It's actually not a disease, it's basically muscle strain from overuse, I think what happens is that a passageway in your wrist, called the Carpal Tunnel (it provides a path for the nerves that go to your hand), gets inflamed and it constricts around the nerves which are responsible for flexing your wrist and fingers, when that happens your hand goes numb and you can't move your wrist, fingers, or thumb, in serious cases you can end up permanently loosing the ability to use your hand because the pinched nerves can die.
https://en.wikipedia.org/wiki/Carpal_tunnel_syndrome