The anterior communicating artery variants: a meta-analysis with a proposed classification system.

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery's hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Magnetic Resonance Angiographic Study of the Anatomical Variations of the Anterior Communicating Artery Complex in a Turkish Population.

AIM: To provide a definition of arterial anomalies in the anterior communicating artery complex (ACoAC), determine their prevalence and investigate their relationship with aneurysms. MATERIAL AND METHODS: The three-dimensional time-of-flight magnetic resonance angiography images of 1,857 adult patients who presented to our hospital between January 2020 and September 2022 were evaluated retrospectively. The images of 1,537 cases were subsequently classified according to their ACoAC anatomical variants. The patients were further grouped as those with no pathology, those with ACoAC aneurysms and those with pathologies other than ACoAC, and the relationship between the ACoAC anatomical variants of each group was investigated using statistical methods. Rare variants such as trifurcations of the A2 segments, single A2 segments, fenestrations of the A1 segment and double AComAs were evaluated in separate groups. RESULTS: The results of the classification of the 1,537 cases revealed the classical anatomical variant in 39.2% of the cases without ACoAC pathologies and 53.3% of the cases with ACoAC aneurysms. There was no significant difference between the sexes in terms of variant distribution (p=0.09), and no significant relationship between the presence of ACoAC aneurysms and sex (p=0.5). CONCLUSION: ACoAC anatomical variants of the cerebral arterial system were detected in 60% of the cases. The most common anterior circulation (AC) vascular variants (VV) were A1 segment hypoplasia and aplasia. No clear relationship was found between intracranial aneurysms and anatomical variation.

Anatomical Variations and Anomalies of the Anterior Communicating Artery Complex.

BACKGROUND: Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all variations and anomalies within the anterior communicating artery complex. METHODS: PubMed was searched with the terms "Anterior Communicating Artery" AND "Variations" OR "Anomalies." Articles were selected based on their description of variants. Cross-referencing was used to broaden the range of variations. Surgical view during pterional craniotomy and transsylvian approach was used as a baseline for schematic drawings of the variations. RESULTS: A total of 42 variants were identified, schematically drawn and classified into A1-A2 segment, anterior communicating artery, and the recurrent artery of Heubner. CONCLUSIONS: The anterior communicating artery complex consists of the anterior cerebral artery, anterior communicating artery and the recurrent artery of Heubner. An overview of these variations may be helpful in distinguishing pathology from anatomical variations, assist neurosurgeons during clipping of cerebral aneurysms, and support interventional radiologists during endovascular treatments. This article summarizes the current knowledge of anatomical variations within the anterior communicating artery complex, their prevalence and clinical relevance. A total of 42 variants were identified and schematically depicted. We encourage all who diagnose, treat, and study the anterior communicating artery complex to use this overview for a uniform and better understanding of its anatomy.

Left anterior cerebral artery arising from a right internal carotid artery: a rare case of carotid-anterior cerebral artery anastomosis.

Carotid-anterior cerebral artery anastomosis (carotid-ACA anastomosis) is described as infrequent vascular connections between the pre-ophthalmic segment of the internal carotid artery (ICA) and the A1 segment of the anterior cerebral artery (ACA). The embryological origin of these variant is still unclear and they are often associated to other vascular anomalies of the circle of Willis, as well as to the presence of aneurysms. Carotid-ACA anastomosis is often right-sided although left and bilateral cases have also been described. We report a rare case by MR angiography of a carotid-ACA anastomosis in which the abnormal vessel arises from the right ICA and takes an infraoptic course to join the A2 segment of the contralateral ACA, making this vascular anomaly function as a 'left ACA with an origin at the right ICA'. The A1 segment of the left ACA is absent and both A2 segments of the ACAs present fenestration. To our knowledge, no similar cases have been reported in English literature so far.

Fenestrated Anterior Cerebral Artery, Anterior Communicating Artery, with Accessory Middle Cerebral Artery-A Conglomeration of Embryologically Different Entities in a Single Individual.

