Management strategy for unruptured cerebral aneurysms based on UCAS Japan and recent literature

Abstract

According to the result of UCAS Japan and recent literature, we summarized the findings on the natural course of unruptured cerebral aneurysms. Rupture risks are significantly related with the size, location and shape of the aneurysms. Also, in previous reports, patients with a history of hypertension, current smoking and subarachnoid hemorrhage were reported to carry a high rupture risk. Indication for managing unruptured cerebral aneurysms should be directed according to the patient’s medical condition, natural course of the individual aneurysm and the probability of the management risk of the individual aneurysms in each institution. In general, aneurysms sized more than 5 to 7 mm in healthy patients, and, even smaller than that, aneurysms located at the anterior communicating and posterior communicating arteries, and irregular shaped aneurysms should be considered for treatment. But of note, small aneurysms can rupture even when smaller than 5 mm under certain risk and aneurysm management carries a morbidity risk. These issues should be well explained to the patients. Regarding growth of aneurysms, there are a few reports documenting aneurysm growth in small aneurysms, and, if the aneurysm is not treated, careful follow-up is mandatory even in cases with small aneurysms.