If the large arteries supplying blood to the brain become blocked, you are at risk of a stroke. This information explains how the arteries become blocked (carotid artery disease) and treatments to reduce your risk of a stroke. 

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What is carotid artery disease?

In carotid artery disease, the arteries inside the neck become narrowed and stiff. This makes it harder for blood to flow smoothly, and makes clots more likely to form.

How do arteries become narrowed?

Arteries are blood vessels carrying blood from the heart to the body and brain. They can get clogged with fatty substances in the blood sticking to the lining of the artery walls. These substances include cholesterol and other fats, which combine with other materials like blood cell fragments. 

This can build up to form thickened areas, also known as plaques, on the artery wall. This is also known as atheroma, or atherosclerosis. These plaques often form where the artery branches off inside the neck.

As we age, our arteries gradually become stiffer and thicker. Atherosclerosis speeds up this process. The build-up of plaques makes the artery narrower inside (also known as stenosis).

Where are the carotid arteries?

The carotid arteries bring blood from the heart to the brain, face and neck. You have two carotid arteries, one on each side. One branch of the artery reaches the face and scalp, and the other branch travels inside the neck up to the brain. 

How can carotid artery disease cause a stroke or TIA?

A stroke is a brain attack. It happens when the blood supply to part of the brain is cut off, killing brain cells. There are two main types of stroke. It can be due to a blockage to the blood supply in the brain (clot), or a bleed in or around the brain. 
Carotid artery disease can lead to a stroke due to a clot in the brain, also known as an ischaemic stroke. It can also cause a transient ischaemic attack (TIA or mini-stroke). A TIA is the same as a stroke, but the symptoms last a short amount of time. Carotid artery disease causes up to 15% of all ischaemic strokes in the UK. 
Blocked carotid arteries can lead to stroke in two ways: 
1. Total blockage (occlusion)

Occlusion is the medical term for when the artery becomes completely blocked, cutting off the blood supply to the brain and causing a stroke.
2. Clot in the artery (thrombosis)

As well as making the arteries narrower (stenosis), plaques of atheroma can damage the lining of the blood vessels. Plaques can become inflamed and make the inner surface of artery walls thinner. If the plaque ruptures, it exposes the artery lining, and a clot forms over the damaged area. 
Clot fragments can then break off and go up to the brain, to block a blood vessel inside the brain and cause a stroke. Sometimes a clot can block the artery itself, cutting off the blood supply at this point. 

How is carotid artery disease diagnosed?

Carotid artery disease doesn't usually have any symptoms, and it's often diagnosed when you have an ischaemic stroke (a stroke due to a clot) or a transient ischaemic attack (TIA). After a stroke, you'll have tests and checks to look for the causes, and you should get advice making healthy lifestyle changes.

Who is at risk of carotid artery disease?

Your arteries become slightly narrowed and stiffer with age, but there are things you can do to reduce the amount of fatty deposits building up in your blood vessels (atherosclerosis). Read our information about how to reduce your risk of a stroke by treating any related health conditions such as high cholesterol and high blood pressure. Staying active, having a healthy diet and stopping smoking are also important lifestyle changes that can help you stay healthy. 

After treatment for carotid artery disease, you can make a big difference to your health by following any medical treatments you need, and making healthy lifestyle choices.

Carotid artery disease is usually diagnosed after you have a stroke or a transient ischaemic attack (TIA).  

Tests and checks 

Your doctor may listen to the sound of your blood flow through your carotid arteries using a stethoscope. A whooshing sound, known as a carotid bruit, can be a sign that there is some narrowing, although this is not very reliable. You will then be referred to a hospital specialist for further tests.
A useful test for carotid artery disease is an ultrasound scan (known as a carotid Doppler). It is a completely painless procedure. A small probe is passed over the side of your neck to build up a picture of your arteries. The specialist can then see whether there is any narrowing and, if so, whether it is severe enough to benefit from having an operation
You will probably have further imaging checks to confirm this diagnosis. These might be computed tomography angiography (CTA) or magnetic resonance angiography (MRA) scans, which usually need a special dye injection (called a contrast agent) into a vein in your arm

Measuring the narrowing of the arteries

In the UK, the NASCET scale (North American Symptomatic Carotid Endarterectomy Trial) is usually used to measure carotid stenosis. This has three categories of measurement which are:

  • Minor: less than 50% narrowed.
  • Moderate: 50-69% narrowed.
  • Severe: 70% narrowed or more. 

Carotid artery disease treatment: carotid endartarectomy

There are procedures that can reduce the risk of a stroke or TIA, but, they will only be offered to you if your artery has moderate or severe stenosis. This is because the procedures themselves carry risks, and are most successful at reducing stroke risk when stenosis is over 50%. The main procedure is an operation called carotid endarterectomy.

For arteries with minor stenosis, the risks of the operation are considered too high. These arteries are much less likely to cause a stroke and can still supply your brain with enough blood.

Carotid endarterectomy

Carotid endarterectomy is an operation to clear the blockages from inside an artery. It is well-established and is the main procedure used.

If you smoke you will be advised to stop smoking before the operation. Smoking reduces the amount of oxygen in your blood and can increase your risk of breathing problems during the procedure or getting a chest infection.

Surgery should be carried out as soon as possible and within one week of your stroke or TIA.

