Radiological anatomy of the anterior ethmoidal artery for functional endoscopic sinus surgery

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.

Implications of the olfactory fossa anatomy in intracranial complications of inferomedial orbital decompression

Two patients with thyroid eye disease underwent inferomedial orbital decompression complicated by a cerebrospinal fluid (CSF) leak. One of the cases developed a postoperative pneumocephalus resolved with conservative measures. In the second case, the CSF leak was managed intraoperatively. In both patients, a computed tomography (CT) scan revealed a pronounced slope of the lateral lamella of the cribriform plate, forming an obtuse angle with its lateral bony extension. When this anatomical disposition of the olfactory fossa (OF) is present, the course of the anterior ethmoidal artery (AEA) is usually embedded in the skull base, and its foramen should not be taken as the upper limit of the transconjunctival ethmoidectomy. The shape and relative height of the olfactory fossa and fovea ethmoidalis, and the course of the AEA should always be assessed before transconjunctival medial decompressions.

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.

A Simple Clinical Application for Locating the Anterior Ethmoidal Artery Using the Anterior Ethmoidal Foramen and the Anterior Nasal Spine

The anatomy and variations of the anterior ethmoidal artery (AEA) are clinically relevant. The anterior ethmoidal foramen (AEF) can be used to locate the initial site of the AEA, and the anterior nasal spine (ANS) is a constant bony marker in the anterior nasal atrium. However, there is no relevant research on AEF and ANS targeting the AEA. Hence, this study aimed to accurately locate the AEA through AEF and ANS using computed tomography.

Computed tomography assessment of anterior ethmoidal canal dehiscence: An interobserver agreement study and review of the literature

PURPOSE

The anterior ethmoidal artery can be injured in functional endoscopic sinus surgery. The ability of computed tomography (CT) to identify dehiscence of the anterior ethmoidal canal (AEC) has not been widely evaluated. The aim of this study was to evaluate the interobserver agreement in the CT assessment of AEC dehiscence.

METHODS

We conducted a retrospective review of consecutive CT scans of the paranasal sinuses (PNS) between January 1, 2012, and December 31, 2012. Two neuroradiologists separately assessed the presence of AEC dehiscence, the presence of PNS opacification, and the best CT plane to evaluate the AEC. Statistical analysis included descriptive analysis and interobserver agreement (kappa coefficient).

RESULTS

The AEC was below the skull base in 199 (22.3%) cases. Dehiscence of the AEC was found in 13.2% for reader 1 and in 7.3% for reader 2. The interobserver agreement for identification of AEC dehiscence was only fair (κ = 0.246). The interobserver agreement for the AEC dehiscence in cases with opacification of ethmoidal air cells was substantial (κ = 0.754).

CONCLUSION

The suboptimal interobserver agreement could potentially limit the usefulness of CT scans for routine assessment of AEC dehiscence. In patients with PNS opacification, CT scans could still add valuable information regarding AEC dehiscence.

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.

In Vivo Computed Tomography Direct Volume Rendering of the Anterior Ethmoidal Artery: A Descriptive Anatomical Study

Introduction  The clinical relevance of the anatomy and variations of the anterior ethmoidal artery (AEA) is outstanding, considering its role as a landmark in endoscopic surgery, its importance in the therapy of epistaxis, and the high risks related to iatrogenic injuries. Objective  To provide an anatomical description of the course and relationships of the AEA, based on direct computed-tomography (CT)-based 3D volume rendering. Methods  Direct volume rendering was performed on 18 subjects who underwent (CT) with contrast medium for suspected cerebral aneurism. Results  The topographical location of 36 AEAs was assessed as shown: 10 dehiscent (27.8%), 20 intracanal (55.5%), 6 incomplete canals (16.7%). Distances from important topographic landmarks are reported. Conclusion  This work demonstrates that direct 3D volume rendering is a valid imaging technique for a detailed description of the anterior ethmoidal artery thus representing a useful tool for head pre-operatory assessments.

