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Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a chronic pain condition that can affect any area of the body, but often affects a limb. Complex regional pain syndrome is marked by intense burning or aching pain, as well as swelling, skin discoloration, altered temperature, abnormal sweating and hypersensitivity in the affected area. It is thought that the sympathetic nervous system may play an important role in the pain or possibly by an immune response, which leads to the inflammatory symptoms of redness, warmth, and swelling in the affected area.

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What to know about CRPS

CRPS is thought to result from damage to the nervous system, including the nerves that control the blood vessels and sweat glands. The damaged nerves are no longer able to properly control blood flow, feeling (sensation), and temperature to the affected area.


Complex regional pain syndrome occurs in two types with similar signs and symptoms, but different causes:

  • Type 1. Previously known as reflex sympathetic dystrophy syndrome. This type occurs after an illness or injury that did not directly damage the nerves in the affected limb. About 90 percent of people with complex regional pain syndrome have type 1.

  • Type 2. Previously referred to as causalgia, this type follows a distinct nerve injury.

Many cases of complex regional pain syndrome occur after a forceful trauma to an arm or a leg, such as a gunshot wound or shrapnel blast. Other major and minor traumas such as infections, surgeries, fractures, or sprains can also lead to complex regional pain syndrome.


The main symptom of complex regional pain syndrome is intense pain, which gets worse over time. Additional signs and symptoms include:

  • “Burning” pain in your arm, leg, hand or foot.
  • Skin sensitivity.
  • Changes in skin temperature – At times may be sweaty; at other times it may be cold.
  • Changes in skin color – can range from white and mottled to red or blue.
  • Changes in skin – may become tender, thin or shiny in the affected area.
  • Changes in hair and nail growth.
  • Joint stiffness, swelling and damage.
  • Muscle spasms, weakness, and loss (atrophy).
  • Decreased ability to move the affected body part.


Diagnosis of complex regional pain syndrome is based on a physical exam and your medical history. There is no single test that can definitively diagnose complex regional pain syndrome, but the following procedures may provide important clues:

  • Bone scan: A radioactive substance injected into one of your veins permits viewing of your bones with a special camera. This procedure may show increased circulation to the joints in the affected area.
  • Sympathetic nervous system tests: These tests look for disturbances in your sympathetic nervous system. For example, thermography measures the skin temperature and blood flow of your affected and unaffected limbs. Other tests can measure the amount of sweat on both limbs. Dissimilar results can indicate complex regional pain syndrome.
  • X-rays: Loss of minerals from your bones may show up on an X-ray in later stages of the disease.
  • Magnetic resonance imaging (MRI): Images captured by an MRI device may show a number of tissue changes.


There is no cure for CRPS. Instead, treatment is aimed at alleviating painful symptoms. The following therapies are often used:

Physical therapy: A gradually increasing exercise program to keep the painful limb or body part moving may help restore some range of motion and function.

Psychotherapy: CRPS often has profound psychological effects on people and their families. Those with CRPS may suffer from depression, anxiety, or post-traumatic stress disorder, all of which heighten the perception of pain and make rehabilitation efforts more difficult.

Sympathetic nerve block: Some patients will get significant pain relief from sympathetic nerve blocks. Sympathetic blocks can be done in a variety of ways. One technique involves intravenous administration of phentolamine, a drug that blocks sympathetic receptors. Another technique involves placement of an anesthetic next to the spine to directly block the sympathetic nerves.

Medications: Many different classes of medication are used to treat CRPS, including topical analgesic drugs that act locally on painful nerves, skin, and muscles; antiseizure drugs; antidepressants, corticosteroids, and opioids. However, no single drug or combination of drugs has produced consistent long-lasting improvement in symptoms.

Surgical sympathectomy: The use of surgical sympathectomy, a technique that destroys the nerves involved in CRPS, is controversial. Some experts think it is unwarranted and makes CRPS worse; others report a favorable outcome. Sympathectomy should be used only in patients whose pain is dramatically relieved (although temporarily) by selective sympathetic blocks.

Spinal cord stimulation: The placement of stimulating electrodes next to the spinal cord provides a pleasant tingling sensation in the painful area. This technique appears to help many patients with their pain.

Intrathecal drug pumps: These devices administer drugs directly to the spinal fluid, so that opioids and local anesthetic agents can be delivered to pain-signaling targets in the spinal cord at doses far lower than those required for oral administration. This technique decreases side effects and increases drug effectiveness.