Anatomical Variations Of Paranasal Sinuses Research Articles

Investigating Anatomical Variations in Paranasal Sinuses: A Comprehensive Analysis through Retrospective CT among the Indigenous Population at Multi - Speciality Hospital, Shillong

Investigating Anatomical Variations in Paranasal Sinuses: A Comprehensive Analysis through Retrospective CT among the Indigenous Population at Multi - Speciality Hospital, Shillong

Paranasal sinuses in patients with chronic rhinosinusitis,Tanzania

Introduction: Chronic rhinosinusitis is inflammation of the nasal cavity and paranasal sinuses that lasts for at least twelve weeks. Paranasal sinus variations account for various pathologies, including chronic rhinosinusitis. This study assessed the anatomical variations of paranasal sinuses among patients with chronic rhinosinusitis attending otorhinolaryngology services in a tertiary hospital in Tanzania.
 Method: This was a descriptive prospective cross-sectional study of 120 patients aged 15 years and above who fulfilled the Rhinosinusitis Task Force criteria. A structured checklist was used to collect socio-demographic characteristics and clinical presentations. Cone-beam computed tomography scan and the Lund-Mackay scoring system were used. Data analysis was done using SPSS version 26, and p-values <0.05 were considered statistically significant.
 Results: A total of 120 patients were enrolled with a median age of 37 (IQR 27-52) years, with 40% aged 30-49 years. There were 65 (54.2%) males, and 55 (45.8%) females. Maxillary sinuses were affected in 85.8% of all patients with chronic rhinosinusitis. The overall proportion of anatomical variation was 53.3%, with concha bullosa, deviated nasal septum, Onodi cells, and septal spur being the most common, accounting for 40.6%, 25.0%, 23.4%, and 20.3%, respectively. Twenty-four patients with concha bullosa had chronic maxillary rhinosinusitis, with 14 (58.3%) having ipsilateral rhinosinusitis.
 Conclusion: Half of the patients had one or more paranasal sinus anatomical variations. The most common variants were concha bullosa followed by deviated nasal septum. Onodi cells and septal spurs were rarely identified. Most patients with concha bullosa had ipsilateral maxillary sinusitis.

The anatomical variations of paranasal sinuses may be related to the formation of antrochoanal polyp by computed tomography imaging study.

There is little investigation into the connection between anatomic variations and the development of antrochoanal polyp (ACP), and the etiology of ACP remains unclear. The study aims to explore the relationship among anatomic variations, maxillary sinus volume, nasal meatus-related parameters, and the occurrence of ACP. There were 127 patients included in this retrospective cross-sectional study with unilateral ACPs hospitalized at Shandong Provincial ENT Hospital between February 2010 and February 2020. Evaluation indicators included anatomic variations, maxillary sinus volume, and nasal meatus-related parameters in 45 children and 82 adults, which were evaluated twice by 3DSlicer software. Parameters were assessed using the Kolmogorov-Smirnov test, followed by paired t-test and Chi-squared test for multiple comparisons. Significant differences were found in the accessory maxillary ostium (AMO) and maxillary sinus retention cyst between two sides (both P<0.001). Maxillary sinus volume and sex had an association of statistical significance on adults' ACP side (P=0.026) and non-antrochoanal polyp (non-ACP) side (P=0.032). The affected side's maxillary sinus volume was significantly larger than the healthy side (P<0.001). The length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate of the ACP side was larger than the non-ACP side in children (P=0.044). Males' length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate of the ACP side was considerably greater than the healthy side (P<0.001). The length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate (P=0.014) and the length from the inferior turbinate to the nasal septum (P=0.013) on the non-ACP side was higher than the affected side in adults. Males' length from the inferior turbinate to the nasal septum was higher on the healthy side than the affected side (P<0.001). Males had a greater maximum length from the maxillary sinus lateral wall to the nasal septum (P=0.024) and the length from the inferior turbinate to the nasal septum (P=0.003) on the non-ACP side than females. Males had a larger maximum length from the maxillary sinus lateral wall to the nasal septum on the ACP side than females (P=0.011). In our study, the occurrence of the AMO, the maxillary sinus's expanded size, and the stenosis of the associated channels around the ostiomeatal complex and common meatus are regarded as probably connected to the formation of ACPs. In addition, the anatomic variations that involve the ostiomeatal complex and may lead to a change in maxillary sinus pressure and nasal ventilation are important factors in the formation of ACPs.

