The WEB is an intra-aneurysmal device intended for use in endovascular embolization of intracranial aneurysms. The intended therapeutic effect of the WEB device is to line the neck of the aneurysm with a metallic structure that disrupts the inflow of blood, causing hemostasis within the aneurysm sac, and leading to thrombus formation within the implant. Subjects will be screened for study eligibility after giving informed consent.

Subjects will be screened for study eligibility after giving informed consent. The WEB embolization procedure will be performed in the catheterization room using standard angiographic techniques.

Proportion of complete (angiographic) aneurysm occlusion as assessed by Core Lab without retreatment, recurrent subarachnoid hemorrhage, without significant parent artery stenosis (>50% stenosis) at one year after treatment.

Proportion of death of any nonaccidental cause or any major stroke (defined as an ischemic or hemorrhagic stroke resulting in an increase of 4 points or more on the National Institutes of Health Stroke Scale) within the first 30 days after treatment or major ipsilateral stroke or death due to neurologic cause from day 31 to the 1 year after treatment.