About Sympathetic Pain
CRPS, also known as complex regional pain syndrome, is a very vague term with a broad definition globally describing prolonged pain, inflammation, and excessive unpleasant sensation that follows an injury to an extremity, either the legs or the arms. The older term for CRPS was reflex sympathetic dystrophy and causalgia.
Classically disorders of the sympathetic system originally referred to as RSD, reflex sympathetic dystrophy, has been renamed complex-mediated pain syndrome, or CRPS type I and CRPS type II. This was done in 1994 by the International Association for the study of pain.
CRPS is generally caused by an imbalance of small peripheral C5 nerves that carry sensations of pain from the source to the brain. When these nerves fire excessively, this triggers an inflammatory response that is designed normally to assist in healing and rejuvenation after injury.
Overactivation of the system, however, results in pathology that can be acute, lasting less than six months, or chronic when it lasts more than six months. CRPS is divided into type I and type II. Type I, the etiology is often unknown. It may be something as subtle as an intravenous needle placement on a skin condition for a minor injury.
CRPS type II is often associated with injury to one of the larger nerves. This could happen with a crush injury or an extremity surgery.
Typical symptoms of CRPS are an increase in painful sensation after a normal or nonpainful touch. We call this hyperalgesia.
The skin may exhibit changes in skin color, swelling of the affected extremity, and temperature changes either cooler or sometimes warmer than the corresponding normal limb.