I shut down sometimes in therapy too most of the tine my shutting down isnt having trouble opening my mouth to say the words. Its there are no words to decribe what I am feeling, kind of like my brain throwing the off switch no thoughts just a total blank. When this happens I eather tell my therapist im not thinking right now just a blank or I open my backpack. There is always something in there that I can pull out and say I brought this for you to see today. That gives me a chance to figure out whats going on. Other times when I cant figure out how to say something I ignore the question and throw one back at my therapist to answer. For example one time not so long ago my therapist and I had just sat down and she asked "how are you?" I threw back at her a question I think I asked her if she got my message on her voicemail. She answered but again "asked how are you?" Instead of answering her question I smiled and asked if she had heard anything about my son yet. She took a deep breath looked at me with her "she's avoiding that question look and answered my question. Then asked a different question of her own. we got around to how I was but not through that "how are you"' question. I could have answered I don't know, I was close to bla bla bla. I could have given her many different answers to that one question, so instead of trying to get all of those answers bouncing around to come out in some coherent way I chose not to answer it at all. Which is kind of how my therapist and I do things if I can't answer or don't want to I don't have to. She knows I have many different types of outlets so having to say the words that I can't say or don't want to say for me isn't a manditory thing. We just let things happen as they happen.