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Effects of left-sided stroke: Aphasia and language apraxia

  • Stroke (also known as a cerebrovascular accident or CVA) usually affects one side of the brain. Movement and sensation for one side of the body is controlled by the opposite side of the brain.

    This means that if your stroke affected the left side of your brain, you will have problems with the right side of your body.

    Some problems that happen after stroke are more common with stroke on one side of the brain than the other.

    • The left side of the brain controls the ability to speak and understand language in most people.
    • The right side of the brain controls the ability to pay attention, recognize things you see, hear or touch, and be aware of your own body.

    In some left-handed people, language is controlled by the right side of the brain and awareness by the left side of the brain.


    You may have problems with:

    • speaking
    • listening
    • reading
    • writing
    • dealing with numbers
    • understanding speech
    • thinking of words when talking or writing

    How much trouble you have with aphasia depends on the type and severity of your brain injury.

    Aphasia means you have problems speaking and understanding language. You may be unable to find the words you need to put sentences together. This is like having a word 'on the tip of your tongue.'

    Not all strokes cause aphasia. About 20 percent of stroke survivors have a loss of speech and language.

    How stroke affects speech and language

    To know why a stroke can cause so many different problems, it is helpful to understand how speech works.

    • Communicating a message means you think about what you want to say, put your thoughts into words and say the words out loud.
    • Understanding a message means you know someone wants to say something, you keep the words in mind and put the words together.

    Your brain controls the complex steps needed to speak and understand language. That's why injury to the brain - such as a lack of blood flow during a stroke - can get in the way of your ability to do these steps.

    Different problems result depending on the location and severity of the stroke.

    If you have aphasia...

    If you have aphasia (a-FAY-zha), you should have your speech and language checked. A speech-language pathologist (or speech therapist) must see how well you can speak and understand. The exam includes four areas:

    • speaking out loud
    • writing
    • listening comprehension
    • reading comprehension

    You may have problems in some or all four areas. For example, you may have problems reading and writing but not in talking.

    This exam can also show which areas of speech and language have been least affected. 

    Language apraxia

    When you have language apraxia (aPRAYX-ee-a), you know the right words but you have problems forming words or putting sounds together. Muscle weakness or loss of feeling does not cause this.

    If you have mild apraxia, you will have clear speech with inconsistent sound substitutions. For example, a "cup of coffee" may come out as "a puck of pappy" or a "bup of foppe."

    If you have severe apraxia, your speech may sound like jargon or you may only be able to repeat a single syllable or phrase over and over. For example, "do-do-do" or "I dunno."

  • Source: Allina Health Patient Education, Understanding Stroke: Information about Stroke and Recovery, fourth edition, ISBN 1-931876-13-4
    Reviewed by: Allina Health Patient Education experts
    First published: 02/01/2006
    Last reviewed: 12/09/2011