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 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 share the same signs and symptoms.
Causes associated with the onset of RSD/CRPS include the following:
- Trauma (e.g., bone fracture, gunshot and shrapnel wounds)
- Cerebral lesions
- Heart disease, heart attack
- Paralysis on one side of the body (hemiplegia)
- Radiation therapy
- Repetitive motion disorder (e.g., carpal tunnel syndrome)
- Spinal cord disorders
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.
Signs and Symptoms
The acute stage occurs during the first 1-3 months and may include burning pain, swelling, increased sensitivity to touch, increased hair and nail growth in the affected region, joint pain, and color and temperature changes.
The dystrophic stage may involve constant pain and swelling, limb feels cool to the touch and looks bluish, muscle stiffness and wasting of the muscles (atrophy), early bone loss (osteoporosis). These symptoms usually occur 3-6 months after development of the disorder.
During the atrophic stage, the skin becomes cool and shiny, increased muscle stiffness and weakness occur, and symptoms may spread to another limb.
Characteristic signs and symptoms of sympathetic nervous system involvement are:
- Burning pain
- Extreme sensitivity to touch
- Skin color changes (red or bluish)
- Skin temperature changes (hot or cold)
- Symptoms associated with an immune reaction include:
- Joint pain
- Swelling (edema)
- Frequent infections
- Difficulty starting movement
- Increased muscle tone, stiffness
- Muscle spasm
- Dermatitis, eczema (inflammation of the skin)
- Excessive sweating
- Migraine headache
Seeking Medical Advice
In addition, any patient who is experiencing an unexplained worsening of pain from an injury that should have been improving over time should do the same.
If pain is spreading to the other non affected extremity (either the lower or even the non affected upper extremity) it should prompt the patient to seek medical evaluation from a specialist who is familiar with RSD.
Screening and Diagnosis
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.
Other conditions are ruled out with appropriate testing that may include MRI scan, a full laboratory panel, electrophysiological studies of the nerves and muscles (e.g., EMG, NCV), and a test known as a thermogram, which uses an infrared video camera to measure the emission of heat from the affected limb. EMG and NCV tests can be used in combination and are often referred to as EMG/NCV studies.
Medications are prescribed to control pain. The type of pain experienced by the patient determines the type of medication prescribed.
Constant pain caused by inflammation is treated with nonsteroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen, naproxen, indomethacin). Due to potenially severe gastrointestinal and cardiovascular side effects, NSAIDs should only be used as instructed.
Constant pain not caused by inflammation is treated with central acting agents such as tramadol (Ultram®).
Sharp pain and pain that disrupts sleep may be treated with antidepressants (e.g., amitriptyline, doxepin, nortriptyline, trazodone) or anticonvulsants (e.g., carbamazapine, gabapentin). Oral lidocaine, a somewhat experimental treatment for RSD/CRPS, also may be prescribed.
Generalized, severe pain that does not respond to other medications may be treated with opioids (e.g., propoxyphine, codeine, morphine).
Muscle cramps (spasms and dystonia) can be treated with clonazepam and baclofen.
Localized pain related to nerve injury may be treated with Capsaicin® cream, but its effectiveness has not been proven.
Medications that affect the sympathetic nervous system such as clonidine (Catapres®) can be useful in some cases.
Muscle stiffness may be treated with muscle relaxants such as
- Tizanidine (Zanaflex®)
- Clonazepam (Klonopin®)
Physical therapy should include daily range of motion exercises. Patients should be advised to avoid activities that could accelerate osteoporosis or joint injury.
Sympathetic nerve block interrupts the transmission of pain signals from a group of nerve cell bodies (called a ganglion). When treating an upper extremity, it is called a stellate ganglion block. A small needle is used to inject a local anesthetic alongside the windpipe. When treating a lower extremity the nerve block is performed in the lower (lumbar) spine, and is termed “lumbar sympathetic block”.
The procedure, which is usually performed by an anesthesiologist familiar with the technique, involves the insertion of a needle into the appropriate location and the injection of anesthesia into the ganglion. The effect is monitored over time.
Patients who have a good but temporary response to nerve block may be candidates for a surgical procedure called sympathectomy. The goal of this procedure, which involves cutting and sealing (cauterizing) a portion of the sympathetic nerve chain that runs down the spine, is suppression of sympathetic nervous system activity in the affected area. Performing sympathectomy for RSD is controversial and in some cases, the procedure worsens symptoms.
A transcutaneous electrical nerve stimulation (TENS) unit may be used to treat the affected area. In some cases, spinal cord stimulators are implanted permanently to supply a low intensity impulse to a location in the spinal cord in an attempt to interrupt the pain signals that are being transmitted to the brain.
RSD/CRPS patients often become depressed and anxious because of chronic pain and loss of physical ability. Counseling, support groups, and chronic pain center programs help patients learn coping strategies and provide emotional and psychological support.
Physicians who are treating patients at risk for these conditions need to keep a vigilant eye on any patient who is not responding to treatment, or who is showing early or even late signs of sympathetic dystrophy. Any patient who appears to be malingering, or requesting continued amounts of analgesics should be assessed for a possibly RSD, and should not just be labeled as narcotics seeking, or malingering.