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Reflex Sympathetic Dystrophy syndrome (RSD) is a complex multi-symptom pain syndrome affecting a limb or limbs that can affect any one of any age.
It usually occurs following tissue damage to the limb, but it can also be triggered by visceral diseases, central nervous system lesions or from unknown causes.
It goes under a variety of names, including Complex Regional Pain Syndrome.
RSD is a disorder of the sympathetic nervous system. The sympathetic system is a network of nerves, located alongside the spinal cord and controls certain functions in our bodies, such as the opening and closing of blood vessels and sweat glands.
RSD often follows an injury, but in 30% of the cases the cause is unknown.
It often affects the hand or foot, but may also involve the knee, hip, shoulder, or other sites.
The main symptom of RSD is severe pain, often burning in nature.
The disorder may eventually result in dystrophy (weakness or wasting) of the area.
Early diagnosis and proper treatment are very important if RSD is to be successfully managed.
"Reflex sympathetic dystrophy" and "causalgia" are now classified by the International Association for the Study of Pain as Complex Regional Pain Syndromes I and II, but the older terms are in common usage and will be used in this discussion.
Allodynia is pain produced by stimuli that normally do not cause pain.
This can be moderate heat or cold or light touch. With RSD, even something as light as the weight of a bed sheet touching the skin can cause pain.
Hyperalgesia is the increased response to a normally painful stimulus, i.e. a lowered pain threshold.
Hyperaesthesia is an abnormal acuteness of sensitivity to sensory stimuli, including touch and light pressure
Sympathetically Maintained Pain has the following characteristics :-
Incidence
It is difficult to pinpoint the number of people who have RSD, though some estimates put the number of people afflicted with this syndrome at 6 million in the USA and other estimates claim between 5% and 10% of the population.
RSD is a major cause of disability, because only 20% of patients are able to fully resume prior activities. Investigators estimate that 2% to 5% of those with peripheral nerve injury and 12% to 21% of those with hemiplegia (paralysis of one side of the body) will suffer from RSD.
RSD 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 is more common in the older age groups, the number of RSD cases among adolescents and young adults is increasing
Clinical course
Pain is a constant feature of this condition. 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 characterised as a burning, aching, searing pain, which may initially be localised to the site of injury or the area covered by an injured nerve but spreads with 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 RSD vary in severity and duration. However, there are usually three progressive stages associated with RSD, and each stage is marked by progressive changes in the skin, nails, muscles, joints, ligaments, and bones.
These stages may be difficult to recognise in some individuals, and not everyone goes through them.
If immediate treatment is started in the first stage, the disorder may not progress further.
Other clinical features are as follows :-
Initially, the main symptom of RSD is pain, usually burning in nature.
In the first stage, the affected area is usuallyswollen and tender. Changes in the temperature and colour of skin may occur, along with sweating.
Other symptoms may include rapid hair and nail growth, and loss of ability to move affected joints normally.
After the condition has been present for weeks or months, the second stage develops.
The pain is often made worse by changes in temperature or by other stimulation, such as breezes, air conditioning, or light touch. The skin becomes cool, and the nails become brittle.
The area may become very swollen and look pale and waxy.
X-rays show thinning or damage of the joints or bones.
Pain may spread, usually moving towards the centre of the body (from the foot to the hip or the hand to the shoulder, for example). The spreading pain often affects the muscles, producing painful spasms.
Permanent changes may result during the final stage of this disorder.
The pain may remain severe, although some people notice less pain. The skin becomes drawn, and the muscles and other tissues become wasted and contracted (tight). Joint movement is greatly impaired.
There is no single test for diagnosing RSD.
Diagnosis is a clinical one and is made through observation of the patient's signs and symptoms.
Special investigations to confirm diagnosis include X-rays, a three-phase bone scan (scintigraphy), electrical tests of nerve function (nerve conduction velocity or NCV), electrical tests of muscle function (electromyogram or EMG), and thermography.
