Carotid stenosis – narrowing of the carotid arteries

What is carotid stenosis?

Carotid stenosis is a narrowing of the carotid artery, usually caused by vascular calcification. The carotid artery is medically called the “carotid artery” and the word “stenosis” stands for “narrowing”. The carotid arteries supply large parts of the brain with blood – and therefore with oxygen and nutrients. This is the only way the brain can function smoothly.

As in all other vessels in the body, deposits can also form on the carotid arteries – so-called plaques. In arteriosclerosis, the vessels become increasingly “calcified”, constrict and lose their elasticity. A narrowed or blocked carotid artery (carotid stenosis or occlusion) can cause a stroke due to reduced blood flow to the brain.

In an ischemic stroke, brain tissue that is normally supplied via the blocked vessel no longer receives enough blood and therefore too little oxygen. The brain cells can no longer be adequately supplied and brain tissue is destroyed. In the event of a stroke, every minute counts, otherwise there is a risk of severe disability and the need for care. A stroke is an absolute emergency and you must call the emergency services (144) as soon as you notice the first symptoms.

Carotid stenosis: causes and risk factors

The causes of carotid stenosis are deposits of calcium, but also of fats, connective tissue and blood clots in the carotid arteries. The plaques often form at the junction of the inner and outer carotid arteries (carotid bifurcation). The internal carotid artery supplies large parts of the brain with blood. If it is narrowed, less blood reaches the brain. In principle, however, the constriction can occur along the entire course of the carotid artery.

Carotid stenosis – risk factors

There are various risk factors that can lead to carotid stenosis.

• Age: With increasing age, the arteries become less elastic and more susceptible to deposits and constrictions – a natural ageing process.
• High blood pressure (arterial hypertension): Excessively high blood pressure damages the arterial wall and makes it more susceptible to deposits.
• High blood lipids: Too much cholesterol in the blood is deposited in the arteries and leads to constrictions.
• High blood sugar/diabetes mellitus: High blood sugar (diabetes mellitus) can lead to inflammation in the arterial wall or damage to the inner layer of the arteries, which can lead to narrowing.
• Smoking: Toxic combustion products from tobacco damage the arteries via various mechanisms.
• Obesity
• Lack of exercise
• Family predisposition
• Previous radiation: damages cells in the artery wall, which can also lead to constriction
• Splitting of the arterial wall layers(dissection): E.g. due to an accident or spontaneously (without apparent previous illness) as well as in certain connective tissue diseases
• Inflammatory arterial diseases (arteritis)

You can positively influence some of these factors through a healthy lifestyle and thus reduce the risk of arteriosclerosis and thus carotid stenosis. You have no influence on other factors, such as your age or your genes.

Carotid stenosis: symptoms

Carotid stenosis can progress for a long time without symptoms, which makes it very dangerous. The first sign may already be a streak or a so-called transient ischemic attack (TIA, Swiss German: “Schlägli”), in which there is a temporary reduction in blood flow to the brain. If the complete interruption of the blood flow lasts too long, a stroke follows with a corresponding scar in the brain.

If a TIA is recognized and treated correctly, it may be possible to prevent a major stroke with life-threatening consequences, as the reduced blood flow to the brain is only temporary. It is not yet possible to differentiate between a streak and a stroke at the time the symptoms appear.

The following symptoms may occur, for example:

• Sudden paralysis, usually unilateral, in the face, arms or legs or the entire side of the body
• Sudden loss of sensation in the face, arms or legs, or the entire side of the body
• Speech production or comprehension disorder (aphasia)
• Slurred speech (dysarthria)
• Sudden visual impairment, e.g. brief temporary blindness in one eye
• Sudden loss of consciousness

Diagnosis of carotid stenosis

Investigations for carotid stenosis are carried out at the University Hospital Zurich either by the general practitioner following a referral or as part of an incidental finding.

We obtain indications of carotid stenosis in an anamnesis interview with you, e.g. with the following questions:

• Do you or your family have a history of heart or vascular disease?
• Have you ever experienced sudden paralysis, loss of sensation or visual impairment?
• Do you have any known risk factors for cardiovascular diseases such as diabetes mellitus, high blood pressure or high cholesterol levels?
• Do you smoke? If yes: Since when and how many cigarettes per day?

A physical examination can provide further indications of carotid stenosis, such as a weakened pulse in the carotid artery or a flow noise above the carotid artery, which can be heard with a stethoscope. In addition, neurological deficits that may not have been noticed by the patient themselves can be detected.

If carotid stenosis is suspected, we first use the following procedure:

• Color-coded duplex ultrasonography: Ultrasound examination of the neck in which the carotid arteries, deposits (hard or soft), constrictions and blood flow can be visualized. The severity of any narrowing (carotid stenosis) can also be assessed. Depending on the location of the narrowing, a stenosis can only be found if the cerebral arteries are also examined (transcranial duplex sonography)

If carotid stenosis has been diagnosed and treatment is planned, further imaging procedures may be used:

• Magnetic resonance imaging (MRI): A contrast agent is administered via a vein in your arm and images of the blood vessels (MR angiography) and/or the brain are taken in the MRI. An MRI does not use X-rays, but strong magnetic fields that enable precise cross-sectional images.
• Computed tomography (CT) with contrast medium which uses X-rays to produce precise anatomical cross-sectional images.
• Diagnostic catheter angiography with intra-arterial injection of contrast medium.

If the carotid artery is narrowed by more than 70 percent, there is an increased risk of a stroke. The risk is also significantly higher if you have already suffered a stroke (TIA) or an ischemic stroke. Treatment is then advisable, in which we remove the constrictions. This can often prevent a first or recurrent stroke.

Carotid stenosis: prevention, early detection, prognosis

Carotid stenosis usually has its origin in arteriosclerosis. Some risk factors favor vascular calcification. Some of them you can influence yourself through a healthy lifestyle. Some tips on how you can prevent carotid stenosis:

• Make sure your blood pressure is healthy. And if you have high blood pressure, make sure you get adequate treatment. This also applies to elevated blood lipids and blood sugar levels, which you can have checked by your family doctor.
• Do not smoke, and if you are a smoker, try to stop smoking.
• Avoid being overweight orobese. Try to lose a few kilos.
• Get plenty of exercise in your everyday life and do sports such as endurance sports like cycling, swimming or hiking. Walk instead of taking the bus or streetcar.
• Make sure you eat a healthy diet, for example plenty of fresh fruit and vegetables and whole grain products with healthy fiber.

There are no targeted measures for the early detection of narrowed carotid arteries. Doctors often discovered the narrowing of the carotid arteries by chance during a routine examination.

Prognosis and course of carotid stenosis

The prognosis and course of carotid stenosis vary from person to person. If the doctor discovers it in time, it can be treated well and the prognosis is favorable. The situation is different if the narrowing of the carotid artery has already led to a stroke. This can result in severe disabilities that considerably restrict everyday life and quality of life.

Carotid stenosis: treatment with or without surgery

The narrowing of the carotid arteries can be treated with or without surgery. Both therapies aim to reduce the risk of a stroke. The treatment strategy we choose after an interdisciplinary discussion depends on the extent of the narrowing, but also on your age, general state of health and your personal wishes.