Abstract
The aim of this study was to analyse the relationship between frontal sinus pneumatization and its effect on various variations of paranasal sinuses on paranasal sinus CT scan. A total number of 100 patients (51 males, 49 females) were included in this study. Patients were divided into three groups on the basis of their frontal sinus pneumatization extent on paranasal sinus CT as Type 1 pneumatization (aplasia and hypoplasia), Type 2 pneumatization (medium) and Type 3 pneumatization (hyperplasia). The prevalence of various variations like pneumatization of upper and middle turbinate, presence of agger nasi, Haller and Onodi cell, maxillary sinus hypoplasia, extent of sphenoid sinus pneumatization, pneumatization of anterior clinoid process, pterygoid process and greater wing of sphenoid sinus, dehiscence and protrusion of internal carotid artery and optic nerve types were ascertained and compared within each group. The prevalence of Onodi cell, anterior clinoid process and greater wing of sphenoid pneumatization and optic nerves type 3 and 4 were higher in Type 3 frontal sinus pneumatization group as compared with other groups. Excessive pneumatization of frontal sinus has various effects on paranasal sinus variations. Surgeons dealing with endoscopic sinus surgery, maxillofacial and skull base surgery must be vigilant of association between these variations preoperatively for avoiding complications.
Keywords: Frontal sinus pneumatization, Paranasal sinus variants, Computed tomography
Introduction
Meticulous assessment of variations in the paranasal sinuses on computed tomography (CT) is essential for the preoperative evaluation of endoscopic sinus and skull base surgery. By correlating the prevalence of these variations with each other, surgeons can anticipate the coexistence of different abnormalities before surgery. When evaluating paranasal sinus CT, directing the surgeon’s attention to a specific variation in the presence of another may also reduce the risk of surgical complications.
The development of the frontal sinus begins during fetal development and reaches its final size in late adolescence (1). Variations in the structure of the pneumatic cavities, including their separation by an intersinus septum or fusion, can result in one or both sinuses being absent. Environmental and genetic factors can also influence the extent of pneumatization in the paranasal sinuses (2). The unique nature of each individual's frontal sinus makes it useful for precise personal identification.
Structural variations, such as a deviated nasal septum, concha bullosa, curved uncinate process, and paradoxical middle turbinate, can obstruct the narrow osteomeatal channels and cause sinusitis. Septal deviation can lead to deformities in the lateral nasal wall, while concha bullosa can cause mucosal thickening, polyps, and cysts. Paradoxical curvature of the middle turbinate can also cause mucosal changes and polyps. The uncinate process can show various anatomical variations, including medial curvature, which narrows the hiatus semilunaris. Other important variations include Haller's cell, agger nasi cells, Onodi cells, secondary middle turbinate, aerated crista galli, internal carotid artery dehiscence, asymmetry of ethmoid roof, hypoplasia of maxillary sinus, and pneumatization variations of the sphenoid sinus.
The present study aims to analyze the relationship of frontal sinus pneumatization on various variations on paranasal sinus CT scan.
Material and Methods
The study was conducted on patients referred to the Department of Radiodiagnosis, Maulana Azad Medical College and associated Lok Nayak Hospital, New Delhi, for a paranasal sinus CT scan. Patients aged over 18 years of age of either gender were included in the study to ensure full paranasal sinus development. Patients having history of paranasal sinus surgery, tumoral lesions, mucocele/polyp involving the frontal sinus, facial trauma, or craniofacial anomaly on paranasal CT scan were excluded from the study to avoid misinterpretation. Ethical clearance was obtained from our own institutional ethics committee (Appendix I) (F.1/IEC/MAMC/(82/10/2020/No.203).
Relevant clinical history was obtained from each patient followed by written informed consent (Appendix II) and a detailed explanation of the objectives (Appendix III) and protocol of the study. All patients underwent high-resolution non-contrast CT scan of paranasal sinuses and nasal cavity on Siemens SOMATOM emotion CT scanner. Thin axial sections (0.63 mm) were obtained for each patient. Thin multiplanar images along coronal and sagittal planes were reconstructed from these axial sets of images.
Patients were classified into three groups regarding their frontal sinus pneumatization extent on paranasal sinus CT scan (3).
For this, supraorbital line (SOL), a horizontal line tangent to the superior edges of both orbits, and midorbital line (MOL), a vertical line of the midpoint of both orbits parallel to the midsagittal line, was drawn on coronal sections of paranasal CT of frontal sinuses and utilized for the analysis (Figs. 1 and 2).
