Complex Regional Pain Syndrome

What is complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is a condition that usually affects a limb (an arm or a leg) after an injury and causes ongoing pain that is much stronger even after the injury has healed. The limb is often very sensitive so that even light touch to it may feel painful. Normal pain in the affected limb or elsewhere in the body may feel much more intense than usual.

The affected limb may also show changes in skin, temperature, nails, or hair, along with unusual sweating. Over time, a person with CRPS may have trouble moving the affected limb and may also develop weakness, tremors, or stiffness in their muscles and joints.

In more severe or long-lasting cases, a person with CRPS can't work or do their usual daily activities. Pain and trouble with everyday tasks can improve over time, but most people with CRPS still have some feelings of pain after a year. 

Types of CRPS

There are two types of CRPS:

• Type 1 happens after illness or injury that doesn’t cause any specific nerve damage. Most people with CRPS have this type.
• Type 2 happens after damage to a specific nerve.

Symptoms of CRPS

Most CRPS symptoms develop because CRPS affects nerves that control the motion of a person’s limbs. CRPS-related pain can happen all the time or come and go. Most often, the pain gets much worse when the affected limb is used or touched.

The most common symptoms include:

Intense pain

A person with CRPS develops intense, often long-lasting pain in their arm or a leg after an injury that itself may seem mild. Examples include a minor burn, cut or scrape, or wrist or ankle sprain. Over time, pain can spread from where the injury happened to include most or all of that limb. 

Often, the skin of the affected limb can be very painful with light touch or normal physical contact, and using the limb can also be very painful.

Less often, pain and other symptoms can happen in the same place on the opposite side of the body. This “mirror pain” is thought to happen when pain signals are processed differently in the spinal cord and brain, leading to pain in the opposite limb. It is usually less severe and may improve over time.

Skin changes in the affected body part

In a person with CRPS, an injured arm or leg may often feel warmer or cooler than the body part on the opposite side. Skin may also change color, becoming blotchy, blue, purple, gray, pale, or red.

Skin in and around the affected area can become shiny and thin, or it can become thick and scaly. Skin changes may also happen because people avoid using the painful arm or leg.

Not using the limb can itself cause swelling and changes in the skin and nails, even without CRPS. Because of this, it can be hard to tell which changes are caused by CRPS and which are caused by reduced movement. Gentle movement and early physical therapy may help.

Nail and hair growth and sweating

In CRPS, hair and nails on the affected limb may grow very quickly or not at all. People may also notice more or less sweating in that area.

Stiffness in affected joints

People with CRPS may find that their joints become stiff and more difficult to move. Stiffness can be made worse by trying to keep the affected body part still because of pain. 

Thinning of bone or excess bone growth

CRPS can cause changes in bones of the affected limb. A person’s bones may change shape or become thinner. In rare cases, the bones of CRPS-affected limbs may change shape. These changes can put pressure on the surrounding tissue and nearby nerves to make CRPS symptoms worse.

These bone changes are often visible on X-rays or with other imaging tests.

Poor muscle strength and movement disorders

Problems with muscle strength and movement may get better when a person recovers from CRPS. But in some cases, severe stiffness can develop around a person’s joint. These people may need orthopedic surgery to make muscle tendons longer to help the affected joint move more easily. Tendons are strong, flexible bands of tissue that connect muscles to bones.

Rarely, people with CRPS may have movements they can’t control in their affected body parts. This could include tremors, making jerky movements, or dystonia. Dystonia is a movement disorder that causes muscles to tighten or contract without control, leading to twisting movements or unusual positions.

Who is more likely to get complex regional pain syndrome?

CRPS is more common in women than men. Most people are diagnosed in middle age or later in life. CRPS is rarer in children.

