Reflex sympathetic dystrophy (RSD), also known as complex regional pain syndrome (CRPS), is a chronic progressive neurological condition that affects skin, muscles, joints, and bones. The syndrome usually develops in an injured limb, such as a broken leg. However, many cases of RSD involve only a minor, seemingly inconsequential injury, such as a sprain. And in some cases, no precipitating event can be identified.
Pain may begin in one area or limb and then spread to other limbs. RSD/CRPS is characterized by various degrees of burning pain, excessive sweating, swelling, and extreme sensitivity to touch. Symptoms of RSD/CRPS may recede for years and then reappear with a new injury.
Two types of RSD/CRPS have been defined:
Type 1 - without nerve injury
Type 2 (formerly called causalgia) - with nerve injury
Both types express the same signs and symptoms.
Incidence and Prevalence
Millions of people in the United States may suffer from this chronic pain syndrome. RSD/CRPS affects both men and women, but is more common in women, and can occur at any age, but usually affects people between 40 and 60 years old.
The National Institute of Neurological Disorders and Strokes reports that 2% to 5% of peripheral nerve injury patients and 12% to 21% of patients with hemiplegia (paralysis on one side of the body) develop reflex sympathetic dystrophy as a complication. The Reflex Sympathetic Dystrophy Syndrome Association of America (RSDSA) reports the condition appears after 1% to 2% of bone fractures.
Causes and Risk Factors
RSD/CRPS appears to involve the complex interaction of the sensory, motor, and autonomic nervous systems; and the immune system. It is thought that central nervous system (brain and spinal cord) control over these various processes is somehow changed as a result of the injury.
Conditions associated with the onset of RSD/CRPS include:
Trauma (e.g., bone fracture, gunshot and shrapnel wounds) Spinal cord disorders Cerebral lesions Heart disease, heart attack Hemiplegia (paralysis on one side of the body) Infection Radiation therapy Repetitive motion disorder (e.g., carpal tunnel syndrome) Surgery In 10% to 20% of cases, no direct cause can be found. Injury that precedes the onset of RSD/CRPS may or may not be significant.
RSD Signs and Symptoms
The symptoms of RSD/CRPS may progress in three stages acute, dystrophic, and atrophic although this notion is subject to debate.
Acute: burning pain, swelling, increased sensitivity to touch, increased hair and nail growth in the affected region, joint pain, color and temperature changes; first 1-3 months
Dystrophic: constant pain and swelling, limb feels cool and looks bluish, muscle stiffness and atrophy (wasting of the muscles), early osteoporosis (bone loss), 3-6 months
Atrophic: cool and shiny skin, increased muscle stiffness and weakness, symptoms may spread to another limb
Characteristic signs and symptoms of sympathetic nervous system involvement are :
Extreme sensitivity to touch
Skin color changes (red or bluish)
Skin temperature changes (heat or cold)
Pain is usually disproportionate to the degree of injury and can be triggered by using the affected limb or by stress and can be spontaneous or constant.
Symptoms associated with an immune reaction include:
Accumulated immune cells in the site
Signs of motor system dysfunction include
Difficulty starting movement
Increased muscle tone
Other symptoms include: Migraine headache
Patients with any chronic illness, including RSD/CRPS, often suffer from depression and anxiety. Skin, muscle, and bone atrophy (wasting) are possible complications of the syndrome. Atrophy may occur because of reduced function of the limb.
RSD/CRPS can be difficult to diagnose and often requires excluding other conditions that produce similar symptoms. A thorough history and neurological examination is of utmost importance. During the exam, the clinician may notice that the response to mild sensory stimuli produces severe pain.
Physical examination involves observing the skin color and temperature, swelling, and vascular reactivity; overgrown and grooved nails; swollen and stiff joints; muscle weakness and atrophy (wasting).
Other conditions are ruled out with appropriate testing that may include MRI studies, a full laboratory panel, EMG/NCV (electrophysiological studies of the nerves and muscles), and a test known as a thermogram, which uses an infrared video camera to measure the emission of heat from the affected limb.