Complex regional pain syndrome (CRPS)

Complex regional pain syndrome (CRPS) is a disorder of the nervous system usually associated with an injury to an arm or leg, or sometimes triggered by another health event.

Symptoms may include burning-type pain, changes in skin and bone tissue, excessive sweating, swelling of an extremity, and sensitivity to touch. CRPS is difficult to diagnose. Better outcomes are more likely if treatment is started during the first three months of the condition.

CRPS is most common between the ages of about 40 and 50 years and occurs more frequently in women than men. CRPS shares many features with fibromyalgia, which is another type of pain syndrome.

Causes

In most cases CRPS is triggered by trauma or injury causing damage to, or malfunction of, the nervous system.

CRPS has traditionally been divided into two types, which have similar signs and symptoms but different causes: CRPS I occurs after an illness or injury that doesn’t directly damage nerves; CRPS II occurs after direct nerve damage.

In more than 90% of cases, CRPS is triggered by a clear history of trauma to an arm or leg (ie: CRPS I). These include:

• Bruise or crush injury
• Fractures
• Sprains or strains
• Surgery.

Other possible triggering events include heart attack, stroke, cancer, concussion, meningitis, carpal tunnel surgery, spinal cord injury, burns and infection. Emotional stress or trauma can also be a trigger for CRPS.

An over-reaction of the body's inflammatory or immune systems might play a part in CRPS. High levels of inflammatory chemicals contribute to the redness, swelling, and warmth reported by many patients.

Signs and symptoms

CRPS can affect the nerves, skin, muscles, blood vessels, and bones simultaneously. Symptoms can develop gradually or rapidly, and can vary in severity.

The primary symptom of CRPS is prolonged severe pain, which is often described as a burning, throbbing or tingling sensation, usually in an arm, leg, hand or foot. In some people the affected area becomes very sensitive, with normal skin contact causing intense pain.

Other signs and symptoms of CRPS include:

• Sensitivity to touch or cold
• Swelling of the painful area
• Changes in skin temperature
• Abnormal sweating in the affected or surrounding areas
• Changes in skin colour, ranging from white and blotchy to blue, purple, or red
• Changes in skin texture in the affected area, which may appear thin or shiny
• Changes in hair and nail growth patterns
• Joint stiffness and swelling
• Tremors or jerking (spasm) of the affected limb
• Reduced ability to move the affected body part.

Variations in skin temperature, skin colour, or swelling of the affected limb are due to abnormal circulation caused by damage to the nerves that control blood flow and temperature.

Diagnosis

CRPS is difficult to diagnose as there is no definitive sign or test for CRPS. A doctor will usually make a diagnosis of CRPS based on the following:

• Pain symptoms
• X-rays, bone scans and magnetic resonance imaging (MRI) scans to assess bone changes
• Tests to detect impaired function of the sympathetic nervous system, which regulates the body's unconscious functions like heart rate and blood flow
• Blood tests to check for inflammation and rule out other causes.

Treatment

Treatment is generally most effective in the first three months of the condition. Without prompt treatment, CRPS can lead to tissue wasting (including skin, muscle, and bones) and muscle tightening. If left untreated the disorder can spread to other areas of the body. The usual pattern of spread is up the affected arm or leg and on to the same side of the body. It may also spread to the opposite side of the body. Specialist intervention early on is the key to a successful outcome.

A doctor may need to try a variety of treatments. Least invasive is the application of cold or heat. Other treatments include:

• Medications to relieve pain and reduce inflammation
• Anaesthetic injections or infusions to block pain
• Desensitisation of the affected area using techniques such as TENS (transcutaneous electrical nerve stimulation), massage, and brushing of the skin
• Implantation of spinal cord stimulation devices and pain medication-releasing pumps into the spinal canal
• Medications to prevent or delay bone loss
• Physiotherapy (exercising the affected limb to prevent muscle tightness, maintain strength and movement, and build aerobic fitness)
• Psychological counselling and education regarding the condition, and to help cope with possible depression and anxiety as a result of living with long term pain
• Relaxation techniques
• Regular aerobic exercise, eg: swimming / brisk walking.

Recovery

Recovery is variable in CRPS but is likely to be better with early treatment.

Some patients experience recurrences of CRPS, sometimes due to a trigger such as exposure to cold or emotional stress.

Some patients with severe symptoms may not respond to treatment. For these individuals, a pain management programme aimed specifically at chronic pain can be beneficial.

Support and information

Living with CRPS can be challenging in terms of maintaining physical and mental health. Community support groups that may be able to assist include:

New Zealand Pain Society

Email: [email protected]
Website: www.nzps.org.nz

References

FamilyDoctor.org (2017). Complex regional pain syndrome (Web Page). Leawood, KS: American Academy of Family Physicians. http://familydoctor.org/familydoctor/en/diseases-conditions/complex-regional-pain-syndrome.html [Accessed: 20/02/20]
Mayo Clinic (2020). Complex regional pain syndrome (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/complex-regional-pain-syndrome/symptoms-causes/syc-20371151 [Accessed: 20/02/20]
Gupta, G. (2018). Complex regional pain syndromes (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. http://emedicine.medscape.com/article/1145318-overview [Accessed: 20/02/20]
National Institute of Neurological Disorders and Stroke (2019). Complex regional pain syndrome fact sheet (Web Page). Bethesda, MD: National Institutes of Health https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Complex-Regional-Pain-Syndrome-Fact-Sheet [Accessed: 20/02/20]

Last reviewed – February 2020

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