Analysis of the Relationship between the Location of the Anterior Ethmoid Artery and Keros Classification

Position of the anterior ethmoidal foramen and trauma to the cranial base during transconjunctival medial orbital decompression: a systematic literature review

PURPOSE

To review the literature on the location of the anterior ethmoidal foramen (AEF) and trauma during transconjunctival medial wall decompression.

METHODS

A comprehensive literature search was conducted using the PubMed, Embase, and Scopus databases, combining the terms "olfactory fossa" and "fovea ethmoidalis" with "trauma," "cerebrospinal fluid leak," "pneumocephalus," "orbital decompression," and "anterior ethmoidal artery" (AEA). All cases of cranial base trauma during medial orbital decompression and the anatomical studies on the location of the AEF and the course of the AEA were reviewed.

RESULTS

Ninety-four articles were identified, of which 37 were related to the AEF, 41 reported the course of the AEA, and 16 to reported cases of cranial base trauma. Out of these cases, 10 were related to transconjunctival medial orbital decompression, affecting 11 patients. Most AEFs are situated at the frontoethmoidal suture, but up to 38.15% of AEFs are located above the suture on the frontal bone. Most AEFs are adjacent to the roof of the ethmoidal sinus. The distance of the AEF to the cranial base increases in the presence of supraorbital ethmoidal cells (SOEC).

CONCLUSIONS

The position of the AEF is variable and should not be considered a safe landmark for all patients.

Asymmetry of the anterior ethmoidal artery in relation to the anterior skull base: a population-based study of 500 arteries

OBJECTIVE

To analyze variability in the distance between the Anterior Ethmoidal Artery (AEA) and the anterior Skull Base (SB), as well as the frequency of lateral asymmetry in a Latin American population using computed tomography.

METHODS

A total of 250 computed tomography scans of paranasal sinuses in coronal reconstruction (500 AEAs) were analyzed. After determining the image with the best anatomical view of the artery, the distance between its midpoint and the ethmoidal roof was measured, and the images were independently interpreted by 2 physicians.

RESULTS

Of the 500 AEAs, 279 (55.8%) adhered to or passed through the SB at a distance of 0mm. A total of 221 AEAs (44.2%) were at some distance from the SB, of which 107 (48.4%) were on the right side, ranging from 1.18 to 6.75mm, and 114 (51.5%) were on the left side, ranging from 1.15 to 6.04mm. The overall mean distance between the AEA and SB was 1.22 (SD=1.57) mm, increasing to 2.77 (SD=1.14) when the arteries adhered to the SB were excluded. Seventy-six individuals (30.4%) had a lateral distance variation > 1mm.

CONCLUSION

Our study includes the largest sample of AEA analyzed with computed tomography scans of paranasal sinuses. There was some distance between the AEA and SB in almost half the patients, and we found a high rate of lateral variability >1mm.

LEVEL OF EVIDENCE

Level 3.

Relation between anterior ethmoidal artery course on computed tomography and supraorbital ethmoid cell and Keros classification

PURPOSE

The anterior ethmoidal artery (AEA) is an important risk area in endoscopic sinus surgery. This study aimed to evaluate the course of AEA according to the Keros classification and the presence of supraorbital ethmoid cell (SOEC) and to prevent possible complications by emphasizing the importance of preoperative paranasal computed tomography (CT) imaging. This approach will increase the effectiveness of endoscopic sinus surgery and improve patient safety.

METHODS

The paranasal CT scan images of patients aged > 18 years between October 2020 and November 2021 from our center were retrospectively analyzed. The images were primarily evaluated in the coronal plane, and the sagittal and axial planes were utilized to evaluate variations in AEA regarding the skull base. Furthermore, the relation of AEA course with Keros classification and SOEC was evaluated. The study included 1000 patients aged 18-80 years (right and left, a total of 2000 samples).

RESULTS

Grade 3 AEA was the most common regarding the skull base. Keros Type 2 was the most common classification. Overall, 48.7% patients had SOEC. The incidence of Grade 3 AEA was higher among patients with SOEC and a higher Keros classification compared with those without SOEC and a lower Keros classification. Furthermore, Keros Type 3 was the most associated with SOEC presence.

CONCLUSION

Consistent with the literature, the probability of Grade 3 AEA in patients with high Keros classification and SOEC was significantly higher in our study. Therefore, we consider that preoperative imaging according to Keros classification and SOEC presence can predict AEA course and guide surgery.

