Dysarthria vs Aphasia: What it is and What You Need to Know

The ability to communicate is essential to the human experience. With it we are able to express our ideas, emotions, thoughts, and feelings. Speech and language disorders such as dysarthria and aphasia, however, can disrupt this essential ability, making both speech and understanding others a challenge.

In this comprehensive guide, we’ll break down the differences between dysarthria and aphasia, and explain their symptoms, causes, and treatments.

What Is the Difference Between Aphasia and Dysarthria?

While dysarthria and aphasia are both communication disorders, they affect different aspects of communication. Aphasia is a language disorder caused by damage to parts of the brain that control language functions. This condition can impair an individual’s ability to speak, understand, read, or write. It usually occurs after a stroke or traumatic brain injury (TBI) and can vary in severity depending on how much of the brain was damaged.

Dysarthria, on the other hand, is a motor speech disorder. It happens when the muscles used for speaking—such as those in the lips, tongue, vocal cords, and diaphragm—become impaired due to damage to the nervous system (e.g., become weak, become too tight, do not move enough, move too much, etc.). Unlike aphasia, dysarthria doesn’t affect a person’s ability to understand language or find words. Rather, it makes it difficult for them to articulate and speak clearly.

What Are the Types of Aphasia?

Aphasia appears in different forms, depending on which parts of the brain are affected. The three most common types are:

1. Broca’s Aphasia: People with Broca’s aphasia can usually understand what others are saying but have trouble expressing their own thoughts. They may speak in short, choppy sentences or struggle to find the right words. Writing may also become a challenge. This form of aphasia is often a result of damage to the left frontal lobe, particularly the Broca’s area, which plays a key role in language production.
2. Wernicke’s Aphasia: Unlike Broca’s aphasia, people with Wernicke’s aphasia often don’t have trouble with the actual act of speaking, though they often say confusing, nonsensical things. People with this condition might make up words as they speak because they have trouble understanding what others are saying, particularly when complex sentences and phrases are used. This type of aphasia is linked to damage in Wernicke’s area, which is located in the temporal lobe and is critical for understanding language.
3. Global Aphasia: This is the most severe form of aphasia and occurs when large portions of the brain’s language centers are damaged, often due to an extensive stroke. People with global aphasia have difficulties with both language comprehension and expression, making it extremely challenging for them to communicate through speaking and writing. They also have difficulty in understanding spoken or written words.

There are also other types of aphasia, which are considered either fluent or nonfluent types of aphasia. A fluent aphasia is one in which the person does not have difficulty with the actual act of speaking, and can oftentimes speak in complete sentences. Wernicke’s aphasia is considered a form of fluent aphasia, along with transcortical sensory aphasia, conduction aphasia, and anomic aphasia.

The differences between these types of aphasia are based on how well a person with aphasia can understand what is being said to them and how well they can repeat information presented to them. On the other hand, non-fluent aphasias are those in which the person speaks choppily, with shorter sentences and significant difficulty finding the right words. Both Broca’s and global aphasia are considered non-fluent forms of aphasia, along with another condition called transcortical motor aphasia. These forms of aphasia are also differentiated in the same way as the fluent forms.

What are the Types of Dysarthria?

Dysarthria, similarly to aphasia, appears in different forms. These forms arise due to what area or areas of the brain are involved, which can lead to many different presentations. The types of dysarthrias are:

1. Flaccid Dysarthria: This form of dysarthria is caused by damage directly to the muscles used for speech, or the nerves that control their movements. People with this condition often experience weakness in the speech muscles, and their speech can be described as being slurred, quiet, and excessively nasalized.
2. Spastic Dysarthria: Spastic dysarthria is caused by damage to higher levels of the brain, and happens when both sides of the brain are impacted. This speech disorder is characterized by a person experiencing spasticity, or excessive muscle tightness, in their speech muscles, which leads to effortfully produced speech, straining of the voice, and difficulty coordinating breathing and speech which leads to shorter sentence lengths.
3. Ataxic Dysarthria: People with ataxic dysarthria have experienced damage to the cerebellum, which is often described as a “smaller brain” at the base of the brain and controls smooth movements. In this condition, people experience discoordination in their speech, with speech breaking down unexpectedly. Persons with this condition may also experience difficulty controlling the loudness of their voice.
4. Unilateral Upper Motor Neuron (UUMN) Dysarthria: UUMN dysarthria is caused by damage to higher levels of the brain, similarly to spastic dysarthria. However, this type of speech problem happens when only one side of the brain is impacted. Symptoms depend on where in the brain damage occurs, but symptoms usually mimic those of flaccid, spastic, or ataxic dysarthria.
5. Hypokinetic Dysarthria: This type of dysarthria is caused by reduction in movements compared to normal (hypo = less than normal, kinetic = movement) and results in damage to an area of the brain known as the basal ganglia. The basal ganglia play multiple roles, though in cases of hypokinetic dysarthria, the ability to control conscious movement is impacted. Speech is often described as being too fast and excessively quiet.
6. Hyperkinetic Dysarthria: Similarly to hypokinetic dysarthria, hyperkinetic dysarthria is caused by damage to the basal ganglia, though in this condition there is excessive – and oftentimes unintentional – movement associated with speech (hyper = more than normal, kinetic = movement). Speech changes associated with this condition can be hard to classify, as it depends on what type of excessive movement is present, how often it occurs, and how severely the movements impact speech.
7. Mixed Dysarthria: This type of dysarthria is actually one that occurs when more than one of the previous dysarthria types is present at the same time. As such, symptoms of mixed dysarthria are very situation dependent.

