Post Anterior Communicating Artery Anastomosis.

We describe a variant where the A2 segment of one anterior cerebral artery anastomose distal to the origin of the anterior communicating artery with the A2 segment of the contralateral anterior cerebral artery. The anastomoses are seen without any hypoplasia or aplasia of A2 segments prior to anastomoses unlike azygous or bihemispheric anterior cerebral artery. The anastomoses occur prior to bifurcation of the anterior cerebral artery into pericallosal and callosomarginal arteries.