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What is a Stroke?

A stroke occurs when a blood vessel, which is carrying oxygen and nutrients to the brain, bursts or is blocked by a clot.1

This causes an interruption of the blood supply to a part of the brain. This can damage or destroy brain cells which will affect body functions.1

A stroke is a medical emergency. Therefore, recognising the symptoms and accessing treatment immediately can be crucial.2

Act F.A.S.T. when stroke strikes3

A simple test can help you recognise if someone has had a stroke:3


Facial weakness

Can the person smile? Has their mouth or eye drooped?


Arm weakness

Can the person raise both arms?


Speech problems

Can the person speak clearly and understand what you say?



Call 999 for an ambulance if you spot any one of these signs.

Every minute matters so act F.A.S.T. Calling an ambulance and getting straight to the Emergency Department can make all the difference. Emergency treatments for stroke patients can save lives and greatly reduce the disability a person may have after their stroke.3

Having a stroke

Stroke symptoms include:4,5

  • Numbness, weakness, or paralysis on one side of the body
  • Slurred speech, difficulty thinking of words or understanding other people
  • Confusion
  • Trouble seeing with one or both eyes
  • Being unsteady on your feet
  • Severe headache

The right half of the brain controls the left side of the body and vice versa. For example, paralysis in the left arm may result from a stroke in the right side of the brain.6

For most people, the left side of the brain controls language.7,8 The right side controls perceptual skills and spatial skills.8

Having a stroke

There are two main types of stroke.9

  1. 1. Ischaemic Stroke:
  2. Over 80% of strokes are caused by a blockage of an artery supplying blood to the brain. This is known as an ischaemic stroke.9,10 It is caused by:

    A blood clot that forms in a main blood vessel (artery) to the brain. This is called a cerebral thrombosis. Clots form in arteries that already have been narrowed by a condition called atherosclerosis (hardening of the arteries).10,11

    Atherosclerosis causes fatty material to build up along the inner lining of the arteries so that they become narrow and the blood flowing through them becomes more likely to clot.10,11

    Lifestyle risk factors for atherosclerosis include abnormal cholesterol, smoking, high blood pressure, diabetes, obesity and physical inactivity.11

    A partial clot that may form elsewhere in the body which is carried in the bloodstream to the brain and gets lodged in an artery. This is embolic stroke.12

    Blockages that occur in the tiny blood vessels deep in the brain. This is a lacunar stroke.13

  3. 2. Haemorrhagic stroke:
  4. Up to 20% of strokes are caused by a bleed into the brain from a burst blood vessel.4 This is called haemorrhagic stroke and is associated with severe morbidity and high mortality.15

References: 1. American Stroke Association. About Stroke. Available at: https://www.stroke.org/en/about-stroke. Accessed on March 2022. 2. MayoClinic. Stroke. Available at: https://www.mayoclinic.org/diseases-conditions/stroke/symptoms-causes/syc-20350113. Accessed on April 2022. 3. Irish Heart Foundation. When Stroke Strikes Act FAST. Available at: https://irishheart.ie/campaigns/fast/f-a-s-t/. Accessed on April 2022. 4. American Stroke Foundation. Stroke Symptoms. Available at: https://www.stroke.org/en/about-stroke/stroke-symptoms. Accessed on April 2022. 5. WebMD. The Warning Signs of Stroke. Available at: https://www.webmd.com/stroke/guide/signs-of-stroke. Accessed on April 2022. 6. American Stroke Association. Effects of Stroke. Available at: https://www.stroke.org/en/about-stroke/effects-of-stroke. Accessed on April 2022. 7. WebMD. The Difference Between the Left and Right Brain. Available at: https://www.webmd.com/brain/the-difference-between-the-left-and-right-brain#:~:text=The%20brain%20is%20divided%20into,segmented%20into%20regions%20called%20lobes. Accessed on April 2022. 8. BCcampus. 4.2 Our Brains Control Our Thoughts, Feelings, and Behaviour. Available at: https://opentextbc.ca/introductiontopsychology/chapter/3-2-our-brains-control-our-thoughts-feelings-and-behavior/. Accessed on April 2022. 9. Boehme AK, et al. Circ Res 2017;120(3):472-495. 10. American Stroke Association. Ischaemic Stroke (Clots). Available at: https://www.stroke.org/en/about-stroke/types-of-stroke/ischemic-stroke-clots. Accessed on April 2022. 11. WebMD. How Atherosclerosis Causes Half of All Strokes. Available at: https://www.webmd.com/stroke/guide/how-artherosclerosis-causes-50-percent-of-strokes. Accessed on April 2022. 12. Healthline. Embolic Stroke. Available at: https://www.healthline.com/health/stroke/embolic-stroke-symptoms#:~:text=A%20cerebral%20embolism%20(often%20referred,narrow%20to%20let%20it%20pass. Accessed on April 2022. 13. Healthline. Lacunar Infarct (Lacunar Stroke). Available at: https://www.healthline.com/health/lacunar-stroke-symptoms#:~:text=Lacunar%20stroke%20is%20a%20type,brain%20are%20called%20ischemic%20strokes. Accessed on April 2022. 14. UpToDate. Patient education: Hemorrhagic stroke treatment (Beyond the Basics). Available at: https://www.uptodate.com/contents/hemorrhagic-stroke-treatment-beyond-the-basics. Accessed on April 2022. 15. Unnithan AKA, Mehta P. Hemorrhagic Stroke. [Updated 2022 Feb 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559173/. Accessed on April 2022.