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What is a Stroke?

Last updated on 28th April 2023

According to the Stroke Association, someone in the UK has a stroke every five minutes, adding up to around 100,000 people each year. Whilst not every stroke sufferer pulls through, there are around 1.3 million stroke survivors in the country.

Cerebrovascular disease is the third leading cause of death in the UK, and 75% of these deaths in 2018 were from strokes. With such staggering statistics, it’s important to understand a little more about strokes, what causes them and how they can be prevented or treated.

What is a stroke?

A stroke occurs when an area of the brain’s blood supply is cut off. As a result of the block, the area of the brain does not gain oxygen or nutrients from the blood and begins to die off. This occurs very quickly in the brain.

Strokes are always medical emergencies. Without rapid medical treatment they can cause permanent or long-term disabilities, brain damage and even death. Strokes range in severity from a mild, temporary paralysis or weakness to complete paralysis on one side of the body. The size of the damaged area of the brain is proportional to the severity of the effects experienced with a stroke.

Looking at MRI scan of brain damage from stroke

What are the different types of strokes?

There are three types of strokes:

  • An ischaemic stroke.
  • A haemorrhagic stroke.
  • A transient ischaemic attack (TIA).

Ischaemic Strokes

An ischaemic stroke is the most common kind of stroke with around 85% of all strokes in the UK being of this type. It is caused by a blockage in the brain’s blood supply (a blood clot) which cuts off a part of the brain. Brain cells die as a result.

The effects of ischaemic strokes will depend on where the blockage in the brain was. They may affect movements as well as thoughts and feelings.

Haemorrhagic Strokes

Haemorrhagic strokes are caused by bleeding around or inside the brain caused by a burst or leaking blood vessel.

There are two types of haemorrhagic stroke:

  • Intracerebral haemorrhage (ICH) – Bleeding within the brain.
  • Subarachnoid haemorrhage (SAH) – Bleeding on the brain’s surface and in the protective layer of fluid surrounding the brain (the subarachnoid space).

Both types of haemorrhagic stroke need to be treated immediately to reduce the extent of the bleeding and reduce the damage to the brain. The effects of these kinds of strokes vary depending on the type, location and size of the bleed in the brain. Only 1 in 20 strokes is a subarachnoid haemorrhage.

Transient Ischaemic Attack (TIA)

A TIA is also known as a ‘mini stroke’. ITAs are the same as the other two kinds of stroke with the difference that the symptoms last for a limited amount of time before resolving, hence why they are called transient. TIAs are not as serious as full-blown strokes but they are a significant warning sign of a bigger stroke and therefore they must be treated very seriously.

What causes a stroke?

Strokes have different causes depending on their type. However, they do share some common features. Strokes are much more common in older people and that is a result of our arteries becoming less flexible and much narrower as we age.

This makes them much more likely to become blocked. Aside from the natural ageing process, certain lifestyle factors and medical conditions can increase the risk of having a stroke and are often considered causal factors.

As with all organs in the body, the brain needs a constant blood flow to provide oxygen and nutrients so that it’s able to function properly. If a blood vessel becomes blocked or is restricted, the brain cells begin to die. This becomes apparent when a person is symptomatic of a stroke. Let’s look in more detail at the causes of the different types of stroke.

Elderly man suffering stroke

What is the cause of an ischaemic stroke?

As mentioned, an ischaemic stroke is caused by a blockage.

These blockages can form for a few different reasons:


Atherosclerosis is another name for narrowed arteries. In atherosclerosis, fatty deposits form inside the blood vessels. These are called plaques (or ‘atheroma’). The plaques build up in the arteries in the neck which travel up to the brain and make the vessels stiffer and narrower.

The plaques can start to break down and cause the vessels to become inflamed. Blood starts to collect at the inflammation and forms a clot. Eventually, this clot can break away from the vessel and travel through the blood vessels into the brain.

When the clot reaches the tiny, narrow blood vessels in the brain, it gets stuck and causes a blockage, which results in a stroke.

Atherosclerosis can be caused by certain medical conditions as well as lifestyle factors. Medical conditions such as having high cholesterol, diabetes or high blood pressure can make a person more likely to have a build-up of fatty deposits in their blood vessels. Being overweight and smoking also causes atherosclerosis.

