reported a lower prevalence of around 5–8% [17]. Onodi cells are important to identify due to their close anatomical relationship to the optic nerve, and their presence does not directly cause sinusitis but increases surgical risk [18]. The overall prevalence of anatomical variations in this study is similar to those reported in other regional and international studies. The identification of these variations by CT is critical in planning endoscopic sinus surgery and preventing complications such as orbital injury or cerebrospinal fluid leak [19]. This study reinforces that while anatomical variations alone may not be the sole cause of chronic sinusitis, their presence in combination with other factors significantly affects disease pathophysiology [20].

This study highlights the critical role of Computed Tomography (CT) in the assessment of chronic sinusitis. The maxillary sinus was the most commonly involved, and anatomical variations such as Concha Bullosa, Agger Nasi cells, Haller cells, and Onodi cells were frequently observed. The presence of a deviated nasal septum was also significant in a substantial proportion of patients. Identification of these anatomical variations and pathological findings helps in accurate diagnosis, better understanding of disease pathogenesis, and optimized surgical planning. Incorporating CT imaging into routine evaluation of chronic sinusitis enhances treatment outcomes and minimizes surgical risks.

1. Fokkens WJ, et al. (2020). European Position Paper on Rhinosinusitis and Nasal Polyps 2020. Rhinology. 2. Rosenfeld RM, et al. (2015). Clinical practice guideline (update): adult sinusitis. Otolaryngol Head Neck Surg. 3. Bhattacharyya N. (2011). Computed tomography in chronic rhinosinusitis. Otolaryngol Clin North Am. 4. Georgalas C, et al. (2011). A systematic review of maxillary sinusitis of odontogenic origin. Clin Oral Investig. 5. Brook I. (2006). Microbiology and management of chronic rhinosinusitis. Am J Otolaryngol. 6. Zinreich SJ, et al. (1988). The role of CT in the evaluation of sinonasal disease. Radiology. 7. Stammberger H. (1991). Endoscopic and CT anatomy of the paranasal sinuses. Thieme. 8. Stammberger H, Posawetz W. (1990). Functional endoscopic sinus surgery. Concept, indications and results of the Messerklinger technique. Eur Arch Otorhinolaryngol. 9. Kohli P, et al. (2017). Relationship between nasal septal deviation and chronic rhinosinusitis. Indian J Otolaryngol Head Neck Surg. 10. Smith TL, et al. (2005). The role of septal deviation in chronic rhinosinusitis. Otolaryngol Head Neck Surg. 11. Albayram S, et al. (2005). Prevalence of Concha Bullosa and its clinical significance in sinus disease. Clin Imaging. 12. Zinreich SJ, et al. (1988). CT evaluation of the osteomeatal complex and ethmoid sinus in chronic sinusitis. AJR Am J Roentgenol. 13. Lee CH, et al. (2011). Anatomic variations of the anterior ethmoid sinus and frontal recess. Acta Otolaryngol. 14. Khalid AN, et al. (2014). Paranasal sinus anatomic variations and their clinical significance. Clin Radiol. 15. Vijayakumar A, et al. (2017). Anatomical variations of paranasal sinuses and their correlation with chronic rhinosinusitis. Indian J Radiol Imaging. 16. Sedaghat AR. (2017). Chronic rhinosinusitis. Am Fam Physician. 17. Lebowitz RA, et al. (2005). CT anatomy of Onodi cells and its importance in sinus surgery. J Comput Assist Tomogr. 18. Brook I. (2006). Microbiology and management of chronic rhinosinusitis. Am J Otolaryngol. 19. Khalid AN, et al. (2014). Paranasal sinus anatomic variations and their clinical significance. Clin Radiol. 20. Sedaghat AR. (2017). Chronic rhinosinusitis. Am Fam Physician.