Complex regional pain syndrome (CRPS) is a chronic condition marked by continuous, intense pain that tends to worsen over time. It usually occurs after a significant trauma to an arm or a leg, such as a fracture, but may also develop after no apparent injury. It is characterized by burning or aching pain along with inflammation, skin discoloration, altered temperature, abnormal sweating and hypersensitivity of the affected area that persist longer than the anticipated healing time for that injury.
There are two types of CRPS. They were formerly known as reflex sympathetic dystrophy syndrome and causalgia.
The cause of CRPS is not known. Some scientists believe it may result from damage to the nervous system, whereas others suggest it is triggered by an immune system response.
There is no known cure, but treatments such as medications, physical therapy, electrical stimulation, biofeedback and injection therapy are available. Patients who have symptoms of CRPS should seek medical attention promptly, as treatment is most effective when started soon after symptoms first appear. Left untreated, CRPS can become disabling.
About complex regional pain syndrome
Complex regional pain syndrome (CRPS) is an uncommon chronic pain condition that usually affects the arms or legs. Patients may experience symptoms such as burning or aching pain along with swelling, skin discoloration, altered skin temperature, abnormal sweating, decreased function and hypersensitivity of the affected area. In rare cases, CRPS may affect other parts of the body.
The cause of CRPS is not completely understood. Some scientists believe it may result from disturbances in the sympathetic nervous system, which controls blood flow and sweat glands. It may also be caused by injury to the peripheral nervous system (nerves outside the brain and spinal cord) or the central nervous system (brain and spinal cord). In other cases it may result from an immune system response.
As with other poorly understood pain conditions such as fibromyalgia and chronic fatigue syndrome, patients may sometimes be told their condition is psychosomatic or be suspected of faking symptoms for attention or other gains. However, U.S. researchers in 2006 reported discovering what they called the first physiological evidence of nerve damage in CRPS. They found injury to small-fiber nerve endings, which is also seen in other causes of nerve pain, such as diabetic neuropathy.
CRPS often occurs after trauma to an arm or a leg. The source of trauma can vary widely, such as a blunt injury, fracture, sprain, animal bite, knife wound or even an injection. CRPS may develop months to years after the initial damage to the nervous or immune system. The disease often gets worse over time, causing pain that is much greater than the initial damage. Conversely, spontaneous remission from symptoms occurs in some patients.
CRPS tends to affect women more frequently than men. It is most common in people between the ages of 40 and 60, though it can affect people of any age, including children.
There is no known cure for CRPS, but treatments are available. Patients who have symptoms of CRPS should seek medical attention early. Treatment is most effective if started earlier after symptoms first appear. Left untreated, CRPS can progress to more disabling signs and symptoms and can progress to the other side of the body as well.
Types and differences of CRPS
There are two major types of complex regional pain syndrome (CRPS):
Type I. Previously known as reflex sympathetic dystrophy syndrome, it is the result of an illness or injury to the skin, joints, bones or other tissues of an affected area but can develop even without a known injury.
Type II. Previously known as causalgia, it occurs after an injury to a major nerve.
When these forms of CRPS are left untreated, they may progress to more dangerous forms of CRPS. For example:
Symptoms migrate from the initial site of the pain (such as the hand or foot) to the shoulder, trunk and face. Such symptoms can affect an entire quadrant of the body.
Symptoms may spread from one limb to the opposite limb.
Symptoms may leap to a distant part of the body.
Risk factors and potential causes of CRPS
It is generally agreed that complex regional pain syndrome (CRPS) is a neurological disorder affecting the central nervous system and the peripheral nervous system. A phenomenon called “central sensitization” has been thought for the basis of some of the symptoms of CRPS.
Exactly how CRPS develops remains unknown, although it usually begins with an injury. CRPS first was described during the Civil War, when patients complained of burning pain that continued long after their wounds had healed.
Some scientists believe it may result from disturbances in the sympathetic nervous system, which is the part of the nervous system that controls blood flow and sweat glands. Others suggest that it is triggered by an immune system response, which leads to the characteristic inflammatory symptoms of redness, warmth and swelling in the affected area.
CRPS may occur after a significant trauma to an arm or a leg, such as from a gunshot wound or shrapnel blast. In other cases, the injury that triggers CRPS may be so minor it goes unnoticed by the patient. Other types of trauma – including surgery, heart attacks, stroke, infections, fractures and sprains – also can trigger CRPS.
Damage to the nervous system caused by disease can trigger CRPS. Diseases of the central nervous system, such as multiple sclerosis, or damage to the peripheral nerves from conditions such as diabetes may cause CRPS in some patients.
Scientists are not sure why some injuries cause CRPS and others do not. However, factors that may contribute to the development of CRPS include:
Genetics. The disease may run in families.
Stress. People under stress at the time of an injury may be more likely to develop CRPS.
Lack of use of an injured body part. Restricting the use of injured body parts because of pain or an outside factor such as a cast or sling may contribute to the development of CRPS.
Signs and symptoms of CRPS
Signs and symptoms of complex regional pain syndrome (CRPS) are similar for both types of the disorder. They may vary in severity and duration from patient to patient. The most common symptom is intense pain, which is often described as a burning sensation. Usually pain is out of the ordinary and seemingly not compatible with the clinical signs. In many patients the affected limb feels as if it is immersed in boiling water.
The skin is greatly affected by CRPS. Sensitivity and tenderness of the skin may increase, and changes may occur in skin temperature, color and texture (such as skin thinning or appearing shiny). The skin may alternate between being sweaty and cold, and skin color may range from white and blotchy to red or blue.
