The Big Picture
Dysarthria makes it difficult for a person to speak clearly. It happens because the muscles used for speech are weak or paralyzed.
Dysarthria is different from aphasia and apraxia of speech. Aphasia affects speech and language skills. Apraxia affects a person’s ability to correctly move the muscles needed for speech, even though those muscles are intact.
Knowing these differences can help you keep three similar-sounding conditions separate when studying.
Start Here If You’re Overwhelmed
Focus on these core ideas:
- Dysarthria is difficulty speaking clearly because the speech muscles are weak or paralyzed.
- Speech with dysarthria is usually slurred, slow, and soft.
- Aphasia is a partial or complete loss of speech and language skills.
- Receptive aphasia affects understanding spoken or written language.
- Expressive aphasia affects speaking or writing.
- Apraxia of speech affects the ability to correctly move the muscles used for speech, even though the muscles themselves are intact.
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Course Notes: Key Ideas You Need to Know
What Is Dysarthria?
Dysarthria means a person has difficulty speaking clearly because the muscles used for speech are weak or paralyzed.
The word can help you remember the meaning:
- dys refers to difficulty.
- arthria refers to speaking clearly.
Common Causes of Dysarthria
Common causes include:
- cerebral palsy
- multiple sclerosis
- head injury
- tumour
- infection
How Dysarthria Can Affect Speech
Clients with dysarthria usually have speech that is:
- slurred
- slow
- soft
Their voice may also sound:
- flat
- harsh
- nasal
Clients often have difficulty:
- forming words
- spacing their words
- breathing while speaking
Dysarthria Speech Errors Are Usually Consistent
Speech errors in dysarthria are usually consistent and predictable.
As you spend more time with a client, you may become more familiar with the way the client speaks.
What Is Aphasia?
Aphasia is the partial or complete loss of speech and language skills.
The difficulty may involve:
- understanding words
- saying words correctly
- speaking
- writing
Aphasia is caused by brain injury. Causes include:
- stroke
- head trauma
- brain tumours
Receptive and Expressive Aphasia
There are two forms described here.
Receptive Aphasia
Receptive aphasia means difficulty understanding language.
The person may have difficulty understanding:
- spoken words
- written words
Expressive Aphasia
Expressive aphasia means difficulty speaking or writing.
What Is Apraxia of Speech?
Apraxia of speech means a person cannot correctly move the muscles used for speaking, even though the muscles themselves are intact.
Apraxia is usually caused by a brain injury.
Causes can include:
- stroke
- accident
- brain tumour
- infection
Some babies are born with apraxia.
Apraxia can occur by itself or together with aphasia.
How Apraxia Can Affect Speech
A client with apraxia may speak very slowly.
The client may also:
- use a word that sounds similar to the intended word but is not exactly correct
- mix up the order of sounds within words
- have difficulty putting words in the correct order
- have difficulty finding the correct words
How Dysarthria, Aphasia, and Apraxia Differ
The main difference is the type of difficulty involved.
Dysarthria: The person has difficulty speaking clearly because the muscles used for speech are weak or paralyzed.
Aphasia: The person has partially or completely lost speech and language skills. The problem may involve understanding language or expressing language.
Apraxia of speech: The person cannot correctly move the muscles needed for speech, even though those muscles are intact.
For dysarthria, think about weak or paralyzed speech muscles.
For aphasia, think about speech and language skills.
For apraxia, think about difficulty correctly moving intact speech muscles.
Fast Review
These are the main facts to review before a quiz or exam:
- Dysarthria is difficulty speaking clearly because speech muscles are weak or paralyzed.
- Common causes of dysarthria include cerebral palsy, multiple sclerosis, head injury, tumour, and infection.
- Dysarthria usually causes slurred, slow, and soft speech.
- A person with dysarthria may speak in flat, harsh, or nasal tones.
- Dysarthria can cause difficulty forming words, spacing words, and breathing while speaking.
- Dysarthria speech errors are usually consistent and predictable.
- Aphasia is a partial or complete loss of speech and language skills caused by brain injury.
- Receptive aphasia affects understanding language, while expressive aphasia affects speaking or writing.
- Apraxia of speech affects the ability to correctly move the muscles used for speech even though the muscles are intact.
- Apraxia can occur alone or together with aphasia.
- A person with apraxia may speak slowly, mix up sounds, use similar-sounding words, or have difficulty ordering or finding words.
Final Pep Talk
These three conditions can be easy to mix up because all of them can affect communication. Focus on the main difference first: weak or paralyzed muscles for dysarthria, language skills for aphasia, and difficulty correctly moving intact speech muscles for apraxia.