CT and clinical correlations in recent aneurysmal subarachnoid hemorrhage: a preliminary report of the Cooperative Aneurysm Study.

Computed tomography was performed on 1,378 patients admitted within 3 days of subarachnoid hemorrhage (SAH) at 71 centers in a cooperative study. CT on the day of SAH (day 0) was abnormal in 95.8%. Intracranial blood was detected in 95.3% of patients on day 0, 90.5% on the first day after SAH (day 1), and 73.8% on day 3. CT was normal in only 1 of 284 patients in stupor or coma but was normal in 14.6% of 638 alert patients. In the first few days after SAH, CT is highly accurate, often obviating the need of CSF examinations. The interval from SAH until CT and the seriousness of the patient's condition are two factors that influence the results of CT.