|Year : 2021 | Volume
| Issue : 2 | Page : 75-78
A cadaveric study of anterior communicating artery
Sunitha Narayanan, GN Geetha
Associate Professor, Department of Anatomy, Government Medical College, (Affiliated to Kerala University of Health Sciences), Kannur, Kerala, India
|Date of Submission||30-Oct-2020|
|Date of Decision||29-Dec-2020|
|Date of Acceptance||30-Jan-2021|
|Date of Web Publication||09-Apr-2021|
G N Geetha
Associate Professor, Department of Anatomy, Government Medical College, Kannur, Kerala
Source of Support: None, Conflict of Interest: None
Background: Anterior communication artery is a collateral channel that connects the right and left anterior cerebral arteries in the circle of Willis. This helps in stabilizing the cerebral blood flow. Different types of variations of this artery were reported in the previous studies. The hemodynamic changes in the blood flow produced by variations induce strain at the sites of bifurcation, which may result in the formation of aneurysms. This commonly occurs at the meeting point of anterior communicating artery (ACoA) with the anterior cerebral artery. The anatomical variations in this portion may complicate the planning and performance of surgery which in turn will lead to postoperative complications. Methodology: The study was conducted in 60 specimens of the brain in the department of anatomy, Government Medical college, Calicut. The artery was carefully dissected and observed. Photographs were taken. The observations were tabulated. Results: Variations were noted in 15 specimens (25%). Duplication of the artery was noted in 6 specimens (10%), hypoplasia in 3 specimens (5%), V-type artery in 1 specimen, and X-type in 6 specimens (10%). There was no triplication or plexiform type noted. An accessory anterior cerebral artery was noted in 3 specimens (5%). Conclusions: As the ACoA acts a collateral channel that stabilizes the cerebral blood flow, when there is any vascular occlusion in any components of the circle, the knowledge of these anatomical variations becomes significant. As the radiological and neurosurgical interventions are increasingly performed, nowadays, the surgeons and radiologists should be aware of these variations in the cerebral arteries.
Keywords: Collateral, duplication, hypoplasia, variation
|How to cite this article:|
Narayanan S, Geetha G N. A cadaveric study of anterior communicating artery. Natl J Clin Anat 2021;10:75-8
| Introduction|| |
An arterial anastomosis is present at the base of the brain, which connects the internal carotid artery with the vertebrobasilar systems, known as the circulus arteriosus (circle of Willis). It has two anterior cerebral arteries from the internal carotid arteries on either side joined by an anterior communicating artery (ACoA) in the anterior part. In the posterior part, there are two posterior cerebral arteries from the basilar artery, which are connected to the internal carotid artery of the respective sides by a posterior communicating artery. These component arteries of the circle vary in the pattern and caliber.
The intracranial saccular aneurysms, which might rupture and produce subarachnoid hemorrhage, are commonly found in the communicating artery in the anterior part of the circle and are frequently associated with an asymmetrical circle of Willis. The fenestration deformity of this artery is easily misdiagnosed as an aneurysm in the computed tomography (CT) angiography of the brain., Therefore, these variations should be kept in mind while evaluating a CT angiogram for aneurysm.
The knowledge of these variations becomes important when this part of the brain is exposed for various surgical procedures and improves the success rate of neurosurgeries. This study aims at studying the ACoA for any variations, which the neurosurgeons and radiologists should be aware of while doing a surgery and also while evaluating a cerebral angiogram.
| Materials and Methods|| |
In an observational study, 60 cadaveric brains were obtained from the Department of Anatomy, Government Medical College, Calicut, which were evaluated for the variations in ACoA. The study protocol was approved by the Institutional Ethics Committee. The study was part of thesis work on variations of circle of Willis. Only ACoA details are presented in this article.
