Azygos Anterior Cerebral Artery Research Articles

The Anatomical Variation of the Distal Anterior Cerebral Artery: An Angiographic Study in a Greek Population Sample.

Objective The current retrospective angiographic study establishes the rates of variants in the distal anterior cerebral artery (DACA) in a sample of the Greek population. Methods Data were collected from 456 patients who underwent two-dimensional (2D) or three-dimensional (3D) digital subtraction angiography (DSA) of the carotid and vertebral arteriesbilaterally. The study focused on patients with good visualization of the anterior and posterior circulations and employed magnetic resonance (MR) or computed tomography (CT) angiography for 3D reconstruction. The anterior cerebral artery (ACA) was classified into one of its two basic configurations, that is, with or without the callosomarginal artery (CMA). The bihemispheric, median, and azygos ACA patterns were also identified. Results The majority (373/456, 81.8%) exhibited a typical DACA pattern. The bihemispheric, median, and azygos patterns were identified in 66/456 (14.5%), 10/456 (2.2%), and 7/456 (1.5%), respectively. The CMA was present in 824/912 (90.4%) of the hemispheres, with a trend towardmale predominance for bilateral presence (males: 167/192, 86.98%; females: 210/264, 79.55%; p = 0.05). In particular, the CMA was present significantly more frequently (p = 0.002) in the left hemispheres of male patients. Gender differences in CMA presence persisted in the analysis of the patients with a typical DACA pattern. Conclusion This study provides insights into the variations of the DACA in the Greek population. The observed gender differences in CMA rates suggest potential morphological variations in cerebral vasculature between males and females and contribute to a better understanding of vascular anatomy for clinical and surgical applications.

КЛИНИЧЕСКОЕ ЗНАЧЕНИЕ НЕПАРНОЙ ПЕРЕДНЕЙ МОЗГОВОЙ АРТЕРИИ

Introduction. Vascular variations in the Circle of Willis occur rather frequently and, according to some observations, are often associated with some cerebrovascular diseases. A single azygos anterior cerebral artery is characteristic of mammals but rare in humans. Increased hemodynamic loads due to the blood supply of both hemispheres by a single azygos anterior cerebral artery can lead to the formation of aneurysms in it. Aim. This study is aimed at assessing the incidence of the azygos anterior cerebral artery and its association with cerebrovascular pathology. Materials and Methods. We analyzed Russian and foreign publications on the structural variants of anterior cerebral arteries over the years 2000-2022. This period was selected due to the wide implementation of cerebral angiographic studies in those years. We also presented two cases of our clinical patients having an azygos anterior cerebral artery. Results and Discussion. According to the literature review, an azygos anterior cerebral artery occurs in 0.3-4% of cases. Azygos anterior cerebral artery is most frequently associated with the development of distal aneurysms. Thrombosis of this artery leads to bilateral ischemic foci in the medial parts of the frontal and parietal lobes. We present clinical cases of a single azygos anterior cerebral artery in patients with distal aneurysms and arteriovenous malformation. Conclusions. A single azygos anterior cerebral artery is a rare variant of the Circle of Willis structure and may predispose to the development of cerebrovascular pathology.

Acute Paraparesis Syndrome after a Ruptured Aneurysm of the Azygos Anterior Cerebral Artery (P12-5.016)

