Chronic rhinosinusitis (CRS) is a frequently encountered condition in otorhinolaryngology outpatient clinics. While the diagnosis of sinusitis is primarily clinical, imaging is often utilized to evaluate the disease and analyze sinonasal anatomy.  Variations in the anatomical structure of the nose and paranasal sinuses are commonly observed and can differ based on factors such as ethnicity, geography, age, and gender. CRS is defined as persistent inflammation of the nasal and paranasal sinus mucosa lasting for 12 weeks or more, confirmed by objective diagnostic methods. The lifetime prevalence of CRS is estimated to be approximately 15%, with about one in eight individuals in India being affected [1-3].

Diagnostic nasal endoscopy (DNE) and computed tomography (CT) scans are widely employed for the diagnosis of CRS. These modalities not only simplify the diagnostic process but also facilitate the examination of anatomical variations in the nose and paranasal sinuses, which may serve as primary etiological contributors to CRS. Additionally, they provide valuable insights into the severity and extent of the condition, aiding otorhinolaryngologists in classifying CRS [4].

Currently, CT imaging and DNE are pivotal in detecting mucosal changes and identifying anatomical anomalies in the paranasal sinuses, contributing to a better understanding of the underlying pathophysiology in sinusitis cases. CT scans are particularly useful in delineating the extent of disease, identifying complications, and detecting abnormalities in the paranasal sinuses. However, nasal endoscopy remains the investigation of choice due to its utility in both diagnostic and therapeutic settings, allowing enhanced access to the sinonasal regions [5,6].

The advent of nasal and sinus endoscopy dates back to 1901, when Hirschmann utilized a modified cystoscope for this purpose. Unlike anterior rhinoscopy, nasal endoscopy provides detailed visualization of sinonasal anatomy. It facilitates the examination of affected areas and enables procedures such as obtaining cultures or biopsies. Furthermore, DNE is essential prior to functional endoscopic sinus surgery (FESS), as it helps evaluate anatomical variations and assess the extent of sinus involvement [7,8].

This observational study was conducted at a tertiary care center and included 145 patients. The study enrolled patients of both genders, aged over 18 years, with fully developed paranasal sinuses and a CRS duration exceeding 12 weeks. Diagnosis was based on the TASK FORCE criteria, requiring either two major symptoms or one major and two minor symptoms. Exclusion criteria included patients below 18 years of age, those diagnosed with sinonasal malignancy, osteomyelitis, or abscess, as well as individuals with a history of altered paranasal sinus anatomy due to facial trauma or previous sinus surgery. Patients unwilling to provide consent were also excluded.

All clinically diagnosed CRS patients underwent diagnostic nasal endoscopy (DNE) following local anesthesia using 4% lignocaine and 0.1% xylometazoline nasal packing for 15 minutes. The procedure was performed with a 4 mm, 0° endoscope, and the Lund-Kennedy Endoscopic Scoring system was applied. This was followed by a non-contrast computed tomography (CT) scan of the nose and paranasal sinuses.

The findings from DNE and CT scans were systematically compiled and analyzed using appropriate statistical methods, with a significance threshold set at P < 0.05.

Table 1 presents the demographic data of patients with CRS, focusing on age and gender distribution. The study included a total of 145 CRS patients, with a mean age of 33.77 years (± 7.34 years). Regarding gender, 42.76% of patients were male, and 57.24% were female, indicating a slightly higher proportion of females in the cohort.

Table 1: Baseline characteristics of CRS patients

Table 2 summarizes the anatomical variations observed in CRS patients based on CT scan findings. Deviated Nasal Septum (DNS) was the most common variation, found in 82.76% of patients, with a majority of cases being unilateral. Concha Bullosa was found in 26.21% of patients, with a higher frequency of unilateral compared to bilateral occurrences. Agger nasi Cell was noted in 68.97% of patients, with a majority presenting bilaterally.

Table 2: Anatomical variations diagnosed by CT scan in CRS patients

Table 3 shows anatomical variations diagnosed by Diagnostic Nasal Endoscopy (DNE) in the same patient cohort. Deviated Nasal Septum was even more prevalent in DNE findings, observed in 86.21% of patients, and with a slight increase in bilateral cases compared to CT. Concha Bullosa was diagnosed in 25.52% of patients by DNE, with a slight decrease in cases compared to CT (26.21%). Bulging Due to Agger Nasi Cell showed a similar pattern to CT findings, with 68.97% of cases, primarily bilateral.

Table 3: Anatomical variations diagnosed by DNE in CRS patients

In the present study, deviated nasal septum (DNS) emerged as the most frequent anatomical variation, observed in 82.76% of patients. Among these, 75.26% exhibited a C-shaped deviation, while 7.5% had an S-shaped deviation. Comparable findings were reported by Kaygusuz et al. [9], who documented DNS in 72.7% of cases, and Perez-Pinas et al. [10], who reported an incidence of 77.7%. DNS is estimated to affect 20–31% of the general population, with severe septal deviations identified as significant contributors to sinusitis [11]. The present study revealed a statistically significant correlation between DNS and CRS.

The second most common anatomical variation was the presence of agger nasi cells, found in 68.97% of patients. Of these, 57.24% had bilateral involvement, while 11.72% were unilateral. This finding aligns with studies conducted by Gupta et al. [12] and Farhan et al. [13], which reported incidences of 68.8% and 67.7%, respectively. Agger nasi cells are known to obstruct the frontal recess outflow tract, thereby contributing to frontal sinusitis.

Concha bullosa was identified in 26.21% of cases, with a highly significant p-value of <0.01. This prevalence is comparable to the 30% reported by Wani et al. [14]. However, studies by Gouripur et al. [15] and Mathuram et al. [16] noted incidences of 12% and 43.5%, respectively, which differ from the findings of the current study.

Paradoxical middle turbinate was observed in 11.03% of patients, with 10.34% having unilateral and 0.69% bilateral involvement. Azila et al. [17] similarly reported an incidence of 12%. The degree of convexity and the size of the middle turbinate are critical factors influencing nasal obstruction and are significant contributors to sinonasal diseases.

Anatomical variations in the olfactory fossa, classified using Keros classification, were also examined. Among the 145 patients studied, 73% had Type II, 17% had Type I, and 12% had Type III. These findings are consistent with those of Karki et al. [18], who reported Type II as the most common variant, present in 88.7% of cases.

Understanding the anatomical variations of the nasal cavity and paranasal sinuses is crucial, as these variations are significant predictors of CRS. Thorough evaluation using CT imaging and diagnostic endoscopy prior to surgery plays a vital role in reducing potential complications during surgical interventions.

Anatomical variations significantly influence the development, severity, and extent of sinus involvement in chronic rhinosinusitis. Diagnostic imaging modalities such as DNE and CT are invaluable for endoscopic surgeons during FESS, aiding in the restoration of sinus physiology and minimizing surgical complications. Together, DNE and CT have enhanced the visualization of regional anatomy, enabling greater precision in the assessment and management of CRS.

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