Trial on Endovascular Aneurysm Management

This study is designed as a pragmatic trial. All candidates for endovascular treatment of one or more unruptured intracranial aneurysms will be offered to participate. Unruptured aneurysms may be recently discovered or prevalent. If they accept, subjects will be randomized to one of the two arms of the trial: Conservative management (Observation) or Endovascular treatment. Both groups will be advised to obtain medical treatment for hypertension if necessary and will receive counselling for behavioural risk factor modelling (smoking or excessive drinking) when indicated. A non-invasive (MRA or CTA) or catheter angiogram and a baseline CT-scan or MRI of the brain are required to enter the study. These studies should demonstrate the unequivocal presence of a saccular aneurysm \>=3 mm treatable by endovascular methods. A catheter angiogram is required if there is doubt. Imaging studies will be reviewed centrally. Both treatments will be standardized. Patients will be followed similarly for a minimum of 10 years.