Spinal cord injuries are way too common. When I see someone who is paralyzed I automatically think that they probably suffered some type of traumatic accident, like a car wreck for example. This is true for many people, but once you learn more about the anatomy of the human body you realize that paralysis is often caused by disease rather than an accident that cuts or damages the spinal cord.
I have a friend who is having problems with movement because her nervous system is not working like it is supposed to, and she has not been in an accident. Her doctors are still trying to figure out what is going on..