How does one perform salaat if a medical condition makes it difficult or impossible to say the words?

As-salaamu alaikum. I try to follow the Hanafi school. Due to a medical condition (from a neck injury) I have serious problems with dizziness. I cannot do ruku or sajda, although I can stand and sit and do ruku and sajda by "signs" (nodding my head causes dizziness, but I can make signs with my eyes). Worst of all, reciting Qur'an and saying the other words of the prayer causes tension in my neck and brings on the dizziness. My question: Is it permitted to say the words of the prayer in my mind only? Or what if I just barely move my lips but don't actually pronounce the words? If not, what should I do? Also, am I obligated to make up prayers that I have missed because of this problem? Thank you for your help.