Analysis of the Agger nasi cell and frontal sinus ostium sizes using computed tomography of the paranasal sinuses

Anatomical variations of the frontal sinus: A computed tomography-based study

Background: The pneumatization of the frontal sinus is variable between individuals, including monozygotic twins. The volumetric anatomic variants of the frontal sinus are classified into aplasia, hypoplasia, medium-sized, and hyperplasia. We aimed to study the frontal sinus morphology in Omani patients using computed tomography (CT) evaluations. Methods: Retrospectively, 1220 frontal sinus CT scans from 610 patients investigated at Sultan Qaboos University Hospital, Oman, from January 2019 to December 2020 were reviewed. The frontal sinus morphology was classified according to the classification proposed by Guerram et al. The Chi-square test was used to determine the influence of sex. Results: With regard to the unilateral occurrence, the most prevalent frontal sinus category observed was medium-sized (13.3%), followed by hyperplasia (7.9%), hypoplasia (5.4%), and aplasia (2%) categories. Similarly, in bilateral occurrence, the most common frontal sinus category observed was medium-sized (53%), followed by hyperplasia (13.1%), hypoplasia (3.4%) and aplasia (2%) categories. Right and left frontal sinus aplasia were observed in 2.1% and 1.8% of cases, respectively. In terms of sex influence, the left unilateral ( p<0.01) and the bilateral hypoplasia ( p<0.05) were significantly higher in females. On the other hand, the left unilateral ( p<0.01) and the bilateral hyperplasia ( p<0.05) were higher in males. Conclusions: The baseline data of frontal sinus category frequencies reported in the present study is helpful in the diagnostic evaluation of sinusitis in the clinical setting. The preoperative recognition of frontal sinus types, particularly frontal sinus aplasia in multiplanar CT scans, is crucial to avoid unexpected complications while performing endoscopic sinus surgery.

Anatomic misconceptions regarding the agger nasi cell: A preliminary analysis utilizing endoscopic anatomic dissection and three-dimensional computed tomography

The agger nasi cell is a key anatomic landmark in endoscopic frontal sinus surgery. However, discord amongst authors regarding anatomic definition and prevalence raises questions of its suitability as a surgical landmark. The purpose of this investigation is to evaluate the agger nasi cell using radiographic imaging correlated with endoscopic anatomic dissection to consider the cell's role as a surgical landmark and to explore if three-dimensional computed tomography (3D-CT) technology can provide enhanced insight into this anatomy. CT scans of 11 cadaveric sinonasal complexes were studied using triplanar CT or 3D-CT scanning with stereoscopic 3D imaging. Endoscopic dissections were performed and video recorded. Attention was given to identify agger nasi pneumatization and its origin. Pneumatization of the agger nasi region was noted in 4/11 cases (36.4%) (in two cases the pneumatization arose from the frontal recess, in two from a true agger nasi cell). The agger nasi region appeared as solid unpneumatized bone in 4/11 cases (36.4%). In 3/11 cases (27.3%) limited pneumatization was noted, bordering on but not pneumatizing the agger nasi proper. It may be confusing for otolaryngologic surgeons in training to rely on the "agger nasi cell" as a surgical landmark due to misconceptions regarding the anatomy, prevalence and anatomic definitions. Using standard CT scans to teach anatomy may have shortcomings as compared to the gold standard of surgical dissection. However, new 3D-CT holds promise to more accurately reflect small microanatomic features and provide an improved road map of a patient's anatomy in surgery.

Radiological anatomical variations of the lateral nasal wall and anterior skull base amongst different populations: A systematic review and meta-analysis

OBJECTIVES

To determine the anatomical variations of the lateral nasal wall and anterior skull base amongst populations in different geographical regions.

DESIGN

Systematic review and meta-analysis.

METHODS

Using PRISMA guidelines, SCOPUS and PUBMED databases were searched from inception until 1 March 2022. The regions and populations identified were from Europe, Asia, Middle East, Australia-New Zealand-Oceania, South America, North America and Africa. Random-effects model was used to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic and Cochran's Q test.

MAIN OUTCOME MEASURES

Anatomical variations of the lateral nasal wall and anterior skull base confirmed by computed tomography scan.

