[Computed tomography in ruptured intracranial aneurysm--sequential changes of the high density area in the basal cistern (author's transl)].

Using the findings of CT scanning in cases of subarachnoid hemorrhage, we have undertaken an investigation of the relationship between the degree of consciousness disturbance at the time of subarachnoid hemorrhage and the degree of high density area within the basal cistern within the 1st day from onset, and the sequential changes of the high density areas. The study included 23 cases of initial attacks of cerebral aneurysm rupture in which 2 or more CT scans were obtained prior to surgery, or in non-operated cases, within 2 weeks of onset. The severity of the attacks were classified into 3 groups: minor attack, cases of subarachnoid hemorrhage without loss of the consciousness; moderate attack, those with loss of consciousness extending for less than 1 hour; and major attack, those with loss of consciousness extending for more than 1 hour. Since a correlation was found between the CT number of high density areas in the basal cistern within the first 24 hours from onset and the severity of the attack, the classification of the severity of the attack is thought to correlate with the volume of the subarachnoid hemorrhage. Disappearance of the high density areas in the basal cistern occurred after about 2 days in the minor, about 4 days in the moderate, and 8--10 days in the major attack cases, but in the group of patients suffering recurrent attacks and in which death occurred without a return of consciousness, the high density areas remained until death. We conclude that by considering the CT number of the high density areas obtained by CT scanning in the basal cistern in cases of subarachnoid hemorrhage, the degree of bleeding can be determined, and the incidence of infarction due to vasospasm can be anticipated.