Dysarthria

Dysarthria (pronounced “dis-AR-three-uh”) is a motor speech disorder that makes it difficult to form and pronounce words. Motor speech disorders occur when damage to your nervous system prevents you from fully controlling parts of your body that control speech, like your tongue, voice box (larynx) and jaw. Dysarthria makes it challenging to speak so that others can understand you.

Dysarthria can be developmental or acquired:

• Developmental dysarthria happens due to brain damage during fetal development or at birth. For example, cerebral palsy can cause dysarthria. Children tend to have developmental dysarthria.
• Acquired dysarthria happens as a result of brain damage later in life. For example, a stroke, a brain tumor or Parkinson’s disease can lead to dysarthria. Adults tend to have acquired dysarthria.

People with dysarthria understand language. They know what they want to say and how to say it. It’s just that muscle weakness makes speaking difficult.

What are the types of dysarthria?

There are six categories of dysarthria. They’re grouped based on the specific part of your nervous system affected. Dysarthria may result from damage to various parts of your nervous system, including your brain and spinal cord (central nervous system) and the network of nerves that carry signals throughout your body (peripheral nervous system).

• Flaccid dysarthria results from damage to the lower motor neurons. The lower motor neurons are part of your peripheral nervous system. With flaccid dysarthria, your speaking may sound breathy and nasal.
• Spastic dysarthria results from damage to the upper neurons on one or both sides of your brain. The upper neurons are part of your central nervous system. Your speaking may sound strained or harsh.
• Ataxic dysarthria results from damage to the part of your brain called the cerebellum. Your cerebellum helps coordinate muscle movement. You may have trouble pronouncing vowels and consonants, and you may have difficulty placing emphasis on the right parts of a word when you’re speaking.
• Hypokinetic dysarthria results from damage to the part of your brain called the basal ganglia. The basal ganglia is a structure inside your brain that helps your muscles move. Hypokinetic dysarthria is associated with slow (“hypo”), monotone, rigid-sounding speech.
• Hyperkinetic dysarthria also results from damage to your basal ganglia. It’s associated with fast (“hyper”) sounding and often unpredictable speech.
• Mixed dysarthria includes a mix of two or more of the other five types. It’s the most common type of dysarthria.

How common is dysarthria?

Dysarthria is more common in people with certain neurological conditions, such as:

• Amyotrophic lateral sclerosis (ALS): Up to 30% of people with ALS (Lou Gehrig’s disease) have dysarthria.
• Multiple sclerosis (MS): Around 25% to 50% of people with MS get dysarthria at some point.
• Parkinson’s disease: Dysarthria affects 70% to 100% of people with Parkinson’s disease.
• Stroke: About 8% to 60% of people with stroke have dysarthria.
• Traumatic brain injury: Some 10% to 65% of people with traumatic brain injury have dysarthria.