The artery that leads to the aneurysm is sealed off. Blood may be rerouted with a bypass.
Occlusion and Bypass
In some cases, it may be best to stop blood flow through the artery leading to the brain aneurysm. This is known as an occlusion. Sometimes the aneurysm has caused severe damage to the artery, so the doctors go in and completely shut down that part of the artery and reroute the blood. This procedure is usually done as an open surgery, which requires similar surgical preparation as in a clipping procedure such as having your head shaved, and a section of the skull bone removed.
Sometimes an occlusion is combined with a bypassBypass
A surgical operation in which the surgeon creates a new channel to bring blood flow to the brain. In rare cases when an aneurysm can't be clipped or coiled, the surgeon may have to perform a bypass operation, bringing blood flow through a new channel beyond the aneurysm and then trapping the segment of the artery with the aneurysm between clips.. A bypass reroutes blood flow around the occluded artery. Doctors take a small blood vessel from another part of your body, usually the leg, and graft it to a section of the brain artery where it makes most sense. This new artery (bypass) brings blood to the part of the brain that had been fed by the damaged artery.