Type 1 pneumatization (aplasia and hypoplasia): No or minimal pneumatisation under the supraorbital line.
Type 2 pneumatization (medium): Frontal sinus limited to medial of the midorbital line.
Type 3 pneumatization (hyperplasia): Frontal sinus extending to lateral of the midorbital line.
Fig. 1.
Classification used for the quantification of frontal sinus pneumatization used in the present study. SOL: supraorbital line. MOL: midorbital line. Dotlines: midsagittal line; medial orbital line (vertical line passing through the most medial orbital point); and lateral orbital line (vertical line passing through the most lateral orbital point)
Fig. 2.
Coronal CT scan showing the classification of frontal sinus based on the extent of pneumatization– A: Type 1 pneumatization, B: Type 2 pneumatization, C: Type 3 pneumatization (arrows point towards the extent of frontal sinus pneumatization; MOL: midorbital line—a vertical line, drawn for each orbit, parallel to the midsagittal line, and passing through the middle of the orbital breadth; SOL: supraorbital line – a horizontal line tangent to the superior margin of both orbits)
Only the patients having the same type of frontal sinus pneumatization on both sides were included in the study.
The following parameters were evaluated on paranasal sinus CT scan based on frontal sinus pneumatization extent and compared within the three groups.
Nasal turbinates (superior and middle) pneumatization.
Ethmoidal air cell variations including agger nasi cells, Haller cells and Onodi cells.
Maxillary sinus hypoplasia and extent of sphenoid sinus pneumatization.
Accessory pneumatization variations of the sphenoid bone, including pneumatization of the anterior clinoid process, pterygoid process, and greater wing of sphenoid.
Dehiscence or protrusion of the internal carotid artery in the sphenoid sinus.
Optic nerve types.
Optic nerve types were assessed based on the classification proposed by Delano MC et al. (4), which is as follows:
Type 1 nerves course adjacent to the sphenoid sinus without indentation of the sinus wall.
Type 2 nerves course adjacent to the sphenoid sinus, causing indentation of the sinus wall.
Type 3 nerves course through the sphenoid sinus, with at least 50% of the nerve surrounded by air.
Type 4 nerves course immediately adjacent to the sphenoidal sinus and the posterior ethmoidal air cell.
The collected data was entered in Microsoft Excel and then analysed and statistically evaluated using Statistical Package for the Social Sciences version 25. Quantitative data was expressed by mean, standard deviation or median with interquartile range. Qualitative data was expressed in percentage, and the difference between the proportions was tested by chi-square test or Fisher's exact test. ‘p-value’ of less than 0.05 was considered statistically significant.
Results
A total of 100 patients were taken up for the study of which 51 were males and 49 were females. They were divided into three groups based on the extent of frontal sinus pneumatization as visualised on CT scan of paranasal sinuses. Of the 100 patients, 52 had type 1 and 24 each had type 2 and type 3 frontal sinus pneumatization.
The age and gender distribution of the patients is presented in Tables 1 and 2. There was no statistical difference (p = 0.804) in patients’ gender with respect to frontal sinus pneumatization groups between the 3 groups.
Table 1.
Age distribution (n = 100)
| Frontal sinus pneumatization | Age range (years) | ||||
|---|---|---|---|---|---|
| 18–30 years | 31–40 years | 41–50 years | 51–60 years | 61–66 years | |
| Type 1 | 14 (25.9%) | 5 (21.7%) | 4 (26.7%) | 1 (16.7%) | 0 |
| Type 2 | 12 (22.2%) | 6 (26.1%) | 3 (20.0%) | 3 (50%) | 0 |
| Type 3 | 28 (51.9%) | 12(52.2%) | 8 (53.3%) | 2 (33.3%) | 2 (100%) |
| Total | 54 | 23 | 15 | 6 | 2 |
Table 2.
Gender distribution (n = 100)
| Frontal sinus pneumatization | Male | Female | p value |
|---|---|---|---|
| Type 1 | 11 (21.6%) | 13 (26.5%) | 0.804 |
| Type 2 | 12 (23.5%) | 12 (24.5%) | |
| Type 3 | 28 (54.9%) | 24 (49.0%) | |
| Total | 51 | 49 |
The prevalence of the anatomical variants of the three frontal sinus pneumatization groups is presented in Table 3.
Table 3.
