Abstract
Unruptured cerebral aneurysm study in Japan (UCAS Japan) is conducted to clarify natural course and treatment risks of unruptured cerebral aneurysms (UCA), and build national data bank. This is a prospective cohort study and enrolled patients are cases with newly diagnosed UCA after Jan. 1, 2001. Data of all patients with UCA, either treated or observed, are registered through internet. All cases are scheduled to have periodic follow-up at 3 months, 12 months and 36 months after the diagnosis. During the last l7months, 2, 979 new patients with UCA are registered from 385 institutions. Male-female ratio was 1 :2. The most frequent reason for imaging, which leaded diagnosis of UCA, was ill-defined symptoms such as headache or dizziness. Multiple aneurysms were found in 18% of cases. Size of aneurysm ranged 3-45mm (median 5mm) and the most frequent location of aneurysm was internal cerebral artery. At the first registration, craniotomy was indicated in 35% and endovascular treatment in 4% of casese. Three months follow-up were reported in 2, 327 cases and 12 months report in 579 cases. Treatment was performed in 943 cases with 1, 074 aneurysms. We are planning to call for further patient's enrollment and conform reliable data source to direct future management of UCA.