RESULTS

Fifty-six articles were included with a total of 11 805 persons. The most common anatomical variation of the ostiomeatal complex was pneumatization of the agger nasi (84.1%), olfactory fossa was Keros type 2 (53.8%) and ethmoids was asymmetry of the roof (42.8%). Sphenoethmoidal and suprabullar cells have a higher prevalence in North Americans (53.7%, 95% CI: 46.00-61.33) while asymmetry of ethmoid roof more common in Middle Easterns (85.5%, 95% CI: .00-100). Bent uncinate process has greater prevalence in Asians while supraorbital ethmoid cells and Keros type 3 more common in non-Asians. The overall studies have substantial heterogeneity and publication bias.

CONCLUSION

Certain anatomic variants are more common in a specific population. The 'approach of analysis' plays a role in the prevalence estimates and consensus should be made in future studies regarding the most appropriate 'approach of analysis' either by persons or by sides.

A CBCT Study for Anatomic Variations of Osteomeatal complex in Patients With Cleft Lip and Palate

OBJECTIVE

To evaluate the anatomy and variations of osteomeatal complex (OMC) by comparing patients with nonsyndromic cleft lip and palate (CLP) and control group.

DESIGN

This case-control study was retrospectively analyzed using cone-beam computed tomography data.

SETTING

Istanbul University Faculty of Dentistry Department of Dentomaxillofacial Radiology.

PATIENTS

The study was conducted with 100 patients (44 females, 56 males) with CLP and 100 patients in the control group, which matched gender and age (with a maximum difference of 3 years).

VARIABLES

OMC variations are grouped as follows: ethmoidal, conchal, uncinate process, and septal variations. Then, we evaluated the presence of these OMC variations and compared them between the two groups.

STATISTICAL ANALYSIS

The McNemar's test was used to determine any significant differences between the groups for all indices at the 95% confidence level.

RESULTS

The most common anatomic variation in this study was Agger nasi cell (97%) and concha bullosa (97%) in the patients with CLP, while Agger nasi cell was the most common variation (99%) in the controls. Moreover, the atelectatic uncinate process was the least observed variation in both groups (1%). The incidences of paradoxical concha (58%;42%), bifid concha (29%;11%), deviated nasal septum (92%;80%) were significantly higher in the CLP group (p < 0.05).

CONCLUSIONS

The statistically significant results found when comparing OMC anatomy between the two groups reveal the importance of three-dimensional evaluation before functional endoscopic sinus surgery in patients with CLP.

Three-Dimensional Volumetric Analysis of Frontal Ethmoidal Cells and Evaluation of Influential Factors: A Helical Computed Tomography Study

In the present study, we aimed to assess frontal ethmoidal cells by using segmentation 3D software to establish a possible correlation between volume variation and both gender and age, as well as a relationship with Keros classification. Helical computed tomography images were obtained from 71 patients for analysis, in which the agger nasi cell, supra agger cell, supra agger frontal cell, supra bulla frontal cell, supraorbital ethmoidal cell, supra bulla cell, and frontal septal cell were identified and segmented to obtain their volume. Significant differences in volume were found for age and gender regarding agger nasi cells (p-value = 0.017), supra agger cells (p-value < 0.001), and frontal septal cells (p-value = 0.049). In the frontal septal cells, an increase of one year in age reduced the volume by 0.309, on average. According to Keros classification, the mean volumes were 10.07 and 25.64, respectively, for types II and III, both being greater than that of type I. Extracting volumetric data by using segmentation software in agger nasi cells, supra agger cells, and frontal septal cells may be useful for obtaining additional information related to age, in addition to possibly contributing to elucidating the anatomical variations in the region and an identification forensic tool.

Anatomic Variation for the Endoscopic Endonasal Transsphenoidal Approach

Knowledge of anatomy and its variations is the key to safe and efficient surgery. The endoscopic endonasal route to the sella has evolved to become the preferred route to access a wide variety of diseases. We describe the skeletal, vascular, and neural anatomic variations that could be encountered from the nasal phase, through the sphenoid phase, to the sellar phase of the operative exposure. A preoperative checklist is also provided.

