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Complex Regional Pain Syndrome

Complex Regional
Pain Syndrome


What you need to know about
Complex Regional Pain Syndrome

Excessive and prolonged pain and inflammation following an injury to an arm or leg are referred to as complex regional pain syndrome (CRPS). Acute (recent, short-term) and chronic (lasting more than six months) versions of CRPS exist. Reflex sympathetic dystrophy (RSD) and causalgia were previously used to describe CRPS. People with CRPS experience a variety of spontaneous or excessive pain that is significantly more than normal in response to something as simple as a touch. Changes in skin colour, warmth, and/or swelling on the arm or leg below the injury site are further signs. Although most people’s CRPS improves over time and eventually goes away, the uncommon severe or chronic episodes are extremely disabling.

The peripheral C-fiber nerve fibres that transmit pain messages to the brain are responsible for the majority of CRPS diseases. Their excessive firing also causes inflammation, which helps the body mend and rest after an injury. The nerve injury may be visible in some persons, but in others, a specialist may be required to locate and treat the lesion.

  • When the exact nerve affected was unknown, persons were previously categorised as having CRPS-I (formerly known as RSD).
  • People with CRPS-II are diagnosed after a specialist determines which nerve was affected (previously known as causalgia). Many persons with CRPS-II have more serious injuries that affect nerves that travel to muscles (motor nerves), causing weakness and muscle shrinking in specific places, making it easier to diagnose. The movement of muscles under conscious control, such as those used for walking, gripping objects, or talking, is controlled by motor nerves.

Because both types of CRPS have the same symptoms, nerve injury could be the reason. However, nerve injuries in CPRS I are usually more modest and go undiagnosed.

CRPS is more common in women, but it can affect anyone at any age, peaking around the age of 40. It’s uncommon in the elderly, who have less inflammation after an accident, and in small children, who heal so quickly.

CRPS has a wide range of outcomes:

  • Most ailments are minor, and the affected nerve regenerates over months to years. If this does not occur, symptoms may persist, resulting in long-term incapacity.
  • The result is determined by the degree of the initial injury as well as the person’s overall and nerve health. Younger people, children, and teenagers, as well as older adults with adequate circulation and nutrition, usually always recover. Smoking, as well as diabetes and prior chemotherapy, are substantial hindrances to nerve regeneration. Removing impediments to healing improves recovery chances and quickness.
  • Despite treatment, a small percentage of people suffer from long-term severe pain and disability. This could signal underlying distinct issues that are interfering with recovery and necessitate further testing and treatment.

CRPS is difficult to treat due to the wide range of symptoms, the fact that symptoms can fluctuate over time, and the difficulty in determining a cause in some cases. There is no remedy for CRPS that works quickly.

View the benefits of a pain clinic.

Symptoms of Complex Regional Pain Syndrome

Most people do not experience all of these symptoms, and the number of symptoms usually decreases as they recover.

Unprovoked or spontaneous pain that can be constant or fluctuate with activity.

Some people describe the sensation as “burning” or “pins and needles,” or as though the affected limb is being squeezed. Even if the original affected area was tiny, if nerves remain chronically irritated, the pain might extend to include most or all of the arm or leg over time. Pain and other symptoms may appear in the same spot in the opposite leg in rare cases. This “mirror pain” is hypothesised to be caused by subsequent spinal cord neuron involvement (nerve cells). As the wounded nerves heal, mirror discomfort becomes less acute and eventually disappears.

Excess or prolonged pain after use or contact.

Allodynia is a condition in which a person experiences enhanced sensitivity in the affected area, making mild touch, normal physical contact, and use extremely painful. Hyperalgesia occurs when minimally painful stimuli, such as a pinprick, cause significant or protracted pain.

Changes in skin temperature, skin colour, or swelling of the affected limb.

