The left hemisphere of the brain controls speech and language abilities for most people. However, in approximately 25% of left-handed individuals the right side of the brain controls these abilities. Regardless of where exactly in the brain this control lies, if this area of the brain is injured then speech and language skills will be affected.
Strokes, brain tumours, brain haemorrhages and acquired brain injury (such as from being hit or from falling) are all means by which speech and language abilities can be disrupted. Aphasia, apraxia of speech, dysarthria and a variety of miscellaneous speech difficulties can be the result of a brain injury.
AphasiaAphasia is a condition that leaves an individual unable to produce or comprehend language, often due to an injury that affects the part of the brain that controls such communications. However, depending upon the cause of aphasia, the individual may be left unable to speak, unable to read or write, both or another combination of communication difficulties.
Many different types of aphasias exist, all with particular signs and symptoms. The prognosis for aphasia will depend upon the type of aphasia, the cause of the aphasia and the age of the individual involved.
Apraxia of Speech/DyspraxiaApraxia of speech, sometimes also called dyspraxia, leaves individuals unable to consistently and correctly say what they mean. There are two main types of apraxia of speech. Developmental apraxia of speech occurs mainly in children and is often present from birth, but acquired apraxia of speech is mostly present in adults and is often the result of injury to the part of the brain that controls language use.
The severity of this type of apraxia will depend upon the type, extent and location of the injury to the brain as well as the age of the individual involved. The prognosis for an acquired apraxia of speech will depend upon the same variables.
DysarthriaDysarthria is a slurring of the speech, otherwise defined as imprecise, slow and/or distorted verbal communications. Brain injury may cause dysarthria because if the area of the brain that controls language is affected, so too will be the nerves that connect to the muscles involved in making speech. If these muscles are thus weakened or begin to receive uncoordinated speech “messages” from the brain, then speech will be disrupted as a result. Often speech therapy can be successful in helping individuals overcome dysarthria.
Miscellaneous DifficultiesIndividuals who sustain brain injuries may also exhibit a variety of other miscellaneous difficulties related to speech and/or language that are not necessarily considered to be a recognised speech disorder. A few of these difficulties might include:
- A reduction in vocabulary
- An inability to understand euphemisms sarcasm, double meanings, puns or other word play
- Poor grammar
- An inability to correctly construct sentences
- A reduction in listening, reading and/or writing skills
- Possibly even associated difficulties with maths skills.