Analysis of the Correlation of the Lamina Papyracea-to-Midline Distance with the Location of Anterior Ethmoidal Artery and Keros Classification

The aim of the study was to investigate the relations between anatomical structures that are susceptible to inadvertent injuries during the surgery using preoperative computed tomography (CT) scans. 153 CT scans were reviewed and the distance from the lamina papyracea (LP) to the midline and the distance of the anterior ethmoidal artery (AEA) to the skull base were measured bilaterally. Also, the depth of olfactory fossa was measured and categorized using the Keros classification. The measurements were analyzed to determine whether LP-to-midline distance was correlated with the distance between the AEA and the skull base and Keros classification. Additionally, correlation of Keros classification with the distance from the AEA to the skull base was investigated. In a total of 306 measurements, 26 (%8.49) were classified as Keros type I, 200 (65.35%) as Keros type II and 80 (25.14%) as Keros type III. Statistically, LP-to-midline distances on the right and left sides were significantly associated with the distance from the AEA to the skull base on the same side (R:p < 0.001, L:p = 0.01) and the Keros classification on the same side (R:p < 0.001, L:p = 0.004). Also, a significant association was found between the Keros classification and the distance from the AEA to the skull base (R:p < 0.001, L:p = 0.02). The locations of anatomical structures are defined in relation to each other during the development of maxillofacial bones. CT scans should be examined and anatomical structures and relations among them reviewed very carefully before ESS. Otherwise, some accidental injuries may arise during the surgery while trying to avoid complications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03931-x.

Biological sex as a modulator in rhinologic anatomy, physiology, and pathology: A scoping review

BACKGROUND

Biological sex is increasingly recognized as a critical variable in health care. The authors reviewed the current literature regarding sex-based differences in rhinology to summarize the data and identify critical knowledge gaps.

METHODS

A scoping review was conducted. Publications reporting sex-based differences in anatomy, physiology, and pathology focusing on disease prevalence, disease burden, and outcomes in rhinology were identified.

RESULTS

Seventy-five relevant manuscripts were identified. While paranasal sinuses are of similar size at birth, they become larger in males leading to differences in ostium location. Females outperform males in olfactory identification but only in the 18- to 50-year age group. Estrogen and progesterone administration can impact muscarinic and α1 -adrenergic nasal mucosa receptor density. Chronic rhinosinusitis (CRS) and CRS without nasal polyps are more prevalent in females while CRS with nasal polyps is more prevalent in males. CRS symptom burden is higher in females before and after endoscopic sinus surgery; however, no difference in endoscopic sinus surgery utilization was found based on sex. Allergic rhinitis is more common in males before puberty and in females after puberty. Epistaxis is more prevalent in males and postmenopausal females compared with premenopausal females, perhaps from differences in sex-hormonal and hypertension status. In nasopharyngeal carcinoma, the incidence of sinus abnormalities was higher in males than females.

CONCLUSIONS

Although many sex-based differences exist in rhinology, further research is necessary to offer evidence-based treatment guidelines. Gonadal hormones should be studied as a therapeutic in rhinologic pathology as baseline physiologic differences exist such as those found in nasal mucosa receptor density.

Supraorbital ethmoid cells (SOECs), anterior ethmoid artery notch and ethmoid roof relation in PNSCT

OBJECTIVES

We investigated supraorbital ethmoid cell (SOEC) presence and types in paranasal sinus computed tomography (PNSCT).

METHODS

The PNSCT images of 188 adult patients (93 males and 95 females) were evaluated as SOEC group (n = 87 sides), and non-SOEC group (n = 289 sides, control). In both groups, anterior ethmoid artery (AEA) notch-ethmoid roof distance and presence of AEA canal were evaluated. In the SOEC group, SOEC types (type 1 to 3) and SOEC angle are also examined.

RESULTS

SOEC was detected in 87 sides (23.13 %). SOEC type 2 was the most detected type (71.3 %). AEA notch-ethmoid roof distance of the SOEC group was significantly higher than those in the non-SOEC group. AEA notch-ethmoid roof distance of the SOEC Type 3 group was significantly higher than SOEC Type 2 group. AEA notch-ethmoid roof distance was 3.74 ± 1.81 mm in the SOEC group and 0.68 ± 1.16 mm in the non-SOEC group. When SOEC types were considered, this distance was 5.29 ± 2.66 mm in type 3, 3.35 ± 1.35 mm in type 2 and 3.48 ± 0.92 mm in type 1. In higher SOEC types, SOEC angle; and AEA notch-ethmoid roof distance increased.

CONCLUSION

In more pneumatized SOEC presence, SOEC angle increase, and AEA notch-ethmoid roof distance increases, AEA runs inferiorly in the ethmoid cells and freely below the skull base; and is more susceptible to injury. The surgeons should be more careful not to damage AEA in the FESS when detecting well-pneumatized SOECs (SOEC Type 3).