It’s possible that the damaged arm or leg is warmer or cooler than the opposite limb. The skin on the affected limb may become blotchy, blue, purple, grey, pale, or red in colour. These skin symptoms usually change over time, indicating a problem with blood flow in the area. The C-nerve fibres, which are damaged in CRPS, control the opening and closing of small blood arteries beneath the skin.

Changes in skin texture.

Inadequate oxygen and nutrient delivery might induce skin texture changes in the affected limb over time. It can become shiny and thin in some situations, or thick and scaly in others. This build-up is aided by avoiding contact or cleansing sore skin.

Abnormal sweating and nail and hair growth.

Hair and nails on the affected limb may grow unnaturally quickly or not at all, and people may notice regions of excessive sweating or no sweating. All are controlled by the brain and affected by local blood circulation.

Stiffness in affected joints.

Reduced mobility causes tendons and ligaments to become less flexible, which is a common condition. In patients who do not have exterior injuries, tight ligaments or tendons might press or crush nerves, causing CRPS on the inside.

Wasting away or excess bone growth.

Bones that receive impulses from injured nerves are rarely impacted in limbs with CRPS. These abnormalities are frequently evident on X-rays or other imaging, and they aid physicians in locating nerve injuries and determining the best treatments. Rough or enlarged bone regions, such as those leftover after a poorly healed fracture or a bone cyst, might irritate passing nerves, triggering or prolonging CRPS.

Impaired muscle strength and movement.

The nerve fibres that govern the muscles and coordinate muscle activity are rarely injured in persons with CRPS. However, the majority of people report being unable to move the affected body part. Pain and irregularities in the sensory input that helps coordinate movements are frequently to blame. Excessive inflammation and inadequate circulation are also harmful to muscles. Rare patients experience aberrant mobility in the affected limbs, dystonia (a fixed abnormal posture), and tremors or jerking. These symptoms could be the result of a secondary spread of abnormal neural activity to the brain and spinal cord. The majority of these symptoms go away on their own when CRPS heals, but some people need orthopaedic surgery to stretch constricted tendons and restore normal flexibility and position.

Diagnosis of Complex Regional Pain Syndrome

There is no precise test that can confirm CRPS or pinpoint the damaged nerve. The following items are included in the diagnosis:

  • Detailed examination by a clinician who is knowledgeable about normal patterns of sensory nerve architecture, such as a neurologist, orthopedist, or plastic surgeon. Patients’ most aberrant skin is often shown by having them draw the outline of the damaged nerve.
  • Nerve conduction investigations can detect some CRPS-related nerve damage, but not all (some injuries involve tiny nerve branches that cannot be detected this way).
  • Using ultrasound or magnetic resonance imaging (MRI), also known as magnetic resonance neurography (MRN), to image nerves can sometimes show underlying nerve damage. On MRI, specific bone and bone marrow anomalies can aid in the identification of the damaged nerve.
  • Excess bone resorption (the normal breakdown and absorption of bone tissue back into the body) is sometimes seen in CRPS-associated excess bone resorption, which can aid in diagnosis and localization.

CRPS generally improves over time, it is best to diagnose it early in the disease.

Causes of Complex Regional Pain Syndrome

Damage to or dysfunction of injured peripheral sensory neurons is the most common cause of CRPS, which has downstream consequences on the spinal cord and brain. The brain and spinal cord make up the central nervous system, while nerve communication from the brain and spinal cord to all other regions of the body makes up the peripheral nervous system.

It’s unclear why some persons with similar stress develop CRPS while others do not. CRPS is caused by nerve trauma or injury to the affected limb that affects the thinnest sensory and autonomic nerve fibres in more than 90% of cases. Pain, itch, and temperature sensations are transmitted by these “small fibres,” which lack insulating thick myelin sheaths (a protective covering that surrounds a wire) and control the small blood vessels and health of practically all surrounding cells.

The following are the most prevalent acts or activities that cause CRPS:


The most common cause, especially wrist fractures, is this. A misplaced or shattered bone, or pressure from a tight cast, might harm nerves. To avoid this issue, very tight or uncomfortable casts must be cut off and replaced right away.


