The purpose of the DIVERT study is to provide a prudent, controlled clinical context for the use of flow diversion, a promising option of yet unproven benefit, in the care of patients with acute blood blister-like and dissecting intradural aneurysms. Hence DIVERT is a simple, multicenter, randomized trial integrated into daily practice. DIVERT addresses the clinical dilemma of whether the use of PED FD truly is a safe and effective alternative to best standard treatment, defined as conventional methods of treatment or in some cases, observation. Selection criteria are few, to facilitate the recruitment of most affected patients confronted with these difficult aneurysms that their physician judges suitable for PED FD. The trial does not obstruct clinical care, does not include extra tests or risks beyond what is necessary and proven beneficial. Endpoints are simple, clinical, meaningful, valuable and resistant to bias. Follow-up visits and tests are "routine', imposing no extra burden on clinical transactions. Data is collected in simple case-report forms filled by physicians.