Complex regional pain syndrome (CRPS)

What is complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is an uncommon condition that causes ongoing pain in an arm or leg that's far more severe and long-lasting than you'd expect from the original injury. It most often follows an injury such as a broken bone, a sprain or an operation, though sometimes there's no obvious trigger at all.

Symptoms of CRPS

Pain is the main feature of CRPS. It's often described as burning, stabbing or stinging, and it usually stays in one limb, although it can occasionally spread further.

Your skin in the affected area may become so sensitive that everyday contact becomes painful. Doctors call this allodynia (feeling pain from something that wouldn't normally hurt, such as a light touch) and hyperalgesia (feeling more pain than expected from something that's already mildly painful).

Along with pain, you might also notice:

• changes in skin colour, such as blotchy, pale, blue, purple or red patches
• your skin feeling warmer or cooler than the same area on your other arm or leg
• skin that becomes shiny and thin, or thick and scaly
• sweating that's more or less than usual
• swelling (oedema) in the affected limb
• hair or nails that grow unusually quickly or slowly, or become brittle
• stiffness and difficulty moving the affected joint
• muscle spasms or tremors
• difficulty sleeping.

Rarely, CRPS can lead to thinning of the bone in the affected limb, skin infections or open sores, or muscles that waste away or become permanently tightened.

Living with constant pain can affect your mood, and some people develop anxiety or depression, or, during periods of severe pain, thoughts of suicide. If this happens to you, speak to a GP as soon as possible, or you can call the Samaritans free, any time, on 116 123.

Causes and risk factors

Doctors don't fully understand what causes CRPS. It usually develops within about a month of an injury such as a fracture, a sprain, a burn, a cut, or surgery to a limb, and it has also been linked to wearing a cast or keeping a limb still for a long period.

The pain that follows is far greater than these injuries would usually cause, and it often spreads beyond the original site to affect the whole limb.

Several theories try to explain why this happens. Your nervous system may overreact to the injury, so that pain signals keep firing even after the tissue itself has healed.

Some experts think the immune system plays a part, since inflammatory chemicals are often raised in people with CRPS. Others point to the sympathetic nervous system (the part of your body that controls your fight-or-flight response), which may become overactive and disrupt blood flow, temperature and sweating in the limb.

You may be more likely to develop CRPS if you:

• are female, since CRPS is diagnosed more often in women than men
• are in midlife or older, as most people are diagnosed in middle age
• smoke, since this can interfere with nerve healing
• have asthma, migraine or osteoporosis (thinning of the bones)
• take certain blood pressure medicines called ACE inhibitors
• are going through menopause
• have diabetes or another condition that affects nerve health
• have a close relative with CRPS, as genes may play a part, though it's still unlikely that other family members will develop it too.

CRPS can affect people of any age, including children, though it's rare in younger people.

Are there different types of CRPS?

CRPS is generally divided into two types, depending on whether there's evidence of nerve damage:

• Type 1: This is diagnosed when there's no confirmed damage to a specific nerve. This is the most common form, and was previously called reflex sympathetic dystrophy.
• Type 2: This is diagnosed when a specific nerve has been damaged. This was previously known as causalgia. Some people are first diagnosed with type 1, but are reclassified as type 2 if later tests find nerve damage.

CRPS can also be acute (recent and short-term) or chronic (lasting more than six months). In the early stage, the affected limb is often warm, red and swollen. Over time, some people find the limb becomes cooler, stiffer and thinner-skinned instead, while pain and sensitivity often get worse rather than better.

How is CRPS diagnosed?

There's no single test that confirms CRPS. A doctor familiar with nerve and pain conditions, such as a GP, neurologist or pain specialist, will ask about your symptoms and examine you. They'll check gently for changes in skin colour, temperature and swelling, without adding to your pain.

You may also have tests to rule out other conditions with similar symptoms. These can include blood tests, an X-ray, an MRI scan (a scan that uses magnetic fields to produce detailed images), or nerve conduction studies and electromyography (tests that check how well your nerves are sending signals).

Some specialists use a checklist of symptoms called the Budapest Criteria. Others may try a diagnostic nerve block, an injection of local anaesthetic near the affected nerves, since reduced pain afterwards can help confirm the diagnosis.

