Clipping is a surgical procedure performed to treat a balloon-like bulge or weakening of an artery wall known as an aneurysm. As an aneurysm grows it becomes thinner and weaker. It can become so thin that it leaks or ruptures, releasing blood into the spaces around the brain - called a subarachnoid hemorrhage (SAH). A neurosurgeon places a tiny clip across the neck of the aneurysm to stop or prevent an aneurysm from bleeding.
The goal of surgical clipping is to isolate an aneurysm from the normal circulation without blocking off any small perforating arteries nearby. Under general anesthesia, an opening is made in the skull, called a craniotomy. The brain is gently retracted to locate the aneurysm. A small clip is placed across the base, or neck, of the aneurysm to block the normal blood flow from entering. The clip works like a tiny coil-spring clothespin, in which the blades of the clip remain tightly closed until pressure is applied to open the blades. Clips are made of titanium and remain on the artery permanently.
Aneurysms vary in their size and shape. Saccular aneurysms have a neck at their origin on the main artery and a dome that can expand and grow like a balloon. These are the easiest to place a clip across. Some aneurysms have a wide neck or are fusiform in shape having no delineable neck. These are more difficult to place a clip across. Since aneurysms have various neck configurations, clips are made in a variety of shapes, sizes, and lengths
The procedure is performed by making a Craniotomy. Working under an operating microscope, the surgeon carefully opens the corridor, locates the artery and follows it to the aneurysm. Before placing the clip, the surgeon obtains control of the blood flow in and out of the aneurysm.
Once vascular control is achieved, the aneurysm neck is prepared for clipping. Often the aneurysm is held tight by connective tissue and must be freed and isolated from other structures. Once released, the jaws of the clip close pinching off the aneurysm from the parent artery. Multiple clips may be used.
No surgery is without risk. General complications related to brain surgery include infection, allergic reactions to anesthesia, stroke, seizure, and swelling of the brain. Complications specifically related to aneurysm clipping include vasospasm, stroke, seizure, bleeding, and an imperfectly placed clip, which may not completely block off the aneurysm or blocks a normal artery unintentionally.
If surgical clipping is not possible or the artery is too damaged, the surgeon may completely block (occlude) the artery that has the aneurysm. The blood flow is detoured (bypassed) around the occluded section of artery by inserting a vessel graft (Fig. 5). The graft is a small artery, usually taken from your leg, that is connected above and below the blocked artery so that blood flow is rerouted (bypassed) through the graft.
A bypass can also be created by detaching a donor artery from its normal position on one end, redirecting it to the inside of the skull, and connecting it above the blocked artery. This is called a STA-MCA (superficial temporal artery to middle cerebral artery) bypass.