Ruptured aneurysm of the medial posterior choroidal artery first demonstrated by the microcatheter technique--case report.

A 50-year-old previously healthy woman presented with symptoms of subarachnoid hemorrhage. Initial cerebral angiography did not determine the site of the hemorrhage but repeat angiography disclosed an aneurysm-like image, probably in the medial posterior choroidal artery (PChA). Selective angiography performed using a microcatheter technique clearly revealed two medial PChAs arising from the ambient segment of the posterior cerebral artery. One medial PChA included an aneurysm on the cisternal segment, then ran peripherally to supply the plexus in the roof of the third ventricle. The other medial PChA mainly supplied the pineal body, tegmentum of the midbrain, and posterior border of the thalamus. The patient underwent open surgery following the zygomatic approach and the parent artery was clipped. She was discharged without neurological deficits or compromise of higher brain functions.