Anatomical variations of anterior ethmoidal artery and their significance in endoscopic sinus surgery: a systematic review

PURPOSE

Anterior ethmoidal artery (AEA) is at risk of injury in endoscopic sinus surgery due to its location. The aim of this review was to assess the anatomical variations of AEA and their significance.

METHODS

A literature search was performed on PUBMED, SCOPUS AND EMBASE. The following keywords were used: ethmoidal artery; anterior ethmoidal artery; anterior ethmoidal canal; ethmoid sinus; ethmoid roof; skull base. The search was conducted over a period of 6 months between October 2016 and April 2017.

RESULTS

105 articles were retrieved. 76 articles which were either case reports or unrelated topics were excluded. Out of the 29 full text articles retrieved, 16 articles were selected; 3 were cadaveric dissection, 5 combined cadaveric dissection and computed tomography (CT) and the rest were of CT studies. All studies were of level III evidence and a total of 1985 arteries were studied. Its position at the skull base was influenced by the presence of supraorbital ethmoid cell (SOEC) and length of the lateral lamella of cribriform plate (LLCP). Inter population morphological variations contribute to the anatomical variations.

CONCLUSIONS

The average diameter of AEA was 0.80 mm and the intranasal length was 5.82 mm. 79.2% was found between the second and third lamellae, 12.0% in the third lamella, 6% posterior to third lamella and 1.2% in the second lamella. Extra precaution should be taken in the presence of a well-pneumatized SOEC and a long LLCP as AEA tends to run freely below skull base.

The Preoperative Sinus CT: Avoiding a "CLOSE" Call with Surgical Complications

Although functional endoscopic sinus surgery is an effective means of treating patients with recurrent and refractory sinusitis, the procedure is not without risk of serious surgical complications. Preoperative computed tomography (CT) affords radiologists the opportunity to prospectively identify anatomic variants that predispose patients to major surgical complications; however, these critical variants are not consistently evaluated or documented on preoperative imaging reports. The purpose of this review is to illustrate important anatomic variants and landmarks on the preoperative sinus CT with a focus on those that predispose patients to surgical complications. These critical variants and landmarks can be quickly recalled and incorporated into the preoperative imaging report through the use of the mnemonic "CLOSE": Cribriform plate, Lamina papyracea, Onodi cell, Sphenoid sinus pneumatization, and (anterior) Ethmoidal artery. This approach will greatly enhance the value of the preoperative imaging report for referring otolaryngologists and help reduce the risk of surgical complications. (©) RSNA, 2016 Online supplemental material is available for this article.

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

Objective We sought to identify a relationship between skull base height and anterior ethmoid artery (AEA) anatomy. Study Design Retrospective radiologic chart review. Setting University of Arkansas for Medical Sciences. Subjects Patients seen in a tertiary rhinology clinic between September 2014 and October 2015. Methods Review of 101 maxillofacial computed tomography scans with institutional review board approval. Skull base height and AEA locations were measured on each side. Prevalence of the AEA outside of the skull base and distance of the AEA from skull base were calculated and compared with Keros classification using χ² testing. Comparisons of skull base height between sexes and age and distance between skull base and the AEA among Keros 2 and Keros 3 patients were made using an unpaired, 2-tailed t test. Results The AEA was located below the skull base in 25.7% of cases and more often in Keros type 3 (55%) than in Keros type 2 (29.5%) or Keros type 1 (0%) ( P < .05). Male patients were significantly more likely to have a greater average skull base height (5.25 vs 4.28 mm) and to have AEAs below the skull base (38.4% vs 14.8%). In addition, the distance of the AEA from the skull base was significantly higher in Keros type 3 patients compared with Keros type 2 patients (4.55 vs 3.42 mm, P = .001). Conclusions Variations in the AEA pathway occur more in male patients and those with higher Keros classifications. The distance between the variant AEA and the skull base increases with higher Keros classification. Keros classification can yield insight to the location of the AEA.

The ethmoidal arteries: a cadaveric study based on cone beam computed tomography and endoscopic dissection

PURPOSE

To describe the anatomical variability of the ethmoidal arteries (EAs). To evaluate the reliability of cone beam computed tomography (CBCT) in preoperative assessment of EAs.

