Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the autonomic nervous system that regulates involuntary functions of the body such as increasing heart rate, constricting blood vessels, and increasing blood pressure. Excessive or abnormal responses of portions of the sympathetic nervous system are thought to be responsible for the pain associated with reflex sympathetic dystrophy syndrome.
The symptoms of reflex sympathetic dystrophy syndrome typically begin with burning pain, especially in an arm, finger(s), palm of the hand(s), and/or shoulder(s). In some individuals, RSDS may occur in one or both legs or it may be localized to one knee or hip. Frequently, RSDS may be misdiagnosed as a painful nerve injury. The skin over the affected area(s) may become swollen (edema) and inflamed. Affected skin may be extremely sensitive to touch and to hot or cold temperatures (cutaneous hypersensitivity). The affected limb(s) may perspire excessively and be warm to the touch (vasomotor instability). The exact cause of RSDS is not fully understood, although it may be associated with injury to the nerves, trauma, surgery, atherosclerotic cardiovascular disease, infection, or radiation therapy.
The symptoms of reflex sympathetic dystrophy syndrome most commonly affect an arm and/or shoulder, and sometimes a leg and/or hip. The onset of symptoms can be slow, often beginning with gradual stiffness, discomfort, a burning sensation, and/or weakness in the affected area. However, in some cases, the symptoms appear suddenly and consist of severe pain, stiffness, and extreme sensitivity (hyperesthesia) of the affected area.
Pain and swelling associated with reflex sympathetic dystrophy syndrome may occur at the site of a previous injury (causalgia), surgery, trauma, or radiation therapy. Pain may extend beyond the original area of the injury and is more severe than the original trauma. Eventually, the entire limb may become involved and, in some cases, symptoms can spread to other areas of the body. Touching or covering the affected area with clothing or bed sheets may cause profound pain. Other early symptoms of this syndrome include redness of the skin, tenderness, excessive localized sweating (hyperhidrosis), and/or limited mobility of the affected extremity. Warm temperatures may intensify pain in some people with RSDS.
The symptoms of RSDS may worsen after 3 to 6 months. Pain generally becomes more intense and range of motion may become more restricted. Muscle weakness is also common during this stage of the disease. The skin over the affected areas may be pale or have a “pitted” appearance with an abnormal blue coloration (cyanosis) due to the lack of adequate blood supply to the area.
In some cases, a later stage of reflex sympathetic dystrophy syndrome may be associated with a decrease in pain. In other late cases, the pain may become constant (intractable). Only mild pain relief may be achieved with most treatment options. Muscle tremors and spasms may be present and muscle mass may diminish in size (atrophy). Strength in the affected limb may also be greatly reduced. Joints (e.g., shoulder) may become “frozen” or fixed in place (tendon contracture); sometimes, these joint changes are permanent. Bone mass may also diminish (osteoporosis), skin lesions may develop (i.e., atrophic changes), and grooves may appear in the nails.
The exact cause of reflex sympathetic dystrophy syndrome is not fully understood, although the syndrome is thought to result from nerve damage in the sympathetic nervous system. Excessive or abnormal responses of portions of the sympathetic nervous system are thought to be responsible for the pain associated with this syndrome.
A number of factors have been identified that may contribute to this disorder. RSDS may occur after trauma, surgery, infection, burns, radiation therapy, and/or paralysis on one side of the body (hemiparesis). In some rare cases, RSDS may develop after a heart attack (myocardial infarct). Disorders of the spine, such as cervical osteoarthritis, have also been associated with RSDS. In approximately 30 percent of the cases, no cause is found. In these cases, scientists do not understand why intense chronic pain evolves out of a relatively minor trauma.
One study suggests RSDS might be caused by a disease of the small blood vessels that supply oxygen to the muscle cells (microangiopathy).
RSDS/CRPS can occur at any age but is most common between the ages of 40 and 60. It occurs slightly more often among females than among males. It has been reported in children and young adults.
The diagnosis of RSDS may be confirmed by a thorough clinical evaluation that includes a complete history of symptoms and a comprehensive physical examination. Other specialized tests (e.g., skin temperature readings, x-rays, thermographic studies, and bone scans) may also suggest the diagnosis. A positive response to sympathetic blockade (see below) confirms the diagnosis of reflex sympathetic dystrophy syndrome.
Although no standard treatment for RSDS has been developed, prevention and early treatment of symptoms are recommended. In most cases, the earlier that treatment begins, the more effective it is likely to be.
Daily physical therapy should begin when the diagnosis of RSDS is confirmed. Whirlpool and paraffin wax baths are sometimes beneficial to help maintain mobility. Ice or heat applications should be avoided in most cases because they may result in overstimulation of nerve endings, leading to increased discomfort. Splinting of the affected area while the patient is at rest may help to prevent muscle contraction deformities (contractures), especially in the hand.
A special device known as a transcutaneous electrical nerve stimulator (TENS) may be used to treat people in the early stages of this syndrome. TENS treatment may also be added to an existing therapy program. The device alters nerve transmissions and helps to block the nerve impulses that cause pain.
Local or systemic glucocorticosteroid drugs (e.g., prednisone) may be effective for the treatment of some cases of reflex sympathetic dystrophy syndrome. However, they must be used with caution. Side effects are rarely seen with the lower doses recommended for the treatment of RSDS, but weight gain, swelling of the face (moon facies), and digestive upset have been reported. Other drugs that relieve pain (i.e., analgesics), including nonsteroidal antiinflammatory medications (e.g., ibuprofen or ketorolac) and muscle relaxants, sometimes help to relieve the symptoms of the disorder.
