Anatomical variations of anterior ethmoidal artery at the ethmoidal roof and anterior skull base in Asians.

PURPOSE: The variations of the anterior ethmoidal artery (AEA) in different populations should be recognized by surgeons to prevent unwarranted complications during surgery. The aim of this study was to assess the anatomical variations of AEA in Asian population. METHODS: A cross-sectional study of 252 AEA identified by computed tomography (CT) of the paranasal sinuses. The multiplanar CT images were acquired from SOMATOM® Definition AS+ and reconstructed to axial, coronal and sagittal view at 1 mm slice thickness. RESULTS: 42.5% of AEA was within skull base (grade I), 20.2% at skull base (grade II) and 37.3% coursed freely below skull base (grade III). The prevalence of supraorbital ethmoid cell (SOEC) and suprabullar cell (SBC) was 29.8% and 48.0%. The position of AEA at skull base has significant association with SOEC (p < 0.001), but not with SBC (p = 0.268). Type I Keros was 42.1% and Type 11 Keros was 57.9%. When lateral lamella's height is longer, the probability increases for AEA to course freely within the ethmoid sinus (p = 0.016). The mean distance of AEA from skull base was 1.93 ± 2.03 mm, orbital floor 21.91 ± 2.47 mm and nasal floor 49.01 ± 3.53 mm. CONCLUSIONS: The position of AEA at skull base depends on the presence of SOEC and length of lateral lamella, but not with SBC. When compared to European population, the mean distance between AEA and nasal floor is shorter in Asians.

An Applied Anatomical Study of the Ethmoidal Arteries: Computed Tomographic and Direct Measurements in Human Cadavers.

Computed tomography (CT) images have been used in very few studies on distances to the ethmoidal arteries in the orbit. Most other studies have included direct measurements on cadavers and frequently quote the 24-12-6 mm rule to describe distances from the anterior lacrimal crest to the anterior and posterior ethmoidal foramina (AEF and PEF), optic canal (OC), respectively. However, the large interindividual variation of distances renders absolute values less applicable in a clinical setting. Preoperative measurements on CT images may provide more precise distances than absolute rules and thus lead to safer orbital surgery. The authors hypothesize that the distances to the ethmoidal arteries and the length of the medial wall are positively correlated and that measurements of the distances from the posterior lacrimal crest (PLC) on CT images are feasible with a low intra- and interobserver variability.Fifty intact orbits from 25 Caucasian cadavers were exenterated and examined. In additional, high-resolution CT scans of 48 orbits from 24 other Caucasian nonexenterated cadavers were examined. Distances were measured from 4 different anterior landmarks to the AEF and PEF and the OC.Distances from the most anterior landmarks to the arteries were positively correlated with the length of the medial wall. Measurements of the distances from the PLC to the ethmoidal arteries on CT images were feasible with a low intra- and interobserver variability. In conclusion, iatrogenic damage to the ethmoidal arteries in the orbit may be best avoided by using CT measurements in presurgical planning.

Study of the relation between medial orbitofrontal artery and anterior skull base performed by computed tomography angiography.

BACKGROUND: The aims of this study were to analyze the relationships between the medial orbitofrontal artery (MOFA) and the anterior skull base (ASB) including anatomical endonasal landmarks using computed tomography angiography (CTA). METHODS: We studied 52 CTAs using OsiriX software. All CTAs were placed in the same anatomical position. MOFA was identified in the sagittal and coronal plane and its correlation with ASB was analyzed. The distance between the MOFA and landmarks for endonasal surgery were obtained, determining the high risk areas for its injury. RESULTS: After arising from the anterior cerebral artery, the MOFA dives inferiorly towards the ASB, close to the midline (average distance of 1.5 mm), approaching the planum sphenoidale (average distance of 1.8 mm) and then ascends away from the ASB as it runs anteriorly, with an average distance of 4.4 mm in the region of the anterior wall of the sphenoid sinus and 12 mm in the region of the anterior ethmoid artery. CONCLUSIONS: The MOFA has an intimate relationship with the ASB and nasal cavity; the regions with the highest risk of surgical trauma are between the posterior ethmoid and the planum sphenoidale.

