CT of subarachnoid hemorrhage due to ruptured aneurysm.

Computed tomographic scans in 81 consecutive patients wih subarachnoid hemorrhage due to ruptured aneurysm were analyzed for patterns of hemorrhage and lucency and correlated with the development of spasm and hydrocephalus. The circulation time was measured angiographically in representative cases of spasm. Hemorrhage corresponded in a general way to the fossa of aneurysm origin and, when there was parenchymal or ventricular hemorrhage, in more specific ways to anterior communicating, middle cerebral, and posterior inferior cerebellar artery aneurysms. Basal ganglionic hemorrhages due to aneurysm ruptures occurred in two cases and could not be distinguished by appearance from hypertensive hemorrhage. Regions of low attenuation (lucencies) were often persistent and had lateralizing value; they showed a high correlation with arterial spasm. Conversely, spasm, particularly of a distal type, showed a significant correlation with increased circulation time and the occurrence of brain lucency. In cases of multiple aneurysms arising from different vessels in which there was hemorrhage or lucency, CT scans correctly predicted the site of aneurysm in 77% of cases. Periventricular lucency was a weak predictor of progressive hydrocephalus, while an intraventricular hemorrhage was a strong predictor of moderate to severe hydrocephalus.