Prevalence of paranasal sinus variations
| Frontal type 1 (n = 24) | Frontal type 2 (n = 24) | Frontal type 3 (n = 52) | Total (n = 100) | p value | |
|---|---|---|---|---|---|
| Nasal turbinates pneumatization | |||||
| Upper concha pneumatization | |||||
| Present | 3 (12.5%) | 4 (16.7%) | 11 (21.2%) | 18 (18%) | 0.646 |
| Absent | 21 (87.5%) | 20 (83.3%) | 41 (81.8%) | 82 (82%) | |
| Middle concha pneumatization | |||||
| Present | 8 (33.3%) | 15 (62.5%) | 28 (53.8%) | 51 (51%) | 0.108 |
| Absent | 16 (66.7%) | 9 (37.5%) | 24 (46.2%) | 49 (49%) | |
| Agger Nasi Cell | |||||
| Present | 21 (87.5%) | 20 (83.3%) | 48 (92.3%) | 89 (89%) | 0.49 |
| Absent | 3 (12.5%) | 4 (16.7%) | 4 (7.7%) | 11 (11%) | |
| Haller cell | |||||
| Present | 1 (4.2%) | 1 (4.2%) | 3 (5.8%) | 5 (5%) | 0.934 |
| Absent | 23 (95.8%) | 23 (95.8%) | 49 (94.2%) | 95 (95%) | |
| Onodi cell | |||||
| Present | 3 (12.5%) | 6 (25.0%) | 22 (42.3%) | 31 (31%) | 0.025 |
| Absent | 21 (87.5%) | 18 (75%) | 30 (57.7%) | 69 (69%) | |
| Maxillary sinus hypoplasia | |||||
| Present | 1 (4.2%) | 1 (4.2%) | 1 (1.9%) | 3 (3%) | 0.805 |
| Absent | 23 (95.8%) | 23 (95.8%) | 51 (98.1%) | 97 (97%) | |
| Sphenoid sinus pneumatization | |||||
| Presellar | 1 (4.2%) | 1 (4.2%) | 3 (5.8%) | 5 (5%) | 0.934 |
| Sellar | 23 (95.8%) | 23 (95.8%) | 49 (94.2%) | 95 (95%) | |
| Accessory pneumatization variants of sphenoid sinus | |||||
| Anterior clinoid process pneumatization | |||||
| Present | 3 (12.5%) | 2 (8.3%) | 18 (34.6%) | 23 (23%) | 0.015 |
| Absent | 21 (87.5%) | 22 (91.7%) | 34 (65.4%) | 77 (77%) | |
| Pterygoid process pneumatization | |||||
| Present | 6 (25%) | 5 (20.8%) | 22 (42.3%) | 33 (33%) | 0.114 |
| Absent | 18 (75%) | 19 (79.2%) | 30 (57.7%) | 67 (67%) | |
| Greater wing of sphenoid pneumatization | |||||
| Present | 4 (16.7%) | 2 (8.3%) | 19 (36.5%) | 25 (25%) | 0.017 |
| Absent | 20 (83.3%) | 22 (91.7%) | 33 (63.5%) | 75 (75%) | |
| Optic nerve types | |||||
| Type 1 | 17 (70.8%) | 19 (79.2%) | 22 (42.3%) | 58 | 0.026 |
| Type 2 | 5 (20.8%) | 2 (8.3%) | 10 (19.2%) | 17 | |
| Type 3 | 1 (4.2%) | 2 (8.3%) | 10 (19.2%) | 13 | |
| Type 4 | 1 (4.2%) | 1 (4.2%) | 10 (19.2%) | 12 | |
| ICA dehiscence or protrusion | |||||
| Present | 1 (4.2%) | 2 (8.3%) | 12 (23.1%) | 15 (15%) | 0.057 |
| Absent | 23 (95.8%) | 22 (91.7%) | 40 (76.9%) | 85 (85%) | |
The prevalence of upper concha pneumatization was 18% which was maximum in group with type 3 frontal sinus pneumatization (21%) and minimum in group with type 1 frontal sinus pneumatization (12.5%). The prevalence of middle concha pneumatization was 51% which was maximum in group with type 2 frontal sinus pneumatization (62.5%) and minimum in group with type 1 frontal sinus pneumatization (33.3%). However, the difference between the groups was not statistically significant (p = 0.646 and p = 0.108).