<h3>Objective:</h3> To describe a rare case of acute paraparesis syndrome (APS) after a ruptured aneurysm of the azygos anterior cerebral artery (ACA). <h3>Background:</h3> The incidence of APS within 24 hours after subarachnoid hemorrhage is very rare. Additionally, the pathophysiology of this syndrome remains poorly defined. Nonetheless, the literature suggests it could emerge from a bilateral ACA vasospasm, acute hydrocephalus, or global cerebral edema and can be associated with poor clinical status. The azygos ACA is a rare variant whose unique anatomy intensifies the hemodynamic stress on the arterial wall, making aneurysm formation closely associated with this anomaly. <h3>Design/Methods:</h3> A 72-year-old man with a past medical history of hypertension presented to the hospital with the complaint of acute paraparesis after a thunderclap headache and transitory loss of consciousness. The physical exam showed paraparesis with brisk patellar and Achilles reflexes and a neutral response to bilateral plantar stimulation. No abnormalities were noticed on the cranial nerves, coordination, and sensory examination. <h3>Results:</h3> Routine laboratory studies were normal. Brain computed tomography revealed an acute punctate hemorrhage of an aneurysm located in the frontal interhemispheric fissure. Magnetic Resonance Imaging (MRI) of the spine was unremarkable. Brain MRI showed unspecific white matter abnormalities, and an MR angiography showed a 4.3 mm saccular aneurysm in the right ACA A3 segment in the bifurcation of an azygos ACA. The patient underwent coiling of the aneurysm and was able to walk unassisted nine weeks after the procedure. <h3>Conclusions:</h3> Acute paraparesis syndrome is a rare manifestation of a ruptured anterior communicating artery or anterior cerebral artery aneurysm. Here, we present an atypical etiology of APS caused by a ruptured aneurysm of the azygos ACA. To the best of our knowledge, this is the first description of an APS after a ruptured aneurysm of the azygos ACA. <b>Disclosure:</b> Dr. Moreno-Zambrano has nothing to disclose. Dr. Jimenez Zambrano has nothing to disclose. Jose Francisco Ortega Tola, MD has nothing to disclose. Dr. Yepez has nothing to disclose. Wilson Cueva has nothing to disclose.

Stenosis of Azygos Anterior Cerebral Artery Results in Bilateral Anterior Cerebral Artery Strokes.

HomeStrokeVol. 53, No. 10Stenosis of Azygos Anterior Cerebral Artery Results in Bilateral Anterior Cerebral Artery Strokes Free AccessCase ReportPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessCase ReportPDF/EPUBStenosis of Azygos Anterior Cerebral Artery Results in Bilateral Anterior Cerebral Artery Strokes Diana Yang, Brian Behdad Miremadi, Anton Mlikotic and Kassi Kronfeld Diana YangDiana Yang Correspondence to: Diana Yang, DO, Harbor-UCLA Medical Center, 1000 W. Carson St, Building N-25, Torrance, CA 90502. Email E-mail Address: [email protected] https://orcid.org/0000-0001-6695-1771 Department of Neurology (D.Y., B.B.M., K.K.), Harbor-UCLA Medical Center, Torrance, CA. Search for more papers by this author , Brian Behdad MiremadiBrian Behdad Miremadi Department of Neurology (D.Y., B.B.M., K.K.), Harbor-UCLA Medical Center, Torrance, CA. Search for more papers by this author , Anton MlikoticAnton Mlikotic Department of Radiology (A.M.), Harbor-UCLA Medical Center, Torrance, CA. Search for more papers by this author and Kassi KronfeldKassi Kronfeld Department of Neurology (D.Y., B.B.M., K.K.), Harbor-UCLA Medical Center, Torrance, CA. Search for more papers by this author Originally published15 Jul 2022https://doi.org/10.1161/STROKEAHA.122.040216Stroke. 2022;53:e448–e449Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: July 15, 2022: Ahead of Print KEY POINTAlthough much rarer than unilateral extremity weakness, bilateral lower extremity weakness may still result from a stroke—specifically due to vascular compromise of an azygos anterior cerebral artery.A 55-year-old female presented with 1 week of acute onset bilateral lower extremity weakness and reduced speech output. Examination was notable for spastic paralysis of lower extremities, trace weakness in bilateral shoulder abduction, and abulia. Magnetic resonance imaging revealed bilateral anterior cerebral artery (ACA) territory strokes. Computed tomography angiography demonstrated absence of the anterior communicating artery, a hypoplastic right ACA precommunicating segment (A1), azygos continuation of a dominant left ACA, and focal stenosis in the lone A2 segment.ACA territory infarcts only account for 1.8% of cerebral infarcts, and bilateral ACA infarcts are even less common.1 Azygos ACA is a rare circle of Willis variant (0.3%–2% of the population) notable for an absent anterior communicating artery and one ACA postcommunicating segment (A2) feeding both ACA territories.2 Despite the initial difficult localization, bilateral lower extremity weakness may still result from a stroke, specifically due to vascular compromise of an azygos ACA (Figure).Download figureDownload PowerPointFigure. Brain magnetic resonance imaging and head computed tomography angiography. Bilateral anterior cerebral artery (ACA) territory diffusion restriction on magnetic resonance imaging diffusion-weighted imaging (DWI) sequence (A) with corresponding hyperintensity on fluid-attenuated inversion recovery (FLAIR) sequence (B). Three-dimensional computed tomography angiography (C and D) demonstrates 2 anatomic variants: hypoplastic right A1 segment (short arrow) with dominant left ACA and an absent anterior communicating artery. There is significant focal stenosis in the A2 segment (long arrows).Article InformationSources of FundingNone.Disclosures None.FootnotesFor Sources of Funding and Disclosures, see page e449.Correspondence to: Diana Yang, DO, Harbor-UCLA Medical Center, 1000 W. Carson St, Building N-25, Torrance, CA 90502. Email [email protected]lacounty.gov

