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.

Morphology and morphometry of the anterior cerebral-anterior communicating artery complex.

PURPOSE: The variations of Cerebral arterial circle (Circle of Willis) are not rare. The study is done to assess the pattern of the component vessels of its anterior part with regard to Right- Left variations and compare with other studies. MATERIAL AND METHOD: 56 formalin fixed cadavers were analyzed. The diameter, length and variations of the following vessels were observed: Anterior Cerebral Artery (proximal A1 segment to distal A2 segment) and anterior communicating artery. Statistical analysis was done by Statistica 14.0.1 software. RESULT: 53.57% had normal anterior cerebral artery- anterior communicating artery complex. Length and diameter were slightly more on left side. Unilateral hypoplasia, Azygos and Tripple Anterior Cerebral Artery was present in 21.43%, 3.57 and 1.78% respectively. Aplastic, double and fenestration type anterior communicating artery were present in 5.3%, 8.92% and 1.78% respectively. CONCLUSION: Anatomical knowledge of variations should be updated regularly for neurosurgeons, radiologists and clinicians to avoid unexpected consequences.

Fenestration of the anterior and posterior cerebral arteries in coexistence with a contralateral posterior cerebral artery of fetal origin.

PURPOSE: The present case report aims to describe the rare coexistence of three variants of the cerebral arterial system diagnosed by computed tomography angiography (CTA). METHODS: A retrospective study on head and neck CTAs was performed on a Greek adult population from the Department of Radiology, University Hospital of Larissa. An interesting case of an 80-year-old male was further investigated. RESULTS: The cerebral arterial circle presented with a combination of three variations. The left anterior cerebral artery (ACA) was fenestrated 1.4 mm proximally to the anterior communicating artery formation. The left posterior cerebral artery (PCA) was also fenestrated, 5.5 mm distally to its origin from the basilar artery. Lastly, the right PCA originated from the ICA supraclinoid segment. CONCLUSIONS: This case report highlights an unusual coexistence of A1 and P1 segments fenestration with a fetal PCA, resulting in a unique cerebral circle. A1 segment fenestration has been previously reported as rare, while the PCA fenestration as extremely rare variant. Awareness of these rare variations could aid interventionists in their preoperative assessments.

Triplicated middle cerebral arteries (duplicated and ipsilateral accessory) associated with triplicated anterior cerebral arteries (accessory) diagnosed by magnetic resonance angiography.

PURPOSE: To describe a case of duplicated middle cerebral artery (MCA) combined with ipsilateral accessory MCA, forming a triplicated MCA, associated with the accessory anterior cerebral artery (ACA), forming a triplicated A2 segment of the ACA detected incidentally on magnetic resonance (MR) angiography. METHODS: A 70-year-old woman with internal carotid artery (ICA) stenosis at the origin, which was detected by ultrasound, underwent cranial MR imaging and MR angiography of the intracranial region for an evaluation of brain and cerebral arterial lesions. The MR machine was a 3-Tesla scanner. MR angiography was performed using a standard 3-dimensional time-of-flight technique. RESULTS: Multiple ischemic white matter lesions are observed. No significant stenotic lesions were observed in intracranial arteries. The right duplicated MCA was originated from right distal ICA. And main MCA was originated from right ICA bifurcation. Right accessory MCA was arisen from the A2 segment of the right ACA. Thus, the right MCA was triplicated. There was also an accessory ACA forming a triplicated ACA at its A2 segment. These findings were clearly identified on partial volume-rendering (VR) images. CONCLUSION: We herein report a case of triplicated MCA associated with triplicated ACA. MCA variations are relatively rare, and this is the third case of triplicated MCA reported in relevant English-language literature. To identify multiple cerebral arterial variations, creating partial VR images using MR angiographic source images is useful.

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.

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.

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.

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.

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.

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.

Bihemisphere Ischemia Due to a Unilateral Lesion: A Case Report.

Bihemispheric ischemic strokes secondary to unilateral vessel disease are uncommon. We present the case of a 70-year-old man with multiple acute/subacute bilateral infarcts. The patient was found to have stenosis of the left internal carotid artery secondary to herpes zoster ophthalmicus vasculopathy, with involvement of the left proximal middle and anterior cerebral arteries. Angiographic studies also revealed A1 segment aplasia of the right anterior cerebral artery (ACA), thus indicating dependence on the left-sided circulation for perfusion of the bilateral ACA vascular territory. This case illustrates how A1 segment aplasia, an anatomic variant of the circle of Willis detected by angiographic studies, can contribute to bilateral infarction in the ACA vascular territory.

