Although there is some controversy in using sign language for a child with severe verbal apraxia, I found it to be extremely useful. Some experts seem to think that non-verbal children with rely only on their signs and not be motivated to speak. In our experience that wasn't the case, using sign language allowed her to communicate her needs with us and greatly reduced her frustration level.
My daughter wasn't diagnosed with apraxia until she was three. At that time she only said about thirty partial words, and they were difficult to understand. Prior to that she was in speech therapy making very little progress, and was prone to frequent outbursts due to her inability to communicate her needs.
We had much difficulty with her at mealtimes. She would point and scream at what she wanted, making for an unpleasant dining experience. Around age twenty-five months we began teaching her sign language related to meal time, such as more, milk and please. It was amazing how quickly she leaned them and how much more pleasant meal time became. Children even younger can learn sign language; I wish we would have started sooner. She very quickly knew about ten signs and became much calmer and was happy to have a way to communicated with us. In order to reenforce speech we would verbalize the word she was signing, however we would never make her say it - as she simply couldn't. A goal of learning one new sign a week could easily be achieved, and in a short period of time have a large vocabulary of signs.
As she grew and learned more language, her need for signs gradually dropped away. It did not slow her progress at all in learning to speak. In fact by the time she was six she was almost fully recovered from apraxia.
To read more about the author's daughter's amazing recovery from apraxia please visit apraxiaspeaks.com