Complex regional pain syndrome (CRPS) is a condition that causes pain, changes in skin color and other symptoms in a certain part of your body — usually in your extremities. Your extremities include your arm, leg, hand or foot.
The symptoms of CRPS can greatly impact the function of your affected limb, sleep, daily activities and your mental health.
Experts believe that CRPS occurs as a result of dysfunction in your central or peripheral nervous systems. Your central nervous system consists of your brain and spinal cord. Your peripheral nervous system relays information from your brain and spinal cord to your organs, arms, legs, fingers and toes. The abnormal functioning results in an overreaction to pain signals that your nervous system can’t shut off.
There are two subtypes of CRPS:
- Type I: This type occurs without nerve damage. It happens after an illness or injury that didn’t directly damage a nerve. Type I was formerly known as reflex sympathetic dystrophy.
- Type II: This type occurs after known nerve damage. It was formerly known as causalgia.
CRPS can also either be acute (short-term) or chronic (lasting longer than six months). It’s usually treatable.
Who does CRPS affect?
CRPS more commonly affects adults than children. The peak onset is around 40 years of age. CRPS affects people assigned female at birth more often than people assigned male at birth.
About 66% to 80% of cases occur in people of European ancestry.
How common is CRPS?
CRPS is relatively rare. It affects about 200,000 people every year in the United States.
What are the symptoms of CRPS?
How severe and how long symptoms of complex regional pain syndrome (CRPS) last varies from person to person.
Symptoms of CRPS typically start within four to six weeks after an injury, fracture or surgery, but they can develop without a known cause.
The most common and prominent symptom of CRPS is pain. The pain is constant or intermittent and is a burning, stinging or tearing sensation. It’s often deep inside your affected limb.
Sensory changes are also common in the affected area and may include:
- Increased sensitivity to painful stimuli (a pinch may feel more painful than usual).
- Feeling pain from stimuli that are usually not painful (such as just touching your skin).
- Numbness.
Other symptoms of CRPS in the affected area include:
- Skin swelling: Swelling may come and go or remain constant.
- Decreased function in your affected limb: You may experience a decreased ability to move your affected limb and/or increased stiffness. You may also have difficulty placing pressure on your affected limb or joint.
- Changes in skin temperature: The skin on your extremity may feel warmer or cooler compared to the opposite one.
- Changes in skin color: Your skin may appear blotchy, pale, purple/bruised or red.
- Changes in skin texture: Your skin may become shiny and thin or excessively sweaty.
- Changes in nail and hair growth: You may have rapid hair or nail growth or no growth.
Since the symptoms of CRPS usually improve over time, it’s easiest for healthcare providers to diagnose it in the early stages. It’s important to see a provider soon after you experience symptoms of CRPS.
What causes CRPS?
Researchers aren’t sure why some people develop CRPS while others with similar injuries don’t. They think it’s due to an inflammatory or immune reaction in both your peripheral and central nervous systems.
In more than 90% of cases, CRPS results from nerve trauma or injury to the affected limb that damages the thinnest sensory and autonomic nerve fibers. These small fibers transmit pain, itch and temperature sensations. They also control the small blood vessels and the overall health of surrounding cells.
The most common injury associated with developing CRPS is a bone fracture, especially a wrist fracture. A displaced or splintered bone or pressure from a tight cast can damage nerves.
Other common injuries that can lead to CRPS include:
- Surgery: A surgical incision, stitches or scarring can cause nerve injury.
- Sprains or strains: When connective tissues are damaged, it can result in excessive movement of a joint, which over-stretches nearby nerves.
- Burns, bruises or cuts: These are all noticeable signs of injuries that may also have damaged underlying nerves.
CRPS can also develop without an obvious injury or due to periods of prolonged immobilization.
Certain factors that may increase your risk of developing CRPS include:
- Poor nerve health: Conditions such as diabetes can leave your nerves less resilient and able to repair themselves. It may be difficult for people with peripheral neuropathy to regrow their nerve cells from an injury that wouldn’t otherwise cause problems. Smoking and previous chemotherapy can also make it difficult for your nerves to regenerate.
- Immune system issues: Your immune system plays a large role in inflammation. Some people with CRPS have elevated levels of inflammatory chemicals called cytokines that contribute to certain symptoms of CRPS. CRPS is also more common in people with other inflammatory and autoimmune diseases, such as asthma.
- Genetics: Your genes can affect your ability to recover from an injury. Researchers have discovered family clusters of CRPS. Although this is rare, it suggests that there may be a genetic link to CRPS.