A study of the anterior ethmoidal artery and a new classification of the ethmoid roof (Yenigun classification).

Aims of this study are to analyze the association of the anterior ethmoidal artery's (AEA) visualization with variations in its adjacent structures in coronal, axial, and sagittal CT images, to assess its relation with the ethmoid roof, and, based on this relation, to introduce a new classification for the ethmoid roof. A retrospective, cross-sectional study was performed in a tertiary referral center. In this retrospective, cross-sectional study, the coronal, axial, and sagittal CTs of 184 patients have been surveyed and the AEA canal, the ethmoid roof, and their relations with surrounding structures have been assessed. The Keros classification used to measure the depth of the lateral lamella of the cribriform plate (LLCP) in the ethmoid roof has been modified to include anterior-posterior length of the LLCP. It was shown that the visualization of the AEA canal increases in a statistically significant manner with an increase in the superior-inferior depth and the anterior-posterior length of the LLCP bilaterally. In the presence of supraorbital pneumatization, AEA visualization was shown to increase bilaterally significantly. This study demonstrated a positive correlation between the AEA canal, the LLCP superior-inferior depth, and the anterior-posterior length. It was shown that with the increased depth and length of the LLCP and in the presence of supraorbital pneumatization, the visualization of the artery and hence the injury risks are increased. The LLCP anterior-posterior length is as clinically relevant as is its depth, and a radiologic classification has been defined according to the anterior-posterior length of the LLCP.

A possible venous connection between the cranial and nasal cavity.

PURPOSE: The foramen cecum (FC) is a fine bony canal with the aperture located immediately anterior to the crista galli (CG). The venous structures in the regions of the FC and CG have been inconsistently described and are not well understood. Here we explore these veins using magnetic resonance imaging. MATERIALS AND METHODS: We enrolled 101 patients who underwent contrast examinations and exhibited intact skin, skull, dura mater, and intracranial dural sinuses. Imaging data were obtained as thin-sliced, seamless sagittal sections and were transferred to a workstation for analysis. RESULTS: In 84 % of the patients, tubular-shaped venous extensions arose from the rostral end of the falx cerebri and were confirmed to lie in the FC. These extensions were supplied by the superior sagittal sinus or the frontal cortical vein, and were classified into four types: rudimental slight projections, short and straight extensions, long and straight channels, and long and tortuous channels. Furthermore, 27.7 % of the patients exhibited a distinct venous channel between the venous extension in the FC and the median vestibular submucosa of the nasal cavity. Among these channels, 81.5 % were connected to the vein lying in the FC via a short channel that vertically pierced the CG. CONCLUSIONS: The FC contains tubular-shaped venous extensions that are supplied by the rostral end of the superior sagittal sinus or the frontal cortical vein. The cranial cavity, FC, and nasal cavity may be connected by a venous channel.

Computer-assisted analysis of anatomical relationships of the ethmoidal foramina and optic canal along the medial orbital wall.

Typically, the medial orbital wall contains an anterior ethmoidal foramen (EF) and a posterior EF, but may also have multiple EFs transmitting the arteries and nerves between the orbit and the anterior cranial fossa. The aim of this study is to determine a patient-friendly landmark of the medial orbital wall and to specify a precise location of the ethmoidal foramens (EF) in order to standardize certain anatomical marks as safe ethmoidal arteries. Orientation points on the anterior ethmoidal foramen (AEF), posterior ethmoidal foramen (PEF) and middle ethmoidal foramen (MEF) were investigated in 262 orbits. Using a software program, distances between each foramen and the midpoint of the anterior lacrimal crest (ALC), the optic canal (OC), and some important angles were measured. The EFs were identified as single in 0.8%, double in 73.7%, triple 24,4% and quadruple in 1.1% specimens. The mean distances between ALC and AEF, ALC and PEF and ALC and MEF were 27.7, 10.6, and 12.95 mm, respectively. The distances from ALC-AEF, AEF-PEF, and PEF-OC were 27.7 ± 2.8, 10.6 ± 3.3, 5.4 ± 1 mm. The angles from the plane of the EF to the medial border of the OC were calculated as 13.2° and 153°, respectively. The angle from the AEF to the medial border of the OC was based on the plane between the ALC and AEF was 132°. The occurrence of multiple EF with an incidence of 25% narrows the borders of the safe region in the medial orbital wall. Safe distance of the ALC-EF was measured as 22.1 mm on medial wall. The line of the location of the EF was calculated 16.2 mm. In this study, it was possible to investigate the variability of the orbital orifice of the EF and the feasibility of the EA, to observe various angles of the orbital wall bones and to calculate the lengths of some parameters with the help of certain software.

