Complex Regional Pain Syndrome
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El Síndrome de Dolor Regional Complejo
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What is complex regional pain syndrome?What is complex regional pain syndrome? Complex regional pain syndrome (CRPS) is a chronic pain condition that is believed to be the result of dysfunction in the
central or peripheral nervous systems. Typical features include dramatic changes in the color and temperature of the skin
over the affected limb or body part, accompanied by intense burning pain, skin sensitivity, sweating, and swelling. CRPS I is frequently triggered by tissue injury; the term describes all patients with the above symptoms but with no underlying
nerve injury. Patients with CRPS II experience the same symptoms but their cases are clearly associated with a nerve injury.
Older terms used to describe CRPS are "reflex sympathetic dystrophy syndrome" and "causalgia," a term first used during the
Civil War to describe the intense, hot pain felt by some veterans long after their wounds had healed.
CRPS can strike at any age and affects both men and women, although most experts agree that it is more common in young women.
What are the symptoms of CRPS? The key symptom of CRPS is continuous, intense pain out of proportion to the severity of the injury (if an injury has occurred),
which gets worse rather than better over time. CRPS most often affects one of the extremities (arms, legs, hands, or feet)
and is also often accompanied by:
Often the pain spreads to include the entire arm or leg, even though the initiating injury might have been only to a finger
or toe. Pain can sometimes even travel to the opposite extremity. It may be heightened by emotional stress.
The symptoms of CRPS vary in severity and length. Some experts believe there are three stages associated with CRPS, marked
by progressive changes in the skin, muscles, joints, ligaments, and bones of the affected area, although this progression
has not yet been validated by clinical research studies.
Stage one is thought to last from 1 to 3 months and is characterized by severe, burning pain, along with muscle spasm, joint stiffness,
rapid hair growth, and alterations in the blood vessels that cause the skin to change color and temperature.
Stage two lasts from 3 to 6 months and is characterized by intensifying pain, swelling, decreased hair growth, cracked, brittle, grooved,
or spotty nails, softened bones, stiff joints, and weak muscle tone.
In stage three the syndrome progresses to the point where changes in the skin and bone are no longer reversible. Pain becomes unyielding
and may involve the entire limb or affected area. There may be marked muscle loss (atrophy), severely limited mobility, and
involuntary contractions of the muscles and tendons that flex the joints. Limbs may become contorted.
What causes CRPS? Doctors aren’t sure what causes CRPS. In some cases the sympathetic nervous system plays an important role in sustaining the
pain. The most recent theories suggest that pain receptors in the affected part of the body become responsive to a family
of nervous system messengers known as catecholamines. Animal studies indicate that norepinephrine, a catecholamine released
from sympathetic nerves, acquires the capacity to activate pain pathways after tissue or nerve injury. The incidence of sympathetically
maintained pain in CRPS is not known. Some experts believe that the importance of the sympathetic nervous system depends on
the stage of the disease.
Another theory is that post-injury CRPS (CRPS II) is caused by a triggering of the immune response, which leads to the characteristic
inflammatory symptoms of redness, warmth, and swelling in the affected area. CRPS may therefore represent a disruption of
the healing process. In all likelihood, CRPS does not have a single cause, but is rather the result of multiple causes that
produce similar symptoms.
How is CRPS diagnosed? CRPS is diagnosed primarily through observation of the signs and symptoms. But because many other conditions have similar
symptoms, it can be difficult for doctors to make a firm diagnosis of CRPS early in the course of the disorder when symptoms
are few or mild. Or, for example, a simple nerve entrapment can sometimes cause pain severe enough to resemble CRPS. Diagnosis
is further complicated by the fact that some people will improve gradually over time without treatment.
Since there is no specific diagnostic test for CRPS, the most important role for testing is to help rule out other conditions.
Some clinicians apply a stimulus (such as touch, pinprick, heat, or cold) to the area to see if it causes pain. Doctors may
also use triple-phase bone scans to identify changes in the bone and in blood circulation.
What is the prognosis? The prognosis for CRPS varies from person to person. Spontaneous remission from symptoms occurs in certain people. Others
can have unremitting pain and crippling, irreversible changes in spite of treatment. Some doctors believe that early treatment
is helpful in limiting the disorder, but this belief has not yet been supported by evidence from clinical studies. More research
is needed to understand the causes of CRPS, how it progresses, and the role of early treatment.
How is CRPS treated? Because there is no cure for CRPS, treatment is aimed at relieving painful symptoms so that people can resume their normal
lives. The following therapies are often used:
Is research currently being done on CRPS? The National Institute of Neurological Disorders and Stroke (NINDS), a component of the National Institutes of Health (NIH),
supports and conducts research on the brain and central nervous system. Some studies are conducted at the Institute’s laboratories
and clinics on the NIH campus in Bethesda, Maryland. Others are funded through grants to major medical institutions across
the country. NINDS-supported scientists are studying new approaches to treat CRPS and intervene more aggressively after traumatic
injury to lower the chances of developing the disorder. Other studies to overcome chronic pain syndromes are discussed in
the NINDS pamphlet, "Pain: Hope Through Research."
For more information on neurological disorders or research programs funded by the National Institute of Neurological Disorders and Stroke, contact the Institute's Brain Resources and Information Network (BRAIN) at:
BRAIN
P.O. Box 5801
Bethesda, MD 20824
(800) 352-9424
http://www.ninds.nih.gov
Information also is available from the following organizations:
American Chronic Pain Association (ACPA) P.O. Box 850 Rocklin, CA 95677-0850 ACPA@pacbell.net http://www.theacpa.org Tel: 916-632-0922 800-533-3231 Fax: 916-632-3208 |
Reflex Sympathetic Dystrophy Syndrome Association
(RSDSA) P.O. Box 502 99 Cherry Street Milford, CT 06460 info@rsds.org http://www.rsds.org Tel: 203-877-3790 877-662-7737 Fax: 203-882-8362 |
American RSDHope Organization P.O. Box 875 Harrison, ME 04040-0875 rsdhope@roadrunner.com http://www.rsdhope.org Tel: 207-583-4589 |
National Foundation for the Treatment of Pain P.O. Box 70045 Houston, TX 77270 NFTPain@cwo.com http://www.paincare.org Tel: 713-862-9332 Fax: 713-862-9346 |
American Pain Foundation 201 North Charles Street Suite 710 Baltimore, MD 21201-4111 info@painfoundation.org http://www.painfoundation.org Tel: 888-615-PAIN (7246) Fax: 410-385-1832 |
National Headache Foundation 820 N. Orleans Suite 217 Chicago, IL 60610-3132 info@headaches.org http://www.headaches.org Tel: 312-274-2650 888-NHF-5552 (643-5552) Fax: 312-640-9049 |
Mayday Fund [For Pain Research] c/o SPG 136 West 21st Street, 6th Floor New York, NY 10011 mayday@maydayfund.org http://www.painandhealth.org Tel: 212-366-6970 Fax: 212-366-6979 |
International Research Foundation for RSD/CRPS USF Medical Clinics c/o Dr. A. Kirkpatrick 12901 Bruce Downs Blvd., MDC59 Tampa, FL 33612 info@rsdfoundation.org http://www.rsdfoundation.org Tel: 813-907-2312 Fax: 813-830-7446 |
NIH Publication No. 04-4173
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Last updated July 31, 2008