Nerve injury can be caused by surgical incisions, retractors, placement, sutures, or post-operative scarring. Although the reason can sometimes be discovered and corrected, CRPS can develop even when surgery goes well.


Excessive movement of a joint might strain surrounding nerves due to connective tissue ruptures, or the causative trauma.

Lesser injuries such as burns or cuts

These are the visual indications of injuries that may have also resulted in nerve damage.

Limb immobilization (often from casting)

Casts impose lengthy disuse of a limb and deprive it of sensory input, in addition to pushing on nerves and restricting blood flow to the hands and feet as described above. After removing a cast, neurons must adjust to normal signalling.

Very rare penetrations

A superficial sensory nerve can be pierced by mistake, such as from a cut or a needle stick. Nerve specialists chart the sensory changes on the skin to assist find the damaged nerve. Larger penetrating nerve injuries should be surgically treated as soon as possible to allow the damaged nerve fibres to regenerate and reconnect with target tissues.

Only about 10% of people with CRPS say they have no trauma-related injuries. Undetected internal nerve damage is frequently the culprit. Nerve rubbing or tethering against hard interior structures or scars are examples. Tiny clots can obstruct blood flow to a nerve, causing injury. A new tumour, infection (such as leprosy), or aberrant blood vessels might irritate a nerve in rare cases. New CRPS with no obvious aetiology necessitates a thorough examination to rule out internal issues.

Poor circulation can impede nerve and tissue healing

Many of the symptoms of CRPS are caused by damage to the tiny fibres that govern blood flow. The affected limb’s blood vessels can dilate (open larger) and spill fluid into the surrounding tissue, resulting in red, puffy skin. This can cause muscle weakening and joint discomfort by depriving underlying muscles and deeper tissues of oxygen and nutrients. The skin becomes cold, white, grey, or bluish when the blood capillaries in the skin constrict (clamp down).

Because circulation is restricted in the limbs, CRPS develops only there. Blood pumped down to the hands and feet must overcome gravity to return to the heart via the veins. Damage to the C-fibers can prevent this, allowing blood fluids to stay in the leg, further obstructing return blood flow. Slowed circulation obstructs the transport of oxygen and nutrients required for healing and can sometimes cause cellular damage to spread. Reducing limb swelling and restoring circulation is typically the key to breaking the pattern and allowing recovery to begin.

  • When resting or sleeping, people with CRPS should keep their arms and legs elevated to let extra fluid return to the heart.
  • It is vital to exercise every day, even if it is only for a few minutes, to promote circulation and oxygenation. Physical therapists can assist in the creation of an exercise programme.
  • Compression stockings or sleeves can help some people reduce swelling, especially when standing.

Other influences on CRPS include:


Poor nerve health

Nerves can become less resilient as a result of diseases like diabetes or exposure to nerve poisons. People with widespread peripheral neuropathies may be unable or slow to rebuild nerve cells after an injury or stress that would not affect healthy nerves. Addressing general nerve health by eliminating or improving problems that delay nerve regrowth is crucial to CRPS recovery.

Immune system participation. C-fibre nerve cells also connect with immune cells to assist in damage healing. Excess or prolonged nerve signalling, as well as CRPS-related impaired circulation, might cause immune cell dysregulation in the affected limb. Some persons with CRPS have high levels of inflammatory molecules called cytokines in their affected limb, which contributes to the redness, swelling, and warmth. Individuals with other inflammatory and autoimmune disorders, such as asthma, are more likely to develop CRPS. Some people with CRPS may have aberrant antibodies that encourage the immune system to attack tiny fibres.

Genetics. The ability to heal from damage is influenced by both genetics and the environment. CRPS has been found in rare family clusters. With an earlier start, increased dystonia, and involvement of more than one limb, familial CRPS may be more severe.

Complex Regional Pain Syndrome Treatment

The majority of early or moderate cases heal on their own. Early intervention is the most beneficial.

