RSD is a very serious, rapidly spreading disorder that must be treated aggressively and properly. Unfortunately, the causes of the condition are unknown, but most often, those who have RSD often have suffered trauma to their extremities, like sprains, fractures, surgery, and even some brain injuries.   Some injuries that RSD has been known to follow include: Abrasions Lacerations Intramuscular injection (injections into the muscle) or medication/drugs Blunt trauma Neck/shoulder/chest injuries and trauma Gunshot wounds Crush injuries   As there is not really a known cause of RSD (just health issues that are known to precede it), there is no single test to decide whether or not a patient has RSD. Sometimes tests like x-rays, MRIs, or nerve tests can be useful for diagnosis. Most of the time, healthcare providers will make the diagnosis when a variety of conditions are met, including the lack of a more specific diagnosis.   Additionally, because there is no defined cause, there is no defined cure.