METHODS

Fourteen cadaver heads underwent CBCT and endoscopic dissection. The following anatomical features were evaluated for anterior (AEA), middle (MEA), and posterior (PEA) EAs: presence, cranio-caudal position, antero-posterior position, and dehiscence of the bony canal. Accuracy of radiological assessment was calculated.

RESULTS

AEA, MEA, and PEA were identified in 100, 28.6, and 100% of sides. They were caudal to the skull base in 60.7, 25, and 17.9%, respectively. CBCT showed a high accuracy in identifying these features. The antero-posterior position of EAs, which was highly variable, was correctly assessed by CBCT. A dehiscent bony canal of AEA, MEA, and PEA was found in 46.4, 12.5, and 28.6% of sides, respectively. Accuracy of CBCT in picking up this feature was poor but negative predictive value was high.

CONCLUSIONS

CBCT was adequate in identifying and localizing EAs. In addition, it can be used to exclude the presence of MEA and dehiscence of ethmoidal canals, whereas the accuracy in detecting these anatomic variants was low.

Three-dimensional evaluation of the danger zone of ethmoidal foramens on the frontoethmoidal suture line on the medial orbital wall

INTRODUCTION

It is clear that the importance of the ethmoidal foramen (EF) is based on its vascular contents. The frontoethmoidal suture (FS) line is recommended as more reliable navigational landmark for identifying the EF.

MATERIALS AND METHODS

The vertical orientation between the EF and the FS line was studied in 188 orbits using a computer software program.

RESULTS

146 anterior EFs (77.7 %) and 42 anterior EFs (22.3 %) were situated in the FS line as intrasutural and extrasutural, respectively. 146 posterior EFs (77.25 %) and 8 posterior EFs (4.25 %) were presented as intrasutural and extrasutural, respectively. Although accessory EFs were detected in 25.5 % specimen exhibited an extrasutural location. Majority of the EFs (1-4 EFs) were situated on the FS line. The mean distances from the FS and the anterior EF, the posterior EF and the accessory EF were measured as 2.1 ± 0.5, 2.0 ± 1.5 and 2.3 ± 1.2 mm, respectively. The range of the distances from the FS to the anterior EF, posterior EF and accessory EF were -1.2 to 3.32 , -1.02 to 5.76 and -1.1 to 3.65 mm, respectively.

CONCLUSION

The ranges of EF changed within 1-6 mm. As the FS is not a single point, it is more suitable to make the incision 7 mm above the suture line. The data from this study to help the orbital surgeons explain and avoid unexpected hemorrhage during the orbital procedures such as posttraumatic orbital reconstruction, orbital tumor resections, anterior skull base reconstruction, and orbital decompression surgery.

Morphometric study of the medial orbital wall emphasizing the ethmoidal foramina

PURPOSE

Ethmoidal foramina on the medial orbital wall show a higher incidence of variation. Surgeons performing endonasal, anterior cranial fossa and medial orbital wall surgeries must be aware of these variations as they are a source of hemorrhage and also serve as landmark in proximity to the orbital apex.

AIM

The present study aims to describe the morphometric distances of various ethmoidal foramina between anterior lacrimal crest to optic canal in south Indian dry human skulls.

MATERIALS AND METHOD

The study was done on 44 adult dry human skulls. The occurrence of Ethmoidal foramina was noted by direct inspection. The distance of Ethmoidal foramina from anterior lacrimal crest to optic canal was measured with the help of ruler, probe and magnifying glass.

RESULTS

The Posterior ethmoidal foramina were found in all 44 skulls bilaterally. Middle ethmoidal foramen was present in 12 and 13 skulls on right and left, respectively. Anterior ethmoidal foramen was found in 38 and 37 skulls on right and left, respectively. The distance between anterior lacrimal crest (ALC) and posterior lacrimal crest (PLC) was in the range of 3-8 mm and that of ALC to anterior ethmoidal foramen was in the range of 24-30 mm. The range of distance between anterior ethmoidal foramen to posterior ethmoidal foramen was 9-17 mm and that between posterior ethmoidal foramen to optic canal was 5-13 mm.

