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Aphasia from stroke

Stroke is the most common cause of aphasia.  There are two main types of strokes:  

  1. ischemic strokes, and
  2. hemorrhagic strokes.  

They both involve the blood vessels of the brain. 


Ischemic strokes

Ischemic strokes are the most common type of stroke. An ischemic stroke happens when there is a blockage in an artery (blood vessel) in the brain. This is usually caused by a blood clot  

Brain cells need oxygen to survive. Blood carries oxygen to the brain cells. A clot can stop blood from getting to the brain cells that are ‘downstream’ from the blockage. Without oxygen from the blood, the
brain cells in that region can die.


Hemorrhagic strokes

Hemorrhagic strokes are another common type of stroke. A hemorrhagic stroke happens when the wall of a blood vessel bursts and the blood from inside the vessel spills out into the brain. Extra blood in the brain increases the pressure in the brain. This can cause brain cells in that region to die.

Different parts of the brain have different functions. In most people the parts of the brain that are important for producing and understanding language are in the left side (hemisphere) of the brain.  

About 2/3 (two thirds) of left-sided strokes cause aphasia. 


Recovery of language 

Aphasia that is caused by a stroke almost always improves over time. The amount of recovery varies and mostly depends on the size and location of the brain damage. 

If the stroke is small or does not badly damage the language areas of the brain, aphasia may recover quickly. Larger strokes, or strokes that have caused more damage to language areas, usually cause long-lasting aphasia. 

The fastest recovery occurs in the first days and weeks after the stroke. 

In these early days and weeks, blood flow in the brain goes back to normal. The brain begins to reorganise itself, making the most of the surviving brain areas that were not damaged by the stroke. 

Recovery slows down over time, and language may never return to how it was before the stroke. However, recovery continues for a long time after a stroke, and most people continue to make gains many years after their stroke.  

Some of the things that can help recovery include: 

  • targeted aphasia treatment by a speech pathologist, 
  • taking part in aphasia groups
  • having conversations, and
  • staying connected with family, friends, and others in the community.


Other difficulties after stroke 

People with aphasia may also have other difficulties after a stroke, such as: 

  • difficulty swallowing (dysphagia)
  • difficulty with coordinating muscle movements (apraxia), and
  • weakness of the muscles needed to speak (dysarthria) 

These often occur together because the brain areas used for them are close to the language areas in the brain, and so they are often damaged at the same time. 

After a stroke, the risk of having another stroke is increased. To reduce the chance of another stroke, doctors may advise stroke survivors to change their diet, exercise, and lifestyle habits. Doctors will also treat any underlying causes such as heart disease and high blood pressure. 

To learn more about strokes, please visit the Stroke Foundation website.


Content contributed by: Associate Professor Stephen Wilson, Dr. Sonia Brownsett and Professor David Copland.
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