Woman touching her throat and ear, embodying listening and vocal exercises for motor speech disorders.

Understanding Motor Speech Disorders: Dysarthria and Apraxia of Speech

Reviewed by Dr. Joyce Richardson, PhD.

Motor speech disorders encompass a range of conditions that affect a person’s ability to speak clearly and effectively.

People with these disorders may experience speech slurring or shaky voice, making communication challenging.

Recognizing and understanding the various types of motor speech disorders is important for both healthcare professionals and those supporting individuals dealing with these conditions.

Let’s take a closer look at the common types of motor speech disorders and their defining characteristics.

What Are Motor Speech Disorders?

Motor speech disorders (MSDs) are a group of neurological conditions that affect the motor aspects of speech production.

These disorders stem from damage or dysfunction in specific areas of the brain responsible for coordinating the muscles involved in speaking.

The two main types are dysarthria and apraxia of speech: Dysarthria and Apraxia.

Let’s take a closer look at each.

Dysarthria

Dysarthria happens when the muscles a person uses for speaking are weak or paralyzed so they have trouble controlling them.

This can make it hard to talk clearly, and listeners might have trouble understanding.

But the important thing to remember is that it’s not due to a lack of effort in speaking clearly. It’s because their brain and mouth muscles aren’t working together like they should.

Young woman practicing with therapy cards, targeting dysarthria, a common motor speech disorder.

Causes

There are a lot of reasons why someone might have dysarthria.

One common reason is if someone has had a stroke, which is when a part of the brain doesn’t get enough blood and oxygen.

Other reasons could be a bad injury to the head, like from a car accident, or having conditions like Parkinson’s disease, multiple sclerosis, or cerebral palsy.

Signs

The way dysarthria shows up can be different for each person, depending on what’s causing it and how bad it is.

Here are some signs to look out for:

  • Articulation difficulties: Their speech might sound slurred or like they’re mumbling because their mouth muscles aren’t moving smoothly.
  • Phonation problems: Sometimes, their voice might sound hoarse or breathy because their vocal cords aren’t working right.
  • Resonance issues: Their speech might sound different because of problems with how sound travels through their nose and mouth.
  • Prosodic abnormalities: Their speech might sound flat or they might put stress on the wrong parts of words or sentences.

If you think you or someone you know might have Dysarthria, your doctor can do some tests to see if that’s what’s going on.

They might do a physical exam to check your muscles and nerves, or they might even send you for a brain scan or a swallowing test.

Treatment

As for treatment, it really depends on what’s causing the Dysarthria.

There are ways to help with Dysarthria, and a doctor or a certified speech and language professional can help you figure out the best treatment plan for you.

Some treatment options they might suggest are:

  • Speech Therapy: Speech therapy can be a huge help to those struggling with Dysarthria and it can help them learn to speak more clearly.
  • Muscle Strengthening Exercises: Just like lifting weights at the gym makes your muscles stronger, there are exercises that can help strengthen the muscles used for speaking. These exercises might involve practicing moving the tongue, lips, and jaw in specific ways to improve speech clarity.
  • Compensatory Strategies: Sometimes, if certain sounds are hard to say, speech therapists can teach people different ways to say them. For example, if someone has trouble with the “p” sound, they might learn to use the “b” sound instead because it’s easier for them.
  • Surgery: In extreme cases, Deep brain stimulation (DBS) is a surgical treatment that may help regain control of the muscles.
  • Augmentative and Alternative Communication (AAC) Devices: In some cases, if speaking is really hard, people might use special devices to help them communicate. These could be things like tablets or computers with apps that turn text into speech, or even simple picture boards.

Apraxia of Speech (AOS)

With AOS, it’s not that the mouth muscles are weak or paralyzed like in dysarthria.

Instead, it’s like there’s a glitch in the brain that affects its ability to plan the movements needed for speech.

This makes it hard for someone to coordinate the muscles used for speaking.

Graphic showing brain and damaged vertebrae, illustrating Apraxia of Speech (AOS), a motor speech disorder.

Causes

Anything that causes damage to the part of the brain that is responsible for muscle movement can cause apraxia of speech.

This can include brain injuries, strokes, brain tumors, Alzheimer’s disease, or any other condition that damages that part of the brain.