Cerebral arterial fenestrations are anatomic variants of undetermined significance where there is a division of a single vessel into at least 2 channels, each having endothelial and muscular layers, that coalesce to a single lumen in the distal course of the vessel. The basilar artery is the most common site, followed by the anterior communicating artery. The accessory middle cerebral artery is defined as the anomalous origin of the vessel from the anterior cerebral artery and its further course along the sylvian fissure parallel to the middle cerebral artery. The embryologic basis of all these has been explained by studies on human embryological development by Padget et al. However, simultaneous existence of all 3 anomalies in a single individual has never been reported. Here we present a case of medial sphenoid wing meningioma with these incidental findings during workup and further delineation of anatomy following surgical resection of meningioma.

Bilateral aplasia of the anterior cerebral artery in the presence of its vascular source: a case report.

PURPOSE: Our goal was to investigate the cases of bilateral aplasia of the anterior cerebral artery (ACA). METHODS: The macro- and microdissection of the target human brain arteries of 388 cadaveric cases was applied under the magnifying glass. Each case was photographed and diagrammatically represented in the workbook. The length and the outer diameter of the corresponding arteries on the photos were measured using a computer software program. RESULTS: There was only one case (1/388 or 0.25%) of bilateral ACA aplasia that belonged to a male adult cadaver. Except for the variations of the posterior communicating artery on one side and the basilar artery, the instance of cerebral pathology was not recorded in this case. We compared the recent case with available literature cases. CONCLUSION: Summarizing small number of literature cases, the recent case of bilateral ACA aplasia as the fifth case discovered so far, represents a true morphological rarity.

Bilateral persistent primitive olfactory arteries associated with an accessory anterior cerebral artery.

Persistent primitive olfactory artery (PPOA) is a relatively rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn before continuing to the A2 segment of the ACA. This variation is usually seen unilaterally, and the anterior communicating artery (ACoA) is usually long or absent. We herein report a case of bilateral persistent PPOAs associated with an accessory ACA. The length of the bilateral A1 segments was normal and the length of the ACoA was normally short. Thus, hypoplasia of the distal A1 segment is important but not necessary for the formation of the PPOA. To our knowledge, no similar cases have been reported in the relevant English language literature.

Double unilateral fenestration of the anterior cerebral artery in the pre-communicating segment: a report of a unique case.

A unique example of two fenestrations of the pre-communicating (A1) segment of the right anterior cerebral artery (ACA) in a 78-year-old woman was a special case among 388 cadaveric specimens. It was found by a retrospective review of the personal data obtained during graduate and undergraduate studies at the Faculty of Medicine. Two unequal fenestrations of the right A1 segment were associated with the presence of a pseudo anterior communicating artery, hypoplasia of the right posterior communicating artery and the left superior cerebellar artery, absence of the right anterior inferior cerebellar artery, and ectasia of the basilar artery; however, the cerebral arteries were without aneurysm(s) or other pathology. The reason could be the almost equal ACA diameter on both sides.

Analysis of Risk Factors for Anterior Communicating Artery Aneurysm Rupture: A Single-Center Study.

BACKGROUND: Congenital hypoplasia or aplasia of the A1 segment of the anterior cerebral artery is associated with an increased incidence of berry aneurysms at the anterior communicating artery (ACoA) complex. We analyzed the factors contributing to ACoA aneurysm rupture. METHODS: We retrospectively analyzed the data of patients with ACoA aneurysms who had undergone cerebral angiography from July 2008 to January 2020. The risk factors for rupture were identified using univariate and multivariate logistic regression models. We used the imaging data of patients without intracranial aneurysms as the control population. RESULTS: We confirmed 253 aneurysms in 253 patients, including 137 men (54.2%) and 116 women (45.8%), with a mean age of 54.6 ± 12.7 years. Of the 253 aneurysms, 218 (86.2%) were ruptured and 35 (13.8%) were unruptured, with a mean diameter of 4.56 ± 1.96 mm and 3.24 ± 1.79 mm, respectively. Of the 253 aneurysms, 176 (69.6%) were <5 mm in diameter, 146 (83%) of which were ruptured. Of the 253 patients, 141 (55.7%) exhibited A1 segment hypoplasia or aplasia: 106 (41.9%) on the right side of the circle of Willis and 35 (13.8%) on the left. Multivariate logistic regression analysis identified the aneurysm diameter (odds ratio, 4.11; 95% confidence interval, 1.601-16.07; P = 0.003) and age <65 years (odds ratio, 0.17; 95% confidence interval, 0.062-0.48; P < 0.001) as independent predictors of rupture. CONCLUSIONS: ACoA aneurysms are small (<5 mm) and have a high risk of rupture. A1 segment hypoplasia or aplasia is a risk factor for ACoA aneurysm formation; however, it was uncorrelated with aneurysm diameter or rupture risk. The strongest independent risk factors for rupture were age <65 years and aneurysm diameter.

