Anatomical Variations of the Nose and Paranasal Sinuses in Sudan

Background: To study the anatomical variations of the nose and paranasal sinuses using Computed Tomography (CT) in Sudan during 2020–2022. Methods: This is a descriptive cross-sectional study conducted in the radiological departments of Sudanese hospitals between 2020 June and 2022 June. The total number of patients was 111 of both sexes. Results : In this study, CT of 111 patients was analyzed. The patients were aged 18–80 years (mean age: 33 years) and comprised of 52.3% females and 47.7% males. The most common anatomical variants in the study group were pneumatization in sphenoid sinus-sellar type (71.2%), attachment of uncinate process into lamina papyrecea (69%), Keros type II (63.1%), deviated nasal septum (42.3%), concha bullosa (37.8%), and Onodi cells (20%). The opacity of the sinus was seen in about half (49.5%) of the CT, with more common sinus involvement being maxillary sinus (35.1%) followed by frontal sinus (8.1%) and ethmoid sinus (6.3%). There was no opacity in the sphenoid sinus in this study. Conclusion : The most common anatomical variants in the study group were pneumatization in the sphenoid sinus-sellar type. The opacity of paranasal sinuses was more common in the maxillary sinuses.


Introduction
Anatomy of the nose and paranasal sinuses have different variations that happen at different phases during the development of the embryo [1].The sphenoid sinus usually has a central septum dividing the sinus into two parts, on the other hand, the frontal recess usually drains into the middle meatus in 62% of people, or into the ethmoid infundibulum for the rest 38% [2].The ethmoid sinuses' number, shape, and size of these air cells vary significantly from person to person [3].The uncinate process of ethmoid bone may insert into the lamina papyracea in 33% of the cases, skull base in 10%, middle turbinate, and a combination of these in 57% [4].The nasal septum maldevelopment gives rise to the most common anatomical variant; a deviation of the septum (DNS) [5].Pneumatization of the nasal septum was seen in 27% of the cases reported by Devarajaetal [1,6].Haller cells are anatomic variants because they may narrow the ostium of the maxillary sinus or the ethmoid infundibulum.These cells are a predisposing factor for recurrent maxillary sinusitis [7].Agger nasi cell is the most common anatomic variant of the paranasal sinuses and nasal cavity [8].Olfactory fossae depth was described by Keros as three variants of fossa [9].Sinuses hypoplasia, Concha bullosa (CB), pneumatized crista galli, pneumatization of the uncinate process, Onodi cells (OC), and paradoxical middle turbinate are other common anatomical variants [7,8,[10][11][12][13][14].
Computed Tomography (CT) is a suitable method for providing anatomical information on the nose and paranasal sinuses, and it gives good results describing the anatomical variations [7,15].CT is useful for endoscopic surgeons in understanding the anatomical variations of the nose and paranasal sinuses to avoid iatrogenic injuries [7,15].This research aimed to study the anatomical variations in the nasal cavity and paranasal sinuses (PNS) in adult Sudanese people using CT.More knowledge of possible variations is essential for the otolaryngologist to operate safely in this complex area that is near the orbit and the brain.

Study design and area
The current study is a descriptive, retrospective cross-sectional study conducted in Khartoum State Hospitals in the capital of Sudan.
Study area: Khartoum state hospitals are wellequipped tertiary hospitals that provide health services to patients referred from other states.Data were collected from all radiological departments of all Khartoum State governmental hospitals.

Data collection
Data were collected using a well-structured checklist.Selected resident doctors in the radiology departments collected data.

Data analysis
Data were analyzed using the SPSS program version 20.

Results
This cross-sectional study was conducted to evaluate the anatomical variations of the nose and paranasal sinuses on CT among adult Sudanese patients.
Of the initial 157 patients, 46 were excluded for not meeting the inclusion criteria.Patients with prior sinonasal surgery (25 cases), sinonasal tumors (15 cases), and maxillofacial trauma (6 cases) were excluded, making the final sample size as 111 cases.
Moreover, the age of the patients ranged from 18 to 80 years, and the mean age was 33.4 years.
Variations in maxillary sinus were seen in nine patients (8.1%), most of its variation was maxillary sinus hypoplasia which was seen in seven patients (6.35%), and pneumatized maxillary sinus was seen in two patients (1.8%; Figure 1; Table 3).
The only variant in superior turbinate pneumatization was found in six patients (5.4%).
Mucosal abnormalities were detected in about half of the patients (49.5%).The most frequently involved sinus was the maxillary sinus in 39 patients (35.1%), followed by the frontal sinus in 9 patients (8.1%), and ethmoid sinus in 7 patients (6.3%); no opacity was detected in the sphenoid sinus (Figure 9).Furthermore, a significant association was seen between the presence of DNS, CB, and the attachment of uncinate process in the middle turbinate, paradoxical of the middle turbinate, and the presence of sinus mucosal opacity (with a significant P-value < 0.001) (Table 7).

