EC-IC bypass is a procedure in which a blood vessel outside the skull is connected to a blood vessel inside the skull. The goal of an EC-IC bypass is to improve blood flow in the brain.
The guidelines on when to perform EC-IC bypass have been evolving. A large study in the 1980s and a more recent study in 2011 indicate that for patients with certain relatively common conditions, such as carotid artery disease, EC-IC bypass surgery offers no benefit over other surgical or nonsurgical treatments. Carotid artery disease, for example, may be treated just as effectively with medication and/or carotid artery surgery, a less invasive procedure.
Therefore, at Columbia Neurosurgery, we use EC-IC bypass only in select groups of patients who can expect to derive significant benefit. These patients tend to have one of three rare conditions with which our neurosurgeons are particularly experienced.
One such condition is rare types of aneurysm. Cavernous carotid aneurysms and giant intracranial artery aneurysms, for example, often cannot be treated with the standard procedures that clip aneurysms shut or seal them off. Untreated, these aneurysms are at great risk for leaking blood into the brain, causing hemorrhagic stroke—a medical emergency that can be deadly. EC-IC bypass reroutes blood flow around an aneurysm. Then the section of the artery with an aneurysm in it can be shut down—eliminating blood flow to the aneurysm and thereby preventing a stroke.
Patients with moyamoya syndrome also often benefit from EC-IC bypass. Moyamoya is a rare condition in which the blood flow in certain brain arteries is restricted. Restriction of blood flow to the brain can damage the brain’s tissues. To compensate, the body grows new blood vessels. However, these vessels are delicate and are prone to leaking, which can cause hemorrhagic stroke. An EC-IC bypass can provide healthy blood flow once again. The treatment is sometimes used in combination with indirect revascularization. (Very young children with moyamoya, approximately 2 years and under, are likely to be treated with indirect revascularization alone. The small size of their vessels makes EC-IC bypass less feasible.)
Finally, patients with skull base tumors may require EC-IC bypass surgery. Tumors of the skull base can become entangled with vital blood vessels at the base of the skull that feed the brain. Removing such tumors may also require removing vessels. An EC-IC bypass can reroute the blood flow so that the tumor can be safely removed.
An EC-IC bypass is a microsurgical procedure performed under general anesthesia.
Imaging tests performed in advance of the procedure help the neurosurgeons build a “map” of blood vessels in the brain and possibly elsewhere in the body. During the procedure, if a graft from a blood vessel in the arm or the leg will be used to connect the vessels, the graft vessel is located and harvested first.
Then the surgeon begins work on the head. The hair in the area is shaved, and the skin cleaned. Then the neurosurgeon locates and exposes the donor artery—the artery on the outside of the skull. The surgeon carefully releases the artery from all the structures to which it is attached. Then the surgeon performs a craniotomy, temporarily removing a small section of the skull bone. This creates a “window” in the skull. Through this window, the surgeon opens the protective covering around the brain called the dura, exposing the surface of the brain.
Using an operating microscope and specialized instruments, the surgeon examines the surface of the brain for the best branch of the recipient artery—the artery on the inside of the skull that will receive the new blood flow. The recipient artery must be surgically accessible on the surface of the brain, and its size must match well with the size of the donor artery (or graft connecting to the donor artery). The surgeon attaches the donor artery to the recipient artery, using the graft from the arm or leg if necessary. Finally, the surgeon tests to make sure the new connections are patent.
Then the surgical site is closed. The section of skull removed in the craniotomy is re-attached with screws and plates—minus a small passageway for the new vessel. The screws and plates are left in place even after the bone has healed. The skin incision is closed with stitches and covered with a small bandage.
Be sure you understand the risks and goals of the procedure. No surgery is without risk. Risks associated with EC-IC bypass include potentially serious complications like seizure and stroke, though these are rare.
Talk with your surgeon about his or her training and experience. EC-IC is not as commonly performed as it once was, and it requires specialized training both in neurosurgery and in vascular surgery. Specialists in this surgery are found at centers like Columbia Neurosurgery, where we routinely treat patients with conditions that would be very rare elsewhere.
How long will I stay in the hospital?
Hospital stay after EC-IC bypass is usually approximately three days. You will see your neurosurgeon for a follow-up visit approximately two to four weeks after discharge, and again after three to six months.
Will I need to take any special medications?
Following surgery, any discomfort will be controlled with pain medication.
You are likely to receive an anti-seizure medication for a short time after surgery.
You are likely to take a blood-thinning medication (aspirin or another medication) on a permanent basis to help prevent clots inside the bypass.
Will I need rehabilitation or physical therapy?
Most people do not need rehabilitation or physical therapy.
The first one to two weeks after the operation, you should focus on rest and recovery. It is helpful to walk as tolerated, but you should refrain from work either inside or outside the home.
By the time of the follow-up visit two to four weeks after surgery, most patients are cleared to resume their normal activities.
Will I have any long-term limitations due to EC-IC bypass?
Speak with your surgeon about your specific situation. In general, it is important that eyeglasses not fit tightly over the ear in patients who have had a bypass in the temple region. In addition, birth control pills are not recommended for patients who have had bypass surgery, since they can cause problems with blood clotting inside the bypass.
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