What Is the Difference Between Aphasia and Dysarthria?

It’s not always easy to tell the difference between aphasia and dysarthria. These two conditions are similar in some ways, but there are also major differences.

Aphasia is a language disorder that can affect how people speak, understand, read, and write. Dysarthria is a motor-speech disorder that weakens the muscles used to speak.

If your loved one potentially has one of these conditions, you may be looking to learn more. Keep reading to learn what causes aphasia and dysarthria, how they’re similar and different, and how speech therapy can help. 

What is aphasia?

Aphasia is a language disorder that occurs as a result of damage to the left side of the brain. Most cases of aphasia occur after a stroke, but aphasia can also be caused by a traumatic brain injury (TBI), neurodegenerative disease, tumor, or certain infections. 

How does aphasia affect communication?

Aphasia can make it difficult for a person to speak, understand, read, and write. The severity of aphasia can range dramatically. In some people, communication can be almost impossible, while in others, the effects are quite minor.

In addition, aphasia may disrupt only a single aspect of language, such as the ability to recall names or clearly string words together in sentences. However, more often, multiple aspects of communication are involved. This can make it difficult for people to communicate with loved ones, navigate activities of daily living, socially connect with friends and family, or perform in the workplace.

It’s important to recognize that people with aphasia are not any less intelligent than they were before. They simply have trouble communicating like they used to. While they may have a hard time expressing their thoughts and ideas, the thoughts and ideas themselves are not disrupted. 

What are symptoms of aphasia?

As mentioned, the signs and symptoms of aphasia can vary based on which areas of the brain are affected, as well as the severity of the damaged areas. Here are some of the most common symptoms of aphasia:

  • Difficulty thinking of the right words to say

  • Using the wrong words in sentences or omitting words altogether

  • Saying related but incorrect words, such as “steak” instead of “hamburger”

  • Switching the order of words, such as saying “bean green” instead of “green bean”

  • Using made-up words

  • Using single words, or stringing a few words together, instead of using complete sentences

  • Not understanding what others are saying; this can be worse if someone is speaking quickly, using more complex sentences, or speaking in a noisy place or in a group

  • Difficulty reading all forms of the written word, including books, newspapers, and computer screens

  • Trouble spelling and writing sentences

  • Trouble using numbers or doing math

What is dysarthria? 

Dysarthria is a motor-speech disorder that weakens the muscles used in speech production. This makes it difficult to coordinate and control these muscles, which can lead to a range of communication challenges. 

What causes dysarthria?

Dysarthria is often caused by damage to specific areas of the brain used for the motor aspects of speech. It can occur at birth, which is called congenital dysarthria. However, dysarthria is often the result of an illness or injury. Some common causes of dysarthria include: 

  • Stroke

  • Brain injury

  • Tumor

  • Parkinson's disease

  • Amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease)

  • Huntington's disease

  • Multiple sclerosis

  • Cerebral palsy

  • Muscular dystrophy

Dysarthria also can be caused by damage to the organs involved in speech production. For example, someone who’s had surgery on the head, tongue, or voice box may develop dysarthria, as well as someone who has experienced trauma to their face or mouth.

How does dysarthria affect communication?

Some people with dysarthria may only have minor speech problems and can maintain everyday conversations without trouble. Others have more severe symptoms that make it difficult for other people to understand them. 

Dysarthria can affect many aspects of speech. For example, a person’s speech may become slow, mumbled, or slurred. They may lose the ability to pronounce sounds and words correctly. They may be unable to control the volume of their voice or the pace at which they talk. 

What are symptoms of dysarthria? 

Dysarthria affects a person’s speech patterns in different ways, depending on its cause. Typical signs and symptoms of dysarthria include: 

  • Changes to the pace of speech; the person may talk rapidly or very slowly

  • Speech that sounds slurred, mumbled, or choppy

  • Abnormal or varied rhythm in speech

  • Difficulty controlling the volume of the voice

  • Difficulty controlling facial muscles and moving the lips, jaw, and tongue

  • A nasal or hoarse voice

  • Trouble with chewing and swallowing

Dysarthria can affect more than just a person’s speech. Because of limited movement of the facial muscles, a person may drool uncontrollably. It may also look like their face is drooping. In addition, dysarthria can affect an individual’s lungs, which causes their breathing to become irregular. 

How are dysarthria and aphasia different?

Let’s look at dysarthria versus aphasia. Dysarthria and aphasia can both happen after a stroke. A person can have both conditions.

However, while aphasia and dysarthria can both affect communication, there are notable differences. A correct diagnosis is important to make the most informed treatment decisions.

  • Dysarthria more commonly affects a person’s speech, while aphasia affects their ability to understand language. 

  • Generally, a person with dysarthria has difficulty making the sounds involved in speech production because of muscle weakness.

  • People with aphasia have limited ability to understand language, find the right words when speaking, or use appropriate sentence structure.

How can speech therapy help aphasia and dysarthria?

Speech therapy helps people regain their ability to communicate. This can include maximizing their remaining language skills and restoring as much language as possible. There are many techniques and strategies that can be used to achieve this.

In more severe cases of aphasia, speech therapists will teach the person other ways of communicating that don’t involve speech. This might include using simple hand gestures, writing, pointing to letters and pictures, or using a computer or electronic device. These forms of communication are referred to as augmentative and alternative communication, or AAC.

In treating dysarthria, speech therapists will help the person regain normal speech and meet their communication goals. Speech therapy for dysarthria may focus on:

  • Strengthening speech muscles

  • Increasing the movement of the lips and tongue

  • Clearly articulating words for clearer speech

  • Adjusting the rate and pace of speech

  • Increasing breathing support for louder speech

  • Practicing communicating in real-life situations

In cases of severe dysarthria that significantly affect the ability to communicate, the speech therapist may recommend alternative communication methods. AAC may also be used with dysarthria. Whether the diagnosis is aphasia or dysarthria, speech therapy will include the person’s caregivers and family. The speech therapist will show them how to create an environment for positive and successful communication with their loved one. 

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