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.

Evaluation of Anterior Ethmoidal Artery by 320-Slice CT Angiography with Comparison to Three-Dimensional Spin Digital Subtraction Angiography: Initial Experiences

OBJECTIVE: To explore the usefulness of 320-slice CT angiography (CTA) for evaluating the course of the anterior ethmoidal artery (AEA) and its relationship with adjacent structures by using three-dimensional (3D) spin digital subtraction angiography (DSA) as standard reference. MATERIALS AND METHODS: From December 2008 to December 2010, 32 patients with cerebrovascular disease, who underwent both cranial 3D spin DSA and 320-slice CTA within a 30 day period from each other, were retrospectively reviewed. AEA course in ethmoid was analyzed in DSA and CTA. In addition, adjacent bony landmarks (bony notch in medial orbital wall, anterior ethmoidal canal, and anterior ethmoidal sulcus) were evaluated with CTA using the MPR technique oriented along the axial, coronal and oblique coronal planes in all patients. The dose length product (DLP) for CTA and the dose-area product (DAP) for 3D spin DSA were recorded. Effective dose (ED) was calculated. RESULTS: The entire course of the AEA was seen in all 32 cases (100%) with 3D spine DSA and in 29 of 32 cases (90.1%) with 320-slice CTA, with no significant difference (p = 0.24). In three cases where AEA was not visualized on 320-slice CTA, two were due to the dominant posterior ethmoidal artery, while the remaining case was due to diminutive AEA. On MPR images of 320-slice CT, a bony notch in the orbital medial walls was detected in all cases (100%, 64 of 64); anterior ethmoidal canal was seen in 28 of 64 cases (43.8%), and the anterior ethmoidal sulcus was seen in 63 of 64 cases (98.4%). The mean effective dose in CTA was 0.6 +/- 0.25 mSv, which was significantly lower than for 3D spin DSA (1.3 +/- 0.01 mSv) (p < 0.001). CONCLUSION: 320-slice CTA has a similar detection rate for AEA to that of 3D spin DSA; however, it is noninvasive, and may be preferentially used for the evaluation of AEA and its adjacent bony variations and pathologic changes in preoperative patients with paranasal sinus diseases.

Ligadura endoscópica da artéria etmoidal anterior: estudo de dissecção em cadáveres / Endoscopic ligation of the anterior ethmoidal artery: a cadaver dissection study

Ligadura da artéria etmoidal anterior (AEA) pode ser necessária em casos de epistaxe grave refratária ao tratamento tradicional. O uso da ligadura endoscópica endonasal da AEA ainda é bastante limitado. Existem poucos estudos na literatura sobre a técnica de abordagem endoscópica desta artéria. OBJETIVOS: Demonstrar a aplicabilidade técnica da ligadura periorbitária da AEA por via endoscópica transetmoidal. MATERIAL E MÉTODOS: Estudo prospectivo. 50 fossas nasais de cadáveres foram dissecadas. Após a realização de uma etmoidectomia anterior e remoção parcial da lâmina papirácea, a periórbita foi cuidadosamente dissecada até a identificação da AEA. Após sua identificação, a artéria foi exposta e ligada dentro da órbita. RESULTADOS: Todas as dificuldades inerentes ao procedimento, as complicações associadas, a curva de aprendizado e variações anatômicas foram coletados. CONCLUSÕES: A abordagem endoscópica da AEA na órbita de cadáveres mostrou-se factível. A identificação da artéria é fácil e a técnica evita incisões externas. Este acesso parece ser uma excelente alternativa para a abordagem da AEA. Estudos clínicos futuros são necessários para comprovar os benefícios desta técnica.

Anterior ethmoidal artery (AEA) ligation may be necessary in cases of severe epistaxis not controllable with traditional therapy. Endoscopic endonasal ligation of the AEA is not used frequently; there are few studies in the literature for standardization of the endoscopic technique for this vessel. AIM: To demonstrate the feasibility of periorbital AEA ligation in a transethmoidal endoscopic approach. METHODS: A prospective study where 50 nasal cavities were dissected. After anterior ethmoidectomy and partial removal of lamina papyracea, the periorbital area was carefully dissected along a subperiosteal plane to identify the AEA. The vessel was exposed within the orbit and dissected. RESULTS: Data on technical difficulties, complications, the learning curve and anatomical variations were gathered. CONCLUSION: An endonasal endoscopic approach to the AEA within the orbit was shown to be feasible. Identifying the artery is not difficult, and this technique avoids external incisions. This approach appears to be an excellent alternative for approaching the AEA. Further clinical studies are needed to demonstarte the benefits of this technique.

Anatomia endoscópica da artéria etmoidal anterior: estudo de dissecção em cadáveres / Endoscopic anatomy of the anterior ethmoidal artery: a cadaveric dissection study

INTRODUÇÃO: a artéria etmoidal anterior (AEA) é um importante ponto de reparo anatômico para localização do seio frontal e da base de crânio. Entretanto, apesar de diversos estudos endoscópicos em cadáveres, ainda não temos um estudo anatômico sobre AEA na população ocidental. OBJETIVOS: Determinar pontos de reparo para localização da artéria, estudar sua relação com a base do crânio e grau de deiscência, assim como variações intra e interindividuais. CASUíSTICA E MÉTODOS: Foram realizadas dissecções das fossas nasais em 25 cadáveres. RESULTADOS: O comprimento médio do trajeto intranasal da artéria etmoidal anterior foi de 5,82mm. O canal etmoidal anterior apresentou algum grau de deiscência em 66,7 por cento. A distância média do ponto médio da artéria à espinha nasal anterior foi de 61,72mm (dp = 4,18mm); à axila nasal foi de 64,04mm (dp = 4,69mm); e à axila anterior do corneto médio foi de 21,14mm (dp = 3,25mm). Para todas as medidas, não houve diferença estatisticamente significativa quando comparados os lados direito e esquerdo (p>0,05). CONCLUSÕES: Concluímos que a axila da concha média é o ponto de reparo mais confiável para a localização da AEA.

INTRODUCTION: The anterior ethmoidal artery (AEA) is an important point of anatomical reference in order to locate the frontal sinus and the skull base. Notwithstanding, despite numerous endoscopic studies in cadavers, we still lack an anatomical study on the AEA in the western population. AIM: to determine reference points used to locate the artery, study its relationship with the skull base and its degree of dehiscence, as well as to study intra and inter individual variations. MATERIALS AND METHODS: we dissected the nasal fossae belonging to 25 cadavers. RESULTS: the average intranasal length of the anterior ethmoidal artery was 5.2 mm. The anterior ethmoidal canal presented some degree of dehiscence in 66.7 percent. The average distance between the artery middle point to the anterior nasal spine was of 61.72 mm (sd = 4.18 mm); to the lateral nasal wall (nasal axilla) was of 64.04 mm (sd = 4.69mm); and from the anterior axilla to the middle turbinate was of 21.14 mm (sd = 3.25 mm). For all the measures there was no statistically significant measures when both sides were compared (p>0.05). CONCLUSIONS: We concluded that the middle conchae axilla is the most reliable point of reference to locate the AEA.