Persistent primitive olfactory artery associated with early bifurcated accessory anterior cerebral artery.

Five types of persistent primitive olfactory artery (PPOA), a rare variation of the proximal anterior cerebral artery (ACA), have been reported. Type 1 is most common, generally following an extreme anteroinferior course and taking a hairpin turn before continuing to the distal A2 segment of the ACA. Triple ACAs are a common variation of the A2 segment of the ACA, and a centrally located artery is called an "accessory ACA" or "median artery of the corpus callosum". This artery usually does not bifurcate or else bifurcates distally and continues to the pericallosal artery. We herein report a 74-year-old woman with type 1 PPOA and early bifurcated accessory ACA, an extremely rare combination of ACA variations, that was diagnosed using magnetic resonance angiography.

A1 Segment Unruptured Aneurysm of Persistent Primitive Olfactory Artery Coexisted with Accessory Middle Cerebral Artery.

A persistent primitive olfactory artery (PPOA) is a rare anomaly of anterior cerebral artery (ACA), which generally arises from the internal carotid artery (ICA), runs along the olfactory tract, and makes a hairpin bend to supply the territory of the distal ACA. PPOA is also associated with cerebral aneurysms. An accessory MCA is a variant of the middle cerebral artery (MCA) that arises from either the proximal or distal portion of the A1 segment of the ACA, which runs parallel to the course of the MCA and supplies some of the MCA territory. We experienced a rare case of coexistence of PPOA with an unruptured aneurysm and accessory MCA. Three-dimensional computed tomographic angiography (3D-CTA) has an excellent picture of the spatial relationship of the surrounding bony and vascular structure.

Combined rare anatomic variants: persistent primitive olfactory artery and azygos pericallosal artery.

The persisting primitive olfactory artery (PPOA) is a rare anatomic variation of the anterior cerebral artery (ACA), being encountered in less than 1% of cases. Different morphological types were reported previously. In type 3, only once reported previously, the PPOA gives off two branches, a nasal one which courses in the olfactory sulcus to supply the territory of the anterior ethmoidal artery, and the callosomarginal artery. It is reported here a combination of rare anatomic variants found in a 71-year-old male patient investigated by computed tomography angiography. A left PPOA left the A1 segment of the ACA and was classified as subtype 3b, as its branches were the nasal one and a frontal trunk, not the callosomarginal artery. That PPOA had a characteristic hairpin turn applied on the anterior fossa floor. The ACA continued as azygos pericallosal artery, which is also a rare finding. As the nasal branch of the PPOA and its hairpin turn is closely related to the anterior fossa floor, such variant should be carefully documented when combined approaches of the skull base are planned by rhinologists and neurosurgeons.

Persistent primitive olfactory artery without a hairpin turn.

Persistent primitive olfactory artery (POA) is a relatively rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn before continuing to the A2 segment of the ACA. There are other extremely rare variations, such as (1) that continuing to the ethmoidal artery without a hairpin turn, (2) that continuing to both ethmoidal artery and distal ACA with a hairpin turn, and (3) that continuing to the accessory middle cerebral artery with a hairpin turn. We herein report a case of persistent POA without a hairpin turn continuing to the A3 segment of the ACA. We propose calling this new type of persistent POA Type 5.

