Childhood apraxia of speech (CAS) is an uncommon speech disorder in which a child has difficulty making accurate movements when speaking.
In CAS, the brain struggles to develop plans for speech movement. With this disorder, the speech muscles aren't weak, but they don't perform normally because the brain has difficulty directing or coordinating the movements.
To speak correctly, your child's brain has to learn how to make plans that tell his or her speech muscles how to move the lips, jaw and tongue in ways that result in accurate sounds and words spoken with normal speed and rhythm.
Childhood apraxia of speech care at Mayo Clinic