Acute Disappearance of Ruptured Aneurysm Located Near the Origin of the Superior Cerebellar Artery

A 63-year-old woman presented with a ruptured aneurysm which apparently spontaneously thrombosed. She was admitted after sudden onset of severe headache. Computed tomography (CT) demonstrated subarachnoid hemorrhage (SAH) in the pontine and interpeduncular cisterns. Initial three-dimensional CT (3D-CT) angiography revealed an aneurysm (diameter, 9 mm) near the origin of the left superior cerebellar artery. However, angiography 3 hours later failed to show the aneurysm. Total thrombosis was thought to have occurred in the aneurysm. The patient returned home with no deficit 1 month after admission. T_1- and T_2-weighted magnetic resonance imaging 75 days after the SAH demonstrated the thrombosed aneurysm as an isointense mass lesion. 3D-CT angiography showed no recanalization of the aneurysm 9 months after the SAH.