Computer tomography as the primary radiologic procedure in acute subarachnoid hemorrhage.

CT was performed in 149 patients with acute subarachnoid hemorrhage and clinical findings consistent with an aneurysm rupture, and was found informative in most cases when performed within one week after the hemorrhage. CT disclosed in 29 per cent of cases other causes for the hemorrhage than a ruptured aneurysm (intracerebral hemorrhage, tumor, trauma, infarct) and an extensive angiographic evaluation could be omitted. In those patients where the hemorrhage was caused by an aneurysm rupture, the distribution of extravasated blood in the subarachnoid space and the brain parenchyma usually indicated the aneurysm location--angiography could thus be restricted to the proper vessel. These capabilities of CT are sufficient to economically motivate its routine use as the primary investigation in cases with an acute subarachnoid hemorrhage.