Dysarthria

Dysarthria is a motor speech disorder in which the muscles that help produce speech are weakened, damaged, or paralyzed. A person with this condition has no control over their voice box or tongue. They might also slur their words or have mumbled or choppy speech.

People with dysarthria are sometimes born with another condition that leads to it, or they may experience an injury or illness that causes it later in life. Many of these conditions are manageable, and there are ways to improve speech in people with dysarthria.

This article will cover the types of dysarthria and their symptoms and causes. It also discusses treatment, diagnosis, and when to seek treatment. 

Types of Dysarthria

The type of dysarthria a person might have and the symptoms they experience are dependent on the part of the brain that is affected. According to the Handbook of Clinical Neurology (HCN), there are six major types of dysarthria, which include the following:

• Flaccid dysarthria: Damage to the peripheral nervous system (PNS) can lead to flaccid dysarthria. The PNS connects your brain and spinal cord (the central nervous system) to the rest of your body. Damage to the PNS can result from a brain stem or spinal tumor, a traumatic brain injury, or damage surgery of the spine.
• Spastic dysarthria: With this type of dysarthria, the part of the brain that controls movement becomes damaged. This leads to speech problems, generalized muscle weakness, and abnormal reflexes.
• Ataxic dysarthria: People with ataxic dysarthria have often sustained cerebellum damage. The cerebellum is the part of the brain that regulates movement and processes sensory information.
• Hyperkinetic dysarthria: This dysarthria occurs when a specific part of the brain—the basal ganglia control circuit—is damaged. The basal ganglia have many functions, including involuntary muscle movement. Hyperkinetic dysarthria causes unpredictable speech production, muscle spasms, tremors, and involuntary jerking or flailing movements. It is common in people with Huntington’s disease or Tourette's syndrome.
• Hypokinetic dysarthria: This type of dysarthria also affects the control circuit of the basal ganglia. It is commonly seen in people with Parkinson’s disease and causes monotonal speech, a stutter or slurred speech, difficulty starting sentences, and problems pronouncing consonant sounds. It is also known for causing reduced movement of the face and neck, tremors, muscle spasms, and problems with swallowing.
• Mixed dysarthria: If someone is diagnosed with mixed dysarthria, two or more types of dysarthria are present. For example, amyotrophic lateral sclerosis (ALS) causes spastic-flaccid dysarthria. It is also common in people who have had multiple strokes. Mixed dysarthria is the most common type of dysarthria, and symptoms will depend on the types involved.

It is also possible for someone to be diagnosed with undetermined dysarthria. In such a case, symptoms point to dysarthria but do not fit any identified types.

Symptoms of Dysarthria

The symptoms will depend on the type of dysarthria you have. Some types will cause more severe symptoms.

In general, symptoms of dysarthria may include:

• Speech that is slurred, nasally, choppy, robotic, or monotonal
• A hoarse or strained voice
• Very quiet or very loud speech
• Problems with speech rhythm, such as frequent hesitation or rapid speech
• Tongue, lip, or jaw movement struggles
• Dysphagia (difficulty swallowing) and drooling resulting from dysphagia

Because of the symptoms, a person with dysarthria might be harder to understand.

Dysarthria, on its own, typically does not affect intellectual ability or development, but its possible causes might. Speech problems might also affect a person's interactions on the job, educational opportunities, and social situations.

Causes of Dysarthria

Dysarthria can be congenital or acquired. Congenital conditions are present at birth, whereas acquired conditions can occur at any age due to an illness or injury.

When dysarthria is congenital, it might have been caused by brain damage that occurs before or after birth. Congenital dysarthria is common in childhood with cerebral palsy.

Acquired dysarthria is the result of brain damage that occurs later in life. Examples might include stroke, a head injury, or progressive neurological disease like Parkinson's. Acquired dysarthria conditions are common in adults.