Frequency of Accessory Maxillary Ostium in Patients With/Without Sinusitis, and Its Correlation with Anatomical Variations of Paranasal Sinuses: A Cone Beam Computed Tomography Study.

This study assessed the frequency of accessory maxillary ostium (AMO) in patients with/without sinusitis and its correlation with anatomical variations using cone-beam computed tomography (CBCT).In this cross-sectional study, 244 CBCT scans were evaluated in two groups: with maxillary sinusitis having > 2mm mucosal thickening and without max sinusitis as a normal group having normal or less than 2mm mucosa. The CBCT scans of each group were carefully evaluated for the presence/absence of AMO, patency/obstruction of the primary maxillary ostium (PMO), and the presence of anatomical variations of the paranasal sinuses. Data were analyzed by independent t-test, Pearson Chi-square test, and Fisher's exact test (alpha = 0.05).CBCT scans of 134 females (54.9%) and 110 males (45.1%) with a mean age of 34.16 ± 19.01 years were evaluated. The presence of AMO had no significant correlation with maxillary sinusitis (P = 0.104). The two groups had no significant difference in the frequency of Haller cell, nasal septal deviation, and concha bullosa (P > 0.05). However, the frequency of paradoxical concha (PC; P < 0.001) and bifid concha (BC; P = 0.017) was significantly higher in the normal group, and the frequency of PMO obstruction was significantly higher in the sinusitis group (P < 0.001). AMO had no significant correlation with any anatomical variation in any group (P > 0.05). Gender had a significant effect on the presence of AMO (P = 0.013).The presence of AMO had no significant correlation with maxillary sinusitis. However, its frequency was significantly higher in females in normal group and males with sinusitis. The presence of AMO had no significant correlation with anatomical variations.

Anatomical variations of the Paranasal sinuses in Javanese patients with Chronic Rhinosinuitis

Variations in paranasal sinuses anatomy are common and vary among populations. Having clear picture of paranasal sinuses anatomy of a chronic rhinosinusitis patients is essential in surgical planning. This study was done to know paranasal sinuses anatomical variations of chronic rhinosinusitis in Javanese patients by Ct-scan. Retrospective chart survey from medical record of the ORL-HNS outpatient unit at Dr. Soetomo hospital Surabaya during the period January 2019 to December 2020. The data of age, gender, anatomical variations of paranasal sinuses and Keros classification of 55 patients who met the inclusion and exclusion criteria were obtained and recorded. The most common paranasal sinuses anatomical variations were deviated nasal septum (71%), concha bullosa (27%) and ager nasi (22%). Genderwise, anatomical variations were seen more in males. Based on Keros classification, type II(47%) is the most frequently found. The high incidence of paranasal sinuses anatomical variations, emphasize the need for proper preoperative assessment for safe and effective endoscopic sinus surgery.

Frontal sinus pneumatization: An isolated finding or a sign of concomitant anatomical variation?

To determine the association between frontal sinus pneumatisation and concomitant anatomical variations in paranasal sinuses as seen on computed tomography. A total of 403 patients who underwent paranasal sinus computed tomography were allocated to three groups according to the degree of frontal sinus pneumatisation (type 1 - hypoplasia; type 2 - medium size; and type 3 - hyperplasia). In this unique model, the prevalence of ipsilateral variations on paranasal sinuses on each side of the head were analysed separately within each pneumatisation group. The type 3 frontal sinus pneumatisation group showed a greater association with ipsilateral variations of the sphenoid bone. Variations included pneumatisation of the anterior clinoid process, lateral sphenoid recess, pterygoid process and greater wing, and exposure of Vidian canal. This group also showed significant associations with male gender, and the presence of frontal and Onodi cells. Interpretation of the paranasal sinus variations is imperative for pre-operative evaluation in functional endoscopic sinus surgery, particularly in patients with frontal sinus hyperplasia. Attention to variation on the ipsilateral side is informative.