Correlation Analysis of the Pneumatization of the Supraorbital Ethmoid Cell and the Position of the Anterior Ethmoidal Artery

OBJECTIVES

This study aimed to measure the supraorbital ethmoid cell (SOEC) and characterize the relationship between the degree of SOEC pneumatization and the position of the anterior ethmoidal artery (AEA) in relation to the skull base.

METHODS

Computed tomography (CT) scans of 100 patients were analyzed. The correlation between the pneumatization of SOEC and the distance of the AEA from the skull base was explored by Spearman's correlation rho efficient test.

RESULTS

The distance of the AEA from skull base was 3.10 (2.60,3.60) mm in patients with SOEC compared with 0.6(0.40,2.10)mm in those without(P < .001). In 50.5% of the patients, the AEA was located below the skull base; the incidence of this localization was significantly higher in those with SOEC than in those without (78.79%vs22.77%, P < .001). Compared to female patients, male patients owned greater SOEC height (9.65vs8.20mm, P = .007). The SOECs volume (r = 0.45, P < .001), height (r = .30, P = .003), and transverse diameter (r = 0.28, P = .005) were all significantly correlated with the distance of the AEA from the skull base.

CONCLUSIONS

The pneumatization of SOEC critically impact the distance between the AEA and skull base. The higher the degree of pneumatization, the farther from the skull base the AEA will be, increasing the risk of complications during nasal endoscopic surgery. These results provide an important reference for protecting the AEA during nasal endoscopic surgery.

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.

The important adjacent structures for anterior ethmoidal artery in FESS: Anterior ethmoidal artery canal angle, supraorbital ethmoid cells and Keros classification

OBJECTIVES

This study investigated the visualization of the anterior ethmoidal artery (AEA) as notch, canal and sulcus, its relationship between supraorbital ethmoid cells (SOECs) and the Keros classification of the olfactory fossa on paranasal sinus computerized tomography (PNSCT).

METHODS

In this retrospective study, the paranasal sinus computerized tomography (PNsCT) images of 204 patients (103 males and 101 females) were analyzed. AEA canal, notch and sulcus, SOECs, the distance between AEA notch and ethmoid roof, AEA canal angle and Keros classification of the olfactory fossa were evaluated.

RESULTS

AEA notch in all patients and AEA canal (37.6 to 45.6%) and AEA sulcus (53.5 to 61.2%) were visualized. In the AEC canal and sulcus visualized patients, the Keros classification revealed higher. AEA notch and ethmoid roof distance increased in patients with higher Keros types. The presence of SOECs was significantly higher in males (41.7%) than females (19.8%) on the left side. There was a positive correlation between SOEC presence and Keros classification. In patients with SOEC, bilateral AEA canal and sulcus visualized more; and bilateral AEA notch and ethmoid roof distance increased. On the right side, the AEA canal angle of the males was significantly higher than that of the females. In patients with SOEC, the left AEA canal angle also increased.

CONCLUSION

When detected SOECs and higher Keros types, the AEA was detected away from the skull base, AEA notch-ethmoid roof distance increased; and the AEA canal angle increased. To avoid intracranial penetrations, PNSCT should be evaluated carefully during the preoperative period.

Variability of the Anterior Ethmoid Artery in Endoscopic Sinus Surgery

INTRODUCTION

The anterior ethmoidal artery (AEA) demonstrates anatomic variability relative to its descent from the anterior skull base. Our study's objective was to assess for correlation of AEA descent and laterality, in addition to correlation of AEA descent and the presence of supraorbital ethmoid cells (SOEC) and concha bullosae (CB).

METHOD

A retrospective study was performed at a tertiary rhinology center from January 2019 to January 2020. Noncontrast maxillofacial computed tomography scans were examined independently by 2 fellowship trained rhinologists. The vertical distance from both left and right AEAs to the ipsilateral skull base were compared and correlated with the presence of ipsilateral SOEC and CB.

RESULTS

Computed tomography scans from 50 subjects were included. Mean age was 50.68 years (40% females). The distance of AEA to the skull base was greater on the left when compared to the right (62% vs 48%) (P < .05). The left AEA had an average descent of 2.84 mm versus 1.78 mm on the right (P < .05). An SOEC was present in 56% of cases. Thirty-eight percent of subjects had both SOEC and AEA descent on the right, while 52% of subjects had both on the left. This reached a statistical significance on both sides (P < .05). Concha bullosa was present in 35% of cases, with both AEA descent and CB present in 16% on the right, and 32% on the left.

CONCLUSION

The AEA displays variability in vertical descent from the skull base, with greater variability on the left. These findings implore vigilance with evaluation of preoperative imaging and during sinus surgery, especially in the presence of SOEC and CB.

