Natural course of unruptured cerebral aneurysms: Cutting-edge knowledge and clinical decision feedback

In this article, we present cutting-edge knowledge on the natural course, risk scores, treatment results of unruptured cerebral aneurysms (UCAs), and characteristics of UCAs in elderly patients. Data from the Unruptured Cerebral Aneurysm Study of Japan (UCAS Japan) are important for understanding the natural course of UCAs in Japanese patients. The prediction model for 3-year rupture risk of UCAs based on UCAS Japan data is reliable and useful in the clinical setting. Both surgical clipping and coil embolization for UCAs have favorable outcomes in Japan. The annual rupture rate of UCAs in elderly patients in Japan has been reported to be 1.6%. Age, size and location of aneurysms are significant risks for UCA rupture in elderly patients. The outcomes of surgical clipping and coil embolization for UCAs in elderly patients were equal in Okayama University Hospital. Numerous foreign studies have, however, demonstrated that the results of coil embolization are superior to those of surgical clipping in elderly patients. In the future, the establishment of treatment risk scores for UCAs and guidelines for UCAs in elderly patients in Japan are warranted.