Childhood Apraxia of Speech
What is childhood apraxia of speech?
Childhood apraxia of speech (CAS) is a motor speech disorder. Children who are diagnosed with CAS have incredible difficulty with individual sounds, syllables and words. This is not to say that there is anything at all wrong with their oral musculature rather, CAS involves the brain.
According to Pam Marshalla (http://www.pammarshalla.com/index.html) Apraxia has nothing to do with receptive language, cognition, memory, organization, following directions, understanding questions, reasoning etc. Rather, Apraxia is a problem of movement and the organization of movement perceptions that, in turn, causes difficulty in planning.
For reasons not yet fully understood, children with apraxia of speech have considerable difficulty coordinating the muscle movements required for intelligible speech. This muscle movement involves the tongue, lips, jaw and palate. Apraxia of speech is sometimes called verbal apraxia, developmental apraxia of speech, or verbal dyspraxia. Difficulty in planning speech movements is the key characteristic of childhood apraxia of speech.
This leads us to a full understanding what we sometimes can take for granted… How we communicate. The following is adapted from Apraxia-KIDS website.
According to “Apraxia Kids” at http://www.apraxia-kids.org/
How Does Speech “Happen”?
•Intention to communicate •An idea forms, outlining what the speaker wants to say. oThe words for the desired message are put in the correct order, using the correct grammar. Each word contains a specific sequence of sounds (also called phonemes) and syllables that must be correctly ordered together. •All of this information is translated from an idea and information about order of sounds and syllables into a series of highly coordinated motor movements of the lips, tongue, jaw, and soft palate. •The brain must tell the muscles of these “articulators” the exact order and timing of movements so that the words in the message are properly pronounced. •Finally, the muscles themselves must work properly with enough strength and muscle tone to perform the movements needed for speech.
Amazingly, all of this happens in the blink of an eye! So fast that we don’t even realize that we are doing it!
When speech is developing in a normal way, children try saying words and use FEEDBACK from people around them and from their own internal sensory system (sight, sound, touch) to try to figure our how “well” the words they made matched to ones that they were trying to say. This information is stored in the brain and is used the next time they attempt to say the word. Basically, typically developing children are “learning from experience”.
Usually once a child makes enough attempts at saying a word, the speech motor act becomes automatic and less effortful. The child doesn’t have to think about how to say the word or phrase they want to say. The targeted word(s) are quickly accessed and put together effortlessly when they are needed. Children with apraxia of speech have the most difficulty in this aspect of speech.
Researchers now believe that children with CAS may not be able to form or reliably access speech motor plans and programs within their brain, or that these plans and programs are faulty for some reason. Unlike children developing typical speech, speech motor plans and programs for children with CAS fail to become automatic and easily accessed when they wish to speak.
Recent research also suggests that for some reason, children with apraxia of speech may have a faulty feedback loop. The feedback loop is needed for learning and gaining accurate speech.
There are several forms of feedback children use to learn speech and the complex series of movements underlying it.
First, children use auditory information (through their hearing system) to judge whether their word attempt was correct. Researchers believe that the child’s speech processing system “couples” (or ties together) an auditory event – what they hear themselves say – with the movements of the oral structures needed to produce an utterance.
Secondly, sensory feedback called proprioception is used so that the child knows where speech structures like lips, jaw, tongue, palate are physically located and how they relate spatially to one another during speech movement. So, for example, during speech attempts the child may not be aware of where their tongue is within the oral cavity or how its position relates to other structures like the lips. Sensory feedback is especially important during the learning of motor plans such as in early speech learning or speech acquisition. If these two feedback mechanisms are not working properly, speech intelligibility is affected.
For more information on CAS, please visit the following links below:
What does CAS look like?