Variations of Anterior Cerebral Artery (ACA) on CT Angiography (CTA)

Introduction: The variations in anterior cerebral artery (ACA) has high clinical significance for surgeons&#x0D; Aim: This study aims to assess the variations of ACA with the help of CT angiography (CTA)&#x0D; Methodology: This retrospective study was conducted from Nov 2019 to Feb 2020 at Lahore General Hospital, Lahore. In total, 150 patients went under detailed analysis. The demographic data such as age and gender were noted for each patient. The CTA was performed with the help of 128-slice CT scanner. The reports were assessed by an experienced radiologist. Anatomic variations were noted and presented as frequencies and percentages.&#x0D; Results: The study included 92 (61.33%) were females and 58 (38.66%) were males with mean age 50.2 ± 3.7 years. Azygos anterior cerebral artery was present in 14 patients (9%), hypoplasia of anterior cerebral artery A1 segment in 43 (35.66%) patients,11 (7.33%) patients showed bi-hemispheric anterior cerebral artery, right anterior cerebral artery dominance in 2 (1.33%) patients, 8 (4.33 %) were detected with congenital absence of A1 segment. Anterior cerebral artery trifurcation had prevalence of 6(3.2%).&#x0D; Conclusion: It can be concluded that anterior cerebral artery variations have low prevalence and CT angiography is a gold method for detecting them.

Pericallosal berry aneurysm associated with azygous anterior cerebral artery – a case report

Introduction. Azygos anterior cerebral artery is a rare variant of the anterior segment of the circle of Willis caused by an unusual fusion of the normally paired A2 segments of the anterior cerebral artery (ACA). Despite its rare occurrence, it is associated with various vascular and structural cerebral abnormalities, particularly berry aneurysms. Aim. We aimed to present a case of a 41-year-old female patient who presented to our neurology department with complaints of headache. Description of the case. She had a positive paternal history of aneurysmal subarachnoid hemorrhage. Magnetic resonance angiography (MRA) of her brain revealed an azygos ACA (bifurcating into two pericallosal arteries) which was associated with a saccular aneurysm at its bifurcation point. She was referred to the interventional radiology department for preventive endovascular treatment. Conclusion. Azygos ACA carries a high risk of aneurysm development and its occlusion can potentially compromise blood supply to both cerebral hemispheres. It is therefore crucial for clinicians to be aware of its significance and to report its presence in angiographic studies.

A case of azygos anterior cerebral artery dissection with subarachnoid hemorrhage and hemorrhagic infarct during treatment for cerebral infarction

A case of azygos anterior cerebral artery dissection with subarachnoid hemorrhage and hemorrhagic infarct during treatment for cerebral infarction

Variantes anatómicas del círculo arterial cerebral en un anfiteatro universitario en Bogotá (Colombia)

Introducción: el cerebro es un órgano altamente irrigado, y esta irrigación es suministrada por el círculo arterial cerebral: una red arterial anastomótica con frecuentes variaciones anatómicas, algunas asociadas con patologías. El objetivo es describir las características antropométricas y variaciones anatómicas del círculo arterial cerebral en una muestra de especímenes cadavéricos humanos. Materiales y métodos: se revisaron 50 encéfalos, de los cuales 24 cumplieron con los criterios de inclusión. Se realizaron medidas de diámetro y longitud y también se describieron variaciones anatómicas y variaciones morfométricas. Resultados: siete especímenes evidenciaron variaciones anatómicas (29.1%); 3 (12.5%), arteria cerebral anterior (ACA) ácigos; uno (4.1%), doble ACA en el segmento A1; uno (4.1%), triple ACA en el segmento A2 y doble arteria comunicante anterior (AcomA); uno (4.1%), agenesia de la arteria comunicante posterior (AComP) derecha; uno (4.1%), de la AComP izquierda. El 29.1% presentó variaciones antropométricas; el 12.5 %, hipoplasia de la AComP derecha; el 12.5 %, de la AComP izquierda, y el 4.1 %, hipoplasia bilateral de la AComP. Conclusión: la presencia de variaciones anatómicas fue inferior a la hallada en otros estudios, con predominio de variantes de la circulación anterior. Se describe la presencia de triple aca en el segmento A2 y doble arteria comunicante anterior.