CONCLUSION

These observations would help to predict the anatomical variations in the position of ethmoidal foramina with respect to anterior and posterior lacrimal crest and ensure the safe and precise performance of medial orbital wall surgeries to avoid injuries to the important neurovascular bundles passing through various foramina and fissures.

Extracranial ligation of ethmoidal arteries before resection of giant olfactory groove or planum sphenoidale meningiomas: 3 illustrative cases with a review of the literature on surgical techniques

Object

There are several surgical techniques for reducing blood loss—open surgical and endoscopic—prior to resection of giant anterior skull base meningiomas, especially when preoperative embolization is risky or not technically feasible. The authors present examples of an institutional experience using surgical ligation of the anterior and posterior ethmoidal arteries producing persistent tumor blush in partially embolized tumors.

Methods

The authors identified 12 patients who underwent extracranial surgical ligation of ethmoidal arteries through either a transcaruncular or a Lynch approach. Of these, 3 patients had giant olfactory groove or planum sphenoidale meningiomas. After approval from the institution privacy officer, the authors studied the medical records and imaging data of these 3 patients, with special attention to surgical technique and outcome. The variations of ethmoidal artery foramina pertaining to this surgical approach were studied using preserved human skulls from the Hamann-Todd Osteological Collection at the Museum of Natural History, Cleveland, Ohio.

Results

The extracranial ligation was performed successfully for control of the ethmoidal arteries prior to resection of hypervascular giant anterior skull base meningiomas. The surgical anatomy and landmarks for ethmoidal arteries were reviewed in anthropology specimens and available literature with reference to described surgical techniques.

Conclusions

Extracranial surgical ligation of anterior, and often posterior, ethmoidal arteries prior to resection of large olfactory groove or planum sphenoidale meningiomas provides a safe and feasible option for control of these vessels prior to either open or endoscopic resection of nonembolized or partially embolized tumors.

Educational value of a preoperative CT sinus checklist: a resident's perspective

OBJECTIVE

The objective of this study is to evaluate the educational value and effectiveness of a preoperative computed tomography (CT) sinus anatomy checklist as a teaching method from the perspective of otolaryngology residents.

DESIGN

Between 2009 and 2011, 15 otolaryngology residents completed a CT sinus anatomy checklist prior to the start of sinus surgery cases. A cross-sectional brief Likert-type questionnaire assessed the resident experience with the checklist. Nine items explored its perceived utility, role in the preoperative setting, incorporation into practice, and recall.

SETTING

St. Michael's Hospital, tertiary care hospital.

PARTICIPANTS

Otolaryngology residents rotating through St. Michael's Hospital between 2009 and 2011 were enrolled into this study. A total of 15 residents entered and finished the study.

RESULTS

Overall, all residents strongly agreed that the checklist was useful. It ensured that the CT imaging was properly reviewed and increased their comfort level with the relevant anatomy. Nearly all the residents continue to use this checklist even after completing the rotation with the senior author (JML).

CONCLUSIONS

The CT sinus anatomy checklist was perceived as useful overall by otolaryngology residents. In the future, checklists should be applied to other areas of head and neck surgical training to further standardize preoperative planning.

Searching for the cheese: does ethmoid pneumatization affect the location of the anterior ethmoid artery?

Endoscopic sinus surgery is a widely used technique in otolaryngologic practice. To avoid complications, the locations of important anatomical structures, such as the anterior ethmoid artery (AEA), should be determined preoperatively. We want to evaluate the effect of ethmoid cavity pneumatization on the location of the AEA and to determine consistent landmark(s) for locating the AEA. 524 consecutive patients undergoing sinus CT scans between February and October 2012 were reviewed retrospectively. After the exclusion criteria were applied, 150 CT scans (300 sides) were selected for the study. A statistically significant positive correlation was found between ethmoid pneumatization and the distance of the AEA to the attachment of the inferior turbinate to the lateral nasal wall (Spearman's rho = 0.305; p < 0.001). Likewise, a statistically significant positive correlation was found between ethmoid pneumatization and the distance between the AEA and the frontonasal junction (Spearman's rho = 0.219; p < 0.001). We found that the artery was located mostly between the second and third lamellae [n 211 (71 %) cases]. There was no statistically significant correlation between ethmoid pneumatization and AEA location in terms of the lamellae. Increased ethmoid volume increases the distance of the AEA from the frontonasal junction and the lateral attachment of the inferior turbinate. However, increased pneumatization of the ethmoid cavity did not affect AEA localization in terms of the lamellae. Based on our findings, we suggest that using the lamellae to locate the AEA is reliable.

