Carotid embolism

What is carotid embolism?

Carotid embolism happens when a piece of debris, usually a blood clot or a fragment of fatty plaque, breaks loose and travels through your carotid artery (the main blood vessel supplying your brain) towards your brain. If it blocks a blood vessel there, it can cause a stroke or a temporary 'mini stroke' called a TIA.

Symptoms of carotid embolism

Carotid artery disease itself often causes no symptoms until it leads to a TIA or a stroke. The warning signs are the same for both, and can include:

• your face drooping on one side – you may have trouble smiling
• weakness or numbness down one side of your body, including your arm or leg
• slurred speech, or trouble finding words, even though you're awake and alert
• sudden loss of vision in one eye, sometimes described as a dark shade coming down
• loss of coordination or balance.

These symptoms can appear suddenly and may last just a few seconds, or up to 24 hours. Even if they pass quickly, they're a serious warning sign and need emergency treatment straight away.

Causes and who is at risk

Most carotid embolisms come from fatty plaque that has built up in your carotid artery over time – a process called atherosclerosis. A piece of this plaque, or a blood clot that forms on top of it, can break away and travel towards your brain.

Things that increase your risk of this plaque build-up include:

• smoking or using tobacco
• high blood pressure
• high cholesterol, particularly LDL ('bad') cholesterol
• diabetes
• being overweight or obese
• an inactive lifestyle
• a diet low in fruit and vegetables
• heavy alcohol use
• a family history of stroke or heart attack
• getting older, particularly over 67
• being male, though it can affect women too.

Less commonly, the clot doesn't come from the carotid artery at all. It can form in the heart, often because of an irregular heart rhythm called atrial fibrillation, and travel from there into the carotid artery or beyond. If you've had more than one TIA (‘mini stroke’) within the space of a month, this can be a sign of an unstable plaque and needs urgent assessment.

Are there different types of carotid embolism?

Carotid artery disease, the underlying cause of most carotid embolisms, is usually classified by how much of the artery is blocked:

• Mild: Less than 50% blocked
• Moderate: Between 50% and 79% blocked
• Severe: Between 80% and 99% blocked.

The more severe the narrowing, the higher your risk of a TIA or stroke, and the more likely you are to be offered a procedure to clear it.

How is carotid embolism diagnosed?

Carotid artery disease often has no symptoms, so it's sometimes picked up during a routine check, when your doctor listens to your neck with a stethoscope for an unusual whooshing sound called a carotid bruit. Not everyone with narrowed arteries has a bruit, so its absence doesn't rule out the condition.

If your doctor is concerned, or if you've had symptoms of a TIA or stroke, you may be offered:

• A carotid ultrasound: Sometimes called a carotid doppler or duplex scan, a painless scan using sound waves to look at blood flow in your neck, usually the first test used
• A CT or MRI scan of your head and neck: This is to build a detailed picture of the arteries and check for any blockage
• A cerebral angiogram: A more detailed test using a catheter and contrast dye to look closely at the blockage
• An ECG and echocardiogram (a heart ultrasound): This is to check whether an irregular heart rhythm or a problem with your heart valves could be a source of clots.

How is carotid embolism treated?

Non-surgical treatment

If your carotid artery disease is mild, or isn't causing symptoms, treatment usually focuses on lowering your risk of a future stroke:

• keeping your blood pressure and cholesterol at healthy levels
• staying as active as you can
• keeping to a healthy weight
• stopping smoking
• keeping good control of your blood sugar, if you have diabetes.

You may also be prescribed a daily low dose of aspirin, or another antiplatelet medicine such as clopidogrel, which helps stop blood clots forming. Medicines to lower your blood pressure and cholesterol are often prescribed too.

Surgical treatment

If your artery is moderately or severely narrowed, especially if you've already had a TIA or stroke, you may be offered a procedure to clear it.

• Carotid endarterectomy: This involves the surgeon opening the artery, removing the blockage, and closing the artery back up. This can be done under local or general anaesthetic, and a temporary tube called a shunt may be used to keep blood flowing to your brain during the operation. This is usually the preferred procedure, and it's often carried out as soon as possible after a TIA or minor stroke.
• Carotid artery stenting: This is a less invasive option done under local anaesthetic, where a small mesh tube (a stent) is used to hold the artery open, sometimes preceded by a balloon to widen it first. This avoids open surgery of the neck, though evidence suggests a slightly higher risk of stroke during the procedure itself compared with endarterectomy.

If you've already had a stroke, getting to a specialised stroke unit quickly matters. Clot-busting medicine can be given if you arrive within four and a half hours of your symptoms starting, and stroke units have been shown to reduce death rates by around a quarter.

When should I see a doctor?

Get emergency help straight away if you or someone else has any signs of a stroke or TIA. Remember the word FAST:

• Face: Has their face dropped on one side? Can they smile?
• Arms: Can they raise both arms and keep them there, or does one arm drift down?
• Speech: Is their speech slurred or garbled, or are they having trouble speaking, even though they're awake?
• Time: If you see any of these signs, call 999 immediately.

Even if the symptoms pass quickly, or seem to disappear altogether, still call 999 and get it checked. A TIA is a serious warning sign that a bigger stroke could follow soon after, and quick treatment makes a real difference to the outcome.