Weill Medical College of Cornell University

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Cerebral Neovascularization (Bypass Surgery)

Cerebral neovascularization, also called bypass surgery, is a type of neurological surgery used to address a condition called cerebrovascular insufficiency. In patients with cerebrovascular insufficiency, the brain does not receive all the blood it should because the arteries that feed blood to it are partially blocked, which can lead to a stroke or a transient ischemic attack (TIA or "mini-stroke").

Cerebrovascular insufficiency most often is caused by carotid artery stenosis, in which plaque, made up of fatty material and blood platelets, blocks blood vessels. This plaque buildup may grow large enough to block the artery, may break off and block a narrower artery, or may cause the development of a thrombus, or clot. In addition, insufficiency may be caused by other conditions, such as moyamoya disease, which occurs when the arteries become blocked and new blood vessels grow in a tangle in the area, and fibromuscular dysplasia, an inherited disease that involves the destruction of arteries.

A stroke occurs when the blood supply to a part of the brain is completely blocked, leading to the death of brain cells and often death. A TIA, or "mini-stroke," is a temporary condition is which the blood flow to the part of the brain is restricted, leading to transient neurological deficits. Neovascularization procedures are used to restore the flow of blood by bypassing the blockage.

Diagnostic Innovation

At Weill Cornell Medical College, patients with cerebrovascular insufficiency undergo an extensive evaluation by a team of nuerosurgeons, neurologists, and neuroradiologists. Assessment begins with a physical examination, including assessment of heart function and tests that can reveal specific neurological, motor, and sensory deficits. In addition, physicians may be able to hear changes in blood flow in the carotid arteries with a stethoscope. A complete diagnostic workup also will include an angiogram, which provides an image of the blood flow in the brain. Carotid Duplex ultrasound and magnetic resonance imaging (MRI) scans also may be used to provide images of the cerebral arteries.

Therapeutic Excellence

Depending on the degree of insufficiency, anticoagulant medications may be given first. If the medical treatment does not work, physicians may recommend

• Carotid angioplasty and stenting, in which a balloon and a small tube are used to open up the obstructed artery;
• Surgery to remove the occlusion; or
• Cerebral neovascularization surgery, which provides new blood supply that can help prevent strokes and TIAs. For neovascularization, we perform microsurgical extracranial-to-intracranial (EC-IC) bypass surgery, in which the blood supply to a portion of the scalp is rerouted to a cerebral artery past the point of the obstruction

Bypass surgery also is used to treat certain aneurysms (outpouchings or sacs of blood that emerge from the sides of blood vessels) in the brain. The treatment of giant aneurysms (those greater that 25 millimeters) may require a bypass before the vessel is closed off so surgeons can treat the aneurysm.

Cebebral neovascularization is a complex procedure, and should be conducted at major centers with experts experienced in the treatment of cerebrovascular insufficiency.