Endoscopic anterior skull base surgery: intraoperative considerations of the crista galli

We sought to measure the anatomic dimensions of the crista galli in a consecutive series of patients undergoing the endoscopic transcribriform approach for anterior skull base tumors at a tertiary academic university hospital. We performed a retrospective chart review of patients undergoing purely endoscopic transcribriform surgery for sinonasal and skull base lesions. Main outcome measures included radiological dimensions of the crista galli. A total of 12 patients were identified and treated by the senior authors at the University of Pennsylvania. The average crista galli dimensions were 12.7 ± 2.4 mm (anterior-posterior) and 12.9 ± 2.5 mm (cranial-caudal dimension). Knowledge of the dimensions of the crista galli is important in preoperative planning for both instrumentation and access.

Management of intractable spontaneous epistaxis

BACKGROUND

Epistaxis is a common otolaryngology emergency and is often controlled with first-line interventions such as cautery, hemostatic agents, or anterior nasal packing. A subset of patients will continue to bleed and require more aggressive therapy.

METHODS

Intractable spontaneous epistaxis was traditionally managed with posterior nasal packing and prolonged hospital admission. In an effort to reduce patient morbidity and shorten hospital stay, surgical and endovascular techniques have gained popularity. A literature review was conducted.

RESULTS

Transnasal endoscopic sphenopalatine artery ligation and arterial embolization provide excellent control rates but the decision to choose one over the other can be challenging. The role of transnasal endoscopic anterior ethmoid artery ligation is unclear but may be considered in certain cases when bleeding localizes to the ethmoid region.

CONCLUSION

This article will focus on the management of intractable spontaneous epistaxis and discuss the role of endoscopic arterial ligation and embolization as it pertains to this challenging clinical scenario.

A novel use of a landmark to avoid injury of the anterior ethmoidal artery during endoscopic sinus surgery

BACKGROUND

The aim of this study was to describe and correlate radiographically the anterior ethmoidal artery (AEA) to useful endoscopic surgical landmarks, such as the nasal beak (NB), nasal crest (NC), and axilla of the middle turbinate, because these are commonly encountered during endoscopic sinus surgery and skull base surgery.

METHODS

A retrospective review and software analysis was performed by three independent observers. Measurements of distance and angulation from the AEA to the NC, NB, and axilla of the middle turbinate were performed. A total of 138 unique computed tomography (CT) scans performed at a university tertiary care center were evaluated.

RESULTS

The average age of the patients whose scans were analyzed was 50.5 (range, 17-90 years) years of age. The gender distribution was 61 male and 89 female patients. After comparing the measurements to the three landmarks noted, it was determined that the NB had the most interpatient concordance and the least interobserver variability. The average distance between the NB and the AEA as it penetrates the lamina papyracea is 2.34 cm (variance, 0.07) at an angle of 45.21° from the Frankfurt horizontal line.

CONCLUSION

The real advantage of this novel use of the NB as a landmark to identify the AEA is that it is easy to use, unobtrusive, and is not time-consuming. This relationship between the NB and the AEA is consistent across genders and ethnicities and is more valuable than others presented previously, which may be more variable.

Preoperative computed tomography evaluation in sinus surgery: a template-driven approach

Anatomic abnormalities in the paranasal sinuses and skull base are not uncommon. Awareness of these abnormalities may be of assistance in pre-operative planning. This content presents a template-driven approach to the analysis of computed tomography scans in preparation for endoscopic sinus surgery.

Radiological correlation between the anterior ethmoidal artery and the supraorbital ethmoid cell

The anterior ethmoidal artery is an important landmark in functional endoscopic sinus surgery.