In addition to leg pain and arm pain, symptoms include:
Pain caused by normally nonpainful stimuli (allodynia)
Extreme sensitivity to pain (hyperalgesia)
Changes in growth of hair and nails
Joint stiffness, inflammation and damage
Muscle spasms and weakness, and loss of muscle (atrophy)
Decrease in range of motion of the affected body part
Tremors in the affected limb
Depression, anxiety and sleep disturbances
CRPS can be treated far more effectively when it is detected early. Left untreated, it can progress to more serious signs and symptoms. Patients should consult a physician if they experience constant, severe pain that affects a limb when it is touched or moved, or if they have trouble moving a limb because of stiffness. Such symptoms may indicate that the skin and muscles are beginning to atrophy.
Patients may also experience tightening of muscles as they lose tone. This can result in a condition in which the hand and fingers or foot and toes contract into a fixed position.
Diagnosis methods for CRPS
Before diagnosing complex regional pain syndrome (CRPS), a physician will review the patient’s medical history and should perform physical examination. In many cases, CRPS can be traced back to a specific accident, illness or injury. The physician will look for changes in the texture and color of skin and problems with range of motion of one or more joints. Blood tests may be performed to rule out other conditions, such as arthritis.
CRPS is a clinical diagnosis, and there are no tests specific and sensitive for it. But other tests that may be performed include:
Bone scan. A type of radionuclide imaging. This nuclear medicine test highlights features of the bones when viewed with a special camera. Bone scans can reveal small fractures and increased circulation to the joints in areas affected by CRPS.
Sympathetic nervous system tests. A group of procedures that help reveal disturbances in the sympathetic nervous system by measuring skin temperature and blood flow or the amount of sweat in affected and unaffected limbs. If comparisons between the two limbs show dissimilarity, it may indicate CRPS. Sympathetic nerve blocks can also be used to determine whether or not a person is suffering a CRPS problem that involves the sympathetic nervous system. If the block reduces pain, the sympathetic nervous system may be the source of some of the signs and symptoms of CRPS.
MRI (magnetic resonance imaging). A noninvasive or minimally invasive imaging test involving powerful magnets. An MRI may show tissue changes such as wasting of muscle or skin caused by CRPS.
X-ray. A painless test in which an image is created of part of the body by using low doses of electromagnetic radiation that are reflected on film or fluorescent screens. Though they are usually not a diagnostic test for CRPS, x-rays can detect a loss of minerals from the bones, which may indicate later stages of the disorder.
Treatment options for CRPS
Treatment of complex regional pain syndrome (CRPS) is most effective when it is started early in the course of the syndrome. This can lead to dramatic improvement of symptoms or remission of the disease. On the other hand, failure to treat CRPS early can result in significant spread of the pain that may be increasingly difficult to treat.
Treatment methods will vary depending on the type of CRPS, the individual needs of the patient and the physician’s recommendations. Treatment options may include:
Medications. Several types of drugs are used to treat symptoms of CRPS. Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce pain and inflammation. Some prescription medications, including antidepressants, anticonvulsants and opioids, are sometimes used to treat pain stemming from a damaged nerve (neuropathic pain), and corticosteroids may be prescribed to ease inflammation. Local application of a lidocaine patch or a cream from peppers has some success in relieving symptoms. Certain medications used to treat bone loss, such as bisphosphonates, may also be helpful.
Some patients may respond to alpha blockers, a class of medication that is also used to treat high blood pressure and benign prostatic hyperplasia. Possible complications of alpha blockers include an eye condition called intraoperative floppy iris syndrome, which even years later may affect cataract surgery, one of the most commonly performed operations.
A physician may recommend injection therapy, such as sympathetic nerve-blocking medication. Injection of an anesthetic can relieve pain by blocking pain fibers in affected nerves. Examples include lumbar sympathetic nerve blocks, stellate ganglion nerve blocks and Bier blocks. In severe cases, leaving a continuous catheter in the epidural space or around ganglion to deliver medicine has been recommended.
Physical therapy. Directed exercise of affected limbs can boost range of motion and strength, particularly when started early in the progression of CRPS. The therapist may also offer modalities such as electrical therapy.
Transcutaneous electrical nerve stimulation (TENS). Procedure that applies electrical impulses to nerve endings, thereby easing chronic pain.
Spinal cord stimulationSpinal cord stimulation. Technique in which tiny electrodes are inserted along the spinal cord before a small electrical current is delivered to these areas. This form of electrical therapy sometimes results in pain relief. Placing the same stimulator device around the affected peripheral nerve may also relieve symptoms.
Biofeedback. Technique that helps patients to become more aware of their bodies so they can relax and blunt pain symptoms.
Acupuncture. Procedure in which needles are inserted at particular points of the body to relieve pain. Acupuncture may be helpful for short-term pain relief in some patients.
Psychological therapy. Patients with CRPS may experience emotional trauma. Cognitive behavioral therapy or other therapy can help patients deal with the stress and depression that sometimes stem from this disorder.
Occupational therapy. Patients who have difficulty performing daily activities may benefit from instruction in ways to adapt.
Sympathectomy. Surgical procedure to sever the sympathetic nerves leading to the affected area. This may be used when other forms of treatment fail.
In addition, researchers have recently found that performing bilateral activities (involving the affected and unaffected limbs) in front of a mirror sometimes helps. They theorize that this treatment may work because CRPS could impair the brain’s image of the body and cause a split between sensory and motor systems.
Questions for your doctor about CRPS
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about complex regional pain syndrome (CRPS):
What could put me at risk of developing complex regional pain syndrome?
What symptoms might indicate I have it?
What diagnostic tests can I expect?
What do these tests involve? When and where will they take place? Who will discuss my results with me?
Which type of CRPS do I have?
What might have caused my CRPS?
What are my treatment options? Which do you recommend for me?
What side effects from recommended medications or other treatments can I expect?