If you're diagnosed with CRPS, or the diagnosis is unclear, you'll usually be referred to a specialist pain clinic as soon as possible so treatment can start without delay.

How is CRPS treated?

There's no cure for CRPS, but a combination of treatments can help manage your symptoms, improve movement in the affected limb and support your day-to-day life.

Around 85% of people see their pain and other symptoms gradually ease within the first two years, though some continue to experience pain despite treatment. Starting treatment early gives you the best chance of a good outcome.

Non-surgical treatment

You'll usually be given information about CRPS and practical advice on managing flare-ups yourself, including relaxation techniques, pacing your activities, and continuing exercises at home.

Physiotherapy and occupational therapy

These play a central role. Your therapist may guide you through gentle stretches, exercises in water, or weight-bearing exercises, alongside desensitisation, where different textures are used against your skin to gradually reduce its sensitivity.

Mirror therapy and graded motor imagery

These are other techniques that use visual tricks, such as watching your unaffected limb in a mirror, to help retrain how your brain processes movement in the affected limb.

Everyday changes

These can include keeping the limb raised when resting, wearing compression garments to reduce swelling, staying active, and stopping smoking, since smoking can interfere with nerve healing.

Psychological support

Because living with CRPS can be emotionally difficult, psychological support such as cognitive behavioural therapy (CBT), a talking therapy that helps you manage how your thoughts and feelings affect your pain, is often part of your care. Acupuncture, biofeedback or hypnosis may also be offered as additional options.

Medicines

Your GP or pain specialist may also prescribe medicines, usually starting with the mildest option first. Options range from over-the-counter painkillers, such as ibuprofen or paracetamol, to anticonvulsants such as gabapentin or pregabalin, which were originally developed for epilepsy but also ease nerve pain.

Antidepressants such as amitriptyline or duloxetine may also be used, here for their effect on nerve pain rather than mood. Other options include topical treatments applied to the skin, such as lidocaine patches or capsaicin cream.

You may also be offered corticosteroids (steroid medicines), bisphosphonates (medicines that help protect bone), or injections to ease muscle tightness.

Opioids such as codeine or morphine are sometimes used for severe pain. However, they're often less effective for CRPS and carry a risk of dependency, so they tend to be used only for a short time and under close supervision.

Surgical and procedural treatment

If other treatments haven't helped enough, your care team may suggest more invasive options.

A sympathetic nerve block

This is an injection of anaesthetic near the nerves in your neck or lower back, which can sometimes provide significant relief and may also help confirm your diagnosis.

Spinal cord stimulation

This involves a small device placed under the skin of your abdomen or buttock, connected to wires positioned near your spinal cord. It sends mild electrical pulses that change how you feel pain, often replacing it with a tingling sensation instead.

This is usually only considered once you've tried other treatments for at least six months, and only after a successful trial period using temporary wires.

Dorsal root ganglion stimulation (which targets a cluster of nerve cells close to the spinal cord) and peripheral nerve stimulation work in a similar way, targeting smaller, more specific groups of nerves instead.

Other options

• Deep brain stimulation (electrodes placed in the brain during surgery)
• Implanted pumps that deliver pain-relieving medicine directly around your spinal cord
• Surgery to release a trapped nerve or lengthen a shortened tendon – in carefully selected cases
• A low-dose ketamine infusion, given over several days in a specialist setting, is sometimes used for pain that hasn't responded to anything else.

Because CRPS is complex, you're likely to be cared for by a team that may include a physiotherapist, occupational therapist, pain specialist, psychologist, social worker and your GP, all working together to help you manage your symptoms and stay as active as possible.

When should I see a doctor?

See a GP if you have ongoing pain, particularly after an injury that's stopping you from carrying out your everyday activities, or if the pain feels far worse than you'd expect for the injury you've had.

CRPS can be difficult to diagnose, so it's best to get help as soon as possible, since early treatment gives you the best chance of reducing your symptoms.

If your symptoms are getting worse, or aren't improving with treatment, ask to be referred to a pain specialist or a specialist pain clinic.