dysarthria, motor speech disorder in which neurological damage impairs the ability of nerves to send messages to the muscles involved in speech production. Dysarthria can affect persons of all ages and varies in type and severity.
Dysarthria can affect any of the muscles involved in speech production, including the muscles used for articulation or pronunciation (such as muscles in the lips, tongue, or jaw) as well as the muscles controlling nasality, phonation, and respiration. The result may be weak or uncoordinated movement, slow movement, or loss of movement.
Manifestations of dysarthria may include restricted movement of the lip, tongue, and jaw; slurred speech; slow speech; rapid mumbled speech; soft or inaudible speech; breathiness; hoarseness; and drooling and difficulty swallowing. Individuals with dysarthria may occasionally be mistaken as being intellectually disabled or deaf.
The different manifestations of the disorder depend on the extent and location of the damage. When damage is isolated to a single small area, only one muscle or muscle group (such as only muscles involved in respiration) may be affected. When damage is more diffuse, many components may be affected, such as those involved in respiration, nasality, phonation, and articulation.
Dysarthria may be present at birth (congenital dysarthria) or may develop later in life. Congenital dysarthria can occur in conjunction with any disorder, inherited or acquired, that affects the muscles of speech production. Dysarthria acquired later in life may result from stroke, brain injury, a tumour, infection, or a progressive neurological disease such as amyotrophic lateral sclerosis, multiple sclerosis, or Parkinson disease.
Some patients benefit from therapy to learn strategies for improving swallowing, muscle strength, and intelligibility of speech or to learn augmentative and alternative methods of communication. To improve speech intelligibility, the patient may learn to talk more slowly and more deliberately. Communication partners, such as teachers and family members, can develop strategies to help those with dysarthria know what parts of their messages are understood and what parts need to be clarified. Some individuals choose to use communication aids. For example, a person who has difficulty producing adequate volume for speech may benefit from a speech amplifier. To clarify speech, persons with dysarthria may learn to use letter or word boards to introduce the topic they want to talk about or to point to the initial letter of each word they say as they speak. Those who are unable to produce speech may also consider an electronic augmentative communication device with voice output so that they can communicate on the phone and talk to unfamiliar people.