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Complex regional pain syndrome (CRPS) refers to a chronic condition that affects the nerves and blood vessels of one or more limbs. Its features include unpleasant burning sensations, swelling, sweating, color changes, and other symptoms.

There are two types of CRPS:

• CRPS 1 (also called reflex sympathetic dystrophy or RSD)— No nerve damage is observable with this type.
• CRPS 2 (also called causalgia)—This produces similar symptoms after a verified nerve injury has occurred.

Complex Regional Pain Syndrome

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The cause of CRPS is not known. The condition likely results from several factors. It may involve overactivity of the sympathetic nervous system. This directs automatic body functions that a person cannot control. Inflammation may also play a role in the disorder.

Factors that may increase your risk of CRPS include:

• Trauma
• Fractures
• Cuts
• Burns
• Frostbite
• Surgery
• Penetrating injury
• Crush injury
• An injection into the muscle
• Blood draws
• Diabetic neuropathy
• Multiple sclerosis
• Stroke
• Carpal tunnel syndrome

If you have any of these symptoms do not assume it is due to CRPS. These symptoms may be caused by other conditions.

The upper limbs, particularly the hands, are most commonly affected. Symptoms progress and may vary during the course of the condition. Pain may spread from one side of the body to another. Many doctors describe symptoms in terms of stages.

Symptoms may include :

• A pale, blue, and/or shiny look to the skin
• Limited joint movement
• Muscle loss

Your doctor will ask about your symptoms and medical history. A physical exam will be done. To diagnose CRPS, the doctor uses four criteria:

• An initial traumatic or painful event to a limb, or keeping the limb still for a period of time
• Continuing pain in the limb that is out of proportion to any stimulus, such as pain with even light touch
• History of swelling, changes in skin blood flow, or temperature only in the affected limb
• No other cause for the symptoms

Tests may be ordered to rule out other conditions. Your doctor may refer you to a pain specialist for further evaluation and management. Tests may include the following:

• Pictures may need to be taken of your bodily structures. This can be done with:
  • X-ray
  • Bone scan
  • Magnetic resonance imaging (MRI)
• The electrical activity in your nerves and muscles may need to be tested. This can be done with:
  • Nerve conduction studies
  • Electromyography
• You may need to have your body's heat measured. This can be done with a thermogram.
• You may need to have your autonomic nervous system evaluated. This can be done with quantitative sudomotor axon reflex test (QSART).

Treatment aims to relieve pain and improve function. Visit the doctor as soon as possible. Early therapy may lead to better outcomes. In some cases, the condition goes away on its own; this is more common in children.

Treatment options include:

• Biofeedback
• Acupuncture
• Physical therapy—Active and passive exercises help maintain function. Exercising in a warm pool may feel better than exercising on land.
• Mirror box therapy—With this therapy, you place your affected hand or foot in a box, which has a mirror on one side. While moving your limb inside of the box, you move your unaffected limb in front of the mirror. To your brain, it appears that you are moving your painful limb easily and without discomfort. Mirror therapy may help to reduce pain and improve motor function in people who have CRPS due to stroke.
• Nerve stimulation devices, such as:
  • Transcutaneous nerve stimulation (TENS)—A device worn on the skin surface that creates a tingling sensation and may relieve pain in some cases
  • Implantable spinal cord stimulation—may be helpful for some patients
• Medicines, such as:
  • Anti-anxiety medicines, low-dose antidepressants, and drugs used to treat epilepsy
  • Pain medicines like narcotics
  • Bisphosphonates—drugs used to treat osteoporosis
  • Steroids
  • Medicines applied to the skin, such as Capsaicin and dimethylsulfoxide
• Sympathetic nerve block—The injection of drugs that prevent signals from being sent along sympathetic nerves may temporarily relieve pain in some cases.
• Sympathectomy—If the nerve block is successful, a surgeon can permanently destroy sympathetic nerves. In some cases, surgery can worsen symptoms.
• Psychological support— Long-term pain often leads to depression or anxiety . Counseling is often required to help patients deal with chronic pain and loss of function.

Quick mobilization after surgery or injury can help minimize the risk of CRPS in the affected limb. Other steps that might be helpful include:

• Early use of pain relievers after trauma
• Use of sympathetic nerve block after trauma
• Desensitization techniques, if needed
• Use of vitamin C may reduce the risk of CRPS after a wrist fracture.