Reflex Sympathetic Dystrophy Syndrome
Complex Regional Pain Syndrome

RSD(S)-CRPS Advisory
Complex regional pain syndrome (CRPS) is a chronic condition characterized by severe pain
following injury to bone and soft tissue.
The International Association for the Study of
Pain has divided CRPS into two types based on the presence of nerve lesion following the
injury. Type I, also known as Reflex sympathetic dystrophy (RSD) or algoneurodystrophy,
does not have demonstrable nerve lesions, while type II, also known as causalgia, has
evidence of obvious nerve lesions.
The cause of these syndromes is currently unknown.The
condition currently known as CRPS was originally described by Weir Mitchell during the
American Civil War, who named the condition causalgia. In the 1940s, the term reflex
sympathetic dystrophy came into use to describe this condition, based on the theory that
sympathetic hyperactivity was involved in the pathophysiology (Evans, 1946). Misuse of the
terms, as well as doubts about the underlying pathophysiology, led to calls for better
In 1993, a special consensus workshop held in Orlando, Florida provided
the umbrella term, complex regional pain syndrome, with causalgia and RSD as its
The symptoms of CRPS usually occur near the site of an injury, either major or
minor, and usually spreads beyond the original area.
It may spread to involve the entire limb
and, rarely, the opposite limb. The most common symptom is burning pain.
The patient
may also experience muscle spasms, local swelling, increased sweating, softening of bones,
joint tenderness or stiffness, restricted or painful movement, and changes in the nails and
The pain of CRPS is continuous and may be heightened by emotional stress. Moving
or touching the limb is often intolerable. Eventually the joints become stiff from disuse,
and the skin, muscles, and bone atrophy. The symptoms of CRPS vary in severity and
duration. There are three variants of CRPS, previously thought of as stages. It is now
believed that patients with CRPS do not progress through these stages sequentially and/or
that these stages are not time limited. Instead, patients are likely to have one of the three
following types of disease progression:

Type one
is characterized by severe, burning pain at the site of the injury. Muscle spasm,
joint stiffness, restricted mobility, rapid hair and nail growth, and vasospasm (a constriction
of the blood vessels) that affects color and temperature of the skin can also occur.

Type two is characterized by more intense pain. Swelling spreads, hair growth diminishes,
nails become cracked, brittle, grooved, and spotty, osteoporosis becomes severe and
diffuse, joints thicken, and muscles atrophy.

Type three is characterized by irreversible changes in the skin and bones, while the pain
becomes unyielding and may involve the entire limb. There is marked muscle atrophy,
severely limited mobility of the affected area, and flexor tendon contractions (contractions of
the muscles and tendons that flex the joints). Occasionally the limb is displaced from its
normal position, and marked bone softening is more dispersed.

No specific test is available for CRPS, which is diagnosed primarily through observation of
the symptoms. However, thermography, sweat testing, x-rays, electrodiagnostics, and
sympathetic blocks can be used to build up a picture of the disorder. Diagnosis is
complicated by the fact that some patients improve without treatment.
A delay in diagnosis
and/or treatment for this syndrome can result in severe physical and psychological
problems. Early recognition and prompt treatment provide the greatest opportunity for

Physicians use a variety of drugs to treat CRPS, including antidepressants, corticosteroids,
vasodilators, gabapentin, and alpha- or beta-adrenergic-blocking compounds. Elevation of
the extremity and physical therapy are also used to treat CRPS. Injection of a local
anesthetic, such as lidocaine, is usually the first step in treatment. Injections are repeated as
needed. TENS (transcutaneous electrical nerve stimulation), a procedure in which brief
pulses of electricity are applied to nerve endings under the skin, has helped some patients in
relieving chronic pain.
Neurostimulation (spinal cord stimulators) may also be surgically
implanted to diffuse the pain by replacing it with a tingling sensation. These devices place
electrodes either in the epidural space (space above the spinal cord) or directly over nerves
located outside the central nervous system. Implantable drug pumps may also be used to
deliver pain medication directly to the cerebrospinal fluid which allows the use of
powerful opioids to be used in a much smaller dose than when taken orally. Ketamine
infusion to treat CRPS has been described (Correll et al, 2004).

Surgical, chemical, or radiofrequency sympathectomy — interruption of the affected portion
of the sympathetic nervous system — can be used as a last resort in patients with impending
tissue loss, edema, recurrent infection, or ischemic necrosis (Stanton-Hicks et al, 1998).

Physical therapy is also an important part of treatment, though it should be noted that many
patients are incapable of participating in physical therapy due to subsequent muscular and
bone problems. People struggling with CRPS often develop guarding behaviors where they
avoid using or touching the affected limb. Unfortunately, inactivity can exacerbate the
disease and perpetuate the pain cycle. Physical therapy works best for some patients,
especially goal-directed therapy, where the patient begins from an initial point, regardless of
how minimal, and then endeavors to increase activity each week. While the unpredictability
of this illness often causes a frustrating pattern of progress and regress, it is essential to
continue to try to increase and normalize physicial activity.

Good progress can be made in treating CRPS if treatment is begun early, ideally within 3
months of the first symptoms. Early treatment often results in remission. If treatment is
delayed, however, the disorder can quickly spread to the entire limb and changes in bone and
muscle may become irreversible. In 50 percent of CRPS cases, pain persists longer than 6
months and sometimes for years.

Similar disorders
CRPS has characteristics similar to those of other disorders, such as shoulder-hand
syndrome, which sometimes occurs after a heart attack and is marked by pain and stiffness
in the arm and shoulder; Sudeck syndrome, which is prevalent in older people and women
and is characterized by bone changes and muscular atrophy, but is not always associated
with trauma; and Steinbrocker syndrome, which includes symptoms such as gradual
stiffness, discomfort, and weakness in the shoulder and hand.

The National Institute of Neurological Disorders and Stroke (NINDS), a part of the
National Institutes of Health (NIH), supports and conducts research on the brain and
central nervous system, including research relevant to RSDS, through grants to major
medical institutions across the country.
NINDS-supported scientists are working to develop
effective treatments for neurological conditions and, ultimately, to find ways of preventing
them.Investigators are studying new approaches to treat RSDS and intervene more
aggressively after traumatic injury to lower the patient’s chances of developing the disorder.
In addition, NINDS-supported scientists are studying how signals of the sympathetic
nervous system cause pain in RSDS patients. Using a technique called microneurography,
these investigators are able to record and measure neural activity in single nerve fibers of
affected patients. By testing various hypotheses, these researchers hope to discover the
unique mechanism that causes the spontaneous pain of RSDS and that discovery may lead to
new ways of blocking pain.Other studies to overcome chronic pain syndromes are
discussed in the pamphlet “Chronic Pain: Hope Through Research,” published by the NINDS.

Grateful to the NINDS for allowing the use of this information.
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