Complex regional pain syndrome, or CRPS, is a relatively recent name for related conditions that have been known by other names in the past, such as “reflex sympathetic dystrophy” (RSD) and “causalgia.” What was often referred to as RSD in the past is now more commonly known as “CRPS-I,” and what was called causalgia is now more typically referred to as “CRPS-II.” Other names have included reflex neurovascular dystrophy, algoneurodystrohpy, sympathetically maintained pain, and Sudek’s syndrome. As might be guessed from the many names for these associated conditions, they are complicated and often not well-understood. They generally involve trauma to the peripheral nerves and have symptoms involving the sympathetic nervous system.
CRPS-I or RSD, can result from even very minor injuries, with no apparent nerve damage — in many cases people may not even recall a specific traumatic event when the complex regional pain syndrome symptoms show up weeks or months later. Fractured limbs, contusions, and even minor surgical procedures can result in the onset of CRPS-I symptoms, which often include a severe burning pain in the limb that is made worse with movement or by touching the limb. Other symptoms can include increased sweating and skin temperature in the affected area, and sometimes swelling. Long term symptoms can include skin constriction and reduced temperature in the limb. The skin, soft tissues and bone can atrophy, and the bone may develop osteoporosis.