Purpose:

Phase 1: (Pilot Phase)

To compare the treatment efficacy of surgical clipping and endovascular coiling for unruptured intracranial aneurysms.

To obtain better estimates of morbidity and mortality related to a surgical or endovascular treatment strategy at one year within the context of an RCT.

To show that an RCT comparing the morbidity and mortality of a surgical management strategy to an endovascular management strategy is feasible.

Phase 2:

To compare the results of surgical and endovascular management strategies, in terms of:

1. Overall mortality and morbidity at 1 and 5 years.
2. The clinical efficacy and safety of a surgical or endovascular management strategy at 1 and 5 years

Hypotheses: Phase 1 Hypotheses:

1. Surgical clipping of intradural, saccular, unruptured intracranial aneurysms is superior to endovascular management in terms of a lesser number of patients experiencing treatment failure.
2. An RCT comparing the clinical outcomes of a surgical versus endovascular management strategy is feasible.

Phase 1 Primary End-points:

• Treatment failure, hereby defined as having occurred when either: the intended initial modality (surgical or endovascular) fails to occlude the aneurysm, a "major" (saccular) angiographic aneurysm recurrence is found, or an intracranial hemorrhagic event occurs during the 1-year follow-up period.

Phase 1 Secondary End-points:

1. Overall morbidity and mortality at one year.
2. Occurrence of morbidity (mRS >2) or mortality following treatment.
3. Occurrence of failure of aneurysm occlusion using the initial intended treatment modality.
4. Occurrence of a "major" (saccular) angiographic aneurysm recurrence.
5. Occurrence of an intracranial hemorrhage following treatment.
6. Peri-treatment hospitalization lasting more than 5 days
7. Discharge following treatment to a location other than home

Treatment:

Trial feasibility, or the capacity for patient recruitment, would require enrollment of at least 8 patients per actively recruiting center per year.

Phase 2 Hypotheses:

It may be too early to explicitly define the primary hypothesis of Phase 2, however, the intent of Phase 2 can be expressed as:

1. One management strategy is superior to the other in terms of clinical outcome at five years.
2. One management strategy is superior to the other in terms of clinical efficacy at five years.

Inclusion Criteria:

• Patients at least 18 years of age with at least 10 years of remaining life expectancy
• At least one documented, intradural, saccular intracranial aneurysm
• The patient and aneurysm are considered appropriate for either surgical or endovascular treatment by the treating team
• Aneurysm size 3-25 mm

Exclusion Criteria:

• Patients with any intracranial hemorrhage, including SAH, within the previous 30 days
• Lesion characteristics not readily suitable for either endovascular or surgical treatment, in the opinion of the physician(s) intending to treat the aneurysm
• Multiple aneurysms, where the treatment plan includes both surgical clipping as well as endovascular coiling
• Aneurysm anticipated (pre-operatively) to require proximal vessel occlusion, a bypass, or other flow-redirecting therapy (such as flow-diverting stents) as part of treatment plan
• Patients with baseline mRS >2
• Patients with a single cavernous aneurysm
• Patients with dissecting, fusiform, or mycotic aneurysms
• Patients with AVM-associated aneurysms
• Pregnant patients (randomization (and treatment) may be delayed until after delivery)
• Patients with absolute contraindications to anaesthesia, endovascular treatment or administration of contrast material, including low-osmolarity agents or gadolinium
• Patients unable to give informed consent

primary care clinic