Well, two.
"Spasmodic torticollis", a variety of "focal dystonia". I.e., when the neck muscles spasm making the head twist in various ways.
This is the most common symptom for me of my tic, and exclusively makes my head face down and to the right (as if looking at the tip of my right shoulder).
'Hemidystonia' - contractions in my right arm - are the second most common.
"Myoclonus" is evidently another word for it, or something very similar at least.
Whee, learned something.
It doesn't seem to include the non-spasmodic bilateral asphyxiating neck clenching, though; I wonder if there's a word for that too.
"Spasmodic torticollis", a variety of "focal dystonia". I.e., when the neck muscles spasm making the head twist in various ways.
This is the most common symptom for me of my tic, and exclusively makes my head face down and to the right (as if looking at the tip of my right shoulder).
'Hemidystonia' - contractions in my right arm - are the second most common.
"Myoclonus" is evidently another word for it, or something very similar at least.
Whee, learned something.
It doesn't seem to include the non-spasmodic bilateral asphyxiating neck clenching, though; I wonder if there's a word for that too.

Comments
The asphyxiation thing could be some truly severe laryngeal dystonia (if you also can't talk), but dunno beyond that, though.
(Surely someone's made a conlang which has only non-pulmonic phones?)
Conlangs: I remember that my boyfriend was working on one solely based on waveforms awhile back, and I've seen a bunch of sketches based on sign language, dancing, etc. But you could always just use Morse code. :P
At least I think that's the case; I'm generally more fighting off instant panic mode during, so it can be a bit hard to track.
Morse code, signed, & theoretical construct based languages are cheating. :-P
The easiest way I could think of to tell would be to ask someone to feel your chest next time one of these things happens. If your doctor decides to pursue targeted treatment (injections, surgery) somewhere down the line, knowing which muscles to target is pretty helpful. Of course, for whoever it is would have to be pretty used to these in order to stay clear-headed and do everything else that might help at once, so... yeah, that takes experience I hope you never get.
If you want to talk more about coping with not breathing, catch me next time I'm on.
Well, there's always the chance that it happens while I'm around the doc. Which, given that thinking about it is also a trigger, is at least plausible. But it's not more than what he already saw; and I can simulate the thing partially at least.
I doubt surgery would help (what would one cut or sew?); botox, meh.
So far I'd be very leery of anything of the sort, especially any nerve surgery. If I were asphyxiating on a regular enough basis that the oxygen depletion damage to my brain were significant I'd consider it, but I'm not.
On the other hand, though, it's not a risky procedure either. They aren't usually cutting major nerves even in surgery. For most people who are candidates for high doses for the paralytics/surgery, that nerve or muscle wasn't really functioning to begin with. For lower-dose paralytics, it doesn't entirely paralyze the muscle, and may not even affect normal motion; it's just keeping it from functioning at its full strength, which it shouldn't be doing anyway.
But this is one of those visceral things where I really really really don't want anyone fucking with my nerves unless there's an amazingly good reason that's the best option.
Regardless, it seems like you're at a point where there aren't any pleasant options. I recommend learning them all at the good times, whenever those may come--otherwise, you can wind up stuck at the bad points with much more stress than needed.