The most common causes of CRPS are:

• Fractures (broken bones): A broken bone, especially a broken wrist, is the most common cause of CRPS. A bone that moves out of place or breaks into pieces, or pressure from a tight cast can injure nerves. Casting may also cause CRPS because it can keep the person from using their limb for a long time. Casts can also change how the affected limb feels, such as increasing sensitivity to touch and temperature.
• Surgery: In rare cases, surgery can damage nerves, which can sometimes lead to CRPS. This could happen from the surgery itself, stitches, or scar tissue that forms after. 
• Sprains or strains: A minor joint injury, such as a wrist or ankle sprain, can sometimes lead to CRPS.
• Burns or cuts: Burns, cuts, and needle sticks can also damage nerves and in rare cases, lead to CRPS.

Risk factors for CRPS

A risk factor is a condition or behavior, like high blood pressure or smoking, that increases the likelihood of having a certain health problem compared to those who don't have the risk factor. Having a risk factor doesn't mean a person will have CRPS, and not having a risk factor doesn't mean they won’t.

Some factors that can increase the risk for getting CRPS are:

• Asthma
• Certain blood pressure medicines (ACE inhibitors)
• Menopause
• Weak bones (osteoporosis)
• Migraine
• Smoking

A person’s genes can also affect whether and when they develop CRPS. For example, families and siblings of people with CRPS may be more likely to develop CRPS at an early age. Researchers are studying whether gene changes (called variants or mutation) may be linked to CRPS.

How is complex regional pain syndrome diagnosed and treated?

Diagnosing CRPS

CRPS is uncommon, but it can happen after an injury or surgery. If pain after an injury seems unusually severe or lasts longer than expected, it’s a good idea to talk with a doctor.

There is no laboratory or blood test for CRPS. The condition is diagnosed based on a person’s symptoms and a physical exam by a doctor who is familiar with nerve and pain syndromes. This could be a neurologist, orthopedist, or plastic surgeon.

A detailed exam might include nerve conduction studies. These tests check how well nerves send electrical signals. They can detect nerve injuries linked to CRPS type 2 but usually cannot confirm CRPS type 1.

To diagnose other conditions that can cause symptoms similar to CRPS, doctors can use certain blood tests along with imaging tests such as ultrasound, MRI (magnetic resonance imaging), or bone scans.

Learn more about neurological diagnostic tests and procedures.

Treating CRPS

There is no cure for CRPS, but treatment can help people manage their symptoms. Since CRPS can affect people differently, treatment may be different for each person.

Treatment for CRPS usually focuses on reducing pain and improving daily life. People may need to try different treatments to find what works best for them. Treatment usually works best when it is started early.

Treatment can include:

Rehabilitation and physical therapy

Physical therapy and gentle movement of the affected limb can be important for treating CRPS. They can help maintain flexibility, strength, and function in the affected limb.

Exercising the affected body part helps prevent or improve changes in the way the spinal cord and brain communicate pain signals that happen in people with chronic pain and from not using the affected body part. Occupational therapy can help people learn new ways to stay active and return to their daily life.

Reducing swelling

Keeping the affected arm or leg elevated when resting or sleeping may help reduce swelling. Compression stockings or sleeves can limit swelling, especially when standing up.

Medicines

Several medicines can help with symptoms of CRPS, especially when used early after diagnosis. These medicines are used “off label” to treat CRPS. This means they are approved for other conditions but are also used to help with CRPS symptoms.

• Acetaminophen (Tylenol)® for bone and joint pain.
• Anti-inflammatory drugs (called NSAIDS, like ibuprofen) for pain and swelling.
• Medicines (like gabapentin) that can work for nerve-related pain conditions.
• Pain-relief sprays, creams, or patches applied to the skin.
• Medicines that strengthen bones.
• Steroid medicines (corticosteroids) to reduce pain and swelling.
• Botulinum toxin (like Botox®) injections to help relax tight muscles and improve hand or foot movement.
• Opioids for severe pain, although long-term use can sometimes make pain harder to control and the body may begin to rely on them.

Dorsal root ganglion (DRG) stimulation

This treatment sends mild electrical signals to a small group of nerve cells near the spinal cord that send pain messages to the brain. By changing how these nerves send pain messages, the treatment can reduce pain in some people with CRPS.

