Site of ruptured intracranial saccular aneurysms in patients in Izumo City, Japan.

ABSTRACT

BACKGROUND AND PURPOSE: A community-based study was conducted to estimate the site distribution of ruptured intracranial aneurysms and to evaluate clinical features related to aneurysm site. METHODS: The author reviewed data from 358 patients with aneurysmal subarachnoid hemorrhage (SAH) treated between 1980 and 1998 in Izumo, Japan. In 291 of these patients, the sites of the ruptured aneurysms were confirmed. RESULTS: The aneurysm arose from the anterior communicating artery (AcoA) in 101 patients, the distal anterior cerebral artery (ACA) in 24, the internal carotid artery (ICA) in 70, the middle cerebral artery (MCA) in 77, and the vertebrobasilar artery (VBA) in 19. Regardless of age, ACoA aneurysms were more frequent in men, whereas ICA aneurysms were more common in women. Intracerebral hemorrhage was more frequent in patients with MCA aneurysms, whereas intraventricular hemorrhage was more common in those with VBA, ACoA and distal ACA aneurysms. While the incidence of symptomatic vasospasm was not related to aneurysm site, the patients who died due to vasospasm harbored an ACoA or ICA aneurysm. The incidence of hydrocephalus was relatively high in patients with ACoA, ICA and VBA aneurysms, and low in those with MCA aneurysms. The overall outcome was best in patients with MCA aneurysms, followed by those with aneurysms of the ACA, including ACoA and distal ACA, ICA and VBA; these results were in good agreement with the admission grades. CONCLUSIONS: The roughly estimated proportions of the sites of aneurysm rupture were 40% for the ACA, including ACoA and distal ACA, 25% for the ICA, 25% for the MCA, and 10% for the VBA. The clinical features showed significant differences according to aneurysm site.