To some extent the diagnosis of RSD is really a process of elimination. They test you for everything it might be and if they're all negative then it's RSD. It's not this simple and some people have more overt symptoms than others. They gave me a thermographic exam which suggested RSD and then a stellate ganglion nerve block which confirmed it. When the ganglion is anesthetized the hand will return to normal. Mine warmed up and the pain and symptoms vanished.