Anatomic variations of para-nasal sinuses in patients undergoing CT scan: spectrum, prevalence and implications

Anatomic variations of para-nasal sinuses in patients undergoing CT scan: spectrum, prevalence and implications

English

BACKGROUND Computerized Tomography (CT) scan plays a very important role in decision making before planning any surgical intervention on paranasal sinuses and is also the modality of choice during management and post-surgical follow-ups. Knowledge of different morphologies of paranasal sinuses is an important prerequisite for surgical decision making. This study was done to describe the impact of gender and age on anatomical and morphological presentations of paranasal sinuses using CT in the North Indian Population. METHODS A cross-sectional type of descriptive study was conducted in the Department of Anatomy in collaboration with the Department of Radiodiagnosis of M. L. N. Medical College and Kriti Scanning and Research Centre, Allahabad (Prayagraj) Uttar Pradesh, to describe various morphological presentations of paranasal sinuses. Based on the findings, the gender and age group variations of paranasal sinuses were evaluated and discussed along with the types of the frontal air cells and concha bullosa. RESULTS Overall 120 subjects were analysed based on their CT-scan findings (72 males and 48 females). The frequencies of major sinus variations were observed as Onodi cells in 19.2 %, Concha bullosa in 47.5 %, Frontal air cells in 25 %, Maxillary sinus septation in 7.5 % and Supraorbital cells in 15 % of the study population. CONCLUSIONS Anatomical variations of paranasal sinuses are very common. These variations must be identified by the radiologists in preoperative computerised tomography evaluation to reduce the risk of intraoperative complications. CT scan provides a virtual roadmap to the surgeon and improves the success of management strategies. KEY WORDS Anatomical Variations, Paranasal Sinuses, Concha Bullosa, Onodi Cell

Evaluation of paranasal sinus anatomic variations and mucosal changes with cone beam computed tomography

Background/Aim: Anatomical variations of paranasal sinuses are common and play an role in disrupting the drainage of the sinuses, which often causes chronic sinusitis. In this article, anatomical variations of the paranasal sinuses and its relationship with mucosal changes were evaluated retrospectively by cone beam computed tomography (CBCT) which is also known as dental volumetric tomography. Material and Methods: CBCT data of 500 patients who applied to Cukurova University Faculties of Dentistry for any reason were retrospectively evaluated by maxillofacial radiologist. Anatomical variants of paranasal sinuses were included in the study. Mucosal thickening greater than 2 mm in the maxillary sinus was considered pathological. Results: The most common anatomic variation in the study was the nasal septal deviation, found in 302 (60.4%) patients. The least common anatomic variation in the study was lower concha pneumatization found in 3 (0.6%) patients. Mucosal thickening of the maxillary sinus was observed in 271 (54.2%) cases in the right sinus and 260 (52%) cases in the left sinus (p&gt;0.05). Conclusions: Nasal septum deviation was the most common variation in the study. According to the results of our study, concha bullosa, haller cell and the uncinate process had no definite effect on mucosal thickening in the maxillary sinus.

Evaluation of Anatomical Variations of Paranasal Sinuses in Children with Coronal Plan Computed Tomography

Evaluation of Anatomical Variations of Paranasal Sinuses in Children with Coronal Plan Computed Tomography

Computer Tomographic study of Anatomic Variations of Paranasal Sinuses in Libyan Population and their Clinical Correlation

Introduction: In the era of Functional Endoscopic Sinus Surgery, precise knowledge of paranasal sinus anatomy and variations are essential for the surgeon. The multi-slice computed tomography is the imaging modality of choice provides accurate evictions of the anatomy, the anatomical variants and the extent of the disease in paranasal sinuses, such a method allowing their accurate identification with high anatomical details. Some of these variants may predispose to sinus diseases or become of high risk for injuries and complication during surgical procedure, therefore, the study of anatomic variants of paranasal sinuses is important in the preoperative endoscopic surgery. Objectives: The purpose of this study is to assess the frequency of anatomic variants and their clinical importance. Materials and methods: This retrospective study was conducted at the Department of Radiology, Benghazi Medical Center, Benghazi, Libya. Data comprised the paranasal sinus computed images of 112 patients (46 males and 66 females) analyzed for the presence of anatomic variants and associated sinus pathology. Results: Our results showed that the most common anatomical variants was deviated nasal septum (60.7%) with slight higher incidence on left side, followed by concha bullosa (22.3%), other variants found were absent frontal sinus (18.8%), Nasal spur (14.3%) , Agger nasi cell (16.1%), Haller cell (5.4%), Onodi cell (2.7%), accessory ostia of maxillary sinuses (10.7%), accessory middle nasal concha (1.8%), paradoxical middle turbinate (1.8%), nasal septum pneumatization (5.4%), Crista galli pneumatization (2.7%), pneumatization of hard palate (1.8%) and pneumatization of clinoid process (6.3%). (53.6%) patients suffered from sinusitis, the results showed that the most common sinus involved was maxillary sinus. Conclusion: Anatomical variations of PNS are quite common. Analysis of every paranasal CT scan obtained for sinusitis for the presence of different anatomic variants is of questionable value unless endoscopic surgery is planned to reduce the risk of intraoperative complications.