Radiological classification of azygos anterior cerebral artery and evaluation of the accompanying vascular anomalies

There is not a classification of azygos anterior cerebral artery (ACA) based on anatomical branching levels in the literature. In the present study, a classification of azygos ACA was made based on radiological imaging for a common terminology, and frequency, accompanying vascular anomalies and malformations were investigated. A total of 4913 cases who had brain CTA, MRA, contrast-enhanced MRI and DSA in January 2010-January 2020 period were screened for the study. Based on anatomical branching level, azygos ACAs were classified into four groups. Aneurysms, anomalies and malformations accompanying azygos ACA were identified. The associations of azygos ACA types with the presence of aneurysm or ACA A1 segment anomalies were investigated. Azygos ACA was observed in 57 cases (29 male and 28 female) and frequency of azygos ACA was 1.16%. Average age of the cases with ACA was 56.19 ± 19.65years. Forty-eight of the cases had type C azygos ACA, four cases type B, four cases type D and one case type A azygos ACA. A total of nine intracranial aneurysms were identified in seven of the cases (12.28%). Five of the aneurysms were located in MCA and four in distal ACA. Most common vascular anomalies accompanying azygos ACA were unilateral vertebral artery hypoplasia and ACA A1 segment hypoplasia. Azygos types did not have significant correlations with the presence of aneurysms or ACA A1 segmental anomalies (p = 0.683 and p = 0.949, respectively). Azygos ACA is a rare variation, but it could be accompanied by aneurysms or other vascular anomalies.

Intracranial arterial variations and their relation with cerebral aneurysms: Analysis of 640 patients

Aim: To evaluate prevalence of cerebral arterial variations in Turkish population and association of the variations with cerebral aneurysmsMaterials and Methods: Digital subtraction angiography of 640 consecutive patients between January 2011-December 2013 were evaluated retrospectively. Patients with aneurysms were compared with patients without aneurysm to determine the effect of variations. Comparisons were made using Chi square or Fisher exact test for categorical variables and Student's t test or Mann Whitney U test for continuous variables.Results: The most common variation in the anterior circulation was hypoplasia of anterior cerebral artery A1 segment and the most common variation in the posterior circulation was fetal origin of the posterior cerebral artery. Hypoplasia and aplasia of the anterior cerebral artery A1 segment was significantly more frequent in patients with anterior communicating artery aneurysms than the control group (p:0.001). Prevalence of azygos anterior cerebral artery variation was higher in distal anterior cerebral artery aneurysms than the control group (p 0.001). There was no association between bihemispheric anterior cerebral artery and anterior communicating artery aneurysms (p = 0.453). Similarly, no significant association of fetal origin of posterior cerebral artery with posterior communicating artery aneurysms was found (p = 0.133). Conclusion: Prevalence of cerebral arterial variations in this study were compatible with literature. Some variations may play a role in development of aneurysms by alterations in hemodynamics and increasing shear wall stress. Further larger studies are needed to clarify the relation between variations in cerebrovascular structure and aneurysm formation.

Persistent Fetal Trigeminal Artery with Septopreoptic Holoprosencephaly: Report of an Unusual Association

AbstractSeptopreoptic holoprosencephaly (HPE) is a type of HPE characterized by failure of separation of the septal and preoptic regions. Vascular anomalies associated with septopreoptic HPE include twig-like cerebral vessels and azygos anterior cerebral artery, the latter common to all forms of HPE. Here, we describe an 8-year-old boy presenting with developmental delay and abnormal movements who was found to have septopreoptic HPE associated with persistent trigeminal artery in magnetic resonance neuroimaging. This persistence of fetal trigeminal artery in HPE provides a further understanding of the pathogenesis of HPE.

