Childhood apraxia of speech (CAS) has unknown causes. It is called apraxia because the errors produced are similar to the adult apraxia. There is no brain damage and no neurological damage, but it is a disorder of coordination, not strength.
Some of the characteristics of CAS include moderate to severe speech intelligibility, inconsistent sound errors (the same word will have different errors when repeated), unusual articulation errors, slow rate of speech and there is usually a gap in receptive and expressive language skills (receptive higher).
Here is a child who has been diagnosed with Apraxia.
Here is the same child 6 months later, with therapy.The best way to help children with this is frequent and intensive treatment. They tend to do better when seen individually rather than in group. In order to improve, they must practice. It is essential that the family practice with the child as well. "One of the most important things for the family to remember is that treatment of apraxia of speech takes time and commitment. Children with CAS need a supportive environment that helps them feel successful with communication." http://www.asha.org/public/speech/disorders/childhoodapraxia.htm#tx