The worst fear about a brain aneurysm is that a brain aneurysm will rupture. There are certain factors about an aneurysm that make it high risk for rupture. Brain aneurysms in the circulation in the back of the brain are more prone to rupture, as are aneurysms that are larger in size. Dr. Robert Brown, a neurologist from the Mayo Clinic, discusses a new study that investigators looked at brain aneurysms and the risk of rupture.