According to The Childhood Apraxia of Speech Association of North America (CASANA) childhood apraxia of speech is a motor speech disorder. For reasons not yet fully understood, children with apraxia of speech have great difficulty planning and producing the precise, highly refined and specific series of movements of the tongue, lips, jaw and palate that are necessary for intelligible speech. "Praxis" means planned movement.
Generally, there is nothing wrong with the muscles themselves. The child does not have difficulty with non-speech activities performed with the muscles such as coughing, chewing or swallowing. However, the area of the brain that tells the muscles how to move and what to do to make a particular sound or series of sounds is damaged or not fully developed. This makes retrieving the "motor plan" for saying a word difficult.
As a result, even though the child knows what he wants to say, he cannot say it correctly at that particular time. Sometimes he cannot even begin. Either the wrong sound comes out, or many sounds are left out altogether. At that particular time, the motor plan is not accessible. These errors are not under the child's voluntary control so he often cannot correct them, even when trying his hardest. Frequently, a child will be able to produce a sound or word at one time and not be able to say is again when he wants to. A parent may hear words when the child is playing alone or when he is angry, but when asked to say the same word, he can't. This can be very frustrating for both the child and the parents.
A child who has Apraxia will not simply "grow out of it". Without speech therapy, the child's communication skills may improve as he grows older, but his speech will still be filled with errors and be difficult to understand. Therapy for Apraxia is generally intensive (2-3 times per week) and is started as soon as the disorder is identified and the child is old enough to participate in therapy (18-30 months).