We evaluated and compared the prevalence of ethmoidal air cell variations in three frontal sinus pneumatization groups. The prevalence of agger nasi cell was maximum in group 3 (92.3%) and minimum in group 2 (83.3%), however the difference was not statistically significant (p = 0.49). The prevalence of Haller cell was maximum in group 3 (5.7%) and (4.2%) each equal in group 1 and 2. Again, the difference between the three groups was not statistically significant (p = 0.934). We also assessed the difference of Onodi cell prevalence between three frontal sinus pneumatization groups. It was maximum in group 3 (42.3%) and minimum in group 1 (12.5%). There was a significant difference between the three groups (p = 0.025).
The prevalence of maxillary sinus hypoplasia was analyzed and the difference between three groups was not statistically significant (p = 0.80). Furthermore, no significant differences were observed among the three groups in terms of sphenoid sinus pneumatization (p = 0.934).
Next, we evaluated and compared the prevalence of accessory pneumatization variants of sphenoid sinus in three frontal sinus pneumatization groups. Statistical analysis revealed significant differences in the prevalence of anterior clinoid process pneumatization and greater wing of sphenoid pneumatization among the three groups (p-values of 0.015 and 0.017, respectively). Notably, the highest prevalence of these variants was observed in group 3. However, there was no significant difference between the 3 groups with respect to pterygoid process pneumatization (p = 0.114).
The difference in prevalence of optic nerve types between three frontal sinus pneumatization groups was assessed in this study. Type 1 optic nerve was most frequent in Type 1 frontal sinus pneumatization group and least frequent in Type 3 frontal sinus pneumatization group. Conversely, type 3 and 4 optic nerves were more frequent in Type 3 frontal sinus pneumatization group and less frequent in Type 1 frontal sinus pneumatization group. The difference between three groups was statistically significant (p-value 0.026).
The prevalence of internal carotid artery dehiscence or protrusion in sphenoid sinus was also evaluated and it was most frequent in Type 3 group and least frequent in Type 1 group. The difference between three groups was found to be close to statistical significance (p = 0.057).
Discussion
This study was undertaken to determine the relationship between frontal sinus pneumatization and different anatomic variants of paranasal sinuses on computed tomography. All the patients were divided into three groups based on their extent of frontal sinus pneumatization and analysed for different paranasal sinus anatomic variants.
In this study, there was a statistically significant difference between the three groups considering Onodi cells, Anterior clinoid process pneumatization, Greater wing of sphenoid pneumatization and Optic nerve types. Type 3 frontal sinus pneumatization group had the most and type 1 group had the least prevalence of Onodi cells, Anterior clinoid process and greater wing of sphenoid pneumatization. Their overall prevalence in our study was 31%, 23% and 25% respectively. Thus excessive pneumatization of the frontal sinus may indicate the presence of these variations.
According to Yoon et al. (5), Onodi cells have been defined as endoscopically identifiable optic canal bulge or the presence of air cells either lateral, superior or superolateral to the sphenoid sinus and present in close approximation to optic nerve canal or Internal carotid artery canal (Fig. 3). The prevalence of Onodi cells varies in literature according to their description and modalities used for identification. The prevalence was 12%, 8%, and 25%, according to Arslan et al. (6), Unal et al. (7), and Nitinavakarn et al. (8) respectively. Yazici (2) found no significant statistical difference between the three frontal sinus groups and Onodi cells in his study.
Fig. 3.
CT scan of the paranasal sinuses (A and B), coronal and sagittal images in a patient with type 3 frontal sinus pneumatization show posterior-most ethmoid air cell that extends superior and lateral to the sphenoid sinus on right side—Onodi cell; (C and D), coronal and sagittal images of a central Onodi cell in a different individual with type 3 frontal sinus pneumatization (arrow, Onodi cells; asterisk, sphenoid sinuses)
Anterior clinoid process (ACP) is a bony projection of the sphenoid bone that is closely related to important structures of the skull base (Fig. 4). The prevalence of ACP pneumatization ranges from 4 to 29% in different studies (8–12). In our study, the overall prevalence of ACP pneumatization was 23%. It was maximum in type 3 frontal sinus pneumatization group, in which 18 out of 52 patients (34.6%) showed ACP pneumatization. There was a significant statistical difference between the three frontal sinus pneumatization groups, which was in agreement with the study done by Yazici (2), which showed similar results.
Fig. 4.
