I am grinning ear to ear. A giant weight has been lifted off my shoulders. I recently switched neurologist's offices and started over with a new team, hoping to find the answers to the parts of my illness that remained unexplained by the POTS/syncope/migraines diagnoses. In particular, the fact that sometimes I am completely paralyzed when I "come to" from a syncope.
I have talked to others with POTS who have had this same problem, and I don't know if this same answer will fit, but I wanted to share in case this information could possibly help someone else who is experiencing this paralysis. Apparently, I have narcolepsy (with cataplexy); by taking a very detailed history all the way back into my early childhood, they were able to determine that I had the narcolepsy BEFORE I had POTS, but the cataplexy only showed up when I started having syncope. It seems that for me, the syncope triggers the cataplexy most of the time; it almost never happens without me fainting first. The sleep specialist said that narcolepsy and dysautonomia are mediated in some of the same parts of the brain, and for reasons that aren't yet completely understood, people who have one tend to have higher rates of the other than healthy people.
He said that this will make treatment of both disorders more complicated, obviously. But I am just so excited to have an answer finally! And to have a doctor who actually understood what I was talking about and who was so thorough and asked so many questions that seemed like the "right" questions if that makes any sense. I don't recall any other doctors ever asking about before I got sick with the POTS, but here it turns out that made it so much more obvious once he knew what he was looking for.
So anyone else out there who is having that same problem of being paralyzed when they come out of the syncope, I would encourage you to at least consider consulting a sleep specialist to have narcolepsy ruled out. There is no cure, but he said there are treatments they can try for it. At any rate, it's reassuring to have an explanation for something that has been so scary and difficult to explain, and that some doctors have treated me like a nut for.