Can You Have Dysarthria Without Aphasia?

Yes, you can have dysarthria without aphasia. Since dysarthria is a motor speech disorder, it only affects the muscles that control speech, not the brain’s language centers. A person with dysarthria may fully understand language, but their ability to communicate verbally is impaired because of difficulty controlling the movements of their mouth, tongue, or vocal cords.

For example, someone with Myasthenia gravis might develop dysarthria due to muscle weakness but retain their ability to understand and write fluently. Alternatively, people with aphasia may have no physical problems with the muscles required for speech but struggle to find words or make sense of sentences due to brain damage.

Symptoms of Aphasia and Dysarthria

While both conditions can affect communication, the symptoms of aphasia and dysarthria are very different.

Aphasia Symptoms

• Difficulty producing words and sentences: Individuals may misplace words, struggle to form sentences, or be unable to speak at all.
• Trouble understanding language: People with aphasia may find it hard to follow conversations or understand what they are reading.
• Inability to read or write: Some people with aphasia lose the ability to read or write in addition to having a difficult time speaking.
• Nonsensical sentences: Individuals with aphasia might speak in grammatically correct but meaningless sentences. This might include using incorrect words or inventing new words that don’t make sense.

Dysarthria Symptoms

• Slurred speech: This is the most commonly described symptom of dysarthria. Speech may sound slow, slurred, or mumbled.
• Difficulty moving facial muscles: Weakness or excessive tightness in the muscles used for speech can cause drooling or difficulty swallowing.
• Voice changes: Dysarthria can affect the vocal cords, leading to a voice that sounds breathy, strained, or hoarse.
• Monotone speech: Some individuals may lose the ability to control the pitch, volume, or tone of their voice.
• Breath control issues: Dysarthria may also affect breath control, making it difficult to speak clearly or for long periods of time.

Causes of Dysarthria vs Aphasia

Aphasia is primarily caused by brain damage to the areas responsible for language processing. Common causes include:

• Stroke: This is the most common cause of aphasia, particularly when a stroke affects the left side of the brain.
• Traumatic brain injury (TBI): Any injury to the brain that impacts language areas can lead to aphasia.
• Brain tumors: A tumor located near the language centers can impact communication abilities.
• Progressive neurological diseases: Diseases like Alzheimer’s can cause aphasia by gradually impairing brain function over time.

Dysarthria, by contrast, is caused by damage to the nervous system that controls speech muscles. Its causes include:

• Stroke: A stroke can also cause dysarthria by damaging the parts of the brain that control the muscles responsible for speech.
• Traumatic brain injury (TBI): Similar to aphasia, TBIs can cause dysarthria if the parts of the brain that control speech muscles are damaged.
• Cerebral palsy: This condition affects movement and muscle tone, which can lead to dysarthria in some individuals.
• Multiple sclerosis (MS): MS can cause damage to the nerves that control speech muscles, leading to dysarthria.
• Parkinson’s disease: Many people with Parkinson’s develop dysarthria as the disease progresses.
• Certain medications: Some medications, such as sedatives, muscle relaxants, and some anticonvulsants can cause dysarthria as a side effect. 

Treatments for Dysarthria vs Aphasia

Treatment for both dysarthria and aphasia focuses on helping individuals improve their communication skills, but the approaches differ depending on the specific condition.

Aphasia Treatments

1. Speech-language therapy: Working with a speech-language pathologist (SLP) is essential for most people with aphasia. Therapists use various techniques to help individuals relearn language skills, including speaking, reading, and writing. Therapy is tailored to the type of aphasia and the severity of the condition.
2. Augmentative and Alternative Communication (AAC): For individuals with severe aphasia, AAC tools, such as communication boards or speech-generating devices, can help them express themselves. These devices range from low-tech options like picture cards to high-tech, speech-generating apps that allow users to select words or phrases.
3. Group therapy: Some people with aphasia benefit from practicing language skills in a group setting. Group therapy can help build confidence in real-world communication situations.

Dysarthria Treatments

1. Speech therapy: Speech-language pathologists also play a key role in treating dysarthria. Therapy often focuses on improving muscle control, breath support, and articulation. This can include practicing speaking slowly and clearly or working on other methods to improve the effectiveness of communication.
2. Assistive devices: People with severe dysarthria may use AAC tools, similar to those used by people with aphasia, to help with communication. This might include speech-generating devices or other aids so they may be understood more easily.
3. Surgical or medical treatments: In some cases, medical intervention can help. For example, deep brain stimulation (DBS) can be an option for people with Parkinson’s disease to improve their motor symptoms.

Constant Therapy: At-home Speech, Cognitive, and Language Therapy

For those navigating the challenges of dysarthria or aphasia, finding the right tools for ongoing therapy is essential. The Constant Therapy app offers a personalized approach to speech and language recovery. With a wide range of exercises tailored to individual needs, the app allows users to practice critical communication skills at their own pace, whether they’re working to regain language comprehension or improve speech clarity. Available on mobile devices, Constant Therapy provides the flexibility to integrate therapy into your daily routine.