Carotid endarterectomy may be carried out under local or general anaesthetic in an operation that takes one to two hours. If both of your carotid arteries need surgery, this is usually done on two separate operations.

The surgeon makes a small cut in the side of your neck so they can see your carotid artery, which will then be clamped shut. If need be, a small piece of tubing (shunt) can be used to re-route blood flow along another artery to make sure your brain still gets enough blood.   

The surgeon then opens up your artery and removes the inner lining and any fatty deposits (plaques). The artery is closed with stitches, or with a patch. The patch can be made of artificial fibres or be a graft taken from another blood vessel.

The operation usually takes between one and two hours. Most people recover remarkably quickly. Within a few hours you can usually sit up in bed, and are able to go home in a couple of days.

The wound in your neck should heal to a fine scar after a few months. You may be advised to limit your physical activity for a short period. Most people can return to work after three to four weeks but extra care needs to be taken in jobs that involve manual labour. Where possible, light duties should be performed until you fully recover.

You will be able to return to driving two to three weeks following your operation, providing that you can perform an emergency stop safely and look over your shoulder. But remember that you can’t drive for one month after a stroke or TIA. Depending on the type of stroke you had and the kind of driving licence you hold, this period can be longer. If you are not sure how this applies to you, check with the  DVLA (or DVA in Northern Ireland) before you start driving again.

What are the risks?

As with any operation, there are some risks associated with carotid endarterectomy. 

There is about a 2% risk of having a stroke during surgery. This is due to the chance of a small blood clot, or other debris, breaking free during the operation and travelling to your brain. So carotid endarterectomy is only recommended if you have a moderate or severe stenosis, where the risk of having another stroke is greater than the risk associated with the procedure. Just under one in a hundred people die, which usually happens when there is stroke or heart attack soon after the operation. 

Complications are more likely if you are older, a smoker, or have had a recent stroke. You can also be more at risk of complications if you have a blockage in both carotid arteries, and if you have other health conditions such as heart disease and high blood pressure. Complications can include:

  • Wound infection, which affects less than 1% of people, and can be treated with antibiotics.
  • Bleeding from the site of your wound.
  • Nerve injury, which affects around 4% of people and is usually temporary. This can cause a hoarse voice, weakness, or numbness on one side of your face. These symptoms usually disappear within a month.
  • Numbness or slight pain around your wound, which can be treated with painkillers.
  • Re-stenosis, or the carotid arteries becoming blocked again. About 2  4% of people will need to have further surgery.

As with any major operation, these risks should be explained to you. It is normal to feel anxious or frightened by this so talk to your surgeon and anaesthetist about your concerns. It is a good idea to prepare for an appointment with specialists by writing down a list of questions in advance. You may like to consider the following:

Questions to ask before the operation

  • What is the success rate for this operation at this hospital? 
  • What is my risk of a stroke without the operation?
  • Am I at an increased risk during this operation because of other health conditions?
  • Can I choose to have a local or a general anaesthetic?
  • Is it likely that I will have to have this operation again in the future?
  • Do you have a diagram to help explain the operation?

Tip: write down what the specialists tell you and discuss it with friends or family.  

Carotid artery disease treatment: carotid artery stenting

There is an alternative to the carotid endarterectomy surgery that is called carotid artery stent placement, often known as stenting.

This procedure is less invasive than the endarterectomy because it does not involve open surgery of the neck. The evidence shows that this procedure is as safe as surgery in carefully selected patients. It iseffective at preventing strokes, with similar long-term risks of a stroke as carotid endarterectomy.

The procedure is done under local anaesthetic. A small flexible tube is passed into the carotid artery through the femoral artery in your groin. This is done under the guidance of an X-ray of your arteries, and a contrast (also known as dye) will be injected. The contrast allows your blood vessels to show up on the X-ray. The tube has a small balloon at the end of it. When this tube reaches the narrowed area, the balloon is inflated up to around 5mm.

A small wire mesh cylinder called a stent is inserted to keep your artery open, improving blood flow. The stent stays there permanently. This widens your artery, allowing your blood to flow through it again. The balloon is then removed.

After the operation you will need to lie flat and still for an hour or so afterwards to prevent bleeding from the artery. You will stay in hospital overnight and go home the following day.

What are the risks?

As with carotid endarterectomy, complications can occur after stenting and the risk of a major stroke and death after both procedures are similar. Therefore, as with endarterectomy, it will also only be recommended if you have moderate to severe stenosis. Other rare complications of this procedure include: 

  • Bruising where the tube enters your femoral artery.
  • Bleeding from this point which may require an operation (affects about 1% of all cases).
  • An allergic reaction or kidney problems due to the X-ray contrast dye.
  • A blockage or rupture in your carotid artery – this is very rare but may need to be treated with a stent. If this isn’t possible, an operation may be needed to repair your artery.

The advantages of stenting are that it is less invasive, avoids wound complications and has a lower risk of nerve damage. However, clinical trials suggest that the short term risk of minor stroke seems to be higher with stenting than endarterectomy, especially in patients over 70. So stenting is usually offered only when endarterectomy is not recommended. 

Speak to your consultant about your options and ask lots of questions until you feel you understand everything. You may wish to ask why you are being offered stenting rather than endarterectomy. There are several possible answers to this question, and they may include the anatomy of your carotid arteries, the experience of the medical staff, or your general health and age.