Accessory anterior ethmoidal nerve and artery: a cadaveric case report.

The anterior ethmoidal artery (AEA) is an important surgical landmark for procedures involving the anterior cranial fossa. Many variations in the location and branching pattern of the AEA have been reported throughout the literature. These anatomical variations are important for surgeons to be familiar with as injury to the AEA can lead to massive haemorrhage, orbital haematomas, and cerebrospinal fluid rhinorrhoea. Anatomical landmarks such as the ethmoidal foramen can be used to identify the location of the AEA; however, it is also important to consider that the foramen may have variable presentations. If there is ever difficulty with identification of the AEA, surgeons should pursue a high-resolution computed tomography to minimise the risk of surgical complications. In this report, we present a rare case of a variant accessory anterior ethmoidal artery and nerve, and variations in the ethmoidal foramen found during cadaveric dissection.

Pediatric Septal Perforation Repair With the Endoscopic Anterior Ethmoid Artery Flap.

Pediatric nasal septal perforations can lead to crusting, obstruction, whistling, and recurrent epistaxis. Current approaches for pediatric nasal septal repair center on combination endonasal and external approaches. Herein we describe the successful utilization of a purely endoscopic anterior ethmoid artery flap, an established technique in adults, for nasal septal perforation repair in 3 children aged 12 to 13 years who presented with septal perforations ranging in size from 6 to 12 mm. Successful closure was achieved with an endoscopic anterior ethmoid artery flap, with all patients achieving complete closure and symptom resolution. Children with nasal septal defects are typically treated with temporizing measures until early adulthood, when definitive open repair may be performed. Our initial experience with the anterior ethmoid artery flap technique suggests that this surgery may be easily performed in children as young as 12 years, without the use of previously described adjunctive procedures such as turbinate translocation.

Endoscopic endonasal anatomy and approaches to the anterior skull base: a neurosurgeon's viewpoint.

OBJECTIVES: The objective of this study was to review the endoscopic anatomy of the anterior skull base, defining the pitfalls of endoscopic endonasal approaches to this region. Recently, these approaches are gaining popularity among neurosurgeons, and the details of the endoscopic anatomy and approaches are highlighted from the neurosurgeons' point of view, correlated with demonstrative cases. MATERIALS AND METHODS: Twelve fresh adult cadavers were studied (n = 12). We used Karl Storz 0 and 30 degrees, 4 mm, 18- and 30-cm rod lens rigid endoscope in our dissections. After preparation of the cadaveric specimens, we approached the anterior skull base by the extended endoscopic endonasal approach. RESULTS: After resection of the superior portion of the nasal septum, bilateral middle and superior turbinates, and bilateral anterior and posterior ethmoidal cells, we could obtain full exposure of the anterior skull base. The distance between optic canal and the posterior ethmoidal artery ranged from 8 to 16 mm (mean, 11.08 mm), and the distance between posterior ethmoidal artery and the anterior ethmoidal artery ranged from 10 to 17 mm (mean, 13 mm). After resecting the anterior skull base bony structure and the dura between the 2 medial orbital walls, we could visualize the olfactory nerves, interhemispheric sulcus, and gyri recti. With dissecting the interhemispheric sulcus, we could expose the first (A1) and second (A2) segments of the anterior cerebral artery, anterior communicating artery, and Heubner arteries. CONCLUSIONS: This study showed that extended endoscopic endonasal approaches are sufficient in providing wide exposure of the bony structures, and the extradural and intradural components of the anterior skull base and the neighboring structures providing more controlled manipulation of pathologic lesions. These approaches need specific skill and learning curve to achieve more minimally invasive interventions and less postoperative complications.

New landmarks in endonasal surgery: from nasal bone to anterior cribriform plate including branches of anterior ethmoidal artery and nerve and terminal nerve.

