This article is part one of a three-part series. This article discusses the definition of CAS, dysarthria and the root mechanisms of childhood apraxia of speech.
What is Childhood Apraxia of Speech?
CAS is an official term recommended by the American-Speech-Language-Hearing Association (ASHA). However, CAS may be referred to as “verbal dyspraxia” in other parts of the world (outside of the USA). Children with CAS/verbal dyspraxia have problems sequencing, coordinating, and timing mouth and vocal movements for speech.
According to ASHA, CAS is “a neurological childhood (pediatric) speech sound disorder, in which the precision and consistency of movements underlying speech are impaired in the absence of neuromuscular deficits.” (1) However, children with neuromuscular deficits (e.g., cerebral palsy and Down syndrome) can also have CAS. This is very confusing for both parents and professionals.
Childhood Apraxia of Speech vs Childhood Dysarthria
Children born with cerebral palsy, Down syndrome, or other neuromuscular disorders have muscle tone and muscle function problems that often result in a speech difficulty called childhood dysarthria. These children frequently have distorted sounding speech (the main characteristic of dysarthria). Although distorted, their speech sounds fairly consistent regardless of:
- The length of words or sentences, and
- Whether or not they are asked to imitate speech.
Childhood dysarthria is different from CAS. Yet, children with neuromuscular disorders can have CAS in addition to childhood dysarthria.
There are also many children without specific neuromuscular deficits who have CAS. These children have generally adequate muscle tone and muscle function for speech (e.g., children with autism or no specific diagnosis). They do not have any documented brain injury or damage.
Roots of Childhood Apraxia of Speech
Overall, children with CAS do not seem to be using the motor programming area of the brain as well as other children. They do not practice speech like other children in order to develop appropriate sequencing, timing, and coordination of speech. Children need to “babble, babble, babble” and “practice, practice, practice” speech sound combinations in order to develop speech. The premotor cortex (in the frontal lobe of the brain) is believed to be primarily responsible for this process.
Children with neuromuscular disorders (e.g., Down syndrome, cerebral palsy) do not move like other children, so they may not be properly using the premotor cortex to set down adequate motor programs for speech in the first place.
Children with generally adequate muscle tone for speech (e.g., children with autism or no specific disorder) may have an inherent weakness in the functioning of the premotor cortex which keeps them from developing adequate sequencing, timing, and coordination for speech.
Brain research using functional MRI and PET (positron emission tomography) may ultimately reveal differences and/or similarities in brain function in these two groups of children who can have CAS.
Summing it Up
In summary, children with childhood apraxia of speech:
- Do not seem to be using the motor programming area of the brain as well as other children
- Do not practice speech like other children
- Do not develop adequate sequencing, timing, and coordination for speech
- Can have childhood dysarthria in addition to CAS
Now that you have a basic understanding of what CAS is, the other articles in this three-part series will discuss the specific characteristics that distinguish CAS from other speech disorders and what parents might look for in the treatment of CAS.
(1) “Childhood Apraxia of Speech.” American Speech-Language-Hearing Association, 2007. Web. 22 May 2016.