Dysarthria is a speech disorder that is due to a weakness or incoordination of the speech muscles. Speech is slow, weak, imprecise or uncoordinated. It can affect both children and adults. "Childhood dysarthria" can be congenital or acquired. It is often a symptom of a disease, such as cerebral palsy, Duchenne muscular dystrophy, myotonic dystrophy, Bell palsy. In both adults and children, it can result from head injury.

In adults, dysarthria is can be caused by stroke, degenerative disease (Parkinson's, Huntington's, amyotrophic lateral sclerosis, multiple sclerosis, myasthenia gravis), infections (meningitis), brain tumours, and toxins (drug or alcohol abuse, lead poisoning, carbon monoxide, etc.).

In order for speech to be clear, a number of subsystems must work together. A weakness in any one of the systems can result in dysarthria. So can an incoordination between systems. The lungs (respiratory subsystem) supply the air necessary to power the speech system. The voice box or larynx (laryngeal) sets the air vibrating and creates voice. The soft palate (velopharyngeal) acts a door between the oral and nasal cavities and channels air to one or both cavities resulting in different sound quality. The lips, tongue, teeth, and jaw (articulatory) move to further channel and shape the sounds into the various vowels and consonants.

If the respiratory subsystem is weak, then speech may be too quiet and produced one word at a time. If the laryngeal system is weak, speech may be breathy, too quiet and slow. If the velopharyngeal subsystem is not working, speech may sound too nasal or nasal sounds may be misssing. If the articulatory subsystem is not working, speech may sound slurred, may have many errors and may be slow and laboured.

Therapy for dysarthria focuses on maximizing the function of all systems. Compensatory strategies are often used. Individuals with dysarthria may be advised to take frequent pauses for breath, to over-articulate, or to pause before important words to make them stand out. If there is muscle weakness, they may benefit from performing oro-facial exercises. This helps to strengthen the muscles of the face and mouth that are used for speech.

For some people, speech is not a viable option. Alternative or augmentative systems are frequently used. These can be low tech or high tech. An example of a low tech system would be an alphabet board. The individual points to letters to spell out messages. "Pic-syms" are picture symbols, black and white line drawings with print that can be combined on a communication board or book. The individual points to the appropriate picture or combination of pictures to communicate. High tech systems include computers and voice output devices. A regular computer keyboard, monitor and word processor can be used to type out and display messages. Programs that predict words and sentences can speed up this method of communicating. Some indivduals are unable to read and have a computer system that uses symbols - they select a symbol and the printed word is produced. Voice output systems are similar to the computer setups already described but rather than having the printed word as output, the spoken word is produced. Simple devices have the ability to let an individual access a limited number of pre-recorded phrases by pushing the appropriate key. More complex systems allow for creative productions. Any of these systems can be used as a back-up by individuals who do have some functional speech. There are times when it is too tiring or too time-consuming to use speech. Then the alternative system is used.

Most dysarthric speakers need more time to get their message across. It helps to allow them extra time and to listen face to face. When you haven't understood what they've said, it's better to say so than to pretend you have understood. It helps to repeat the part that you did understand as a question, so they only have to repeat the part you didn't get. For example, if you hear "I would like a XX", rather than saying pardon and getting a repetition that may sound the same, try asking "You would like a... ?" with rising inflection, or "What would you like?" If a person is using an augmentative device, consider it to be valid and equal to speech. Don't insist that they "say it" if you have understood they message they sent by the augmentative system.