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.

Severe unilateral refractory epistaxis arising from the septal branch of the anterior ethmoid artery.

KEY POINTS: The septal branch of the anterior ethmoid artery (sbAEA) is an underrecognized source of severe refractory epistaxis. Herein, we describe the presentation, predisposing factors, treatment strategies, and outcomes of a series of patients with this condition.

The tortuous course of the anterior ethmoidal artery in the orbit: A cadaveric study.

AIM: The study aimed to define the coursing pattern of the anterior ethmoidal artery (AEA) in the orbit to minimize complications during endoscopic interventions. MATERIALS AND METHODS: A total of ten formalin-fixed cadaveric halves were included in the study. Orbital regions were shown with a superior approach. The superior rectus and superior oblique muscles, as well as the connective tissue and vessels were removed to observe the path of the anterior ethmoidal artery. Measurements such as the width of the artery, the anterior-posterior length of the U formation, the length of the intraorbital part of the ophthalmic artery, and the distance of the AEA from its opthalmic origin to the anterior ethmoidal foramen were made. RESULTS: Ten of the AEAs originated from the ophthalmic artery. The AEA branches originated from the ophthalmic artery approximately 18.4 mm after the orbital artery entered the orbital, and the mean width of the AEAs was 0.82 mm. In seven of the total anterior ethmoidal arteries, they coursed in the intraethmoidal cavities below the cranial base. The mean distance from the origin of AEAs to the medial wall of the orbit was 4.9 mm. After leaving the ophthalmic artery, seven of the AEAs were coursing forward and turned back ('U' turn formation), which have proximately 1.5 mm in anteroposterior direction. CONCLUSION: The anterior ethmoidal artery is 0.8 mm wide, originates from the distal part of the ophthalmic artery, entering the orbit after a 1.5 mm U-turn.

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.

A Consistent Endoscopic Landmark to Identify the Anterior Ethmoidal Artery.

OBJECTIVE: The anterior ethmoidal artery (AEA) is an important structure to identify during endoscopic sinus surgery. Although identification on imaging is easily taught, a consistent endoscopic landmark for the AEA, independent of anatomic ethmoid cell variation, is lacking, leaving many surgeons unclear about the exact location without dependence on navigation. Here, we describe a consistent endoscopic landmark, regardless of anatomical ethmoid variation. METHODS: We prospectively enrolled adult patients undergoing endoscopic surgery involving frontal and ethmoid sinuses in this observational study. The AEA landmark was defined simply as the septation or ridge one step back along the ethmoid skull base from the posterior table of the frontal sinus. The gold standard to calculate the sensitivity of our endoscopic landmark was an image-navigation system, registered to within 1.5 mm accuracy, locating the AEA within three planes. Both endoscopic and computerized tomography (CT) images of the pointer at the landmark were taken simultaneously. The concordance of endoscopic to navigation images was independently assessed by three blinded rhinologists. RESULTS: Forty patients were included in our study with 73 sides analyzed. Diagnoses included chronic rhinosinusitis without polyps (52.5%), with polyps (22.5%), recurrent acute sinusitis (15%), sinonasal tumors (7.5%), and odontogenic sinusitis (2.5%). The AEA was accurately identified using our endoscopic landmark in 97.3% of the cases (71/73). Of the two cases in which the AEA was not found within the landmark, the artery was located ≤1 mm posteriorly. CONCLUSION: We describe a consistent endoscopic landmark to identify the AEA, conserved across various clinical diagnoses and anatomic variations in sinus structure. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:1096-1099, 2024.

Comparing Endoscopic Measurements of the Anterior and Posterior Ethmoidal Arteries with CT Measurements: A Cadaveric Study.

OBJECTIVE: To reveal the reliability of radiological measurements of the ethmoid arteries. METHOD: Five fresh frozen cadaveric heads underwent computed tomography and endoscopic sinus surgery. The lateromedial length of the anterior ethmoidal artery (AEA) and its distance to the axilla of the middle turbinate (MTA), the sphenoethmoidal recess (SR) and the posterior ethmoidal artery were measured. The posterior ethmoidal artery (PEA) was referenced to the SR. These anatomical parameters were measured both radiologically and endoscopically, and the compatibility of the two was examined. RESULTS: Ten nasal cavities were dissected. We found that the distance of MTA to the AEA was 16±8 mm in dissection, 21±4 mm radiologically in the sagittal section, the distance of SR to the AEA was 14±3 mm in dissection, 19±4 mm radiologically in the sagittal section, and the distance of the AEA to the PEA was 10±3 mm in dissection, 12±3 mm radiologically in the axial section. The distance of the PEA to SR was 6±3 mm in dissection, 8±2 mm radiologically in the sagittal section. CONCLUSIONS: The distance of the AEA to the MTA, the distance of the AEA to the PEA and the distance of the PEA to the SR were compatible with each other in the dissection and in the radiologically evaluation, whereas the distance of the AEA to the SR was not compatible.