Anterior Ethmoidal Artery: A Computed Tomography Analysis and New Classifications

Objective  to determine the anterior ethmoidal artery (AEA) anatomy and variations by computed tomography (CT) in adult and their relations to and presents new AEA classifications. Methods  One hundred and fifty paranasal CT scans (300 sides) were included. Axial images were acquired with multiplanar reformates to obtain delicate details in coronal and sagittal planes. Results  One hundred and forty-four AEAs canal (48%), 293 AEAs foramen (97.7%), and 229 AEAs sulcus could be detected (76.3%). The mean AEA intranasal length was 6.7 ± 1.27 mm (range: 4.24-10.6 mm). The mean angle between AEA and lamina papyracea was 105.49 ± 9.28 degrees (range: 76.41-129.76 degrees). Of them, 95.8% AEAs had an angle with lamina >90 degrees, while 4.2% had angle <90 degrees. The mean angle between AEA and lateral lamella of cribriform plate was 103.95 ± 13.08 degrees (range: 65.57-141.36 degrees). Of them, 87.5% AEAs had an angle >90 degrees and 12.5% had an angle <90 degrees. The mean distance between AEA and skull base was 1.37 ± 1.98 mm (range: 0-8.35 mm). The AEA types in relation to skull base was type 1 (0-2 mm from skull base; 64.6%), type 2 (2-4 mm; 22.2%), type 3 (4-6 mm; 11.1%), and type 4 (>6 mm; 2.1%). The mean distance between the AEA and frontal sinus ostium was 9.17 ± 4.72 mm (range: 0-25.36 mm). AEA classification according to distance from AEA to frontal sinus ostium was 17.4% type 1 (<5 mm), 41.7% type 2 (5-10 mm), 31.9% type 3 (10-15 mm), and 9% type 4 (>15 mm). Conclusion  Provided AEA details improve surgeons' awareness of AEA variations in the endoscopic field and can help residents in training.

An artificial intelligence algorithm that differentiates anterior ethmoidal artery location on sinus computed tomography scans

OBJECTIVE

Deep learning using convolutional neural networks represents a form of artificial intelligence where computers recognise patterns and make predictions based upon provided datasets. This study aimed to determine if a convolutional neural network could be trained to differentiate the location of the anterior ethmoidal artery as either adhered to the skull base or within a bone 'mesentery' on sinus computed tomography scans.

METHODS

Coronal sinus computed tomography scans were reviewed by two otolaryngology residents for anterior ethmoidal artery location and used as data for the Google Inception-V3 convolutional neural network base. The classification layer of Inception-V3 was retrained in Python (programming language software) using a transfer learning method to interpret the computed tomography images.

RESULTS

A total of 675 images from 388 patients were used to train the convolutional neural network. A further 197 unique images were used to test the algorithm; this yielded a total accuracy of 82.7 per cent (95 per cent confidence interval = 77.7-87.8), kappa statistic of 0.62 and area under the curve of 0.86.

CONCLUSION

Convolutional neural networks demonstrate promise in identifying clinically important structures in functional endoscopic sinus surgery, such as anterior ethmoidal artery location on pre-operative sinus computed tomography.

Reliability of the supraorbital ethmoid cell vs Keros classification in predicting the course of the anterior ethmoid artery

BACKGROUND

We previously showed that the supraorbital ethmoid cell (SOEC) is a reliable landmark for identifying the anterior ethmoid artery (AEA). Recent data have suggested that Keros classification is also a dependable predictor. We aim to characterize the location of the AEA and its relation to the skull base in patients with and without SOEC using the Keros classification.

METHODS

Retrospective radiographic evaluation of computed tomography (CT) scans of 76 patients (40 with SOEC, 36 without) was conducted. Distance of AEA from skull base and prevalence of AEA outside of the skull base were measured on each side and compared between groups using the 2-sample t test and χ² test, respectively. Subgroup analysis was carried out based on the Keros classification.

RESULTS

Mean distance of AEA from the skull base was 1.32 ± 1.5 mm in patients with SOEC and 0.47 ± 1.08 mm in those without (p < 0.001). Prevalence of AEA outside of the skull base was 53.8% in those with SOEC and 18.1% in those without (p < 0.001). Comparing patients with SOEC to those without, AEA was found below the skull base in 30% vs 0% of cases with Keros type 1 (p = 0.45), 58% vs 14.5% with Keros type 2 (p < 0.001), and 60% vs 50% with Keros type 3 (p = 0.72).

CONCLUSION

The presence of SOEC is associated with a higher prevalence of the AEA coursing below the level of the skull base in all Keros types, thus placing the artery at greater risk for injury. Careful surgical planning is needed to avoid potential orbital complications.