The carotid arteries are the main blood vessels to your brain. Located on each side of your neck and extending from your aorta in your chest to the base of your skull, they supply oxygen-rich blood to your brain. Plaque forms when the carotid arteries become blocked by fat and cholesterol build-up, a process called atherosclerosis. Blockage of the carotid arteries can reduce blood supply to the brain, and may lead to a stroke.
The plaque may cause the blood to flow abnormally, which can cause blood clots. A clot may remain at the site of narrowing and prevent blood flow to all of the smaller arteries it supplies, or a clot can travel and wedge into smaller vessels (an embolism). If a clot or plaque blocks the blood flow to your brain, it can lead to an ischemic stroke, which may cause brain damage or death. If a clot or plaque blocks a tiny artery in the brain, it may cause a transient ischemic attack (TIA), also known as a mini-stroke.
Severe blockage is called carotid stenosis, which may cause you to experience a TIA. Common temporary symptoms of TIA include difficulty speaking or understanding others, loss or blurring of vision in one eye and loss of strength or numbness in an arm or leg. Usually these symptoms resolve in less than 10 to 20 minutes, and almost always within one hour. Call 911 even if your symptoms resolve; you should be evaluated by a neurologist immediately.
Carotid stenosis is frequently asymptomatic. Your doctor may detect it through an abnormal sound called a bruit when listening to your carotid arteries with a stethoscope.
Your doctor may order tests to help diagnose the extent of blockage:
Cerebral angiography is also called vertebral angiogram or carotid angiogram. A contrast dye allows your doctor to view your arteries on an x-ray. You will be given a local anesthetic, after which an artery is punctured, usually in your leg, and a needle is inserted into the artery. A catheter – a long, narrow, flexible tube – is inserted through the needle and into your artery, and threaded through the main vessels of the abdomen and chest until it is properly placed in your carotid artery. The procedure is monitored by a fluoroscope, a special x-ray that projects the images on a monitor. The contrast dye is then injected into the neck area through the catheter, and x-ray images are taken.
Carotid duplex, also called carotid ultrasound, is used to help detect plaque, blood clots or other problems with blood flow in the carotid arteries. Ultrasonography is very reliable in identifying stenosis, but does not accurately assess the degree of stenosis. Because treatment is based on the degree of stenosis, treatment decisions can’t be made from ultrasonography alone.
During carotid duplex, a water-soluble gel is placed on your skin where a transducer – a handheld device that directs the high-frequency sound waves to the arteries being tested – is to be placed. The gel helps transmit the sound to your skin surface. The ultrasound is turned on and images of the carotid arteries and pulse waveforms are obtained. The test is noninvasive and painless.
Magnetic resonance angiography (MRA) is a noninvasive study conducted in an MRI scanner. The magnetic images are assembled by a computer to provide an image of the arteries in your head and neck.
MRI produces three-dimensional images of your head using powerful magnets and computer technology.
Prior to determining if you’re a candidate for a carotid endarterectomy to resolve carotid stenosis, your doctor will give you a thorough examination, including your medical history. Individuals with the following medical conditions are at higher risk of having complications from this surgery:
- Past strokes, especially large strokes without recovery
- A heart attack within the last 6 months
- Congestive heart failure
- Uncontrolled high blood pressure
- Unstable angina (chest pain)
- Serious disease, such as severe heart or lung disease
- Plaque that can’t be reached through surgery
- Severe blockage in other blood vessels that supply blood to your brain
- New blockage in a previous carotid endarterectomy on the same side
- Alzheimer’s disease or other progressive brain disorders
If your neurosurgeon recommends carotid endarterectomy, you’ll be given either a general or local anesthetic before surgery. In this procedure, the neurosurgeon makes an incision in your carotid artery and removes the plaque using a dissecting tool. Removing the plaque is accomplished by widening the passageway, which helps to restore normal blood flow. Your artery will be repaired with sutures or a graft.
An alternative, a relatively new form of treatment called carotid angioplasty and stenting, shows some promise in patients who may be too high risk to undergo surgery. Carotid stenting is a procedure in which a tiny, slender metal-mesh tube is fitted inside your carotid artery to increase the flow of blood blocked by plaques. The stent is inserted following a procedure called angioplasty, in which the doctor guides a balloon-tipped catheter into your blocked artery. The balloon is inflated and pressed against the plaque, flattening it and re-opening the artery. The stent acts as scaffolding to prevent the artery from collapsing or from closing up again after the procedure is completed. You are awake during this procedure, and usually discharged from the hospital the following day.
Source: American Association of Neurological Surgeons