Anatomic Variants of the Anterior Cerebral Artery and Anterior Communicating Artery: A Digital Subtraction Angiographic Study

Background Several anatomic variants can result from developmental anomalies of the cerebral arteries during the embryonic period. Some of them predispose to the development of aneurysms or cerebrovascular ischemic disease. Failure to identify them may lead to misdiagnosis. This study aimed to document the frequency and type of anatomic variants of the anterior cerebral artery (ACA) and the anterior communicating artery (ACoA). Methodology A retrospective, record-based, cross-sectional study was conducted among 500 subjects (188 females, 312 males) whose four-vessel digital subtraction angiographic images of the ACA and ACoA were reviewed for the presence of anatomic variants such as aplasia, hypoplasia, azygous ACA, fenestrations, duplications, and associated aneurysms. Results Among the total 500 images evaluated, anatomic variants of the ACA were present in 3.6%. The most common variant was aplasia of the A1 segment of the ACA (2%), followed by hypoplasia of the A1 segment of the ACA (1.4%) and azygous ACA (0.2%). No anatomic variants were seen in the ACoA. Associated aneurysms were noted in 4.2% of subjects, among which 3.2% were seen in the ACoA and 1% in the distal ACA. Among the aneurysm cases associated with anatomic variants, six were associated with aplasia of the A1 segment of the ACA, one with hypoplasia of the A1 segment of the ACA, and one with azygous ACA. Conclusions Anatomical variations of the ACA were seen in less than 5% of the study population. The most common anatomic variants were aplasia and hypoplasia of the A1 segment of the ACA, followed by azygous ACA. Few aneurysms were seen, the majority of which were in the ACoA. Some of the aneurysms noted were associated with anatomic variants. Presence of vascular variations of the ACA and ACoA can be asymptomatic and uncomplicated, but knowledge and identification of them may help neurosurgical planning and prevent medical errors.