Comment on Bilateral Anomalous Posterior Inferior Cerebellar Artery-Anterior Inferior Cerebellar Artery Anastomotic Arteries Associate with a Ruptured Cerebral Aneurysm

Abstract

We previously reported an unusual case of bilateral posterior inferior cerebellar artery (PICA)-anterior inferior cerebellar artery (AICA) anastomosis associate with a ruptured aneurysm. Moreover, also this case had segmental absence of both distal vertebral arteries (VA). During the 7 to 12 mm embryonic stage, the basilar artery is formed by fusion of the longitudinal neural arteries. The VAs is formed by fusion of multiple segmental arteries, from C1 to C6. Inferior cerebellar arteries develop later than VAs. There is no literature concerning bilateral regression of the VAs. There is in contradiction of developmental stage between segmental regression of the VA and formation of VA- PICA-AICA-basilar artery anastomosis. Phylogenetically, PICA and AICA belong to pial arteries of the spinal cord. It is appropriate to consider segmental regression/occlusion of VAs to be acquired, and followed by development of pial collateral network involving the anterior spinal artery, the lateral spinal artery and inferior cerebellar arteries, same as the leptomeningeal anastomosis of the supratentorial circulation.