Surgical Challenge

"Fortunately, the overwhelming majority of aneurysms are smaller than an inch," says Dr. Jafar, " and though I would not characterize the necessary surgical repair as simple, it has become relatively routine and somewhat predictable. With larger aneurysms - or giant aneurysms, as we refer to them - the situation is entirely different. The surgical challenge is monumental. But without the surgery, the prognosis is very bleak. We are basically willing to undertake very difficult surgery to rescue patients from the jaws of death. Surgical intervention in these cases, therefore represents our best attempt to rescue a patient form an essentially hopeless situation.

Calculated Risk

Every surgical procedure involves some degree of risk, and brain surgery, in particular, usually involves invasive techniques in close proximity to very sensitive tissue and structures. In repairing weakened, bulging arteries, surgeons have the added difficulty of trying to maintain the blood flow that nourished the surrounding brain tissue. Ordinarily, small aneurysms can be clipped or cut off relatively quickly without significantly impairing the flow of blood through the vessel. Often, the aneurysm can be safely obliterated with novel endovascular techniques being pioneered at NYU - using devices threaded through the arteries - which avoids having to open the skull.

In contrast, giant aneurysms present much greater difficulty. "They often incorporate the whole wall of the blood vessel," Dr. Jafar explains, and frequently become hardened and unwieldy because of atherosclerotic deposits. To alleviate the symptoms and to eliminate the threat of rupture, we have to cut off the blood flow to the aneurysm. But we still have to make sure that blood continues flowing to the parts of the brain that are ordinarily nourished by the damaged blood vessel. The bottom line is that you couldn't find a more difficult set of surgical challenges or a more serious threat to life. I'm really not surprised that many surgeons don't want to operate on these patients."

Alternative Blood Flow

About half of the population has the good fortune to possess a configuration of blood vessels that permits blood to circulate in a loop to both sides of the brain. This pattern, known as the Circle of Willis, provides alternate routes for blood to reach brain tissue in case of a blockage in one of the arteries. For these patients, maintaining the flow of blood may not be a problem, and the vessel with the aneurysm can often be simply sealed off using a variety of methods.

For the rest of the population, however, surgeons face a significant challenge in trying to preserve the blood flow. For these patients, an EC-IC bypass creates an alternate route for the blood, which ensures that that all parts of the brain will be adequately nourished. We essentially build a detour around the aneurysm. In many respects, what we do is similar to what is done in a heart bypass," says Dr. Jafar. " We take a vein from the leg connect it to the artery in the neck, and connect the other end to an artery in the brain - creating a new blood conduit to supply the brain." Once the bypass is working, the surgeon can focus exclusively on eliminating the aneurysm, usually by clipping or ligating the artery feeding it.