[A ruptured aneurysm of the distal posterior inferior cerebellar artery associated with basilar artery occlusion: a case report].

We presented a case of a distal posterior inferior cerebellar artery (PICA) aneurysm associated with basilar artery occlusion. A 66-year-old female was found unconscious at home and transferred to our hospital in a deep coma on February 9, 1991. Emergency CT scan revealed subarachnoid hemorrhage in the posterior fossa. She was treated conservatively because of her poor neurological status. The angiograms performed on February 13 showed occlusion of the basilar artery and a saccular aneurysm at the cortical branch of the PICA. The contrast material remained in the aneurysm for a long time throughout the venous phase. The left vertebral artery was markedly hypoplastic. The patient improved remarkably after admission and became almost alert late in February, although she still presented tetraparesis, dysfunction of lower cranial nerves and other neurological signs linked with the brain stem. The unusual angiographical findings in this case prompted us to perform the examination again, expecting some angiographical changes. The angiograms taken on March 15 revealed spontaneous disappearance of the aneurysm, although the basilar artery occlusion remained unchanged. The authors discussed some problems involved in this case, including the relation between the aneurysm and the arterial occlusion, and the mechanism of spontaneous disappearance of the aneurysm.