AIMS

We undertook this study to determine the reliability of identification of the artery on the coronal CT scan and to determine whether a correlation exists between the pneumatisation of the suprabullar recess and the vertical distance of the artery from the base skull.

MATERIALS AND METHODS

50 randomly selected CT scans were studied. The anterior ethmoidal artery was identified on each side and the vertical distance between the artery and the base skull was measured. The orbital beak and the superior oblique muscle were used as landmarks to identify the artery. The CT scans were divided into two groups based on whether the supraorbital cell was present or absent. These groups were each further subdivided into 3 groups depending on the vertical distance between the anterior ethmoidal artery and the base skull.

RESULTS

The anterior ethmoidal artery was reliably identified in 97% of the cases. When the supraorbital cell was absent, the mean distance between the artery and the base skull was 1.5 mm; while when the cell was present, the mean distance was 4.86 mm. When these groups were evaluated for statistical significance, the p value was 0.000 (highly significant).

CONCLUSION

The orbital beak and superior oblique muscle are reliable landmarks to identify the anterior ethmoidal artery. There exists a strong correlation between the vertical distance of the artery from the base skull and the presence of the supraorbital ethmoid cell.

[Anterior ethmoidal artery at ethmoidal labyrinth: Bibliographical review of anatomical variants and references for endoscopic surgery]

INTRODUCTION

The anterior ethmoidal artery (AEA) has a trajectory with multiple anatomical variations. In addition, there are no clear references to locate it, so it is easy to produce an iatrogenic lesion. The goal of this study was to carry out a bibliographical review to analyse variants and endoscopic reference reports in the scientific literature.

MATERIAL AND METHODS

A review in Medline and Embase data bases was carried out, looking for AEA-related anatomical and radiological studies. After the revision, the principal study results, together with several distances and angles useful for locating the AEA, are presented in this study.

RESULTS

There were 13 main articles that analysed a total of 1388 AEA. It was absent from 2 to 14%. It was identifiable in computed tomography (CT) between 95 and 100%. It was located between the second and third ethmoidal lamella in 74.2% and at the skull base level in 66.6%. Ethmoidal sinuses pneumatisation was related to AEA location at the skull base. Between 83 and 85.3%, it was found at the suprabullar recess.

CONCLUSIONS

CT is useful for presurgery planning. AEA are more frequent between the second and third lamella and at skull level. Ethmoidal pneumatisation and Keros grades could be predictive factors for AEA relationship with the skull base level. The AEA, the axilla of the middle turbinate and the superomedial edge of the nose are in a straight line, being a simple and useful reference in endoscopic sinus surgery.

Morphological characteristics of the anterior ethmoidal artery in ethmoid roof and endoscopic localization

OBJECTIVES

To provide anatomical data to help identify and locate the anterior ethmoidal artery (AEA) precisely during endoscopic procedures.

METHOD

We dissected 15 adult cadaver heads, which provided 30 specimens, to study morphological characteristics, courses, and several types of variations.

RESULTS

We found the average diameter of the AEA to be 0.80 +/- 0.24 mm. In 85.7% of the cases, the artery was seen between the second and third lamella. Other locations were over the roof of the frontal recess cells (10.7%) and the roof of the posterior ethmoid sinus (3.6%). The AEA ran parallel to the ethmoid roof and formed a slight curve. When viewed from the superior side, the angle formed by the long axis of the artery and the lamina papyracea was 60.5 degrees +/- 16.4 degrees. In 83.3% of the cases, the anterior ethmoidal canal (AEC) was identified as a separate canal, and in 16.7% the canal was embedded in the ethmoid roof. In 10 of the 30 cases (33.3%), the AEC presented some degree of dehiscence.

CONCLUSION

As a result of these dissections, we found that the AEA's course in the ethmoid roof varies. The morphological characteristics-that the AEA runs parallel to the ethmoid roof, forming a slight posterolateral to anteromedial curve as it passes from the orbit to the cribriform plate-are the most reliable factors used to identify the artery during surgery.