I have something called craniocervical instability. Basically the vertabrae in my neck, especially top two are way too mobile/unstable, an effect of a genetic syndrome called ehlers danlos syndrome and suffering whiplash 18 months ago.

When I turn my head or look up or down, the vertebrae can hit the important nerves that come out there, my brainstem, or the arteries going up to my brain. My case is actually fairly mild, but it’s enough to cause some real problems. So I wear a neck brace when I go to sleep (so I don’t sleep with my head turned) and when I’m in the car as an accident could be very dangerous for me. You can read more about CCI and related things here if you want

To give you an idea of the mobility I have here is one of my x-rays …