Agger Nasi Cells Versus Lacrimal Cells and Uncinate Bullae in Cone-Beam Computed Tomography

The maxillary bone's frontal process, lacrimal bone, and ethmoidal labyrinth's uncinate process can each harbor pneumatizations, referred to as agger nasi cells (ANCs), lacrimal cells (LCs), and uncinate bullae (UBs), respectively. Different studies have failed to differentiate ANCs from LCs. We aimed at studying these 3 anatomic sites to establish the anatomical patterns that could be encountered. We performed a retrospective study on cone-beam computed tomography scans of 36 patients (72 sides); the anatomic identification was supported by bidimensional multiplanar reconstructions (MPRs) in all 3 planes and 3-dimensional volume renderings. We established 6 patterns of pneumatization as follows: (1) type I: single LCs (47%), (2) type II: distinctive adjacent LCs and ANCs (8%), (3) type III: LCs expanded as UBs (6%), (4) type IV: ANCs adjacent to LCs expanded with UBs (1%), (5) type V: ANCs expanded as LCs (27%), and (6) type VI: ANCs expanded as LCs and further expanded as UBs (11%). In a type I pattern case, we found a cell-in-cell aspect on sagittal MPRs, which was further demonstrated as being an anterolateral recess of the middle nasal meatus projected in front of an LC. Such an "agger nasi recess" of the middle meatus was not previously described. For an accurate anatomical diagnosis, computed tomography studies should use complementary MPRs in all anatomical planes, as well as 3-dimensional models, to avoid confusing ANCs with LCs and better document the drainage pathways.

A computed tomographic analysis of frontal recess cells in association with the development of frontal sinusitis

OBJECTIVE

This study was done to determine frontal recess anatomy cell variations and its association with frontal sinusitis. The incidence of frontal recess cells in the population, the presence of frontal recess cell variations in chronic rhinosinusitis and non-chronic rhinosinusitis and the association of frontal recess cell variation in the development of frontal sinusitis were also assessed.

METHODS

This was an observational, retrospective cross-sectional study of computed tomography (CT) scan of paranasal sinus that had been performed on patients in Hospital Universiti Sains Malaysia and Hospital Sultanah Bahiyah done from January 2009 until December 2016. The presence of frontal recess cells variation was compared with other populations.

RESULTS

A total of 312 sides from 156 patients' CT scan images were analyzed. Left and right sinuses were considered individually. A total of 63 sides showed evidence of frontal sinusitis, 37 were male and 26 were female, whereas 249 sides were clear from frontal sinus disease. It was not much difference in mean age for frontal sinusitis patient (46.51±14.00) and patients without frontal sinusitis (48.73±16.44). The percentage was almost equal for CRS and non-CRS groups regardless of side and gender. In our study, the frontal recess cell such as agger nasi cell was found in almost all patients 98.1%, frontal ethmoidal cell type 1, type 2, type 3 and type 4 comprised of 28.8%, 31.1%, 14.4% and 0% respectively. Whereas, suprabullar cell can be seen in 40.3%, supraorbital ethmoid cells 16.7%, frontal bullar cell 33.0% and inter-frontal sinus septal cells 10.8%. There was a statistically significant association between the presence of frontal bullar cell and the development of frontal sinusitis (p value<0.001).

CONCLUSION

The frontal recess cells variation in Malaysian subjects were almost similar to those reported in other Asian populations such as Japanese, Taiwanese, Chinese and Korean. Our study found that frontal bullar cells had a significant association with the development of frontal sinusitis than other frontal recess cells. The understanding of the frontal recess anatomical structures was very important as this would lead to a successful treatment of CRS and at the same time it helped the surgeon to have a better plan of endoscopic sinus surgery to prevent the disease recurrence and surgical complication.

The association of superior attachment of uncinate process with pneumatization of middle turbinate: a computed tomographic analysis

The frontal sinus outflow pathway is complex and can be influenced by the configuration of the uncinate process (UP). The UP can attach superior to the lamina papyracea, skull base, and middle turbinate. The factors associated with superior attachment remain unclear. This study analyzed the relationships between different types of superior UP attachment and characteristics of the surrounding structures including the agger nasi cell, skull base, and middle turbinate. This retrospective study utilized computed tomography images of 836 sides with identifiable sinus structure from 434 Taiwanese patients. Types of superior UP attachment, height of the ethmoid cribriform plate, prevalence of agger nasi cell, and degree of pneumatization of the middle turbinate were analyzed. In the current study, neither the presence of an agger nasi cell nor height of the cribriform plate had significant relationship with superior UP attachment type. However, UP attachment type was statistically significantly associated with pneumatized middle turbinate (PMT) type (p < 0.01). The PMT group had a higher incidence of UP attachment to the middle turbinate (38%) than the non-PMT group (18%). In the extensive PMT group, the incidence of UP attachment to the middle turbinate was high to 49%. In conclusion, superior UP attachment to the middle turbinate was associated with pneumatization of the middle turbinate. The UP has a greater tendency to attach to the middle turbinate in cases with more PMT.