Complex Regional Pain Syndrome
Complex regional pain syndrome is an uncommon form of chronic pain that usually affects an arm or leg. Complex regional pain syndrome typically develops after an injury, surgery, stroke or heart attack, but the pain is out of proportion to the severity of the initial injury, if any.
The cause of complex regional pain syndrome isn’t clearly understood.
Complex regional pain syndrome (CRPS), also called reflex sympathetic dystrophy syndrome, is a chronic pain condition in which high levels of nerve impulses are sent to an affected site. Experts believe that CRPS occurs as a result of dysfunction in the central or peripheral nervous systems.
Complex regional pain syndrome (CRPS) is a chronic pain condition most often affecting one of the limbs (arms, legs, hands, or feet), usually after an injury or trauma to that limb. CRPS is believed to be caused by damage to, or malfunction of, the peripheral and central nervous systems. The central nervous system is composed of the brain and spinal cord, and the peripheral nervous system involves nerve signaling from the brain and spinal cord to the rest of the body. CRPS is characterized by prolonged or excessive pain and mild or dramatic changes in skin color, temperature, and/or swelling in the affected area.
There are two similar forms, called CRPS-I and CRPS-II, with the same symptoms and treatments. CRPS-II (previously called causalgia) is the term used for patients with confirmed nerve injuries. Individuals without confirmed nerve injury are classified as having CRPS-I (previously called reflex sympathetic dystrophy syndrome). CRPS type I requirements feature causation by an initiating noxious event, such as a crush or soft tissue injury; or by immobilization, such as a tight cast or frozen shoulder. CRPS type II is characterized by the presence of a defined nerve injury.CRPS symptoms vary in severity and duration. Studies of the incidence and prevalence of the disease show that most cases are mild and individuals recover gradually with time. In more severe cases, individuals may not recover and may have long-term disability.
The key symptom is prolonged pain that may be constant and, in some people, extremely uncomfortable or severe. The pain may feel like a burning or “pins and needles” sensation, or as if someone is squeezing the affected limb. The pain may spread to include the entire arm or leg, even though the precipitating injury might have been only to a finger or toe. Pain can sometimes even travel to the opposite extremity. There is often increased sensitivity in the affected area, such that even light touch or contact is painful (called allodynia).
People with CRPS also experience constant or intermittent changes in temperature, skin color, and swelling of the affected limb. This is due to abnormal circulation caused by damage to the nerves controlling blood flow and temperature. An affected arm or leg may feel warmer or cooler compared to the opposite limb. The skin on the affected limb may change color, becoming blotchy, blue, purple, pale, or red.
Other common features of CRPS include:
- Changes in skin texture on the affected area; it may appear shiny and thin.
- Abnormal sweating pattern in the affected area or surrounding areas.
- Changes in nail and hair growth patterns.
- Stiffness in affected joints.
- Problems coordinating muscle movement, with decreased ability to move the affected body part.
- Abnormal movement in the affected limb, most often fixed abnormal posture (called dystonia) but also tremors in or jerking of the affected limb.