BACKGROUND: Despite the development of anterior skull base surgery, the anatomy of the nasal bone and anterior cribriform plate remains unclear. A recent study confirmed 2 distinct foramina in the anterior part of cribriform plate: the ethmoidal slit (ES) and the cribroethmoidal foramen (CF). The aim of this study was to specify their content, their anatomic relationship to the frontal sinus and skull base, and their potential value in skull base surgery. METHODS: Dissections were performed on 36 cadaver heads. Macro- and microscopic examinations were carried out. Microcomputed tomography scans contrasted with osmium were performed to identify vessels and nerves. Histology with neural, meningeal, or luteinizing hormone-releasing hormone immunomarkers was performed on the content of the foramina. Finally, endonasal surgical dissections were carried out. RESULTS: The ES and the CF were observed in all cases. They measured a mean of 4.2 and 1.6 mm, respectively. The ES contained dura mater, arachnoid tissues, lymphatics, and the terminal nerve. The CF contained the anterior ethmoidal nerve and artery. This foramen continued forward with the cribroethmoidal groove, which measured a mean of 2.5 mm. This groove was under the frontal sinus and in front of the skull base. We also described a "cribroethmoidal canal" and a "nasal bone foramen." CONCLUSION: The clinical applications of this new anatomic description concern both cribriform plate and frontal sinus surgeries. Identifying the terminal nerve passing through the ES is a step forward in understanding pheromone recognition in humans.

Management of severely bleeding ethmoidal arteries.

OBJECTIVES: Ethmoidal arteries (EAs) can be responsible for severe bleeding. Clinical features of EA bleeding are rather extensive because it can occur within the nasal cavity or in orbital spaces. Furthermore, surgical management of EA bleeding is challenging. STUDY DESIGN: Retrospective evaluation. METHOD OF STUDY: Five clinical patients with severe bleeding from EAs and/or epistaxis refractory to sphenopalatine artery closure were included in this work. Careful anatomic dissection of the orbitoethmoidal region was performed in 3 fresh injected heads. RESULTS: Ethmoidal artery management is not uniform because it depends on the rapidity and severity of the bleeding and the chambers within which it happens. Trauma-related bleeding usually requires a lateral canthotomy, whereas in intraoperative bleeding, efforts should be made to directly coagulate the bleeding vessel, even within the orbital fat. Spontaneous epistaxis refractory to sphenopalatine artery closure is to be addressed externally, preferably under endoscopic vision. CONCLUSIONS: Ethmoidal artery management differs according to the clinical situation. Elective surgery is advisable for spontaneous epistaxis, whereas emergency treatment, ranging from intraorbital coagulation of the bleeding vessel to lateral canthotomy (when the patient is in a sight-threatening condition), is necessary when the bleeding occurs within orbital spaces. A treatment management algorithm is useful in cases of severe and refractory EA bleeding.

Anterior ethmoidal artery evaluation on coronal CT scans.

UNLABELLED: The anterior ethmoidal artery (AEA) is an important point for frontal and ethmoid sinuses surgery. CT scans can identify landmarks to help the surgeon find the AEA. AIM: To identify the landmarks of the AEA on the orbital medial wall and on the lateral wall of the olfactory fossa. and to correlate the presence of supraorbital ethmoidal cells with spotting the anterior ethmoidal artery canal. MATERIALS AND METHODS: Retrospective review of 198 direct coronal paranasal sinuses computed tomography (CT) scans from August to December, 2006. RESULTS: Supraorbital pneumatization was seen in 35% (70 scans). The AEA canal was seen in 41% (81 scans). The anterior ethmoidal sulcus was seen in 98% (194 scans) and the anterior ethmoidal foramen was seen in all the scans (100%). CONCLUSION: The anterior ethmoidal foramen and the anterior ethmoidal sulcus were anatomical landmarks present in almost 100% of the scans studied. There was a correlation between the presence of supraorbital pneumatization and AEA canal visualization.

[CT imaging of the anterior ethmoidal artery: anatomic correlation]. / Imagerie tomodensitométrique de l'artère ethmoïdale antérieure: confrontation radio-anatomique.