Imaging of Brain Infarctions: Beyond the Usual Territories.

In this review, our intension is to present imaging features of several categories of uncommon cases of brain infarctions including infarctions associated with neurovascular variants, infarctions along small arterial territories, and brainstem stroke syndromes. Infarctions associated with neurovascular variants include azygos anterior cerebral artery territory infarction and artery of Percheron infarction. In the second group, we discuss anterior choroidal artery infarction and artery of Heubner infarction. The third group highlights brainstem stroke syndromes, including Claude and Benedikt syndromes due to midbrain infarction; Foville, Marie Foix, and locked-in syndromes due to pontine infarction; and Dejerine (medial medullary), bilateral medial medullary, and Wallenberg (lateral medullary) syndromes.

Tętniak gigant pojedynczego pnia tętniczego segmentu A2 tętnicy przedniej mózgu. Trudności w postępowaniu chirurgicznym

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Andrychowski J. Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery. Medical Studies/Studia Medyczne. 2019;35(4):327-330. doi:10.5114/ms.2019.91252. APA Andrychowski, J. (2019). Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery. Medical Studies/Studia Medyczne, 35(4), 327-330. https://doi.org/10.5114/ms.2019.91252 Chicago Andrychowski, Jarosław. 2019. "Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery". Medical Studies/Studia Medyczne 35 (4): 327-330. doi:10.5114/ms.2019.91252. Harvard Andrychowski, J. (2019). Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery. Medical Studies/Studia Medyczne, 35(4), pp.327-330. https://doi.org/10.5114/ms.2019.91252 MLA Andrychowski, Jarosław. "Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery." Medical Studies/Studia Medyczne, vol. 35, no. 4, 2019, pp. 327-330. doi:10.5114/ms.2019.91252. Vancouver Andrychowski J. Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery. Medical Studies/Studia Medyczne. 2019;35(4):327-330. doi:10.5114/ms.2019.91252.

Ruptured Anterior Cerebral Artery (A1) Dissecting Aneurysm Accompanied with an Azygos Anterior Cerebral Artery

Ruptured Anterior Cerebral Artery (A1) Dissecting Aneurysm Accompanied with an Azygos Anterior Cerebral Artery

A saccular aneurysm of an azygos anterior cerebral artery: A rare anatomical variation and review of literature

The azygos anterior cerebral artery (ACA) is a rare variation in the circle of Willis. Azygos ACAs often associated with other vascular or nonvascular anomalies. These aneurysms can be noninvasively imaged either by conventional computed tomography (CT) angiography or magnetic resonance angiography, but digital subtraction angiography is the gold standard for diagnosis. We report a case of saccular aneurysm of azygos ACA, diagnosed by multidetector CT cerebral angiography and treated by craniotomy and clipping of aneurysm. The clinical significance of the rare anomaly is highlighted. We report this rare clinical experience with review of the literature.

Aneurisma da artéria cerebral anterior ázigos

São apresentados dois casos de aneurismas da artéria cerebral anterior ázigos, operados com boa evolução. São analisados a rara incidência de aneurismas deste vaso e as variações anatômicas da artéria cerebral anterior distal.

Anisocoric pupil generated by azygos anterior cerebral artery: a case report

Abstract Introduction: In the embryonic period, several developmental anomalies of the cerebral arteries occur. The knowledge of these anatomic variations is important to avoid unnecessary surgery and to undergo surgery or interventional radiology with safety. Objective: In this report, we discuss the hypothesis of the presence of azygos anterior cerebral artery as a possible cause of anisocoric pupil found in a patient with 35 years old. To our knowledge, this variation has not been previously reported. Results: In this study we reported a case of this artery emphasizing some morphological, functional and clinical data about this rare vascular abnormality. Conclusion: The results could be important to offer useful information to anatomists, radiologists, ophthalmologists, neurologists and head and neck surgeons.