Discussion
This study depended on CT for the evaluation of the varied findings in patients with anatomical variations of the nose and PNS, for which 111 cases were enrolled, their ages ranging from 18 to 80 years, and the mean age being 33.4 years.
In this study, patients had a significantly greater incidence of nasal septal deviation and CB which is similar to Calhoum et al.'s results [16].DNS was shown in 42.3% of CT scans in comparison to an Indian study published by Devaraja et al., where DNS was the most prevalent alteration seen in 83.4% of the cases so the frequency was higher than in the current study [6].
Furthermore, in a previous Sudanese study including 100 CT scans, the most common anatomical variant of the nose and paranasal sinuses was DNS and it was present in 78% of the scans, again this frequency is higher than what was reported in the current study [25].This might be because in the current study, we eliminated all scans of participants who had a previous history of trauma, tumors, and previous nasal surgery, hence the DNS frequency was low.Regarding the frequency of CB, it was found in 37.8%, compared with the study done in 2017 by Koo et al. in which it was reported in 53.7% [11].However, Pérez-Pias et al. in 2000 reported the percentage of CB as 24.5% [5].Again,

CB was reported with low frequency in a previous
Sudanese study [25].
Maxillary sinus hypoplasia (MSH) was seen in 6.35% of patients in the current study, so it is an uncommon abnormality that comes across in clinical practice.It was in line with a previous study by Sirikci et al. who reported it in 10.4% of their patients [17].
Moreover, in this study, pneumatization of frontal sinuses was about 9.9%, and agenesis was 4.5%.
Whereas, a local study done in Sudan showed pneumatized frontal sinus and agenesis in 37% and 11%, respectively, which were higher than this study [19].DOI   Variations in the ethmoid cell, BE, in the present study were found in 9% of the study population, this is similar to Pérez-Pi na et al. [5].
In this study OC were found in 20.7%, Tawfitk et al. reported the prevalence of OC in 18% of   Egyptian cases, this agrees with what was found in [20].
Regarding pneumatization of the sphenoid sinus, the most common type was the seller one and is found to be in 71.2%, this agrees with a local study done in Sudan by Kajoak et al., who reported that the sellar type was found in 85% of   their sample, also similar to a regional study done in Egypt by Tawfitk et al. [2,20].
In this study, Keros type II was found in 63.1%, followed by type I at 30.6% and type III at 6.3%, compared to a local Sudanese study by Dafalla et al., who found that the most common was the type I in 72% of the patients, while Alazzawi et al.
classified 80% of the cases as Keros type I, and 20% of the cases as type II, they considered none to be Keros type III [9,19].
Regarding variations in frontal recess, Frontoethmoidal air cells with their all types in Kuhn classification are seen ranging from 4.5% to 16.2%In this study, the opacity of the sinuses was found in 49.5%, the maxillary sinus was the most commonly involved, followed by the frontal sinus, similar to the study of Devaraja et al. who reported the maxillary sinus opacification in 70.1% [6].
Statistically, there was a significant association (P-value < 0.001) between the presence of DNS, CB, attachment of uncinate process in the middle turbinate, paradoxical of the middle turbinate, and the presence of sinus mucosal opacity which was seen in agreement with Fadda et al., who showed a specific association of anatomic variations in sinus opacity [24].2. The CT should be reviewed in all three cuts to accurately understand the complex regions.

Conclusion
The most common variation was found to be a sellar type of sphenoid sinus pneumatization.The opacity of paranasal sinuses was found to be more common in the maxillary sinuses.A statistically significant association was found between the presence of DNS, CB, attachment of uncinate process in the middle turbinate, paradoxical of the middle turbinate, and sinus mucosal opacity (Pvalue < 0.001).

Figure 2 :
Figure 2: Variants in the nasal middle turbinate.

1 .
The current study lacks more descriptive reports describing the anatomic variants, critical variants, and sinus opacity.Moreover, it lacks precision in the detection of pathology and anatomical variations, because of the absence of a standard protocol for CT scanning of the nose, paranasal sinuses, and skull base, including window specifications and thickness of cuts.

3 . 4 .
The current study lacks proper history taking and clinical examination including endoscopic findings.The study also lacks collaboration between endoscopic nasal surgeons and radiologists to reach a proper diagnosis and interpretation of scans of the nose and sinuses.

Table 2 :
Variants of the nasal septum.

Table 3 :
Variants in the maxillary sinus.

Table 5 :
Variants of the frontal recess (Kuhn classification).

Table 6 :
Variants of the frontal recess.

Table 7 :
Correlations between anatomical variations and sinus opacity.