Anatomical Variations of Paranasal Sinuses on Multidetector Computed Tomography

Multi detector computed tomography (MDCT) scan of paranasal sinuses has become mandatory for all patients undergoing functional endoscopic sinus surgery. It depicts the anatomical variations in much simpler way and acts as a roadmap for endoscopic sinus surgery [1]. Some anatomical variations may predispose to nasal and paranasal diseases, constituting areas of high risk for injuries and complications during surgical procedures. Therefore, the recognition of such variations is critical in the preoperative evaluation for endoscopic surgery [1].

Evaluation of optic nerve variations in relation to posterior paranasal sinuses among study population of Mandya District of Karnataka State

This study aims to determine relationship of optic nerves to posterior paranasal sinuses, its types, incidence and prevalence among study population of Mandya district, Karnataka. This observational study comprised 124 patients who were recommended for FESS and were referred to radiology department for CT scan between July 2019 to December 2019 at MIMS, Mandya. The age and sex of the patients along with the symptoms and its duration was recorded. All the patients underwent a comprehensive medical history and head and neck physical examination. A high resolution, 1.25 mm thick CT scan was taken for the study. Relationship of optic nerves to posterior paranasal sinuses was categorized according to Delano classification. Descriptive statistics like mean and percentages were used for analysis using SPSS v.22. The findings showed the prevalence of Onodi cells in 22.6% of the patients. Onodi cells were observed in 8.9% on the right side and 5.6% on left side of the patients respectively. In 8.1% of the patients, bilateral Onodi cells were present. ACP pneumatization was present in 25.1% of the patients bilaterally. ACP pneumatisation was found on the right side and left side in 10.5% and 6.5% respectively. 124 patients underwent CT of paranasal sinuses during study period and course of 248 optic nerves were examined in relation to posterior paranasal sinuses. Type 1, Type 2, Type 3, and Type 4 optic nerves was present in 83.33%, 8.87%. 12.1%, and 21.78% respectively. Bilateral Type 1 optic nerves was present in 58.88% patients, both Type 2 and Type 3 optic nerves were seen bilaterally in 3.23% of patients and bilateral Type 4 optic nerve was seen in 10 (8.06%) cases. Optic nerve Type 1 (83.88%) was the most frequent nerve type, followed by Type 4 (21.78%). In conclusion, the anatomical variations of paranasal sinuses are very important to be identified preoperatively since sphenoid sinus and optic nerve relation is known for its variation. Before endoscopic sinus surgery, one needs to know this anatomy using CT of paranasal sinuses using Delano classification of optic nerve.

Identification of Significant Anatomical Variations in the Nose and Anterior Skull Base Using Computed Tomography: A Cross-Sectional Study.