The following are examples of common primary therapies:

Rehabilitation and physical therapy

The most significant treatment for CRPS is this. Maintaining flexibility, strength, and function while moving the painful limb or body part promotes blood flow and reduces circulatory symptoms. Secondary spinal cord and brain alterations linked with disuse and persistent pain can be prevented or reversed by rehabilitating the affected limb. Occupational therapy can assist people in resuming work and daily duties by teaching them new methods to become more active.


Secondary psychological disorders like depression, situational anxiety, and post-traumatic stress disorder are common in people with severe CRPS. These intensify pain perception, impair activity and brain function even more, and make it difficult for patients to seek medical help and participate in rehabilitation and recovery. Psychological therapy can help patients with CRPS feel better and recover more quickly.

Graded motor imagery

Individuals are taught mental exercises such as identifying painful body parts on the left and right while staring in the mirror and envisioning moving those unpleasant body parts without actually moving them. This is supposed to send non-painful sensory messages to the brain, assisting in the reversal of brain alterations that contribute to the progression of CRPS.


Several medications have been found to be beneficial in the treatment of CRPS, especially when used early in the disease. However, The Medicines and Healthcare products Regulatory Agency (MHRA) has not approved any drugs or combinations to be marketed particularly for CRPS, and no one drug or combination is guaranteed to be successful for everyone. The following medications are frequently used to treat CRPS:

  • Acetaminophen is used to treat pain caused by inflammation and bone and joint problems.
  • Nonsteroidal anti-inflammatory medicines (NSAIDs) to treat moderate pain and inflammation, such as aspirin, ibuprofen, and naproxen in adequate amounts.
  • Nortriptyline, gabapentin, pregabalin, and duloxetine have all been shown to be beneficial for different neuropathic pain syndromes. Amitriptyline, a more traditional medication, is effective but has greater adverse effects than nortriptyline, which is chemically quite similar.
  • Lidocaine and fentanyl patches are examples of topical local anaesthetic ointments, sprays, or creams. These can help with allodynia and provide additional protection by covering the skin with patches.
  • Bisphosphonates reduce bone alterations, such as high-dose alendronate or intravenous pamidronate.
  • Prednisolone and methylprednisolone are corticosteroids used to treat inflammation, swelling, and oedema.
  • In severe situations, botulinum toxin injections can assist relax constricted muscles and restoring normal hand and foot postures.
  • Individuals with the most severe pain may require opioids such as oxycodone, morphine, hydrocodone, and fentanyl. Opioids, on the other hand, might cause increased pain sensitivity and reliance.
  • Dextromethorphan and ketamine, which block the N-methyl-D-aspartate (NMDA) receptor, are contentious and unproven treatments.

Spinal cord stimulation

Outside the spinal cord, stimulating electrodes are introduced by a needle into the spine. They provide tingling sensations in the painful location, which serve to suppress pain perceptions and restore spinal cord and brain signals. Electrodes can be temporarily implanted for a few days to see if stimulation will be beneficial. The stimulator, battery, and electrodes must be implanted under the skin on the torso, which requires minor surgery. Stimulators can be turned on and off and adjusted with an external controller once they’ve been implanted.

Other types of neural stimulation

Other places where implanted neurostimulation can be used include near wounded nerves (peripheral nerve stimulators), under the skull (motor cortex stimulation with electrodes), and within brain pain regions (deep brain stimulation). Nerve stimulation of the peroneal nerve in the knee is one of the most recent noninvasive commercially available treatments. Another is rTMS, which is a non-invasive form of brain stimulation that employs a magnetic field to modify electrical transmission in the brain. Small transcranial direct electrical stimulators are also being studied for usage at home. These stimulation methods are non-invasive, however, they need time because they require multiple treatment sessions to maintain benefit.