A low-cost prosthetic orbital simulation model for endoscopic anterior ethmoid artery ligation.

OBJECTIVE: This study aimed to develop and evaluate a low-cost orbital prosthesis for simulation of endoscopically assisted intra-orbital anterior ethmoidal artery ligation. METHODS: A low-cost orbital prosthesis was built and evaluated by ENT surgical trainees. Feedback was given following the assessment in the form of a face validity questionnaire. RESULTS: Results were scored on a Likert scale of 1-7 (low to high). Trainees had limited exposure to the procedure (40 per cent) and predominantly low levels of confidence (mean, 3.67) that correlated with a lack of first-hand experience. The anatomy and likeness to human tissue of the prosthesis were both ranked highly, with mean scores of 5.0 and 4.93, respectively. CONCLUSION: The results of this study support the idea that a simple anatomical prosthesis for the simulation of endoscopic anterior ethmoidal artery ligation can be created with potential value to otolaryngology surgical training. To the authors' knowledge, this is the first documentation of simulated surgical epistaxis management using an artificial anatomical model.

Anatomical landmarks for localisation of the anterior ethmoidal artery: a combined radiological and cadaveric (endoscopic) study.

PURPOSE: The anterior ethmoidal artery is a major surgical landmark that is susceptible to iatrogenic injury during surgery of the anterior ethmoidal sinus, frontal sinus, and skull base. The present study aimed to define the location of the anterior ethmoidal artery in relation to specific anatomical landmarks using radiological imaging and endoscopic dissection. METHODS: Eighty-six anterior ethmoidal arteries were assessed using computed tomography scans (bilateral analyses) and forty anterior ethmoidal arteries were assessed using cadaveric specimens (bilateral analyses). The skull base, anterior nasal spine, anterior axilla of the middle turbinate, and nasal axilla were morphometrically analysed to determine their reliability as anterior ethmoidal artery landmarks. RESULTS: Distances to the skull base, anterior nasal spine, and nasal axilla displayed statistically significant differences between sexes and sides (p < 0.05). All landmarks demonstrated excellent reliability as anatomical landmarks for the localisation of the anterior ethmoidal artery, radiologically and endoscopically (ICC values ranged from 0.94 to 0.99). CONCLUSION: The middle turbinate axilla was the most reliable landmark, due to the lack of statistically significant differences according to sex and laterality, and the high inter-rater agreement between measurements. Anatomical knowledge of variations and relationships observed in the present study can be applied to surgeries of the anterior ethmoidal sinus, frontal sinus, and skull base to improve localisation of the anterior ethmoidal artery, preoperatively and intraoperatively, and avoid iatrogenic injury of the vessel.

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).

Radiological relationship of the ethmoid slit with the frontal sinus and the anterior ethmoidal artery and applications to the frontal sinus drillout.

PURPOSE: To compare two types of CT acquisition parameters: CT scan of the facial bone and CT scan of the sinuses, for studying the ethmoidal slit and its relationship with the frontal sinus and anterior ethmoidal artery. MATERIALS AND METHODS: Retrospective study of 145 scans of the sinuses and 79 of the facial bones performed between 2012 and 2016. On each scan, the visibility of the ethmoidal slits, their length, their distance from the ethmoidal artery, and their relationship with the anterior and posterior wall of the frontal sinus were studied. RESULTS: The ethmoidal slit was better visualized on CT scans of the facial bone (58.2%) than on those of the sinuses (43.1%) (p = 0.02). The distance between the anterior ethmoidal artery and the anterior part of the cribriform plate was 9.3 mm for CT scans of the facial bone and 8.4 mm for CT scans of the sinuses. The theoretical risk of damaging the glabellar soft tissue and that of damaging the meninges during a frontal sinusotomy was evaluated, respectively, at 9.6% and 26.1% for CT scans of the facial bone, and at 6.2% and 21.5% for sinus scans. CONCLUSIONS: CT scans of the facial bone are better than CT scans of the sinuses for identifying ethmoidal slits and their distance from the canal of the anterior ethmoidal artery. The identification of these elements is relevant for the surgeon during frontal sinus surgery and makes it possible to assess the risk of damaging the glabellar soft tissue or meninges. Performing a CT scan of the facial bone seems preferable to that of a CT scan of the sinuses in certain pathological situations, such as cerebrospinal rhinorrhea or revision surgeries of the frontal sinus.

