Aphasia vs. dysarthria: What is the difference?

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Aphasia occurs when a part of the brain that is responsible for language suffers damage, affecting a person’s ability to speak or understand language.

In contrast, dysarthria occurs due to neurological damage that weakens the muscles people need to speak. This damage may affect different areas, including the tongue, lips, throat, and upper respiratory tract.

Many of the same conditions can cause both aphasia and dysarthria, such as strokes, brain tumors, and head injuries.

There are different types of aphasia. Doctors split them into two broad categories: fluent and nonfluent.

Fluent types allow a person to speak in full sentences, but the words may not make sense. Nonfluent aphasia may cause a person to struggle to speak fluently or to miss out words.

Wernicke’s aphasia

Wernicke’s aphasia is the most common type of fluent aphasia. This type of aphasia is most often the result of a stroke that reduces blood flow to the posterior temporal lobe.

The symptoms include:

• difficulty understanding speech
• difficulty repeating words or sentences
• anosognosia, which means a person is not aware of their symptoms
• possible visual impairment

Despite these symptoms, people with Wernicke’s aphasia can usually speak in full, fluid sentences, although the words may be out of place or made up.

Broca’s aphasia

Broca’s aphasia is the most common type of nonfluent aphasia. Often, the cause is a stroke that affects the inferior frontal lobe on the side of the brain that controls language.

The symptoms include:

• broken or short sentences
• leaving small connecting words out
• struggling to express thoughts or ideas
• difficulty repeating words or sentences

Unlike Wernicke’s aphasia, Broca’s aphasia does not cause difficulty understanding what others are trying to say, and people are aware of their symptoms.

Global aphasia

Global aphasia is the most severe form of aphasia. The cause is extensive damage to the parts of the brain that are responsible for language.

Many symptoms of Broca’s aphasia and Wernicke’s aphasia occur in global aphasia, including:

• difficulty understanding speech
• difficulty with repetition
• nonfluent speech

The symptoms are usually severe in global aphasia. People with the condition may only be able to say one or two words at a time. Some are unable to speak, write, or understand any words.

Other types of aphasia

Other types of aphasia include:

• Transcortical sensory aphasia: This is a less severe form of Wernicke’s aphasia that causes difficulty understanding speech but no difficulty speaking fluently.
• Transcortical motor aphasia: This is similar to Broca’s aphasia but is less severe and does not cause difficulty with repetition.
• Mixed transcortical aphasia: This is similar to global aphasia, but it does not affect repetition.
• Anomic aphasia: This type of aphasia specifically affects a person’s ability to recall certain words, such as objects.
• Conduction aphasia: This type of aphasia only affects a person’s ability to repeat words, but not understanding or expression.

The types of dysarthria include:

Spastic dysarthria

This type of dysarthria affects motor function and is a result of damage to motor neurons in the central nervous system. Cerebral palsy can cause it.

People with this type of dysarthria may speak with a strained voice. Speech may be monotone and slow.

Flaccid dysarthria

Flaccid dysarthria causes difficulty pronouncing consonants. This occurs when there is damage to the peripheral nervous system.

People with flaccid dysarthria may speak in short phrases, and their voice may sound more breathy or nasal than usual.

Hypokinetic dysarthria

Hypokinetic dysarthria is most often due to Parkinson’s disease. The symptoms include:

• rapid and slurred speech
• stuttering
• difficulty pronouncing consonants
• stiffness and reduced movement in the face and neck
• monotone and breathy-sounding speech
• difficulty swallowing
• tremors
• muscle spasms

Hyperkinetic dysarthria

Hyperkinetic dysarthria causes involuntary movements and can cause unpredictable speech. The cause is damage to the basal ganglia, which is part of the brain.

The symptoms include:

• slow and slurred speech
• shaky voice
• shortness of breath and fatigue due to speaking
• tremors and muscle spasms
• involuntary movements

Ataxic dysarthria

Damage to the cerebellum can cause this type of dysarthria. The symptoms include slurred speech and reduced coordination.

The treatment for both aphasia and dysarthria will depend on the cause of the condition.

Treating aphasia

Some causes of aphasia can be temporary, such as infections, seizures, or migraine. In this case, treating the underlying cause may mean it goes away entirely.

When the cause is brain damage, symptoms may improve with various types of speech and language therapy. This therapy can not only help with speaking and understanding but also with finding new ways to communicate.

Learn more about aphasia treatment here.

Treating dysarthria

Speech and language therapy can also help people with dysarthria. It may help a person:

• strengthen muscles necessary for speech
• learn to control the speed of speech
• learn techniques to control the volume of speech
• learn to effectively communicate in other ways, such as hand gestures and writing

There are other speech impairments that can result from brain or nervous system damage. These include:

• Ataxia: This is a group of conditions that affect coordination, balance, and speech.
• Apraxia: This causes a person to no longer be able to perform an action they used to be able to do. People with apraxia are able to describe how to do the action but are unable to carry it out physically. This condition can affect the ability to pronounce some words.
• Dysphonia: This term describes the change in the quality of a person’s voice, sometimes known as hoarseness. This can happen due to aging or more serious causes, such as a tumor.

People may come across the term “dysphasia” when learning about speech impairments. This is an outdated term that doctors previously used to describe general language difficulties that occur due to brain damage.

Aphasia or dysarthria that occurs due to temporary conditions may go away completely. If the condition causes lasting complications, though, the outlook will vary depending on the person’s unique circumstances.

In many cases, particularly following a stroke, people with aphasia can recover a lot of their language abilities within 2 weeks of the event. If the aphasia continues for more than 2–3 months, it is unlikely that the person will fully recover all language skills. However, with treatment, symptoms can still improve over time.

Dysarthria can also completely resolve in some cases. For long-term neurological conditions such as Parkinson’s disease, ongoing treatment can be effective in reducing dysarthria symptoms and improving communication. However, some conditions that cause dysarthria, such as Parkinson’s disease, are progressive.

Aphasia and dysarthria are disorders that can affect speech. Aphasia occurs due to brain damage that affects the ability to express and understand speech.

Dysarthria, on the other hand, is a condition that affects the muscles necessary for speech. It does not affect the ability to understand language.

There are various underlying causes for both aphasia and dysarthria, ranging from injuries to long-term neurological conditions. The treatment and coping methods will vary depending on the underlying cause. Speech and language therapy is an option to treat both conditions.