Dysarthria is loss of the ability to articulate words normally.
- Speech may be jerky, staccato, breathy, irregular, imprecise, or monotonous, but people can understand language and use it correctly.
- Practitioners evaluate muscle strength and movement by asking the person to do some simple tasks involving their mouth and tongue and to repeat words and sentences.
- Speech therapy helps some people with dysarthria.
Although dysarthria seems to be a language problem, it is really a problem with controlling the muscles of speech (a motor problem).
Causes of Dysarthria
Dysarthria may be caused by damage to the following:
- Parts of the brain that control muscle movement.
- Cerebellum: The cerebellum, which is located between the cerebrum and brain stem, coordinates the body’s movements.
- Basal ganglia: These large collections of nerve cells help coordinate and smooth out movements (see figure Locating the Basal Ganglia).
- Brain stem: The brain stem controls the muscles that are used in breathing and those used to help make sounds.
- The nerve fibers that connect the outer layer of the cerebrum (cerebral cortex) to the brain stem: These nerve fibers relay information needed to control and coordinate the muscles used to produce speech, including muscles of the lips, tongue, palate, and vocal cords.
- Neuromuscular junction: Nerves connect with muscles at the neuromuscular junction.
These structures can be damaged by degenerative disorders (such as amyotrophic lateral sclerosis, Parkinson disease, and Huntington disease), multiple sclerosis, head injuries, brain tumors, strokes, or infections such as Lyme disease.
Symptoms of Dysarthria
People who have dysarthria produce sounds that approximate what they mean and that are in the correct order. However, speech may be jerky, staccato, breathy, irregular, imprecise, or monotonous, depending on where the damage is.
Because the ability to understand and use language is not usually affected, most people with dysarthria can read and write normally.
The disorder that causes dysarthria can also cause difficulty chewing and swallowing.
Diagnosis of Dysarthria
- A doctor's evaluation
- Standardized tests of brain function
- Imaging tests
To diagnose dysarthria, a doctor asks the person about symptoms and does a physical examination. A speech therapist often helps in the evaluation. The practitioner may also do the following:
- Ask the person to do some simple tasks, such as blowing out a candle, biting the lower lip, and sticking out the tongue: Observing the person doing these tasks helps the practitioner evaluate the strength and movement of the muscles involved in speech.
- Ask the person to repeat words and sentences, sing, and count: Observing the person producing sounds helps the practitioner detect problems with speaking, such as breathiness and jerky speech.
Standardized tests of brain function (neuropsychologic testing) may be given by a neuropsychologist or speech therapist. These tests also help practitioners plan treatment and determine how likely recovery is.
Imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI), are done to help identify the cause.
Other tests may be done, depending on the suspected cause. These tests may include blood and urine tests, a spinal tap (lumbar puncture), electroencephalography (EEG), and electromyography and nerve conduction studies.
Treatment of Dysarthria
- Speech therapy
- Sometimes use of a communication device
Speech therapy helps some people with dysarthria. Speech therapy may involve breathing and muscle exercises and repetition of words or sentences.
If dysarthria is severe, therapists may recommend using a letter or picture board or a computer-based device with a keyboard and message display.