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.

Angiographic study of the transdural collaterals at the anterior cranial fossa in patients with Moyamoya disease.

Unlike its parietal, temporal, and occipital counterparts, the frontal lobe has a broad basal surface directly facing the anterior cranial fossa dura mater which could permit establishment of transdural collaterals (TDCs) with the frontal lobe. Studies on the TDCs from the anterior cranial fossa in moyamoya disease (MMD) are scarce and inadequately investigated. A retrospective study of 100 hemispheres in 50 patients who were diagnosed with MMD by catheter angiography between January 2015 and June 2019 was performed in our institution. TDCs through the anterior ethmoid artery (AEA) or posterior ethmoid artery (PEA) were divided into 3 types respectively based on their respective angioarchitecture. Furthermore, we also studied TDCs to the temporal, parietal, and occipital lobes and collaterals from the posterior circulation to the territory of the anterior cerebral artery. TDCs through the AEA and PEA were identified in 89 (89/100, 89%) and 73 (73/100, 73%) of the hemispheres. The vascularization state of the frontal lobe was good in 89 (89/100, 89%) hemispheres. Rete mirabile and TDCs through the PEA were statistically different among patients with different Suzuki stages. No statistical difference was noted in TDCs through the AEA, frontal TDCs from other sources, and the vascularization state of the frontal lobe with regard to different Suzuki stages. TDCs through the AEA and PEA at the anterior cranial fossa play a very important role in compensating the ischemic frontal lobe. The frontal lobe could be well compensated in most of the patients with TDCs at the anterior cranial fossa.

Analysis of anatomical variation of the inclination of lamellas attached to the skull base and its correlation with the anterior ethmoidal artery floating in the ethmoid sinus for use in endoscopic sinus surgery.

PURPOSE: Attention to the inclination of lamellas attached to the skull base, including the basal lamella of the middle turbinate, facilitates the intraoperative identification of each lamella without requiring the use of a navigation system. We classified the inclination between the lamella and the skull base in preoperative computed tomography (CT) images and examined the relationship between the lamellas attached to the skull base, including the basal lamella of the middle turbinate, and the position of the anterior ethmoidal artery (AEA). We aimed to develop a preoperative classification to help prevent intraoperative injury of the AEA. METHODS: We retrospectively investigated the paranasal sinus sagittal section CT slices of 366 sides of 183 patients to assess the inclination of lamellas attached to the skull base and the AEA location. We also reviewed the AEA position, its correlation with the supraorbital ethmoid cell, and the lateral lamella of the cribriform plate. RESULTS: We classified the lamella inclination at the skull base as the anterior direction, perpendicular direction, and posterior direction types. Lamellas containing a floating AEA inclined in the anterior direction toward the skull base were observed in 68.9% of sides, inclination in the perpendicular direction was noted in 30.5% of sides, and inclination in the posterior direction was noted in 0.5% of sides. CONCLUSION: It is easier to identify the AEA intraoperatively when the lamella inclination of the skull base attachment is recognized based on preoperative CT findings. This approach could be applied to all paranasal sinus lamellas and assist in identifying the AEA and other nearby structures.

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

Abstract 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.

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.

Longstanding diplopia after ethmoidal artery ligation for epistaxis.

PURPOSE: In the rare case of intractable, posterior, non-sphenopalatine artery epistaxis, ligation of ethmoidal arteries using an external approach like a Lynch-type incision is required. Orbital complications, especially extra-ocular motility disorders with diplopia, are known, but in the literature rarely described. Our aim was to analyse the complication type, rate, and outcome of ethmoidal artery ligation for epistaxis. MATERIALS AND METHODS: Data between 2012 and 2017 of patients treated with ethmoidal artery ligation were analysed retrospectively and through a telephone interview using a non-standardized questionnaire. RESULTS: Data of 18 patients (m/f = 3/15) aged 53-83 years were reviewed. Epistaxis recurred in only one patient after 1 month. Five patients (28%) suffered from diplopia shortly after surgery. Motility analysis revealed full recovery with free motility in four out of five reported cases after 4-8 months, one patient still reports intermittent mild diplopia more than 1 year postoperatively. CONCLUSION: In patients with intractable, non-sphenopalatine artery epistaxis, anterior ethmoidal artery ligation was highly effective. Diplopia, however, occurred in one-third of our patient group. Information about motility restriction with longer standing diplopia are mandatory when consenting patients for ligation of ethmoidal arteries. Special care needs to be taken during dissection in the region of the trochlea and superior oblique muscle. LEVEL OF EVIDENCE: Case Series, level 4.

