Variations of anterior cerebral artery and anterior communicating artery: Their embryological correlation and clinical significance

Background & Objectives: To study variations of the Anterior cerebral artery –anterior Communicating complex (ACA- ACoA complex). Anomalies of the ACA- ACoA like fenestrations and median trunk – Azygous ACA and Bihemispheric ACA are exceedingly very rare anomalies. Any variation in the vessels of anterior part of Circle of Willis influences the change in the hemodynamics of blood supply of frontal lobe. The awareness of this rare anatomical variant is important considering today advanced imaging modalities and give consideration to its potential serious complications with fellow clinicians. Method: The study variations of the Anterior Cerebral Artery (ACA) and Anterior Communicating Artery (ACoA) of the circle of Willis at the base of the brain were studied in 50 human brain specimens. Results: In the anterior part of the circle, complete absence, double ACoA and fenestrated ACoA was found in one case each 2%. The 'H' complex was seen more commonly in the ACoA - ACA complex found in 80%, ‘V’ shaped complex in 8%. Absence of A1 segment on the right side was seen in one case (2%) and hypoplasia of the A1 segment was seen in another case (2%). In one case (2%), both the A2 segments arose from contralateral ACA – Bihemispheric ACA. An Azygous anterior cerebral artery/ median trunk ACA was found in 6.66% of the cases.