Small Vessel Disease

Small vessel disease, as its name implies, affects the tiny vessels within the brain. These vessels become increasingly narrower which restricts blood flow in the brain, making strokes more likely.

Small vessel disease can lead to a person experiencing a few small strokes and can increase the risk of haemorrhagic strokes. Aside from the typical effects, small vessel disease can affect a person’s mood and cognitive ability. It is also linked to dementia.

Small vessel disease is caused by high blood pressure. People with high blood pressure usually receive medication that reduces their blood pressure to help minimise the risk of developing or worsening their small vessel disease.

Heart Conditions: Atrial Fibrillation, Holes in the Heart, and Arterial Dissection

Atrial fibrillation (shortened to AF) simply means that the heartbeat is not regular and is beating abnormally quickly. When this happens, the heart is not getting a chance to empty its chambers each time it pumps. Clots can form in the blood that remains in the chambers due to lack of movement. When AF resolves, the clot can then travel to the brain where it causes a blockage.

Many people experience AF without any symptoms but the most common symptom is palpitations where the heart feels like it is skipping beats or is beating too quickly

Holes in the heart are another common cause of ischaemic strokes. Medically, they are known as patent foramen ovale or PFO. Before they are born, all babies have a hole in their heart (the foramen ovale) which is necessary for the baby whilst it is receiving its blood supply from its mother. However, once a baby is born, it no longer needs this hole and it should close up. Nevertheless, for many people, this hole does not close and is referred to as ‘patent’ (open).

You may wonder why this causes strokes. With the presence of a hole, blood can collect in the space and form a clot. As with other conditions, this clot may become dislodged, travel up to the brain and cause an ischaemic stroke. Sometimes children have surgery to close their PFO.

Arterial dissection is where an artery is damaged within its lining. This little tear can happen as the result of an injury or can happen seemingly randomly with no clear cause. The blood collects in the area where the damage is located, forming a clot. The clot can then break off, travel to the brain and cause a stroke.

What is the cause of a haemorrhagic stroke?

As mentioned, there are two types of haemorrhagic stroke, an intracerebral haemorrhage and a subarachnoid haemorrhage. Haemorrhagic strokes have different causes than ischaemic strokes.

What causes an ICH?

  • Small Vessel Disease
    Believe it or not, small vessel disease can also cause intracerebral haemorrhages as well as ischaemic ones. Because the small vessels are damaged, blood can leak into the tissue within the brain. High blood pressure can cause or have an impact on small vessel disease. The pressure of the blood can cause vessels to burst and then leak, causing an ICH.
  • Cerebral Amyloid Angiopathy (CAA)
    This is a specific type of small vessel disease where the amyloid beta protein collects inside the small blood vessels in the brain and increases the likelihood of them bleeding. This results in a haemorrhagic stroke or tiny bleeds that are not obvious and don’t always cause typical stroke symptoms. This condition is very common in the elderly, particularly people with dementia.
  • Blood Vessel Abnormalities
    Sometimes people are born with vascular malformations. This can include usually large blood vessels in the brain or a series of tangles in the brain’s blood vessels. Two main types of these abnormalities are called arteriovenous malformation (AVM) and cavernous malformation (cavernoma).AVM is where the blood vessels in the brain grow tangled and don’t link to the full brain blood vessel network. Blood flow can be reduced and can also compress the brain tissue in the surrounding areas. The blood has a high pressure within the AVM and then when the blood subsequently flows into smaller vessels, it can cause a leak and a bleed into the brain.With cavernoma, a raspberry-like blood vessel cluster develops. These bubbles are like caverns and can fill with blood. Sometimes there are no associated symptoms but they are more likely to bleed than other, regular vessels.

What causes a SAH?

  • Aneurysm
    Most SAHs are caused by an aneurysm that has burst. An aneurysm is like a little bubble in a blood vessel that has weak walls due to pressure build-up. Often, the aneurysm can be dealt with via surgery so that it doesn’t burst. However, sometimes aneurysms are silent and people do not know they are there until they burst.
Aneurysm being fixed from surgery

Who is more at risk of a stroke?

Strokes are much more common in older people due to their blood vessels naturally ageing and becoming weaker. However, certain factors make a person much more susceptible to strokes.

