Natural history of unruptured intracranial aneurysms

Abstract

Since 2003, five prospective studies on unruptured intracranial aneurysms have demonstrated their natural course (i.e. annual rupture rates) in detail. Recently, in addition, several meta-analyses, pooled analyses, risk scoring studies have been reported. Because there are many quotations of clinical data between these kinds of analyses, one must understand precisely where the pooled data come from. The risk factors for aneurysmal rupture proposed in the five prospective studies differ greatly from each other, and one must also understand these differences as well. UCAS, which is the prospective multicenter study across Japan published in 2012, has marked the milestone in the field of intracranial aneurysm research especially in the Japanese cohort. To make reasonable judgements in daily clinical activities, physicians should read the UCAS manuscript and its supplementary appendix carefully and understand the true natural course of unruptured intracranial aneurysms in Japan.