Accessory pneumatization variants of sphenoid bone – Coronal CT (A–C) in bone window in individuals with type 3 frontal sinus pneumatization shows pneumatization of left pterygoid process (arrow in A), bilateral pterygoid processes (arrows in B) and right pterygoid process with part of the right greater wing of sphenoid (arrow in C). Pneumatization of left anterior clinoid processes in A and B (arrowheads) is also seen. Axial CT (D) shows mild protrusion of the right internal carotid artery into the sphenoid sinus (arrow) in an individual with type 2 frontal sinus pneumatization
Tawfik et al. (13) reported greater wing of sphenoid pneumatization (Fig. 4) rate as 31.8% for Egyptian patients, Hewaidi et al. (14), 20% for Libyan patients and Lu et al. (15), 21.2% for Chinese patients. The prevalence of pneumatization of greater wing of sphenoid pneumatization in our study was 25%. It was maximum in type 3 frontal sinus pneumatization group, in which 19 out of 52 patients (36.5%) showed greater wing of sphenoid pneumatization. There was a significant statistical difference between the three groups with higher degree of frontal sinus pneumatization correlating with pneumatization of greater wing of sphenoid, which was in agreement with the study done by Yazici (2).
In our study, the overall prevalence of pterygoid process pneumatization (Fig. 4) was 33%. It was maximum in type 3 frontal sinus pneumatization group, in which 22 out of 52 patients (42.3%) showed pterygoid process pneumatization. There was no significant statistical difference between the three frontal sinus pneumatization groups. However, in contrast, Yazici (2), in his study showed statistical difference between them. This difference may be attributed to different populations or study sample size.
Optic nerve is a vital structure in close relation to posterior ethmoid and sphenoid sinuses. Damage to the optic nerve is one of the major complications of endoscopic sinus surgeries. Delano et al. (4), classified the relation of optic nerve canal to the posterior ethmoid and sphenoid sinus into four categories (Fig. 5). In their study, Type-1 optic nerve canal occurred in 76% of patients. In our study too, Type-1 optic nerve canal was the most common, with a 58% prevalence. In study done by Delano MC et al. 15% showed Type-2, 6% showed Type-3, and Type-4 optic nerve canal was seen among 3% of the patients. In our study, the prevalence of Type-2 and Type-3 optic nerve canal was 17% and 13%, respectively. However, the prevalence of Type-4 optic nerve canal (12%) in our study was much higher than in the Delano et al. study. Yazici (2), showed statistically significant difference between frontal sinus pneumatization and optic nerve types, with type 1 optic nerve most common in people with type 1 frontal sinus pneumatization. Our study also showed similar results, with 17 out of 24 patients in the type 1 frontal sinus pneumatization group having type 1 optic nerve canal. Type 3 and Type 4 optic nerves were more common in type 3 frontal sinus pneumatization group. Our study showed a significant statistical difference between frontal sinus pneumatization and optic nerve types.
Fig. 5.
Coronal CT in bone window shows Delano’s optic nerve types (arrows): A Type 1 nerve courses adjacent to the sphenoid sinus without indentation of the sinus wall, B Type 2 nerve courses adjacent to the sphenoid sinus, causing indentation of the sinus wall, C Type 3 nerve courses through the sphenoid sinus with at least 50% of nerve surrounded by air, D Type 4 nerve courses immediately adjacent to the sphenoidal sinus and the posterior ethmoidal air cell. Central Onodi cell is also seen (asterisk in D)
In our study, we evaluated the prevalence of upper and middle concha pneumatization with respect to frontal sinus pneumatization groups (Fig. 6). In our study, the overall prevalence of upper and middle concha pneumatization was 18% and 51%, respectively (Fig. 3). In literature, there has been wide variation in the prevalence of these variations, with upper concha pneumatization prevalence varying from 12.2 to 46% and middle concha pneumatization prevalence varying from 13 to 53%, depending on the recency and the place the study was performed (16–18). In our study, the prevalence of upper concha pneumatization was maximum in group with type 3 frontal sinus pneumatization (21.2%) and minimum in group with type 1 frontal sinus pneumatization (12.5%). The prevalence of middle concha pneumatization was maximum in group with type 2 frontal sinus pneumatization (62.5%) and minimum in group with type 1 frontal sinus pneumatization (33.3%). There was statistically no significant difference between the three groups considering upper and middle concha pneumatization. This contradicted the study done by Yazici (2), which showed a significant association between frontal sinus pneumatization and conchal pneumatization. This could be attributed to a different study population and larger sample size in the above mentioned study.
Fig. 6.