Thermography is 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 RSD. A colour-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) to the surrounding areas of the corresponding part on the other side of the body.
The quantitative sudomotor axon reflex test, also known as the quantitative sweat response test (QSART), measures both resting sweat output and evoked sweat output. High sympathetic activity is indicated by a high resting sweat output and sympathetic overactivity is associated with an increased evoked sweat output. Increased sweating is common in RSD patients.
Sympathetic blockade is often used to diagnose sympathetically maintained pain. A positive response to an appropriately controlled sympathetic block is often believed to be an indicator of RSD. A successful block can only be assumed if signs of sympathetic activity in the affected area are absent.
Skin temperature must be near core temperature and sweating must be absent.
Management
When diagnosed and treated within the first 3 to 6 months, there is the highest possibility of cure and treatment of RSD is most effective. Unfortunately RSD is not well known within much of the medical community so diagnosis is often overlooked. Further, many uninformed medical personnel have categorised the symptoms as psychosomatic or malingering, delaying treatment for years.
This is no cure for RSD.
Treatment in the first three to six months after onset with nerve blocks, medications and physical therapy has been reasonably effective. After six months treatment becomes more difficult and the success rate diminishes the longer one has RSD.
Early treatment includes sympathetic nerve blocks, medication (such as tricyclic antidepressives, anticonvulsives, beta-blockers, and NSAIDs), physiotherapy, psychotherapy, and electrical stimulation.
For reflex sympathetic dystrophy of the leg, a lumbar sympathetic block (LSB) is a type of nerve block most commonly used for treatment. The lumbar sympathetic chain lies at the anterolateral border of the vertebral bodies. Since most of the nerve fibres of the lower extremity pass through the second and third lumbar ganglia, a sympathetic block at this level provides almost complete sympathetic denervation to the lower extremity.
The pain relief obtained from this block is often immediate and can be long lasting, though some patients can experience a delayed reaction of several hours.
More invasive treatments can be considered in the later stages of RSD, including chemical sympathectomies, spinal cord stimulators, dorsal column stimulators, and possibly morphine pumps.
Though still used by some doctors, surgical sympathectomies and amputation of the affected limb are not effective and cause serious side effects.
The most important element of treating RSD syndrome is restoring normal movement to the affected part.
This condition is easiest to treat in its early phases.
Much of the treatment is based on a courageous effort of the patient to get the hand or foot moving again, even if it is uncomfortable. A formal physiotherapy, exercise programme or occupational therapy program with supervised exercises and other treatments may help maintain flexibility and strength.
Medical management includes paracetamol, aspirin, and other nonsteroidal anti-inflammatory drugs may be used for pain relief, but narcotics should usually be avoided.
A TENS (Transcutaneous Electrical Nerve Stimulator) unit or biofeedback may be tried. A TENS unit is a small, battery-operated device which relieves pain by blocking nerve impulses. Biofeedback is a technique which can help control pain, blood flow, and skin temperature.
Another treatment approach for RSD consists of blocking the sympathetic nervous system by injecting a numbing agent near the affected nerves or alongside the spinal column. A series of three to five blocks may be given.
Living with reflex sympathetic dystrophy syndrome can be difficult. There may have to be changes in relationships, in work situations, or in leisure-time activities.
Psychological help may be indicated.
Prognosis
Treatment and success rate will improve as more practitioners are made aware of the symptoms and effective treatment. More research is needed to determine the systems through which RSD operates. Double blind studies are needed to determine the effectiveness of most common treatments of RSD.
Good progress can be made in treating RSD 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% of RSD cases, pain persists longer than 6 months and sometimes for years.
Aggressive treatment, which may include sympathetic blockade, medications, physical therapy and psychotherapy, is essential for a favourable outcome.
Despite treatment, many patients are left with varying degrees of chronic pain and disability. Many patients who are not treated early will experience spread of RSD, and this may become a lifelong problem.
Even with early treatment, RSD may become a chronic condition.
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