Objective: We report a case of a ruptured cerebral aneurysm in which a bifurcation pattern at the tip of the basilar artery was asymmetric fusion type and the superior cerebellar artery (SCA) branched from the posterior cerebral artery (PCA) on the caudal fusion type side.
Case presentation: A 45-year-old woman presented with a subarachnoid hemorrhage with a headache. Cerebral angiography revealed that the right SCA diverged from the PCA and a small cerebral aneurysm had developed at this site. This cerebral aneurysm was successfully treated by coil embolization.
Conclusion: There have been no previous reports on cerebral aneurysms at the site of this normal variation.
Keywords: asymmetric fusion type; cerebral aneurysm; superior cerebellar artery.
©2021 The Japanese Society for Neuroendovascular Therapy.