Aneurysm of azygos anterior cerebral artery associated with falcine meningioma: Case Report and review of the literature

Background:The azygos anterior cerebral artery (ACA) is an uncommon intracranial vascular anomaly of the circle of Willis. Identification of aneurysm from azygos ACA with anterior falcine meningioma is an extremely rare association. The aim of the present study is to report the case of an adult female with a ruptured aneurysm from azygos ACA in association with an anterior falcine meningioma.Case Description:A 65-year-old female was admitted in the Emergency Department reporting sudden onset of severe headache. Computed tomography (CT) revealed an intracerebral hematoma and an expansive calcified lesion. AngioCT showed the presence of a large aneurysm in the distal portion of the azygos ACA. During the surgical procedure, it was possible to visualize the aneurysm in contact with an expansive lesion arising from the anterior third of the falx. Microsurgical clipping of the aneurysm was performed uneventfully and partial resection of the tumor was done. Histopathological analysis showed a fibrous meningioma. The patient was discharged home on the seventh postoperative day in good clinical conditions.Conclusion:The association of aneurysm from azygos ACA and falcine meningioma is an extremely rare event and must be remembered when expansive masses are present in the vicinity of vascular lesions.

Adaptation of the cerebrocortical circulation to carotid artery occlusion involves blood flow redistribution between cortical regions and is independent of eNOS.

Cerebral circulation is secured by feed-forward and feed-back control pathways to maintain and eventually reestablish the optimal oxygen and nutrient supply of neurons in case of disturbances of the cardiovascular system. Using the high temporal and spatial resolution of laser-speckle imaging we aimed to analyze the pattern of cerebrocortical blood flow (CoBF) changes after unilateral (left) carotid artery occlusion (CAO) in anesthetized mice to evaluate the contribution of macrovascular (circle of Willis) vs. pial collateral vessels as well as that of endothelial nitric oxide synthase (eNOS) to the cerebrovascular adaptation to CAO. In wild-type mice CoBF reduction in the left temporal cortex started immediately after CAO, reaching its maximum (-26%) at 5-10 s. Thereafter, CoBF recovered close to the preocclusion level within 30 s indicating the activation of feed-back pathway(s). Interestingly, the frontoparietal cerebrocortical regions also showed CoBF reduction in the left (-17-19%) but not in the right hemisphere, although these brain areas receive their blood supply from the common azygos anterior cerebral artery in mice. In eNOS-deficient animals the acute CoBF reduction after CAO was unaltered, and the recovery was even accelerated compared with controls. These results indicate that 1) the Willis circle alone is not sufficient to provide an immediate compensation for the loss of one carotid artery, 2) pial collaterals attenuate the ischemia of the temporal cortex ipsilateral to CAO at the expense of the blood supply of the frontoparietal region, and 3) eNOS, surprisingly, does not play an important role in this CoBF redistribution.

Detailed description of the anterior cerebral artery anomalies observed in a cadaver population

Anomalies of the anterior cerebral artery (ACA) include the median ACA (MedACA), bihemispheric ACA (BihemACA) and the azygos ACA. Knowledge of these anomalies can be crucial to clinicians and neurosurgeons, especially during surgeries involving the interhemispheric region and in the interpretation of the clinical signs of a stroke. Since few reports exist on the origin, area supplied, diameter and length of the ACA anomalies, the aim of this study is to give a detailed description on the anatomy of the ACA anomalies.The ACAs of 60 brains were injected with a colored silicone. When an anomaly was observed, a detailed illustration of the course and pattern of the ACA and cortical branches were made. The origins and the areas supplied by the anomalous arteries were noted. The external diameter was measured using a digital micrometer and the length was measured using string and a ruler.There were seven cases (11.7%) of a MedACA and 12 cases (20.0%) of a BihemACA. The MedACA originated mostly from the anterior communicating artery, and from the A2 segment in one case. The MedACA was bilateral in four cases and unilateral in three cases. Excluding Cases 5 and 9, the BihemACA cases can be divided into two groups; one branch to the left hemisphere (n=3), and one branch to the right hemisphere (n=7). The average diameter of both the BihemACA and MedACA was 1.8mm.Studies rarely provide additional information on these anomalies. Therefore, the present study elaborated on the origin, diameter, length and the area supplied by these anomalies. The definitions are described in the literature, although additional criteria were still lacking and this was provided in the present study. Since information on these aspects of the ACA anomalies is scarce, future research should give detailed descriptions on the ACA anomalies.