Some people with reflex sympathetic dystrophy syndrome may be treated with other drugs that block nerve function such as intravenous infusion of the drug guanethidine (an orphan drug). Propranolol (a beta blocker), nifedipine (a vasodilator), phenytoin (an anticonvulsant), and tricyclic drugs (antidepressants) have also been used with occasional success to treat people with reflex sympathetic dystrophy syndrome. Drugs that reduce the activity of the sympathetic nerves (sympatholytic agents), such as phenoxybenzamine, have also been used to treat RSDS. Electroacupuncture has had some success in treating people with early, mild cases of RSDS.
A specialized procedure known as a sympathetic blockade can be helpful for the treatment of intractable pain associated with RSDS. This procedure should be done as early in the course of the disease as possible since those treated earlier seem to experience better pain relief. During this procedure, drugs (e.g., lidocaine, buflomedil, or bupivacaine with epinephrine) are injected directly into the site of the suspected group of overactive nerve fibers. When the pain is located in an arm or shoulder, a stellate ganglion block is used. When pain is in a lower extremity, a lumbar sympathetic block is performed. The block is considered successful if blood circulation to the affected area is improved and if the patient reports a significant reduction in pain. These treatments can be given in a series or as indicated by the relief of symptoms. Sympathetic blocks have a unique advantage in that, when successful, they can confirm the diagnosis as well as provide rapid pain relief in many cases.
If blockade is not successful in reducing the symptoms of reflex sympathetic dystrophy syndrome, some people may then undergo a procedure known as a sympathectomy. During a pharmacologic (chemical) sympathectomy, nerves that control the constriction of blood vessels are destroyed by the injection of certain drugs. This allows the blood vessels to widen (dilate), allowing more blood to flow to the affected area and reducing pain. In a surgical sympathectomy, sympathetic nerves surrounding certain blood vessels (sheath) are surgically removed. The risks associated with a surgical sympathectomy are usually greater than those of a chemical sympathectomy.
Other treatment for RSDS is symptomatic and supportive.
An interdisciplinary committee of the Reflex Sympathetic Dystrophy Syndrome Association has written practice guidelines for the diagnosis, treatment, and management of RSDS. The guidelines, written in English and Spanish, are available on the organization's web site at http://www.rsds.org.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
The drug CC-5013, an investigational immunomodulatory drug, has undergone phase II testing as a treatment for adults with type 1 complex regional pain syndrome. This drug is manufactured by the Celgene Corporation. For information, contact the company at:
7 Powder Horn Drive
Warren, NJ 07059
Tel.: (732) 271-1001
The National Institute of Dental and Craniofacial Research (NIDCR) is conducting (2004) a phase II study to determine the effectiveness and safety of the drug neurotropin as a treatment for acute dental and chronic neural pain. This study is listed on the Clinical Trials web site. For information, use the NIH Patient Recruitment e-mail address and phone number listed above. The NIDCR is also sponsoring a study of proteins associated with complex regional pain syndrome. For this study, healthy volunteers and patients of any age with complex regional pain syndrome who are otherwise generally in good health may be eligible. Use the NIH contact information to learn more about this study.
The Massachusetts General Hospital is conducting ongoing research regarding several aspects of RSDS. For information, contact:
Massachusetts General Hospital
Boston, MA 02115
Tel.: (617) 726-4660
Preliminary investigation of a specialized spinal implant device, known as a dorsal column stimulator, shows some promise for the treatment of reflex sympathetic dystrophy syndrome (RSDS). A similar device, the implanted morphine pump, is being tested to deliver morphine directly into the spinal fluid of those severely affected individuals who are not responsive to other therapies. The morphine pump shows most promise in cases of reflex sympathetic dystrophy syndrome that involve several body areas. However, treatment with morphine can be associated with substantial side effects, including addiction. Therefore, it is not used in cases other than those in which all other options have been exhausted.
Research is in progress to study a new approach to sympathetic blockade for the treatment of “frozen shoulder” that is associated with reflex sympathetic dystrophy syndrome. In this procedure, the chemical blockade (i.e., bupivacaine and adrenaline) is injected into a certain bundle of nerves (i.e., suprascapular) that contain a high proportion of sympathetic nerve fibers. More studies are needed to determine the long-term safety and effectiveness of this procedure for the treatment of “frozen shoulder” due to RSDS.
Other drugs and combinations of drugs (i.e., bretylium and lidocaine) are also being studied to evaluate their ability to relieve pain when used during sympathetic blockade.
In another study, patients with severe, chronic reflex sympathetic dystrophy syndrome were given the drug clonidine by injection directly into the space around the spine (epidural). The dosage needed to obtain sustained pain relief is being studied. The side effects of clonidine may include sedation and abnormally low blood pressure (hypotension). More extensive studies are needed to determine the long-term safety and effectiveness of this procedure for the treatment of RSDS.
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FROM THE INTERNET
Complex Regional Pain Syndrome (also called Reflex Sympathetic Dystrophy Syndrome) Fact Sheet. National Institute of Neurological Disorders and Stroke. Reviewed October 9, 2003. 6pp.
Reflex Sympathetic Dystrophy/Complex Regional Pain Syndromes (CRPS): State-of-the-Science. Reviewed August 1, 2002. 6pp.