Deep brain stimulation

Electrical stimulation in areas of the brain that control pain can also work for some people with CRPS. In a treatment called deep brain stimulation (DBS), small wires are placed in the brain during surgery and connected by wires under the skin to a battery placed in the chest. A person can turn the stimulation on and off using a handheld controller.

Implanted pain medicine pumps

Small pumps can be implanted under the skin to deliver pain-relieving medicines directly into the fluid around the spinal cord.

Exploratory treatments

People with CRPS may not get enough relief for their severe pain from any of the treatments described above. In some specialized medical centers, doctors may use low doses of a medicine called ketamine to help reduce pain. Ketamine is a medicine originally used for anesthesia during surgery that can also help reduce severe pain in some conditions.

Ketamine changes how the nervous system responds to pain signals. Because it can cause side effects, it is used only in specialized settings.

Spinal cord stimulation

For spinal cord stimulation, doctors place small wires near the spinal cord during a minor surgery. The wires send mild electrical signals to nerves. These signals create a tingling sensation that can help block pain. A person can turn the stimulation on and off using a handheld controller.

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Spinal cord stimulation (SCS) is giving new hope to people with neurological disorders.

Explore SCS

Psychological and other supportive therapies

Living with severe or long-lasting pain from CRPS can affect a person’s mood, sleep, and daily life. Psychological therapies such as cognitive behavioral therapy (CBT) can help people learn skills to cope with chronic pain, reduce stress, and stay active. These approaches can be helpful even if a person does not have depression or anxiety.

Some people with CRPS may get relief from a rehabilitation technique called graded motor imagery. In this approach, people use mental exercises to “retrain their brain.” These exercises include imagining moving painful body parts without actually moving them and using a mirror to watch the healthy limb move. 

Other therapies like acupuncture may help relieve symptoms in some people with CRPS.

What are the latest updates on complex regional pain syndrome?

The National Institutes of Health (NIH), which includes NINDS, is the nation’s leading federal funder of research on neurological disorders. NIH conducts research on disorders including CRPS and funds research at major institutions and universities.

NIH funds a broad range of pain research, including studying pain pathways in the brain, how the brain senses pain, and how short-term pain changes into long-term pain. NIH also supports the development of new therapies for pain, and funds research on potential new targets for pain treatments, as well as clinical trials testing new pain treatments.

The Helping to End Addiction Long-term® Initiative, or NIH HEAL Initiative® is an NIH-wide effort to improve prevention and treatment for addiction and to develop better ways to manage pain. The HEAL Initiative supports research to develop safe and effective treatments for pain and help reduce use of opioids.

HEAL Initiative-supported scientists are studying how chronic pain works in the body and are trying to develop new, effective pain treatments that are less likely to lead to addiction. This research may lead to new treatments for pain disorders like CRPS.

The National Institutes of Health Brain Research Through Advancing Innovative Neurotechnologies® Initiative, or The NIH BRAIN Initiative®, is developing new tools to study the brain in precise detail. Scientists working with the BRAIN Initiative are also studying ways to change brain activity to treat pain. 

NIH-supported scientists are studying new ways to better understand and treat CRPS. Research includes:

• Understanding how problems with types of T cells (part of the immune system) may lead to CRPS. This research may lead to new ways of targeting the immune system to treat CRPS. 
• Studying how the brain responds to touch, temperature, and pain in children with CRPS.
• Improving how DBS is used for chronic pain conditions like CRPS

For more information on research about CRPS, check NIH RePORTER, a searchable database of current and past research projects funded by NIH and other federal agencies. RePORTER also has links to publications and resources from these projects. 

For research articles and summaries on CRPS, search PubMed, which contains citations from medical journals and other sites.

How can I or my loved one help improve care for people with complex regional pain syndrome?

Consider participating in a clinical trial so clinicians and scientists can learn more about CRPS. Clinical research with human study participants helps researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of participants are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities. This helps make sure that study results apply to as many people as possible and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research, visit the NINDS Clinical Trials site and NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with CRPS at ClinicalTrials.gov, a searchable database of current and past clinical studies and research results.

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