Septal floor rotational flap pedicled on ethmoidal arteries for endoscopic skull base reconstruction.

OBJECT: Expanded endonasal approaches have dramatically changed how skull base surgery is performed, and nasoseptal flap (NSF) has significantly improved skull base reconstruction. However, challenges remain when the pterygopalatine artery is invaded by tumors; when it must be sacrificed to approach the lateral sphenoidal recess; when late-occurrence leak occurs in the sella after transsphenoidal surgery; and also when the leak is on the posterior wall of the frontal sinus, which is too distant for NSF to reach. This article describes a septal floor rotational flap pedicled on ethmoidal arteries for endoscopic skull base reconstruction in certain cases. STUDY DESIGN: Case series. METHOD: In this article, we retrospectively review a series of 19 patients who underwent skull base reconstruction with a septal floor rotational flap pedicled on the ethmoidal arteries. RESULT: All 19 flaps, including the anterior and posterior artery pedicled flaps, survived without significant complications, and no postoperative cerebrospinal fluid leak occurred during follow-up. CONCLUSION: Ethmoidal arteries pedicled septal floor rotational flap, with their strong blood supply and large coverage area, are ideal replacements for NSF. These flaps are qualified in locations ranging from the posterior wall of the frontal sinus to the lateral sphenoidal recess and in cases ranging from tumor invading the pterygopalatine fossa to sellar late-occurred leak after transsphenoidal surgery. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:2696-2701, 2019.

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.

Increased Accuracy, Confidence, and Efficiency in Anterior Ethmoidal Artery Identification with Segmented Image Guidance.

OBJECTIVE: To determine whether using image guidance technology with 3-dimensional image segmentation increases the endoscopic surgeon's accuracy, efficiency, and confidence in identifying the anterior ethmoidal artery. METHODS: This is a cross-sectional study of attending physicians and residents at an academic medical center. Because identification of the anterior ethmoidal artery during image-guided surgery can be challenging, we studied the effect of anterior ethmoidal artery image segmentation (ie, partitioning and coloring) on surgeon test performance. A computerized test was administered to 16 surgeons who were asked to identify the anterior ethmoidal artery on multiplanar computed tomographic images and to answer multiple-choice questions. Half the questions showed segmented images of the anterior ethmoidal artery, and half showed images without segmentation. Efficiency and accuracy of identification and subjective surgeon confidence were determined for each question. Descriptive statistics were used to compare test performance for identification of the anterior ethmoidal artery on images with or without segmentation. RESULTS: Percentage of correct answers ( P < .001), efficiency ( P < .001), and confidence ( P < .001) in identification of the anterior ethmoidal artery were significantly better with segmented computed tomographic images. DISCUSSION: We demonstrated that use of segmented images improves surgeons' accuracy, confidence, and efficiency for identification of the anterior ethmoidal artery. IMPLICATIONS FOR PRACTICE: We describe how segmentation can allow surgeons to improve the surgical course by increasing their accuracy, confidence, and efficiency in identifying the anterior ethmoidal artery.

Nasal branch of the anterior ethmoid artery: a consistent landmark for a midline approach to the frontal sinus.

BACKGROUND: Frontal sinusotomy can be challenging when significant scarring or distorted anatomy is present. Identifying a reliable anatomic structure, when traditional landmarks or navigation are absent, may assist the surgeon in revision and complicated frontal sinusotomies via a midline approach. We aimed to characterize the anatomic relationship of the nasal branch of the anterior ethmoid artery (NBAEA) to the frontal infundibulum, specifically the first olfactory fili, posterior frontal infundibulum, and anterior cribriform plate. METHODS: Dissection of the NBAEA was carried out in 11 cadaveric heads, resulting in a total of 21 dissections (1 aplastic frontal). Mean with standard deviation and a range were established for 7 relative measurements. RESULTS: The total length of NBAEA cleft when present (mean 2.43 mm), the anterior edge of NBAEA cleft to anterior infundibulum coronal plane (mean 1.71 mm), the posterior edge of NBAEA cleft to posterior infundibulum coronal plane (mean 3.33 mm), the posterior edge of NBAEA cleft to 1st olfactory fili (mean 2.86 mm), and the first olfactory fili to posterior infundibulum coronal plane (mean 0.48 mm) were consistent measurements supporting the use of the NBAEA as a consistent anatomical landmark for the correct surgical coronal trajectory into the midline frontal sinus. CONCLUSION: The NBAEA is a consistent anatomic landmark with minimal intercadaveric and intracadaveric variation. It can be used reliably as a "sentinel artery" notifying the surgeon when one is approaching the first olfactory fili, to determine the correct trajectory into the midline frontal sinus.