Sometimes brain injury causes communication difficulties by impairing the physical ability to speak, rather than the ability to understand and express language. The two main speech disorders are dysarthria and dyspraxia of speech.
Dysarthria occurs when there is damage to parts of the nervous system involved in the control of muscles used for speech. It can also occur because of injury or weakness more directly affecting the muscles themselves. Dysarthria results in reduced control and clarity of speech.
When dysarthria occurs in isolation, a person's ability to speak will be impaired, but their ability to understand language and construct sentences will be intact. However, in practise there are often elements of both aphasia and dysarthria present.
Features may include:
- Reduced movement (range or strength) of the lips, tongue, and soft palate
- Problems controlling the flow of air from the lungs when speaking
- Difficulty in producing varied and controlled changes in the volume of speech
- Difficulty in producing varied and controlled patterns in the tone of speech
- Slurring of speech
Dyspraxia of speech
Dyspraxia is a disorder of planned and co ordinated movement. It occurs because of injury to areas of the brain responsible for conscious movement, mainly situated in the frontal lobes.
Dyspraxia of speech causes people to have difficulty saying what they are consciously thinking about saying. However, some individuals may be able to speak perfectly normally when not thinking about it, for example, if someone asks them a question and they have to respond spontaneously. Long words tend to be more difficult to say then short words for some people with dyspraxia of speech.
The disorder can range from mild in some people to very severe in others.
A Speech and Language Therapist will be able to identify and assess dysarthria and dyspraxia of speech. Recovery and degree of difficulties will depend upon the severity of the initial brain injury. However, for a variety of reasons (e.g. presence of other difficulties), individuals may respond differently to therapy. Some people will make more progress than others, despite having had a similar injury.
In severe cases, those with speech difficulties may be unable to achieve recognisable speech. In such cases, they may benefit from the use of an Augmentative Aid to Communication (AAC). Headway's booklet Coping with communication problems after brain injury contains a section on communication aids which explains this in more detail.