IntroductionThis study is aimed at the identification of anatomic variations in the nose, paranasal sinuses (PNS), and anterior skull base, which are substantially important to ensure safe and complete endoscopic sinus and skull base surgery.Materials and methodsThis cross-sectional study was conducted at the Dow Institute of Radiology, Dow International Medical College, Dow University Hospital. We included adult patients (i.e., those aged 18 years or older) undergoing a non-contrast CT of the nose and PNS. Two consultant radiologists reviewed the scans on the picture archiving and communication system independently. Any conflict was resolved with consensus. Anatomical variations in the nose, PNS, and anterior skull base of both sides were evaluated.ResultsWe reviewed the CT of the PNS of 130 patients with an age of 35.8 ± 14.48 years (mean ± standard deviation). The proportion of men (64/130; 49.2%) and women (66/130; 50.8%) was equal. All patients had one or more variations. The most common abnormality was a deviated nasal septum (DNS), observed in 115 of 130 participants (88.5%) with unilateral occurrence predominant. It was followed by inferior nasal turbinate hypertrophy and agger nasi cells in 76.2% and 67.7% patients, respectively. Optic nerve variation type I (160/260 sinuses; 61.5%) and Keros type II, for olfactory depth (162/260 sinuses; 62.3%), were most common.ConclusionsHere we report anatomical variations in PNS in all patients of our study; the commonest of all anatomical variations was a DNS. A CT scan is instrumental in surgical planning and patient safety in functional endoscopic sinus surgery.

Evaluation of anatomical variants in paranasal sinuses with computed tomography in central India region

Aim: This study aimed to assess the congenital anatomical variations in paranasal sinuses (PNS) and determine the incidence of these variants using helical computed tomography (CT) scan. Materials and Methods: The study included 477 cases in whom unenhanced CT of the brain and PNS was performed in the axial plane, complemented by reconstructed coronal and sagittal sections. These patients were then reviewed for anatomical variants of the PNS and their relation to sinusitis. The results were statistically analyzed by using descriptive and inferential statistics with Chi-square test and predictive values. Statistical Package for Social Sciences version 17.0 and GraphPad Prism 5.0 were used for analysis. Results: Among all the patients studied, deviated nasal septum was noted as the most common anatomical variant in 178 (37.3%) patients followed by concha bullosa in 124 (26%) patients. Other variations found were agger nasi cells in 109 (22.9%), paradoxical middle turbinate in 45 (9.5%), Haller's cells in 47 (9.8%), and Onodi cells in 34 (7.1%) patients. Other uncommon anatomical variants such as hypoplastic frontal sinus and hyperpneumatization of PNS were noted in eight (1.68%) and two (0.42%) patients, respectively. Conclusion: The presence of anatomical variants may predispose to sinus pathology. Radiologists must pay close attention to anatomical variants in the preoperative evaluation, which helps avoid possible complications and improves the success of management strategies.

STUDY OF NORMAL ANATOMICAL VARIATIONS IN PARA-NASAL SINUSES USING COMPUTED TOMOGRAPHY SCAN: A CROSS SECTIONAL STUDY FROM CENTRAL INDIA

Background: The standard imaging in the assessment of the para-nasal sinuses is currently computed tomography scanning. This provides an applied anatomical view of the area as well as the common anatomical variants. The advancement and improvement of computed tomography scans has provided for a comprehensive evaluation of patients' para-nasal sinuses, allowing Functional Endoscopic Sinus Surgery surgeons to operate with a guide chart.&#x0D; Objectives: To study normal anatomical variations in para-nasal sinuses using Computed Tomography.&#x0D; Material and Methods: This research took place in a tertiary healthcare center's radiology department over the course of two years. Axial para-nasal sinuses cuts were taken using a multi-slice (128 slice scanner), followed by coronal and sagittal reconstruction.&#x0D; Results: The most common anatomic variation, according to the findings, was nasal septal deviation. The rarest variation in our sample was Haller cell and pneumatized septum. There was also a close connection between unilateral Concha bullosa and contra-lateral septal deviation, as evidenced by the research.&#x0D; Conclusion: A wide range of lesions can affect the para-nasal sinus area. Normal anatomical differences and congenital abnormalities in this area are significant because they can have pathological consequences or cause difficulty/complication during surgery.&#x0D; Keywords: Para-nasal sinuses, Computed Tomography, Functional Endoscopic Sinus Surgery.

The Analysis of Computed Tomography of Paranasal Sinuses in Nasal Septal Deviation.