Signs

Signs of apraxia can vary from person to person, but some common signs include:

  • Inconsistent speech sound errors: They might say the same word differently each time, even though they’re trying to say it correctly.
  • Difficulty initiating speech: It might take them a while to get started talking as if the words are stuck on the tip of their tongue.
  • Effortful speech production: They might seem like they’re really concentrating and working hard to say each word.
  • Increased errors with increased speech complexity: The more complicated the word or sentence, the harder it is for them to say it correctly.

To figure out if someone has apraxia, a speech and language pathologist can do some tests to see how well they can move the parts of their mouth and how their speech sounds.

Treatment

As for treatment, it’s usually a team effort involving things like speech therapy, physical therapy, and occupational therapy.

Here are some common tactics used in treatment:

  • Drill-Based Therapy: People with AOS may practice saying specific words or phrases multiple times to improve their speech planning.
  • Melodic Intonation Therapy: This therapy uses singing and rhythm to help people with AOS produce speech sounds more easily. It’s like turning speech into a song, which can make it easier for the brain to plan the movements.
  • Visual and Tactile Cueing Techniques: Speech therapists may use visual cues, such as mirrors, or tactile cues, like tapping a hand in a certain rhythm, to help with speech planning.

The goal of treatment is to improve the person’s ability to execute the movements they’re struggling with effectively.

Finding the right combination of exercises and strategies tailored to each individual is key to achieving this goal.

Distinguishing Between Dysarthria and AOS

Distinguishing between the two can be difficult because there are many similarities. And some people may experience both Dysarthria and AOS.

What it boils down to is that with dysarthria, it’s more about the muscles not working right whereas AOS is more about the brain having trouble planning the speech movements.

They also differ slightly in the way they present themselves.

In dysarthria, individuals tend to show consistent errors in speech, while patients with apraxia show more inconsistent and unpredictable errors.

Tips for the Listener: Talking to Someone with a Motor Speech Disorder

Woman supporting her older mother, highlighting the importance of patience for those with motor speech disorders.

As you can imagine, trying to have a conversation may become a bit frustrating if, every time you speak, the words get stuck or twisted.

This can bring up communication challenges, affect social interactions, impact work environments, and hinder learning and school interactions for those with motor speech disorders.

The overall emotional toll of dealing with these problems can take a toll on those affected, so taking the time to support them can make the conversation smoother and more enjoyable for both of you.

Here are some ways you can create a more inclusive and supportive environment for communicating with someone who has a motor speech disorder:

  • Be Patient: Allow the person with the speech disorder extra time to speak. Avoid interrupting or finishing their sentences for them. Patience and understanding go a long way in making the person feel valued and respected.
  • Maintain Eye Contact: Keeping eye contact shows that you are actively listening and engaged in the conversation. It also helps the person with the speech disorder feel more connected and supported.
  • Ask Clarifying Questions: If you’re unsure about something the person said, politely ask for clarification. Instead of pretending to understand, it’s better to ask for repetition or rephrasing to ensure clear communication.
  • Use Non-Verbal Communication: Pay attention to the person’s body language and facial expressions, as they can often provide additional context to what they’re saying. Nodding or smiling to show understanding and encouragement can be reassuring.
  • Focus on the Message, Not the Speech: Remember that the most important thing is to understand the person’s message, not necessarily the way it’s delivered. Try to focus on the content of what they’re saying rather than getting hung up on pronunciation or speech clarity.
  • Minimize Distractions: Find a quiet and calm environment for conversations to minimize distractions. Background noise or other disruptions can make it harder for someone with a speech disorder to communicate effectively.
  • Be Supportive and Encouraging: Offer words of encouragement and praise for their efforts in communicating. Positive reinforcement can boost their confidence and motivation to keep trying.
  • Educate Yourself: Take the time to learn more about motor speech disorders and how they affect communication. Understanding the challenges the person faces can help you better support them in conversations.

Conclusion

Understanding motor speech disorders like dysarthria and apraxia of speech is important in order to provide the best possible support and treatment for individuals affected by these conditions.

By raising awareness and educating ourselves, we can help those struggling with these disorders communicate more effectively and improve their quality of life.