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Complex regional pain syndrome

Complex regional pain syndrome is a debilitating, painful condition in a limb, associated with nerve, skin and bone abnormalities. The condition often follows an injury to that limb. However, there is no relationship to the severity of the injury, and in some cases there is no history of any injury. It usually affects one limb, but can later spread to involve additional limbs.

The symptoms of complex regional pain syndrome vary in severity and how long they last.

The main symptom is pain in an arm or leg, which is often burning, sharp, stabbing or stinging. Early treatment is often effective in treating symptoms. Complex regional pain syndrome can sometimes cause severe problems and be difficult to treat.

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What is complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is a stronger than normal reaction of the body to an injury. The cause of CRPS is not known. The nerves in the affected limb are much more sensitive than other nerves and this causes pain and tenderness in the affected area. The brain is also involved. The way the brain communicates with your affected arm or leg changes.

The pain usually starts after an injury but may occur without an injury. It usually affects an arm or a leg but can affect another part of the body. The injury may be severe, such as a broken bone or a damaged nerve, or may be a minor injury.

CRPS is not in your imagination or in your mind. However, some emotional factors, like fear, worry or feeling depressed, can make the pain worse than it already is.

What causes complex regional pain syndrome?

There is often a history of an injury. The injury may be very minor, such as a cut to the finger. The symptoms do not appear to be related to the severity of the injury. The injury may not be remembered.

CRPS can also start after other problems such as a head injury, stroke or prolonged bed rest.

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How common is complex regional pain syndrome?

CRPS affects about 1 in 4,000 people each year. CRPS can affect any age but is more common between the ages of 40 and 60 years. It can also affect children, although it is very rare in children aged younger than 6 years. The number of CRPS cases among teenagers and young adults is increasing. Although CRPS can start after a minor injury, it is more common after an injury to a nerve or after a fracture.

What are the symptoms of complex regional pain syndrome?

The symptoms of CRPS vary in severity and how long they last. Symptoms usually begin within one month after an injury or after having to stay in bed for a long time. The main symptom is pain in the arm or leg, which is often burning, sharp, stabbing or stinging. There may also be tingling and numbness.

The symptoms are usually much worse than you would expect from the injury. CRPS pain continues after the original injury has healed. The symptoms are often severe and have a big effect on day-to-day activities. The pain may spread to other limbs. The pain is constant and can become worse rather than better with time. Staying in bed and not moving around makes the pain and stiffness worse.

Movement may be limited, both because of the pain and because joints can feel stiff. The muscles may become weak. Other muscle problems may occur and include sudden and severe spasms, tremors, severe jerking and other abnormal movements.

The pain and other symptoms often spread up the arm or leg from the site of the original injury. The symptoms may suddenly affect the opposite limb.

Many patients say that their limb 'feels strange'. It can feel as if it does not belong to the rest of the body and as if it is not your own limb. Sometimes the limb feels bigger or smaller than normal.

As well as pain, the affected area may have other symptoms such as:

  • Skin sensitivity: the skin may become oversensitive to light touch.

  • Allodynia: this means that you feel pain even after just a gentle touch, such as clothes brushing your skin or even air blowing on your skin. This may be felt as severe pain.

  • Swelling: may occur over the painful region.

  • Temperature differences between opposite sides: the affected arm or leg may often be warmer or cooler and the temperature may keep changing.

  • Abnormal sweating.

  • Skin changes:

    • Abnormal skin changes may occur, like 'goosebumps' and skin rashes.

    • There may be changes in the skin colour of the affected limb.

    • Skin infections can occur and can be very severe.

    • Your skin may become shiny, dry or scaly.

  • Hair changes: hair may become coarse but then become thin.

  • Fingernail or toenail changes: nails in the affected area may become brittle (crumbly or break easily) and grow faster at the beginning and then slower.

Psychological symptoms

Psychological symptoms may include:

  • Difficulty relaxing.

  • Feeling less confident in yourself.

  • Feeling unable to cope.

  • Difficulty getting or accepting support from friends or family.

  • Depression (this is common).

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Are there any tests for complex regional pain syndrome?

The diagnosis is usually made by an examination by a specialist. The diagnosis may be difficult, especially in the early stages. It is very important to diagnose CRPS as early as possible because early treatment helps you to recover more quickly.

There are no specific blood tests or other investigations. However, investigations may be important to rule out any other cause for your symptoms.

Are there treatments for complex regional pain syndrome?

Editor’s note

Dr Sarah Jarvis, 2nd June 2021

New guidance on chronic pain from NICE
The National Institute for Health and Care Excellence (NICE) has issued new guidance on chronic pain. This includes both 'primary' chronic pain, such as that caused by CRPS, and 'secondary' chronic pain, seen in conditions such as rheumatoid arthritis.

Most of the guidance is very much in line with the recommendations in this leaflet. It stresses the importance of exercise and physical activity. It also recommends a multidisciplinary team approach to help you manage your symptoms.

Where medication is concerned, the guidance makes several recommendations for CRPS:

  • You should not be started on strong 'opioid' painkillers. If you are taking them, your doctor should advise you about the risks (including the risk of addiction) and how they can work with you to find alternatives.