Association of Anterior Cerebral Artery Variants and Cerebral Infarction in Patients with Balloon-Assisted Coil Embolization for Unruptured Internal Carotid Artery Aneurysms.

BACKGROUND: Balloon-assisted coiling (BAC) is an endovascular treatment that may be associated with increased complications and thromboembolic events compared with other coiling techniques. We compared clinical outcomes of endovascular treatment (simple coiling, stent-assisted coiling, and BAC) in patients with unruptured intracranial aneurysms at the internal carotid artery and assessed risk factors that could cause cerebral infarction in patients who underwent BAC. METHODS: We retrospectively reviewed the records of 528 patients with 544 aneurysms who underwent endovascular treatment for unruptured intracranial aneurysms between January 2013 and November 2019. Demographic features, clinical information, balloon inflation time, fetal posterior cerebral artery, anterior cerebral artery (ACA) variants, and angiographic results were analyzed to determine risk factors for cerebral infarction. RESULTS: There were no significant differences among the 3 groups in terms of general characteristics. In the BAC group, 14 of 39 patients showed a significantly higher incidence of cerebral infarction on diffusion magnetic resonance imaging compared with the stent-assisted coiling (37/238) and simple coiling (21/267) groups (P < 0.001). There was no significant difference between the ACA variants (normal vs. hypoplasia or aplasia) and cerebral infarction in the simple coiling and stent-assisted coiling groups, but the proportion of aplasia or hypoplasia in the BAC group was significantly higher (P = 0.001). CONCLUSIONS: There is a significant association between anatomic ACA variants and cerebral infarction occurrence after BAC. Identifying the variant of the anatomic ACA using digital subtraction angiography would help to predict cerebral infarction after BAC.

Persistent Primitive Olfactory Artery: Three Cases.

ABSTRACT: The persistent primitive olfactory artery is a very rare arterial variant with a little over a score of cases reported in literature so far. We present 3 cases illustrating this entity, which were incidentally diagnosed while imaging for other indications.

Anatomical variants of anterior communicating artery complex. A study by Computerized Tomographic Angiography.

Advances in imaging techniques have led to the identification of normal variations and abnormalities of cerebral arteries. Although the anterior communicating artery complex (ACAC) variations are usually asymptomatic, their description is essential in the radiologic report, since they can have clinical relevance. The aim of this study is to describe arterial anomalies of the ACAC and their prevalence. A retrospective observational descriptive analysis of ACAC variations in Computerized Tomographic Angiography (CTA) was performed. All CTA (426 studies) obtained in our center from 2015 to 2017 were included. Presence of aneurysm was recorded and its relationship with arterial variants was analyzed with a Chi-square test. The most common variants found in our study are linked to the A1 segment (42.3%) of the anterior cerebral artery (ACA): absence: 10.6%, hypoplasia: 31.2%, fenestration: 0.5%. A2 segment variants were present in 15.3% (absence: 0.2%; hypoplasia 8.5%; Azygos artery: 1.4%; triple ACA: 5.2%). Anterior Communicanting Artery was typical in 92.5%, absent in 4.7%, double/fenestrated in 0.9%, triple in 0.2%, X-shape in 1.2% and Y-shape in 0.2%. Aneurysms were present in 10.7%. Anterior circulation aneurysm involved the 50% of patients with aneurysm. Although the 60.9% of them showed artery variants, they did not reach statistical significance (p = 0.6). In conclusion, the Anterior Communicating Artery Complex presents variations in its anatomy. The most common anterior circulation vascular variants are the hypoplasia and the absence of the A1 segment. There does not appear to be a clear association between intracranial aneurysms and anatomical variations.

Fetal posterior cerebral artery duplication, true fetal posterior cerebral artery variation and trifurcation anterior cerebral artery association.

We would like to present a case with fetal posterior cerebral artery duplication and anterior cerebral artery trifurcation, which we detected using magnetic resonance angiography. We believe this is the first case defined in the literature. Embryological explanation of posterior cerebral artery variations is discussed in light of the literature.