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 voicemail or language. They may also slur their words or have mumbled or jerky speech.
People with dysarthria are sometimes born with another condition that causes 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 and symptoms
The type of dysarthria a person may have and the symptoms they experience depend on which part of the brain is affected. According to the Handbook of Clinical Neurology (HCN), there are six main types of dysarthria, including 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 brainstem or spinal tumor, traumatic brain injury, or spinal surgery.
- Spastic dysarthria: With this type of dysarthria, the part of the brain that controls movement is damaged. This leads to speech problems, generalized muscle weakness and abnormal reflexes.
- Ataxic dysarthria: People with ataxic dysarthria often have damage to the cerebellum. 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 jerks or restless movements. It is common in people with Huntington’s disease or Tourette’s syndrome.
- Hypokinetic dysarthria: This type of dysarthria also affects the basal ganglia control circuitry. It is commonly seen in people with Parkinson’s disease and causes monotonous speech, stuttering or slurred speech, difficulty starting sentences, and problems pronouncing consonants. It is also known to cause reduced facial and neck movements, tremors, muscle spasms and swallowing problems.
- 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 depend on the types involved.
It is also possible for a person to be diagnosed with indeterminate dysarthria. In such a case, the symptoms indicate dysarthria but do not correspond to any identified type.
Symptoms will depend on the type of dysarthria you have. Some types cause more severe symptoms.
In general, symptoms of dysarthria can include:
- Scrambled, nasal, jerky, robotic, or monotonous speech
- A hoarse or strained voice
- Very quiet or very loud speech
- Speech rhythm problems, such as frequent hesitation or rapid speech
- Tongue, lip or jaw movement struggles
- Dysphagia (difficulty swallowing) and drooling resulting from dysphagia
Due to the symptoms, a person with dysarthria may be more difficult to understand.
Dysarthria, on its own, usually does not affect intellectual ability or development, but its possible causes could. Speech problems can also affect a person’s interactions at work, educational opportunities, and social situations.
Causes of dysarthria
Dysarthria can be congenital or acquired. Congenital conditions are present at birth, while acquired conditions can occur at any age due to illness or injury.
When dysarthria is congenital, it may have been caused by brain damage that occurred 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 may include a stroke, a head injury, or a progressive neurological disease like Parkinson’s disease. Acquired dysarthria conditions are common in adults.
In addition to congenital diseases and progressive neurological conditions, dysarthria can be a complication of other health conditions, including:
- Demyelinating diseases (those that damage 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 shingles
- Neoplastic diseases, including tumors of the central nervous system or cerebral, cerebellar or brainstem tumors
- Toxic or metabolic diseases, such as botulism and Wilson’s disease
- Vascular diseases, including strokes and arteriovenous malformations
Traumatic brain injury, skull fracture, and neck trauma can also lead to dysarthria.
What drugs can cause dysarthria?
Some medications can cause dysarthria as a side effect of their use. These include drugs that act on the central nervous system, such as narcotics and anticonvulsants like Dilantin (phenytoin) and Tegretol (carbamazepine).
Certain antipsychotic drugs can also affect speech and lead to dysarthria. A 2015 study examined 140 patients on risperidone (92), olanzapine (28), aripiprazole (14) and clozapine (6) for three months or longer. Here, researchers found that the duration of use and the effect of certain antipsychotic drugs can affect the palate (roof of the mouth) and respiratory function, leading to speech disturbances.
The drugs studied were also found to affect noise-harmonic ratios (a measure of the components of speech sounds) and may lead to extrapyramidal symptoms. Extrapyramidal symptoms include involuntary muscle twitching, tremors, stiff muscles, and involuntary facial movements.
How to Treat Dysarthria
Treatment for dysarthria will depend on the type, severity, and underlying cause. Treatment for dysarthria can help improve a person’s speech. If the dysarthria was caused by a prescription medication, changing or stopping the medication may resolve or reduce the speech disturbance.
The main treatment for dysarthria is speech therapy. With the help of a speech therapist, you may be able to return to your normal speech and improve communication.
A speech therapist can help you work on:
- Slow down speech
- Use breathing to increase the volume of speech
- Strengthen the muscles of the mouth
- Use lips and tongue more
- Learn to say consonants more clearly in words and sentences
- Communication methods, such as computers, writing, or gestures
Are there tests to diagnose the cause of dysarthria?
A healthcare provider would perform a physical exam, medical history, imaging, and other tests to explore the underlying cause of dysarthria. They can refer you to specialists for further diagnosis and treatment.
A speech therapist can assess a person’s speech to determine what type of dysarthria they might have. Once diagnosed, this specialist can 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.
Assessment for dysarthria includes:
- Medical history, including information about symptoms and their onset, medications you are currently taking, family history, family reports of signs and symptoms, and identification of barriers and triggers related to speech disorders
- Motor and language task assessments, including repeating words and phrases, sticking out your tongue, biting your lip, or blowing out a candle
- Diagnostic tests, including magnetic resonance imaging (MRI) or computed tomography (CT) of the neck and brain, swallowing tests, muscle and nerve function tests, and blood tests to check for infection or inflammation
When to See a Health Care Provider
If you are having speech problems, you should contact your health care provider. Your provider can perform tests to help determine the source of your symptoms and whether treatment is needed.
Dysarthria is a motor speech disorder that occurs due to weakness of the muscles needed to produce speech or damage to the nervous system. This can affect a person’s ability to produce and understand language.
Many congenital and acquired conditions can lead to dysarthria. It can also be a side effect of certain medications, including antipsychotics and anticonvulsants.
You should contact your health care provider if you have signs of dysarthria. A speech therapist can help diagnose a person’s dysarthria and refer them to a neurologist if needed.
If medications are causing symptoms, stopping the medication or reducing the dose may help. Dysarthria is usually managed with speech therapy and treatment of the underlying causes.
A word from Verywell
Speech problems can lead to anxiety, trust issues and frustration for the affected person and those close to them. 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 alone.
Frequently Asked Questions
Can someone be born with dysarthria?
Dysarthria can result from a congenital condition (one that is present at birth). Conditions that could cause a baby to be born with dysarthria or develop it soon after birth include birth injury or neurological disorders like cerebral palsy or multiple dystrophy.
How does dysarthria affect speech?
A person with dysarthria cannot control their voice box or language. Their speech may be garbled, mumbled, or sound robotic. They may speak too quickly, loudly, or quietly, or their voice may be hoarse, breathy, or nasal.
Can someone have more than one type of dysarthria?
People with two or more types of dysarthria are usually diagnosed with mixed dysarthria. This type is often seen in people with amyotrophic lateral sclerosis (ALS) who have spastic-flaccid dysarthria.