The traumatized specimens and those with gross lesions were excluded from the study. They were numbered and fixed in formalin. The component arteries of the circle were dissected. The ACoA was noted for any variations (presence, number, hypoplasia, and orientation). Using a divider and scale, the external diameter of the vessel was taken. Here, an artery was considered as hypoplastic if its external diameter is <1 mm. The photographs were taken.
| Results|| |
In the 60 brain specimens studied, the artery was normal in 45 specimens (75%) and the variations were noted in 15 specimens (25%) and double in 6 (10%) specimens [Figure 1]. In one specimen, a “V-shaped” double ACoA was noted [Figure 2], X-type in 6 (10%) specimens [Figure 3], and hypoplastic in 3 (4%) specimens [Figure 4]. Absence, triplication, or plexiform type of artery was not observed in the present study. The orientation of the vessel was in a transverse plane in 34 (56.7%) specimens [Figure 1], in an anteroposterior plane in 14 (23.3%) specimens [Figure 5], and in oblique plane in 12 (20%) specimens [Figure 6].
|Figure 4: Circle of Willis showing hypoplastic anterior communicating artery|
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|Figure 5: Circle of Willis showing anteroposterior orientation of anterior communicating artery|
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|Figure 6: Circle of Willis showing oblique orientation of anterior communicating artery|
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A third anterior cerebral artery, arising from the ACoA, was found in 3 specimens [Figure 7]. It is also known as accessory anterior cerebral artery (AACA). Its caliber was almost the same as that of the anterior cerebral arteries.
| Discussion|| |
The duplication of the ACoA was the most common variation observed here, which was found in 10% of cases. Pai et al. had reported duplication of the artery in as high as 20% cases and Puchades et al. in as low as 6.4% of cases. De Ranil and De Silva and Kardile et al. had reported it in 10% of cases in their study which matches with the present study.
Various kinds of duplications were noted by previous workers. However, apart from a “V-shaped” duplication of the artery in 1 case, other kinds of duplication were not observed in this study.
In the previous studies, triplications and plexiform types of the artery were noted by different workers. Karim et al. have reported a double ACoA joined in the middle by a short segmental artery. However, there were no such variations observed in this study [Table 1].
|Table 1: Variations of anterior communicating artery as observed by other workers|
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An X-type communicating artery, as described in earlier studies, in which there is fusion between the two anterior cerebral arteries at a narrow point, was present in 6 cases.
Windle had reported this type of communication as the absence of ACoA in his work. However, Alpers et al. had reported such a communication in 2% of cases. It was observed here in 10% of cases which was consistent with the observation made by Serizawa et al. [Table 1].
True absence of ACoA was described as a very rare variation by previous workers. Puchades et al. had reported it in 3.2% of their series and Poorwa et al. had reported it in 8% of cases. The artery was hypoplastic in 5% of cases in the present study. Puchades et al. had reported it in 6.4% of cases and Poorwa et al. reported it in 6% of cases. Alpers et al.'s found this in as low as 3% of cases and Riggs and Rupp's reported as high as 27% of cases of hypoplastic arteries [Table 1].
In the present study, the artery was found above the optic chiasma in a transverse plane in 56.7% of the cases, in an oblique plane in 20%, and in an anteroposterior plane in 23.3%. Perlmutter et al. had also reported similar observations without mentioning their incidence. According to them, the anterior part of the circle with the communicating artery is difficult to visualize in angiography as the plane of orientation of the artery differs in different brains. Hence, in addition to the anteroposterior and lateral views, angiography may also be taken in oblique position to outline the artery.
The AACA was found in 5% of cases. De Ranil and De Silva observed it in as low as 2% of cases, Windle in 4.5% of cases, and Ogawa et al. in 13.1% cases.
The ACoA develops as a network of anastomosing small arteries in a 18-mm-size human embryo connecting the two anterior cerebral arteries. Later, this network disappears partly and persists as a single ACoA in adults. If this arterial network persists, it will appear as plexiform type or duplicated type of ACoA, as was observed in the present study. This may produce hemodynamic changes in the blood flow through the arteries which induce strain at the weak points of the arteries resulting in the formation of aneurysms.
| Conclusions|| |
Variations were present in 25% of specimens. Among the variations, duplication and X-type artery was noted most frequently (10%). Hypoplasia was noted only in 5% of cases. A V-type artery was noted in a case. An AACA was found in 5% of cases. There was no absence of ACoA. As variations of the circle of Willis may play a role in the development of aneurysms, the surgeons and the radiologists should be aware of these types of variations.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]