Anarthria and Dysarthria Overview

Dysarthria is a speech deficit caused by problems controlling the muscles involved in speech production. Anarthria is the most severe form of dysarthria, resulting in the inability to produce clear, articulate speech.

Dysarthria and the more severe form, anarthria, are caused by brain damage. They can be caused by conditions that are present at birth, such as cerebral palsy or muscular dystrophy. When dysarthria is present from birth, this means that a person never developed the ability to produce understandable speech. Dysarthria and anarthria may also occur as a result of neurological conditions such as multiple sclerosis and stroke, causing a decline in speaking abilities after a person already had attained the ability to speak clearly.

The following conditions can all cause dysarthria or anarthria:

• Stroke
• Traumatic brain injury
• Brain tumor
• Parkinson’s disease
• Amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s disease
• Huntington’s disease
• Multiple sclerosis
• Myasthenia gravis
• Bell's palsy
• Wilson’s disease
• Guillain-Barre syndrome
• Lyme disease
• Medications: certain medications, such as narcotics or sedatives, can also cause dysarthria. Typically, this type of dysarthria resolves after the medication wears off.

If you have dysarthria, you are likely to have speech characterized by one or more of the following characteristics:

• Slowed rate of speech
• Mumbling quality to speech that is difficult to understand
• Limited movement of the tongue, lip, and jaw
• Abnormal vocal pitch
• Abnormal rhythm to speech
• Hoarseness or breathiness to speech
• Nasal or stuffy sounding speech
• Inability to speak loudly

All types of dysarthria are characterized by slurring of speech. If you have dysarthria, when you attempt to speak, you may notice that your vowels sound distorted.

Dysarthria may be mild, moderate, or severe. The level of dysarthria depends on the degree of damage to the neurological system.

If you or a loved one is affected by dysarthria, you might notice one or more of the common speech patterns characteristic of dysarthria. These patterns include:

• Spastic dysarthria– As the name suggests, this speech pattern is characterized by bursts of sounds as you try to speak. This type of dysarthria is caused by damage to the pyramidal tract, which is a pathway in the brain that controls motor function in the face and body.
• Hyperkinetic dysarthria – This is a slow pattern of speech caused by lesions of the basal ganglia, which is a region in the brainstem.
• Hypokinetic dysarthria – This is a rapid pattern of speech associated with Parkinson’s disease.
• Ataxic dysarthria – This is a haphazard speech pattern caused by damage to the cerebellum, which controls balance and coordination.
• Flaccid dysarthria – This is a 'weak' speech pattern caused by damage to the cranial nerves, which are the nerves that directly control the mouth and throat muscles.
• Mixed dysarthria – This is a difficult to define speech pattern caused by damage to several regions of the nervous system, such as the upper or lower motor neurons.

Dysarthria and its more severe form, anarthria, are diagnosed by a medical professional. Your medical team will listen carefully to your speech and your medical history, and you should expect a thorough physical examination.

One or more of the following diagnostic tests may need to be performed to determine the cause of your dysarthria:

• MRI
• CT scan
• Brain and nerve studies
• Blood test
• Urine test
• Lumbar puncture
• Brain biopsy

A speech language pathologist can identify the best course of treatment after your medical evaluation. A variety of techniques may be used during treatment. If your muscles are weak or stiff, you might need exercises tailored to your specific problem. Typically, treatment includes incorporating relaxation techniques, lingual and mandibular exercises, including isometrics, and phonetic stimulation.

Anarthria and dysarthria are not caused by problems with language comprehension or with problems thinking or finding the right words. Aphasia, in contrast, is a speech problem that is caused by trouble producing and/or understanding speech due to problems with one or more areas of the brain that are responsible for language. 

People who experience anarthria have the ability to understand words but are unable to produce understandable speech. Dysarthria, also known as dysarthosis, is a motor speech disorder that partially affects the muscles used for speech production. Anarthria is due to a more significant loss of muscular control of the speech muscles. The muscles involved in speech include the muscles of the lips, tongue, mouth, vocal folds, and diaphragm.

Living with dysarthria can be frustrating because it makes it difficult to communicate, and it may also be embarrassing.

Dysarthria can partially or completely improve on its own, depending on the cause. If your dysarthria is not expected to improve on its own, therapy and exercises will help optimize your ability to speak and communicate clearly.