Dysarthria

See also: Aphasia

Dysarthria is the term used to describe a difficulty in speaking because of a weakness in the muscles used to produce speech (that is, to move your mouth, tongue and jaw). It can be caused by various conditions that damage your brain or your nerves, including Parkinson’s disease and stroke. It may therefore develop suddenly or gradually, over time.

This page explains more about the symptoms of dysarthria, and how they may differ from (and be similar to) those of other speech and language problems such as aphasia. It also explains something about how dysarthria may be treated through speech therapy.

Is it a stroke?


Someone who has had a stroke may have trouble speaking. They may slur their words, and their mouth may droop on one side, or they may be unable to move one side of their mouth. You will notice this when they try to speak.

Technically, this is dysarthria: a problem with the muscles controlling speech.

If someone is showing these signs, you should immediately call the emergency services, as they need to be taken to a hospital for specialist treatment as quickly as possible.

Understanding Dysarthria

Dysarthria is a speech problem caused by a weakness in the muscles used in speaking.

These are largely those around the mouth, tongue and jaw, including the larynx (voice box) and palate, as well as the lungs (breath control).

This is a relatively common issue in neurodegenerative disorders and conditions such as Parkinson’s disease. The damage may be very localised, affecting only one muscle group, or more generalised.

Signs of dysarthria include:

  • Unclear speech, whether slightly or very unclear;

  • Difficulty moving your tongue, mouth or lips;

  • Slurred or ‘mumbling’ speech;

  • Problems controlling the volume of your speech, so that you speak either too loudly or too quietly;

  • Changes in the pace of your speech, usually slowing down but not always;

  • A change in the voice: it might become monotonous, or a bit nasal, or possibly sound higher or more strained; and

  • Using lots of pauses in your speech, or speaking in short bursts, rather than full sentences.

As with many other speech and language disorders, including stammering and cluttering, being tired or stressed may make dysarthria worse.

Also like many other speech and language disorders, dysarthria can become a barrier to effective communication with others. Someone with dysarthria generally has no problem understanding others, but can find it hard to make themselves understood.

Distinguishing dysarthria


How can you tell whether a speech problem is dysarthria or another speech or language problem such as aphasia?

There are several ways to distinguish between them.

The key distinction is that dysarthria is a speech problem.

That is, it is an issue in how speech is produced by the body: in this case, the muscles that control the voice or the mouth to shape sounds. Someone with dysarthria knows what they want to say, they simply cannot coordinate the production of the right sounds.

Other speech problems include stammering and cluttering.

Aphasia, by contrast, is a language problem. It is an issue with how language is processed in the brain. Someone with aphasia effectively has difficulty finding the words to express their thoughts. They may use the wrong words, or in the wrong order, or use the wrong sounds.

Delayed speech may be either a speech or a language problem—which is why it needs investigation.

Causes of Dysarthria

Dysarthria is generally caused by damage to the brain or conditions that affect the nervous system. For example:

  • Stroke or brain tumours may cause damage to the brain that mean that you cannot properly control the muscles required to speak.

  • Severe head injury may also have a similar effect.

  • Neurological conditions like Parkinson’s disease, multiple sclerosis and motor neurone disease (MND), also known as amyotrophic lateral sclerosis (ALS), affect the nerves that control various muscles. Dysarthria may therefore be one symptom of these conditions, among many others.

  • Cerebral palsy and Down’s syndrome are issues of development, including of the brain, and may be associated with issues with muscle control.

This list of causes should make it clear that dysarthria can be a condition that is present from birth, for example for children with Down’s syndrome. However, it may also arise at any stage of life from a brain injury or degenerative condition. Some medications can also cause dysarthria, as indeed can drinking alcohol.

If you start to develop symptoms of dysarthria with no obvious cause (for example, you have not had a blow to the head), you should consult a doctor.

Case study: Stephen Hawking


Stephen Hawking was an English theoretical physicist and Lucasian Professor of Mathematics at Cambridge University between 1979 and 2009. In his final year as an undergraduate, he noticed that he was becoming a bit clumsy, and fell on the stairs once or twice. His family noticed that his speech was slurred, a sign of dysarthria. In 1963, at the age of 21, he was diagnosed with an early-onset slow-progressing form of motor neurone disease. This is a condition that affects the neurones that control muscles. Over the next five decades, he gradually became more and more paralysed.

By the late 1970s, his dysarthria was so extreme that he could only be understood by family and close friends. He lost the last of his speech as the result of a tracheotomy following an episode of pneumonia in 1985. From then until his death in 2018, he used various aids to help him communicate, including a spelling card where he chose letters by raising his eyebrows, and then a computer program called the Equalizer. This required him to press a switch to choose from a bank of words and phrases. Later, when he could no longer control the switch with his hand, Hawking chose his words by twitching a single muscle in his cheek. His final adaptation was a form of predictive software that was trained using his papers and other written materials to ‘understand’ his language/speech patterns.



Treatment for Dysarthria

The main treatment for dysarthria is—like that for many other speech and language disorders—speech therapy.

The precise form of therapy will depend on the cause of the dysarthria. However, speech therapists will generally concentrate on three main aspects. The first is strengthening the muscles used for speech, the second is finding strategies to make it easier to be understood, such as slowing down speech, and the third is working with communication aids such as those used by Professor Hawking.

Sometimes treating the underlying cause of dysarthria will help.

For example, if it is caused by taking a particular medication, changing the medication may help.

Improving Communication with Dysarthria

If you have dysarthria, there are strategies that you can use to make it easier for others to understand you. These include:

  • Telling new people that you have trouble talking. This can be hard to do, because it can feel embarrassing, but it is worth it to ensure that they are concentrating.

  • Use one word or phrase to launch a new topic. This will tell your listener what you are going to talk about.

  • Use body language and gestures to reinforce your meaning. It is also a good idea to watch your listener’s body language to check their understanding.

  • Try strategies to improve communication, such as talking more slowly. Don’t try to change too much at once: one thing at a time is sufficient.

  • Rest before you have to talk a lot. Being tired can make your speech harder to understand.

For those talking to someone with dysarthria, it may be helpful to consider:

  • Choosing a quiet area with good lighting. This will ensure you can see mouth movements and body language.

  • Focusing on the person talking, and using active listening techniques to improve your listening.

  • If you don’t understand, say so. It is much better to do so than to let a phrase slide, or reply inappropriately. It may be helpful to say what you did understand, to avoid the whole conversation having to be repeated.

  • Use closed questions and reflecting to check your understanding.


A Final Thought

Like any other barrier to communication, unresolved dysarthria can cause isolation and social problems.

However, this does not have to be the case: Stephen Hawking is proof that you can live well and continue to contribute to society even when your ability to speak is extremely limited.


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