  • You should not be offered treatment with medicines developed to treat epilepsy, including gabapentinoid medicines, unless it is as part of a clinical trial.

  • You may be offered treatment with a local anaesthetic, either through a vein or applied to the skin. However, this should only be offered if it is as part of a clinical trial.

  • You should not be offered cannabis-based medicines.

Care for CRPS aims to give education, pain relief, physical rehabilitation and psychological support. There is a lack of high-quality evidence for the effectiveness of most individual treatments and further research is needed.

However, early treatment that looks at the whole problem is often effective. Treatment includes helping you to understand the condition and what you can do to help yourself. Other treatments may reduce pain, or be physical treatments like physiotherapy, or be support and treatment for any psychological difficulties. The right treatment for CRPS is different for each person but the aim of all treatments is to allow you to use your affected arm or leg as normally as you can. The success of some treatments may depend on how much effort you are able to put into them.

Do I need to see a specialist?

Your GP will usually refer you to see a specialist so that:

  • The diagnosis of CRPS can be confirmed.

  • Other causes for your symptoms can be ruled out.

  • You can be helped with a treatment plan to control the difficult symptoms, including pain and distress.

  • Treatment to keep you as active as possible can be provided, including physiotherapy.

If your symptoms are more severe and don't improve with treatment then you may need to be referred to a Pain Clinic or another specialised unit for further treatments. Because of the different symptoms with CRPS, you may need to see other teams of doctors too, such as:

  • A bone specialist (orthopaedic specialist).

  • A bone and joint specialist (rheumatologist).

  • A nerve specialist (neurologist).

  • A skin specialist (dermatologist).


Rehabilitation should be considered for anyone with CRPS and should be started early. Support and treatment from a physiotherapist and an occupational therapist are incredibly important. Although exercise may make the pain worse, not exercising also makes the pain worse and the therapist will help you to find the 'happy medium'.

Rehabilitation includes helping you to use the limb with gentle exercises and helping to make the limb less sensitive. Other treatments help you to use the limb more normally and reduce any swelling (oedema).

Specialised units may also use more specialised treatments such as mirror visual feedback and graded motor imagery.

Mirror visual feedback involves you describing your affected and your unaffected arm or leg with your eyes closed. Then you imagine moving your affected arm or leg and then do this while looking at it in a mirror.

Graded motor imagery involves you imagining moving your affected arm or leg and also watching your normal limb in a mirror while you move it.

Medication treatment

Medicines can be used to help reduce the pain and help you to sleep. Simple medicines for pain relief such as non-steroidal anti-inflammatory drugs (NSAIDs) are used first. Then the strength and doses of the medicines are increased until the pain is controlled well enough for you to be able to use your arm or leg a little.

If the pain is not reduced then other types of medicine are used - for example, tricyclic antidepressants or gabapentin. See the separate leaflet called Neuropathic Pain for more details.

Medications may also be needed for depression.

Pamidronate is a bisphosphonate medicine that is given by slow injection into a vein. It may be given as a one-off treatment if you have had CRPS for less than six months but it isn't getting any better.

Psychological support and treatment

Sometimes psychological treatment can help to reduce distress. A psychological assessment by an expert in chronic pain may help to identify problems that can be helped. Psychological interventions (including cognitive behavioural therapy and relaxation techniques) can help the emotional difficulties associated with CRPS.

What are specialised treatments for CRPS?

There are two particular specialised CRPS treatments:

Pain management programme (PMP)

This is a programme to help you to improve your quality of life and manage your pain better. PMP is given to a group of people with CRPS and includes help from different health professionals, including doctors, physiotherapists, occupational therapists and psychologists.

Spinal cord stimulation (SCS)

This involves using a fine wire which is placed close to the nerves in your back and is connected to a 'stimulator'. The wire is kept in place for a short time and, if it works well, an operation can be done to make it permanent. The SCS can be taken out when it is no longer needed. There is some research suggesting that the effects of SCS may not be permanent.

Research shows that in some patients these treatments can work very well. Specialised centres may also use other treatments. The evidence for these specialised treatments is not completely proven but many people with CRPS have found one or more of them very helpful.

What is the outcome (prognosis)?

Most people with CRPS get better. CRPS is very variable both in how severe the symptoms are and how long the symptoms last. CRPS may be mild and get better by itself or with treatment.

In some people, CRPS can cause severe symptoms and last for many years, leading to severe physical and psychological difficulties, and even suicide.

There is no way of knowing whether your CRPS will be the type to get better or when. Even if you have CRPS for several years, the rest of your body will continue to work as normal.

Some people with CRPS have times when the symptoms are bad (exacerbations) and other periods of time when the symptoms are much fewer or even disappear (remissions). The periods of exacerbation may last for weeks, months or years.

If it is not diagnosed and treated, CRPS can spread and affect other limbs. This makes CRPS much harder to treat.

Can complex regional pain syndrome be prevented?

People experiencing fractures should try to move the part of their limb that they can move as much as possible. They are also advised to have a good intake of vitamin C but there is no proven way that CRPS can be prevented.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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