A follow-up study of CT scan after the rupture of giant aneurysm of the bifurcation of an internal carotid artery

A 42-year-old female with a giant intracranial aneurysm of the right IC bifurcation is reported. She had experienced severe headache with nausea and vomiting on July 6, 1984, and was admitted to a certain hospital. She was then transferred to our hospital on July 23; she was asymptomatic then. There was no neurological deficit, and a craniogram showed no abnormal findings. A plain CT scan, however, showed a round, homogenous, slightly high-density area on the right basal ganglia, and it was intensely enhanced by the infusion of a contrast medium. The right anterior horn was compressed to the anteromedial side. By the angiographical study, we found a large aneurysmal shadow with a bleb on its top, arising from the right IC bifurcation. While she waited for an operation, meanwhile undergoing reported Matas tests, the aneurysm began to bleed again. Suddenly generalized convulsions and the rapidly progressing left hemiparesis occurred, and she lost consciousness. The CT scan at that time showed a ring-shaped high-density area surrounding the aneurysms, accompanied by perifocal edema and a midline shift. An urgent operation was performed, but she died three days after the second attack. The autopsy showed a ruptured saccular aneurysm (3.5 x 4.0 x 4.0 cm in size) on the right IC bifurcation, with its neck extending to the M1 portion. There was neither calcification on the wall nor any organized thrombosis. Giant aneurysms usually affect the surrounding brain tissue as mass lesions. In this case, though, there was no sign or symptoms of any compression of the brain tissue or cranial nerves, though a CT scan soon after the rupture showed progressive perifocal edema. This suggests that there had been a previous disturbance of the autoregulation of the surrounding brain tissue, caused by the mass effect of the giant aneurysm. (author)