Spinal-fluid drug pumps

Pain-relieving drugs are delivered directly into the fluid that bathes the nerve roots and spinal cord via these implanted devices. Opioids, local anaesthetic agents, clonidine, and baclofen are common ingredients. The benefit is that very low doses can be utilised that do not spread outside of the spinal canal and damage other body systems. This reduces negative effects while increasing drug efficacy.

Alternative and holistic therapies

Some people are looking into treatments including medical marijuana, behaviour modification, acupuncture, relaxation techniques (such as biofeedback, progressive muscle relaxation, and guided motion therapy), and chiropractic treatment based on research on other painful disorders. Although these do not address the root cause of CRPS, some people find them helpful. They’re usually easy to find and aren’t risky to try.

Limited use therapy for the most severe or non-resolving pain that has not responded to conventional treatment

Ketamine is a limited-use therapy for the most severe or non-resolving pain that has not responded to other treatments. Low doses of ketamine, a potent anaesthetic, given intravenously for many days have been shown to help some researchers. Ketamine has been demonstrated to be effective in relieving pain that has not responded well to other treatments in several clinical situations. However, it has the potential to cause long-term delusions and other psychotic symptoms.

Rarely used former treatments include:

Sympathetic nerve block

Sympathetic blocks, in which an anaesthetic is injected near the spine to stop sympathetic nerve activity and enhance blood flow, were previously utilised. Recent studies have shown that there is a little long-term benefit after the injected anaesthetic wears off, and needle injections can cause harm, therefore this method has fallen out of favour.

Surgical sympathectomy

Some of the nerves that convey pain signals are destroyed as a result of this. Some specialists believe it is unnecessary and causes CRPS to worsen, while others claim occasional positive results. Sympathectomy should only be done in people whose pain is significantly reduced by sympathetic nerve blocks.

Cutting injured nerves or nerve roots

People with CRPS frequently wonder if severing the damaged nerve above the injury site may relieve their agony. Indeed, this results in a greater nerve lesion that affects a larger portion of the leg. In addition, when the spinal cord and brain are deprived of input, central pain syndromes can develop. This should not be done until in rare conditions, such as palliative care.

Amputating the painful lower limb

This is a more severe and disabling form of nerve cutting, with irreversible repercussions, whereas CRPS almost invariably recovers with time, albeit slowly. Amputation is thus not ideal for pain relief alone, but it is occasionally necessary to treat a bone infection or allow the use of a prosthesis in long-term non-recovering patients. This last resort should not be undertaken without the advice of multiple experts and psychiatric treatment.

Recovery from Complex Regional Pain Syndrome

There are several variables that can raise your chances of developing knee difficulties, including:

  • A lot of weight. Even during everyday tasks like walking or going up and downstairs, being overweight or obese puts more strain on your knee joints. It also increases your chances of developing osteoarthritis by hastening the degradation of joint cartilage.
  • Muscle weakness or a lack of flexibility. Knee ailments can be exacerbated by a lack of strength and flexibility. Muscle flexibility can help you attain a full range of motion by stabilising and protecting your joints.
  • Certain sports or jobs. Some sports place more strain on the knees than others. Alpine skiing, with its rigid ski boots and propensity for falls, basketball with its jumps and pivots, and running or jogging with the constant hammering on your knees all raise your risk of knee damage. Work that puts a lot of strain on your knees, such as construction or farming, can put you in danger.
  • Injury in the past. It’s more likely that you’ll damage your knee again if you’ve had one before.


Long-term pain can be mentally and emotionally draining. Being sad or having other psychological issues can make recovery more difficult. So inform your physician. Therapy, dietary changes, and medication may all be beneficial.

Your doctor should also be able to refer you to other healthcare providers who can assist you. They could, for example, teach you relaxation or meditation practises. In support groups, you can rely on the strength of others while also sharing your own.

CRPS UK  a registered UK charity is a patient-led organisation for people with Complex Regional Pain Syndrome, their family and friends and anyone working within the healthcare system.  CRPS UK offers support, education, literature, assistance with research and raise awareness of CRPS.