A stroke occurs when part of the brain dies as a result of oxygen deprivation, typically due to a blockage in one of the arteries leading to the brain or one of the small vessels deep inside the brain. Such blockages can arise within the blood vessel itself, but can also be caused by a clot moving through the blood stream from another part of the body. Some strokes are also the result of bleeding from a ruptured artery in or around the brain.
The three main types of stroke
1. Ischaemic stroke
The most common type of stroke, ischaemic strokes account for about 85% of all strokes in the UK. This type of stroke occurs when a blockage cuts off the blood supply to the brain.
There are four main causes of ischaemic stroke:
- Atherosclerosis: fatty deposits build up on the inside walls of arteries causing them to become hard and narrow, raising the risk of blockages. Sometimes, a blood clot forms on the fatty deposit and if this clot breaks away, it can travel to the brain and cause a stroke.
- Small vessel disease: tiny blood vessels deep within the brain are damaged causing malformations.
- Atrial fibrillation and other heart conditions: blood clots form in the heart and travel to the brain.
- Arterial dissection: tears develop in the lining of an artery and allow blood to get between the layers of the artery’s walls. This can happen for no clear reason or it can happen because of an injury to the neck.
2. Haemorrhagic stroke
Also known as a brain bleed or brain haemorrhage, this type of stroke is caused by bleeding in or around the brain:
- Intracerebral haemorrhage: an artery inside the brain bursts, causing bleeding within the brain.
- Subarachnoid haemorrhage: an artery on the surface of the brain has burst, causing bleeding into the fluid-filled space between the brain and skull. This creates a build-up of pressure within the skull making it difficult for the brain to function properly.
There are a number of things that can cause haemorrhagic stroke:
- High blood pressure: known as the ‘silent killer’ high blood pressure is a contributing factor in about 50% of all haemorragic strokes. However, high blood pressure can have all sorts of negative effects on the body so it’s important to have yours checked regularly at the GP or your local chemist.
- Cerebral amyloid angiopathy: a condition where a protein called amyloid builds up inside the blood vessels in the brain which weakens the vessels and increases the risk of a tear. More common amongst older people, it can still affect those in their youth.
- Aneurysm: an artery becomes thin and weak and balloons in size, which raises the risk of it rupturing. This is more likely in people with high blood pressure, although other causes can include a malformation present before birth, smoking cigarettes, or a family history of aneurysm.
- The wrong dose of anticoagulant (blood-thinning) medication: this can raise the risk of developing bleeding in the brain. While the risk is low, and your risk of stroke is carefully monitored when you’re taking blood-thinning medications, do visit your GP as often as they ask you to – regular follow up visits are important.
- Drugs such as cocaine can affect blood vessel function and make them more susceptible to haemorrhage.
3. Transient ischaemic attack or TIA
Also referred to as a mini-stroke, the symptoms of TIA only last for a short amount of time because the blockage that stops the blood getting to your brain is temporary – either the blockage dissolves on its own or moves to a less critical place in the body. Technically – because no brain tissue is permanently damaged and there are no lasting symptoms – a TIA is not a stroke, but it is a warning sign that the person is at risk of having a full-blown stroke in the future.
What are the signs of stroke?
According to the Stroke Association, someone experiences a stroke every five minutes in the UK. Stroke doesn’t discriminate and can affect anyone regardless of age, though it is more common in older people. The Stroke Association offers advice about how to recognise the signs of a stroke in yourself or someone else. Using the FAST test is a simple way to do this:
- Face: can the person smile? Has their face fallen on one side?
- Arms: can the person raise both arms and keep them there?
- Speech problems: can the person speak clearly and understand what you say? Is their speech slurred?
- Time: is of the essence, so if you see any of these three signs, call 999 immediately.
However, there are other signs that you or someone else may be having a stroke which can include:
- Sudden weakness or numbness on one side of the body, including legs, hands or feet
- Difficulty finding words or speaking in clear sentences
- Sudden blurred vision or loss of sight in one or both eyes
- Sudden memory loss or confusion
- Dizziness or a sudden fall
- A sudden, severe headache.
How is stroke treated?
The treatment depends on the type of stroke which has occurred. In all cases, the sooner the person reaches hospital – to be assessed and treated – the better. Some people may require surgery to remove a clot or repair the damage to the brain, while others might need certain types of medication, and rehabilitation support. To learn more about treatments, visit the NHS website.
How can I reduce my risk of having a stroke?
- Stop smoking, you can also get help from your pharmacist or GP.
- Take all prescribed medications exactly as directed – this is particularly important if you are taking a medication for a health condition which raises your risk of stroke.
- See your GP to have your blood pressure and cholesterol level checked, and also ask for a test for diabetes and heart health.
- Lose weight if you need to. Being overweight increases the risk of stroke by 20% while being obese sees the risk rise by 64%.
- Cut back on alcohol.
- Stay active and ensure that you are getting the recommended amount of daily exercise.
- Eat healthily, avoiding processed foods and high amounts of sugar.
You can also visit the Stroke Association to download their guide to reducing your risk of stroke.