There are several reasons why blockages can form and cause an ischaemic stroke.
Atherosclerosis (narrowed arteries)
Atherosclerosis is where fatty deposits build up on the inside walls of the blood vessels carrying blood away from the heart (arteries). These deposits are called plaques or atheromas.
Atheromas can build up in the large arteries in your neck leading to the brain, making them narrower and stiffer. Atheromas can break down or become inflamed. When this happens, a clot forms on the surface of the atheroma, which can block the blood vessel. It may break off and move through the bloodstream into the brain, causing a stroke.
What causes atherosclerosis?
Some things can make you more likely to have a build-up of fatty materials in your blood vessels. These include:
- Medical conditions including high blood pressure, high cholesterol and diabetes.
- Lifestyle factors such as smoking, being overweight and not being physically active.
After a stroke, you should get advice about treating your medical conditions and making healthy lifestyle changes. Our Managing risk section has tips on staying healthy after a stroke.
Small vessel disease
Small vessel disease means having damage to the tiny blood vessels deep inside the brain. The blood vessels become narrowed which reduces blood flow and makes a stroke more likely. It can also lead to many small strokes, as well as increasing the risk of bleeding in the brain (haemorrhagic stroke).
Small vessel disease can be diagnosed on a brain scan, where it looks like scars in the brain structure. It can affect your thinking ability and your mood, and it’s linked to memory problems and dementia.
What causes small vessel disease?
High blood pressure over a long time and diabetes are risk factors for small vessel disease. But what causes some people to get small vessel disease is not fully understood.
Heart conditions
Atrial fibrillation (irregular heartbeat)
Atrial fibrillation (AF) means your heartbeat is irregular and may be abnormally fast. Because the heart does not empty itself of blood at each heartbeat, a clot can form in the blood left behind. If this clot travels through the bloodstream to the brain, it can cause a stroke.
Patent foramen ovale (PFO, or hole in the heart)
All babies in the womb have an opening between the right and left side of their heart, known as the ‘foramen ovale’. This gap is needed while the baby is connected to the mother’s blood supply. After birth, the baby’s blood circulation changes and this gap usually closes up.
However, in as many as one in four people, the gap stays open. This is known as a ‘patent’ (open) foramen ovale, or PFO. It’s sometimes referred to as a ‘hole in the heart’.
Usually, a PFO does not have symptoms or cause problems, and may not need to be treated. However, a PFO may be a risk for stroke if a blood clot forms in a vein and travels through the PFO and then to the brain. But most people with a PFO never have a stroke.
If you have a stroke at a younger age, or your medical team cannot find the cause of your stroke, you may be assessed to decide if a PFO could have been a reason for your stroke and what treatment you need.
Treatment options include blood-thinning medication to reduce the risk of clots or a procedure to close the PFO. Your doctor will talk to you about the best treatment for you.
Other heart conditions
Other heart problems, such as a recent heart attack, heart failure, or a mechanical heart valve, may also make a stroke more likely.
Arterial dissection (damage to the artery)
Arterial dissection is when the lining of an artery (a blood vessel leading away from the heart) gets torn. It can happen after an injury, but it can also happen with no obvious cause. Blood builds up in the damaged area, and a clot can form. If this clot restricts the flow of blood to your brain, or moves up into your brain, it can cause a stroke.
Other causes
Sometimes stroke can be associated with other health conditions, such as inherited blood clotting disorders, autoimmune disorders or heart infections. Your medical team will investigate these too to try to find a cause.