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.

Carotid-anterior cerebral artery (ACA) anastomosis associated with azygos ACA and ophthalmic artery arising from the middle meningeal artery: a case report.

Among variations of the anterior cerebral artery (ACA), anastomosis of its A1-A2 junction with the ophthalmic segment of the internal carotid artery is rare and described as carotid-ACA anastomosis or infraoptic course of the ACA. One common variant, an azygos ACA, demonstrates no pairing of the A2 segment. To our knowledge, association of a carotid-ACA anastomosis with an azygos ACA is not reported in the English-language literature. We report a case diagnosed by magnetic resonance angiography in which right carotid-ACA anastomosis was associated with an azygos ACA and the right ophthalmic artery originated from the middle meningeal artery.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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 ± 19.65 years. 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). CONCLUSION: Azygos ACA is a rare variation, but it could be accompanied by aneurysms or other vascular anomalies.

Fatal subarachnoid hemorrhage caused by rupture of variant anterior communicating artery: a case report and literature review.

Fatal subarachnoid hemorrhage (SAH) caused by anterior communicating artery (ACoA) rupture is a rare event in medicolegal practice. Anatomical variations of the ACoA tend to make its anatomical structure, and as a result, blood flow through it, more complicated, which may increase hemodynamic stress and cause weak spots in the affected blood vessels. Variant ACoAs are prone to rupture in the event of a blunt-force trauma. Here, we report a fatal case of SAH caused by the rupture of a variant ACoA when the victim's head was struck from behind, causing the head to rotate and the victim to fall forward onto the ground. A medicolegal autopsy revealed diffuse basal SAH and ACoA duplication. The smaller of the two variant ACoA branches had ruptured near its junction with the right anterior cerebral artery. No basal aneurysms or other fatal diseases or injuries were found. This case highlights the significance of anatomical variation in forensic pathology.

Bilateral carotid-anterior cerebral artery anastomoses associated with bilateral ophthalmic arteries arising from the anastomotic arteries diagnosed by magnetic resonance angiography: a case report.

Rarely, the anterior cerebral artery (ACA) arises from the ophthalmic segment of the internal carotid artery, a condition described as carotid-ACA anastomosis or infraoptic course of the ACA that generally demonstrates right-sided predominance. We diagnosed a case of bilateral anastomoses of the carotid and ACA vessels in which bilateral ophthalmic arteries arose from the origins of the anastomotic vessels using magnetic resonance (MR) angiography. Identification of rare arterial variations on MR angiography requires careful scrutiny of source images, and creation of partial volume-rendering images can aid visualization of detailed anatomic structures.

Median pericallosal artery with double proximal origin: case report and clinical consideration.

A 76-year-old male patient underwent magnetic resonance angiography of the head and neck vessels due to a recent incident of transitory ischemic attack. Cerebral angiogram uncovered the double proximal origin of the median unpaired pericallosal artery from the duplicated anterior communicating complex. The vessel curved around the corpus callosum and irrigated the paracentral lobule and the medial parietal cortical areas. The main trunks of the anterior cerebral arteries showed a branching pattern of the marginal callosal arteries, supplying orbital and frontal territories. The pre-communicating segment of the left anterior cerebral artery was identified as hypoplastic. The co-existence of the duplicated anterior communicating artery, with the medial pericallosal artery ascending from it, represents a potential danger for both open and endovascular surgery on the anterior circle of Willis as the deep half of this complex is obscured from the surgeon's eyes. Thorough interpretation of preoperative radiographic images and understanding of the developmental mechanisms of such variability are vital. The described branching arrangement of the anterior communicative region and possible mechanisms of migration with following fusion of the pericallosal arteries are discussed in this paper.

"True" Accessory Anterior Cerebral Artery: A Newly Reported Anterior Cerebral Arterial Anomaly and a Proposal for Its Classification.

If we use the same naming policy of middle cerebral arterial anomalies, then accessory anterior cerebral arteries (ACAs) should be applied for ACA anomalies originating from the ACA. We experienced such a rare ACA anomaly, which we referred to as true accessory ACA.