Medical Conditions:

  • Heart conditions such as irregular heartbeat.
  • High cholesterol.
  • High blood pressure.
  • Diabetes.

Lifestyle Factors:

  • Smoking.
  • Drinking too much alcohol.
  • Being overweight.
  • A diet high in fat.

Family History:

  • Having a relative who has had a stroke.
  • Having a relative who has a condition that increases the risk of stroke.


  • Strokes are more common in black and South Asian people.


  • Women who take hormonal medication such as the combined contraceptive pill.
  • Pregnant women are more likely to suffer from a stroke than those who are not pregnant.

Sickle Cell Disease

  • SCD is an inherited blood condition that can increase the risk of strokes.
  • SCD occurs in people of African, Asia, Caribbean and Mediterranean origin.


  • Migraine sufferers have a slightly elevated risk of stroke but are not a cause of stroke themselves.

What are the signs and symptoms of a stroke?

There’s a well-known way of remembering the signs and symptoms of a stroke with the acronym FAST. FAST stands for Face, Arms, Speech, Time.

This acronym is useful for people to help them if they are worried a loved one might be having a stroke.

  • FACE – The person’s face may have drooped on one side. They might not be able to smile if you asked them to. Their mouth or eye may have dropped when their face is relaxed too. To test whether their face has dropped, you should ask the person you suspect might be having a stroke to smile. If their smile is uneven, this is a worrying sign that they may be having a stroke and need medical help urgently.
  • ARMS – Can the person lift both arms above their head equally and evenly and hold them there? If they can’t, they may be having a stroke. Sometimes people can do this but they can still feel some weakness and/or numbness in one of their arms.
  • SPEECH – Is their speech slurred? Can they speak at all? Do they understand what you’re asking them to do? If not, this is a sure sign that something is going on in the person’s brain.
  • TIME – The last one is there to remind you to call 999 immediately if someone you are with shows any of the signs or symptoms above. This is because you must act FAST when someone is showing signs of a stroke. Rapid treatment means they are much more likely to recover well.

Treating a stroke

The treatment for a stroke depends on what type of stroke a person has had, where it is in the brain and what the cause of the stroke is. Often, strokes are treated with medication. These medicines prevent blood clots and dissolve any existing ones as well as reduce cholesterol levels and blood pressure.

Sometimes, a person may need to undergo surgery to resolve and treat the cause of their stroke. This can be to help with brain swelling or to remove blood clots. Surgery is sometimes used to help reduce the risk of more bleeding too.

Taking medication to help with stroke

How to recover from a stroke?

Recovering from a stroke is dependent on the severity, type and location of the stroke within the brain. For some people, their stroke may be minor and short-lived, meaning they recover quickly within a couple of weeks. For others, their stroke could be severe and cause them to be left with significant disabilities if they manage to survive.

Serious strokes can result in someone being in a coma or dying as a result. However, no matter what kind of stroke someone experiences, the quicker the person receives treatment, the more likely they will recover and the quicker they should recover.

Many people who’ve suffered a stroke spend time in hospital. They may then be discharged home or admitted to a rehabilitation facility. The rehabilitation will include physiotherapy and occupational therapy to help them recover as much of their independence as possible. They may need to relearn some skills such as walking or even talking.  This is also called ‘reablement’.

Even when people return to their homes they may need ongoing support including care from relatives or care workers visiting their homes. Such care may need to include help with washing, dressing and cooking as well as companionship.

How to reduce your risks of having a stroke?

Thankfully, many people do recover from a stroke and go back to living a normal life.

However, there are certain things that you can do to reduce your risk of having a stroke:

  • Eat a well-balanced, healthy diet.
  • Exercise regularly.
  • Stick to the guidelines when it comes to alcohol intake (you should not drink more than 14 units of alcohol in a week).
  • Not smoking.

For people who have a condition that puts them at an increased risk of stroke, it is even more important that they follow this advice. Likewise, if someone has already had a stroke or TIA, they must follow advice to try and reduce the risk of recurrence.

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About the author

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Laura Allan

Laura is a former Modern Foreign Languages teacher who now works as a writer and translator. She is also acting Chair of Governors at her children’s primary school. Outside of work, Laura enjoys running and performing in amateur productions.

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