That happened to Valerie a few years ago. She has MS, and she woke up paralyzed in half of her body. She got her movement back and retrained herself: to play the violin again (listen here), to dance the tango, to do things more deft and skillful than anything I've learned how to do without ever having been paralyzed.
What I think is really cool about Valerie (besides her intelligence and talent and temperament and humor) is how this experience has made her aware and grateful of how precious it is to move. Yesterday her arm fell asleep, and it scared her into thinking that it might be her last day with her body, so she went up to the Eastern Prom and swang on the swingset overlooking the ocean, in the setting sun. I've never even been on that swingset, but you can bet I'm going to go now.