There’s a pain rating scale called the McGill Pain Index. This scale starts at zero (no pain) and goes up to 50. A bone fracture is around a 15. Natural childbirth without preparation ranks just below amputation of a finger or toe, and both rank below a 40. Complex Regional Pain Syndrome (CRPS), also called Reflex Sympathetic Dystrophy (RSD), however, tops the list at a 42. And unlike childbirth or a broken bone, things with set beginnings and ends, CRPS never goes away.