International Subarachnoid Aneurysm Trial II

Surgical clipping will be performed as soon as possible following randomization, according to standards of practice, and under general anesthesia. Aneurysms thought by the treating physicians to require deliberate permanent proximal vessel occlusion, construction of a surgical bypass, or other flow-redirecting treatments that do not directly clip the aneurysm will not be excluded; these non-ISAT aneurysms are expected to be more difficult lesions to manage surgically as well as endovascularly.

Endovascular treatment will also be performed as soon as possible following randomization,according to standards of practice, and under general anesthesia. Details regarding type of coils, use of adjunctive techniques such as balloon-remodeling, stents or flow-diverters, as well as post-treatment medical management issues, will be left up to the physician performing the endovascular treatment.