PURPOSE: To identify the anterior ethmoidal artery (AEA) of a skull specimen on CT prior to transnasal endoscopic surgical management of anterior epistaxis. MATERIALS AND METHODS: From a medial canthotomy approach, the AEA was located and a marker placed on 9 skull specimens (18 AEA). CT with 2D reformations was then performed. The AEA were then dissected using an endoscopic anterior ethmoidectomy approach. The presence of AEA procidence was recorded. RESULTS: Correlation between CT and surgical findings allowed identification of 2 criteria predictive of AEA procidence: 1) presence of an ethmoid bulla above the AEA canal 2) AEA canal located below (not within) the ethmoid roof, anterior to the bulla. CONCLUSION: High resolution CT depiction of the AEA provides information regarding its accessibility for endoscopic ligation in patients with severe anterior epistaxis as an alternative to external ligation while demonstrating the upper limit of the anterior ethmoid.

Anterior ethmoidal artery aneurysm and intracerebral hemorrhage.

The association between the formation of intracranial aneurysms and situations of increased blood flow in certain areas of the brain is well accepted today. It has been seen in association with arteriovenous malformations of the brain, carotid occlusion, and Moyamoya disease. The occurrence of aneurysms in small arteries of the skull base, with the exception of the intracavernous carotid artery, however, is rare. We report a case of a 55-year-old woman who presented with an intracerebral hemorrhage caused by a ruptured anterior ethmoidal artery aneurysm. To the best of our knowledge, this is only the second case of documented intracranial bleeding from such a lesion.

Endovascular treatment of cribriform plate dural arteriovenous fistulas: technical difficulties and complications avoidance.

OBJECTIVE: Cribriform plate dural arteriovenous fistula (dAVF) is a rare pathology, for which the treatment of choice used to be neurosurgery. Technological advances in micro-catheters and embolic agents permitted new endovascular alternatives. METHODS: We included all patients treated endovascularly for a cribriform plate dAVF between 2008 and 2013. We retrospectively analysed data focusing on the type of treatment chosen. RESULTS: Ten patients were treated by endovascular approach, with a need for an additional surgical exclusion of the fistula in two cases. Thirteen embolisation sessions were done. Embolisation of the fistula through an ethmoidal artery was the technique of choice; the catheterism of the ophthalmic artery was impossible in two cases and the embolic agent did not penetrate in four cases. The embolisation through the middle meningeal artery was successful in one case but the tortuosity of this artery prevented good penetration of the embolic agent. Venous approach was successful in all cases but was limited to fistulas with superficial venous drainage. CONCLUSIONS: Endovascular treatment of cribriform plate dAVF is safe and effective. The embolisation through ethmoidal artery is the method of choice. Branches of the middle meningeal artery are tortuous and prevent the penetration of embolic agent. Venous approach is effective but is limited to cases of failure of the arterial approach.

Haematoma of anterior ethmoidal artery after reduction of fracture of zygomatic complex.

Extraconal intraorbital haemorrhage is a rare complication after reduction of a fracture of the zygomatic complex. We present a case of postoperative intraorbital haematoma that arose from the anterior ethmoidal artery. We stress the advantages of imaging before decompression and of the medial approach.

Ethmoidal dural arteriovenous fistula with unusual drainage route treated by transarterial embolization.

Ethmoidal dural arteriovenous fistulas (AVFs) are rare intracranial lesions associated with a high risk of intracranial hemorrhage. In particular, this entity with reflux drainage directly into the ophthalmic vein is extremely rare. We report a case of ethmoidal dural AVF with direct drainage of the superior ophthalmic vein (SOV) and inferior ophthalmic vein (IOV), successfully treated by endovascular surgery. A 58-year-old man presented with progressive diplopia. Angiography and contrast-enhanced CT showed an ethmoidal dural AVF supplied via the bilateral anterior ethmoidal arteries and venous drainage through the left SOV and IOV. A transarterial approach through the bilateral anterior ethmoidal arteries was used to place the microcatheter close to the fistula site. After intra-arterial embolization with 20% N-butyl cyanoacrylate, the dural AVF was completely occluded. In patients with good vascular access, endovascular transarterial embolization may be an effective and less invasive treatment strategy for ethmoidal dural AVF.