In addition to congenital diseases and neurological, progressive conditions, dysarthria be a complication of other health conditions, including:

• Demyelinating diseases (those causing damage to the myelin sheath surrounding nerve fibers in the central nervous system) and inflammatory diseases, such as multiple sclerosis, meningitis, and Guillain-Barré syndrome
• Infectious diseases, including human immunodeficiency virus (HIV), Creutzfeldt-Jakob disease, and herpes zoster
• Neoplastic diseases, including tumors of the central nervous system or cerebral, cerebellar, or brain stem tumors
• Toxic or metabolic diseases, such as botulism and Wilson's disease
• Vascular diseases, including stroke and arteriovenous malformations

A traumatic brain injury, skull fracture, and trauma to the neck can also lead to dysarthria.

What Medications Can Cause Dysarthria?

There are medications that can lead to dysarthria as a side effect of their use. These include medicines that act on the central nervous systems, such as narcotics and anti-seizure drugs like Dilantin (phenytoin) and Tegretol (carbamazepine).

Some antipsychotic drugs might also affect speech and lead to dysarthria. One 2015 study looked at 140 patients on risperidone (92), olanzapine (28), aripiprazole (14), and clozapine (6) for three or more months. Here, researchers found the duration of use and the effect of some antipsychotic drugs can affect the palate (roof of the mouth) and respiratory function leading to speech troubles.

The studied drugs were also found to affect noise-harmonic ratios (a measure of components of speech sounds) and could lead to extrapyramidal symptoms. Extrapyramidal symptoms include involuntary muscle contractions, tremors, stiff muscles, and involuntary facial movements.

How to Treat Dysarthria

Treatment for dysarthria will depend on the type, severity, and underlying cause. Treating dysarthria can help to improve a person's speech. If the dysarthria has been caused by a prescription drug, changing or stopping the medication might resolve or reduce speech troubles.

The primary treatment for dysarthria is speech and language therapy. With the help of a speech therapist, you might be able to regain your normal speech and improve communication.

A speech therapist can help you to work on:

• Slowing down speech
• Using breathing to increase speech volume
• Strengthening the muscles of the mouth
• Utilizing the lips and tongue more
• Learning to more clearly say consonant sounds in words and sentences
• Methods to communicate, such as computers, writing, or gestures
  

Are There Tests to Diagnose the Cause of Dysarthria?

A healthcare provider would conduct a physical examination, medical history, imaging, and other tests to explore the underlying cause of dysarthria. They may refer you to specialists for further diagnosis and treatment.

A speech-language pathologist can evaluate a person's speech to determine what type of dysarthria they might have. Once a diagnosis is made, this specialist might suggest treatment options or refer you to a neurologist (specialist in conditions of the central nervous system) who will look for an underlying cause of your dysarthria.

Assessing for dysarthria includes:

• Medical history, including information about symptoms and their onset, medications you are currently taking, family history, family reporting on signs and symptoms, and identification of barriers and triggers related to speech troubles
• Movement and language task assessments, including repeating words and sentences, sticking out the tongue, biting the lip, or blowing out a candle
• Diagnostic testing, including magnetic resonance imaging (MRI) or computed tomography (CT) scans of the neck and brain, swallow testing, muscle and nerve function tests, and blood work to look for infection or inflammation

When to See a Healthcare Provider

If you are having speech troubles, you should reach out to your healthcare provider. Your provider can conduct testing to help determine the source of your symptoms and if treatment is necessary.

Summary

Dysarthria is a motor speech disorder that happens because of weakness in the muscles necessary for producing speech or due to damage to the nervous system. It can affect a person's ability to produce and understand language.

Many congenital and acquired conditions can lead to dysarthria. It might also be a side effect of some medications, including antipsychotics and antiseizure drugs.

You should contact your healthcare provider if you experience signs of dysarthria. A speech pathologist can help diagnose a person's dysarthria and make a referral to a neurologist if necessary.

If medication is the source of symptoms, stopping the drug or reducing the dose might help. Dysarthria is typically managed with speech therapy and addressing underlying causes.

A Word From Verywell

Speech problems might lead to anxiety, confidence issues, and frustration for the person affected and their loved ones. If you or a loved one is struggling to cope with the emotional and psychological effects of dysarthria, make an appointment with a mental health professional. Don't go at it alone.