Coronal CT scan of paranasal sinuses in bone window shows pneumatization of superior turbinate A on right side (arrow) and B bilaterally (arrows) in individuals with type 1 and type 2 frontal sinus pneumatization, respectively. Coronal CT shows (C and D) bilateral pneumatization of middle turbinates—concha bullosa (arrows) in individuals with type 3 frontal sinus pneumatization
Agger nasi is the anterior-most ethmoidal air cell and is seen in most of the patients. Its size may directly influence and determine the patency of the frontal recess and the anterior middle meatus. The overall prevalence of agger nasi cell in the literature varies from 56.7% to 95.3%, depending upon the target population (19, 20). In our study, we evaluated and compared the prevalence of agger nasi cells in 3 frontal sinus pneumatization groups. The overall prevalence of agger nasi cell was 89%. It was maximum in group 3 (92.3%) and minimum in group 2 (83.3%). There was no statistical significance between the three frontal sinus pneumatization groups.
According to Mathew et al. (21), Haller cells are recognized as air cells of any size, located along the medial portion of the orbital floor and/or the lamina papyracea inferior to the bulla ethmoidalis, and continuous with the ethmoid capsule. The prevalence of Haller cells in the literature is quite variable, ranging from 2.7% to 45.1% in different studies (22, 23). The overall prevalence of Haller cells was 5% in our study. There was no significant statistical difference between the three groups. However, Yazici (2), in his study, showed an association between the prevalence of Haller cells and the type of frontal sinus pneumatization, with higher degree of frontal sinus pneumatization correlating with higher prevalence of Haller cells.
The maxillary sinus is the first paranasal sinus to develop and is present at birth. Maxillary sinus hypoplasia is frequently reported, with the prevalence of hypoplasia reported in literature as high as 10.4%. In our study, the overall prevalence of maxillary sinus hypoplasia was 3%, with one subject in each of the three groups having hypoplasia of maxillary sinus. Ozcan et al. (25), classified hypoplastic maxillary sinuses using the classification system defined by Bolger et al. (26), and classified the frontal sinuses as aplastic or hypoplastic, medium-sized, and hyperplastic as previously described by Guerram et al. (3). They inferred that there is a statistically significant effect of maxillary sinus hypoplasia on frontal sinus pneumatization and marked the duo’s coexistence in their study. The incidence of frontal sinus hypoplasia and/or aplasia was significantly higher in patients with maxillary sinus hypoplasia compared to bilaterally normal maxillary sinuses in their study. On the contrary, our study evaluated the effect of frontal sinus pneumatization on maxillary sinus development and did not find any significant association between them.
Elwany et al. (27), divided the sphenoid sinus into presellar and postsellar types using a vertical line passing through the tuberculum sella boundary. Khanduri et al. (28), reported a case with combined aplasia of bilateral frontal and sphenoid sinus with hypoplasia of bilateral maxillary and ethmoid sinus. Combined aplasia of multiple sinuses is extremely rare, along with hypoplasia of other sinuses. In our study, we found no statistical difference between the type of frontal sinus pneumatization and the degree of sphenoid sinus pneumatization in our study.
Finally, we also analysed the association between frontal sinus pneumatization type and the presence of dehiscence or protrusion of the internal carotid artery in sphenoid sinus (Fig. 4). In current literature, the protrusion rate of ICA varies from 5.2 to 41% and the dehiscence rate varies from 1.5 to 30% (14, 29). The prevalence of internal carotid artery dehiscence or protrusion in sphenoid sinus according to three frontal sinus pneumatization groups was evaluated, and dehiscence or protrusion was most frequent in Type 3 frontal sinus pneumatization group (23%) and least frequent in Type 1 group (4.2%). The difference between the three frontal sinus pneumatization groups was close to statistical significance.
Conclusion
The relationship between frontal sinus pneumatization and various paranasal sinus variations was analysed in this study using paranasal sinus CT scan. The results showed that the type of frontal sinus pneumatization affects the presence of Onodi cell, anterior clinoid process, greater wing of sphenoid pneumatization, and optic nerve type. Surgeons who perform endoscopic sinus surgery, skull base surgery, or transsphenoidal surgery should carefully interpret and analyze preoperative paranasal sinus CT scans, particularly in cases of excessive frontal sinus pneumatization, to identify paranasal sinus variations and prevent potential complications or injury to important structures. This study is the first of its kind in Indian literature to evaluate the effects of frontal sinus pneumatization on paranasal sinus variations, but it had limitations due to its small sample size. Further studies with larger sample sizes are required for a more comprehensive evaluation.
Appendix
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