Hmm... it wouldn't take "much change" to cause problems.

A lot of what you're saying sounds familiar. If I turn my head too much to either side or tilt it back, even slightly, I'm in big trouble.

Another thing people often forget to take into account is inside damage. Although your exterior might look okay, when you have a violent slip or shake, your internal organs can go smashing about. A rehab specialist friend gently touched the area around my liver - and I jump off the table. That was two years after the crash.