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.

Inclusion Criteria:

- At least one documented subarachnoid aneurysm, never ruptured

- Patient aged 18 or older

- Life expectancy more than 10 years

Exclusion Criteria:

- Patients with recent (less than 3 months) intracranial haemorrhage

- Lesion characteristics unsuitable for endovascular treatment

- Patients with a single extradural aneurysm

- Aneurysms < 3 mm or giant aneurysms (≥ 25 mm)

- Patients with a poor outcome (Rankin scale ≥ 3) after the rupture, surgical or
endovascular treatment of another aneurysm

- Patients with incompletely treated aneurysms that have previously ruptured

- Patients with associated arteriovenous malformations

- Patients with new severe progressive symptoms in relationship with the aneurysm
(sudden onset, severe persisting headaches suggestive of impending rupture,
third-nerve palsy, mass-effect)

- Patients with previous intracranial haemorrhage from unknown etiology

- Patients with multiple unruptured aneurysms in whom surgical clipping of one or many
aneurysms is planned in addition to endovascular management

- Patients with absolute contraindications to anaesthesia, endovascular treatment, or
administration of contrast material, including low-osmolarity agents or gadolinium

- Pregnant patients

- Patients unable to give informed consent