Anatomic variations of paranasal sinuses are frequent among population that should be analyzed and interpreted accurately. The purpose of this study is to analyze anatomical variants and their relationships of paranasal sinuses in patients with nasal septal deviation undergoing septoplasty. A total number of 150 patients (74 males, 76 females) with nasal septal deviation undergoing septal surgery were included in this retrospective study. The authors analyzed the direction and the angle of the nasal septal deviation, variations of the nasal turbinates, ethmoidal air cells, paranasal sinus pneumatization, accessory pneumatization of the paranasal complex and sphenoid sinus-related structures and the Keros, optic nerve and Vidian canal classification, and relationships between these structures in the paranasal computed tomography of the patients. The incidence of concha bullosa, Onodi cell, and anterior clinoid pneumatization were higher in patients with nasal septal deviation when compared with current literature. Physicians and surgeons dealing with the nose and maxillofacial region should be able to analyze paranasal computed tomography by themselves and must be aware of these variations during performing septal and craniomaxillofacial surgery.

Retrospective analysis of Anatomical Variations of Paranasal Sinuses on Multidetector Computed Tomography – A Randomized Cross-Sectional Study

Retrospective analysis of Anatomical Variations of Paranasal Sinuses on Multidetector Computed Tomography – A Randomized Cross-Sectional Study

A clinico-radiological study of anatomical variations of nose and para-nasal sinuses in chronic rhinosinusitis patients

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; There are a lot of&lt;strong&gt; &lt;/strong&gt;anatomical variations in para-nasal sinuses that are responsible for various sinus pathologies. CT scan of paranasal sinuses prior to functional endoscopic sinus surgery has become extremely important to know the anatomy and its variations to avoid complications during surgery.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; This study was performed in 100 patients at King George’s Medical University, Lucknow UP, India to compare the anatomical variations between nasal endoscopy and CT scan findings. The outcome measures were deviated nasal septum, paradoxical middle turbinate, concha bullosa, medialized/lateralised uncinate process, pneumatized uncinate process, large ethmoid bulla, accessory ostium, Agger nasii cells, Haller’s cells and Onodi cells. &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; In this&lt;strong&gt; &lt;/strong&gt;study&lt;strong&gt; &lt;/strong&gt;the age of the patients were 30.00±9.56 yrs. with male to female ratio 1.9:1. Deviated nasal septum was the most common anatomical abnormality (70%) followed by large bulla ethmoidalis 17%. Occurrence of different types of special cells were studied which are better visualized on coronal CT scan images. Among these cells Agger nasi was the most common variety (15%) followed by Haller’s cells (11%) and Onodi cell (3%). Concha bullosa was present in 8%.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; The importance of CT and nasal endoscopy can be seen in patients with persistent symptoms to identify the anatomical variations that may responsible for the development of chronic sinus disease. In cases of sinusitis patients all the para-nasal sinus should be properly investigated to avoid complications. &lt;/p&gt;

Role of computed tomography in identifying anatomical variations in chronic sinusitis: An observational study

Background/Aim: Clear visualization of bony wall, mucosal layer, sinus contents, and compartment by computed tomography (CT) helps to identify the anatomical variations in chronic sinusitis (CS). We describe the clinical and radiological features in CS. Materials and Methods: We included patients of both genders aged ≥15 years, with CS. Unenhanced CT images of the nasal cavity and paranasal region were taken in coronal, complemented by axial and sagittal reconstructions. Analysis of anatomical variants was performed using a soft tissue window and a bone window. Results: Headache (64%), nasal obstruction (53%), and nasal discharge (38%) were common complaints of 100 patients (male = 52) whose mean ± standard deviation age was 32.55 ± 10.9 years. Significant mucosal thickening in at least one of the paranasal sinuses (PNSs) was seen in all except four patients. All had a minimum of one anatomical variant, 72% had >1 variant. Maxillary antra were most commonly involved (62.0%), followed by ethmoid sinuses (36.0%). Deviated nasal septum (60%) was most common, followed by concha bullosa (38%); paradoxical middle turbinate (18%), ethmoidal bulla (20%), agger nasi cells (33%), Haller cells (21%), and onodi cells (10%) were other features. All had optic nerve involvement with Type I (84%) involvement being common. Kero's classification Type I was noted in 71%. None had Type IV. Cribriform plate and carotid canal wall were normal in all while 2% had dehiscence of lamina papyracea. Conclusion: CT plays an important role in visualization of anatomical variations in PNSs, and anatomical variations particularly in the ostiomeatal complex are the key factors in the causation of CS.