The role of vasospasms in the pathogenesis of cerebral infarction following rupture of the intracranial aneurysms has not been well determined. To clarify the importance of vasospasms, 135 cases of ruptured intracranial aneurysms without fatal attack or intracerebral hematoma which were admitted within two weeks after the last episode of subarachnoid hemorrhage were studied. Analysis was carried out mainly by cerebral angiography, computed tomography (CT), and periodic clinical checks.
Vasospasms were identified in 92 cases (68%) of all of those studied by angiography. Cerebral infarction due to vasospasms was revealed in 29 cases (21%) by CT. In the CT scans, the ischemic region shown as low density area appeared 9±3 days after the onset, contrast enhancement became positive after 17±5 days and in six cases, the low density area turned into a high density area (hemorrhagic infarction) 26±5 days after the onset. The area of cerebral infarction, which was more complicated than that ofinfarction due to occlusion of a cerebral artery, depended upon severity and distribution of the vasospasm. For simplification, patterns of infarction were classified into four types. These were (1) main trunk area type … 69%, (2) branch area type … 10%, (3) white matter dominant type … 14% and perforator area type … 7%. In CT scans, cerebral infarctions due to vasospasm were shown mainly in the cortex and the white matter and rarely in the basal ganglionic region perfused by perforating arteries. Hemorrhagic infarction occurred in six cases (21%) among the 29 cases with cerebral infarction due to vasospasms. In the six patients with hemorrhagic infarction, the low density area turned into a high density area after relaxation of the vasospasm with angiographical findings of hyperemia. Distribution of the hemorrhagic infarction in CT was cortical (gyrus type) in five cases and subcortical in one case (subcortical type).
From these reults, it was concluded that there really is a process of cerebral infarction following vasospasms (subarachnoid hemorrhage→vasospasm→cerebral ischemia→infarction). Cerebral infarction following vasospasm is one of the important factors determining prognosis.