Abstract
We studied the angiograhpic finding on subarachnoid hemorrhage of unknon etiology (Unknown group).
The subjects consisted of 19 cases of Unknown group, 181 cases of cerebral aneurysm (An group) and 110 cases of control group (C group).
The incidence of vascular variation or anomaly such as A1 hypoplasia, fetal type posterior cerebral artery, azygos anterior cerebral artery or A2 fenestration was 63.2% in Unknown group, 65.8% in An group and 52.7% in C group. No remarkable difference in the frequency could be observed between Unknown and An group.
But the incidences of these two groups were significantly higher than that of C group. Hemodynamic stress on the weakened arterial wall due to vascular anomalies or variation should participate in the subarachnoid hemorrhage.
Nine cases (47.3%) out of 19 patients in Unknown group were accompanied by hypertension and angiographic arteriosclerosis was observed in 6 cases (31.6%).
The authors have discussed about the source of hemorrhage in Unknown group with case presentation.
