Reflex sympathetic dystrophy syndrome (RSDS) - also known as complex regional pain syndrome - is a chronic condition characterized by severe burning pain, pathological changes in bone and skin, excessive sweating, tissue swelling, and extreme sensitivity to touch. The syndrome, which is a variant of a condition known as causalgia, is a nerve disorder that occurs at the site of an injury (most often to the arms or legs). It occurs especially after injuries from high-velocity impacts such as those from bullets or shrapnel. However, it may occur without apparent injury.
The symptoms of RSDS usually occur near the site of an injury, either major or minor, and include: burning pain, muscle spasms, local swelling, increased sweating, softening of bones, joint tenderness or stiffness, restricted or painful movement, and changes in the nails and skin. One visible sign of RSDS near the site of injury is warm, shiny red skin that later becomes cool and bluish. The pain that patients report is out of proportion to the severity of the injury and gets worse, rather than better, over time. It is frequently characterized as a burning, aching, searing pain, which may initially be localized to the site of injury or the area covered by an injured nerve but spreads over time, often involving an entire limb. It can sometimes even involve the opposite extremity. Pain 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 RSDS vary in severity and duration. However, there are usually three stages associated with RSDS, and each stage is marked by progressive changes in the skin, nails, muscles, joints, ligaments, and bones.
Stage one lasts from 1 to 3 months and 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.
In stage two, which lasts from 3 to 6 months, the pain intensifies. Swelling spreads, hair growth diminishes, nails become cracked, brittle, grooved, and spotty, osteoporosis becomes severe and diffuse, joints thicken, and muscles atrophy.
As the patient reaches stage three, changes in the skin and bones become irreversible, and pain becomes unyielding and may now 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.
The cause of RSDS is unknown. The syndrome is thought to be the result of damaged nerves of the sympathetic nervous system - the part of the nervous system responsible for controlling the diameter of blood vessels. These damaged nerves send inappropriate signals to the brain, interfering with normal information about sensations, temperature, and blood flow.
Since RSDS is most often caused by trauma to the extremities, other conditions that can bring about RSDS include sprains, fractures, surgery, damage to blood vessels or nerves, and cerebral lesions. The disorder is unique in that it simultaneously affects the nerves, skin, muscles, blood vessels, and bones.
RSDS can strike at any age, but is more common between the ages of 40 and 60. It affects both men and women, but is most frequently seen in women. Although it can occur at any age, the number of RSDS cases among adolescents and young adults is increasing. Investigators estimate that two to five percent of those with peripheral nerve injury and 12 to 21 percent of those with hemiplegia (paralysis of one side of the body) will suffer from RSDS.
RSDS is often misdiagnosed because it remains poorly understood. 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 recovery.
RSDS is diagnosed primarily through observation of the symptoms. However, some physicians use thermography - a diagnostic technique for measuring blood flow by determining the variations in heat emitted from the body - to detect changes in body temperature that are common in RSDS. A color-coded "thermogram" of a person in pain often shows an altered blood supply to the painful area, appearing as a different shade (abnormally pale or violet) than the surrounding areas of the corresponding part on the other side of the body. An abnormal thermogram in a patient who complains of pain may lead to a diagnosis of RSDS. X-rays may also show changes in the bone.
Physicians use a variety of drugs to treat RSDS, including corticosteroids, vasodilators, and alpha- or beta-adrenergic-blocking compounds. Elevation of the extremity and physical therapy are also used to treat RSDS. Injection of a local anesthetic, such as lidocaine, is usually the first step in treatment. Injections are repeated as needed. TENS (transcutaneous electrical 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.
In some cases, surgical or chemical sympathectomy - interruption of the affected portion of the sympathetic nervous system - is necessary to relieve pain. Surgical sympathectomy involves cutting the nerve or nerves, destroying the pain almost instantly. But surgery may also destroy other sensations as well.