Clinicopathological study of bacterial intracranial aneurysms

The authors report the clinicopathological findings in six cases of bacterial intracranial aneurysms. All patients received appropriate high-dose antibiotics, and four were treated surgically. One patient with multiple aneurysms of the main trunks died of disseminated intravascular coagulation. Autopsy disclosed no apparent aneurysm or inflammatory cell infiltration, but a partially interrupted internal elastic lamina and thickened intima were disclosed at the angiographical aneurysm sites. These findings suggest that 1) appropriate high-dose antibiotics are effective against inoperable bacterial aneurysms in the main trunks, 2) new aneurysms may be formed in patients with cyanotic congenital heart disease, because bacterial emboli can directly reach the cerebral circulation and reimplant on the fragile arterial walls after vasculitis. Histological examination of aneurysmal walls revealed inflammatory cell infiltration after resolution of clinical endocarditis. This suggests that both appropriate high-dose antibiotic therapy and surgery should be considered in patients with distal bacterial aneurysms.