Reflex sympathetic dystrophy (RSD), now more commonly known as complex regional pain syndrome (CRPS), is a nervous system disorder that often results in severe chronic and burning pain and other symptoms. It often follows trauma to one of the limbs, surgery, infection, and radiation therapy. This syndrome is thought to affect millions of people in the United States and has a predilection for women between the ages of 40 and 60 years of age. It can cause swelling, temperature changes, vascular abnormalities, motor weakness, and osteoporosis in the affected limb. Treatment often involves many different modalities including physical therapy, medications, and nerve blocks.

Symptoms

Many of the symptoms of RSD/CRPS result from overactivity of the sympathetic nervous system, the branch of the nervous system responsible for involuntary control of blood pressure, heart rate, and blood vessel tone. Most patients describe searing, burning, lancinating pain that is usually disproportionate to the degree of injury that was sustained. The pain can be triggered by using the limb or by stress, and can be spontaneous or constant. There is usually edema (swelling) of the affected limb, and the skin may be reddened and warm to the touch. The limb may feel alternately hot and cool, as perceived by the patient. Excessive sweating and joint pain are other symptoms that can be experienced by the patient.

The symptoms of RSD/CRPS often develop in three stages. In stage one, the acute period, which usually lasts 1-3 months, there is burning pain, swelling, increased sensitivity to touch, increased hair and nail growth in the affected region, joint pain, and color and temperature changes. During stage two, lasting 3-6 months, there is constant pain and swelling, and the limb may feel cool and look discolored. At this time there is often muscle stiffness and atrophy (wasting of the muscles), and x-rays may reveal early osteoporosis (thinning of the bones). In stage three, the skin is cool and shiny, muscle stiffness and weakness increase, and the symptoms may spread to another limb.

Depression and other negative psychological effects often afflict people with chronic pain, because the syndrome is often difficult to diagnose and many clinicians are not fully aware of the treatment options, which frustrates patients in their efforts to get adequate treatment.

Causes

The injury that precedes the onset of RSD/CRPS may or may not be significant; some patients diagnosed with the syndrome do not remember the causal event. Its occurrence has been documented after nerve injuries, such as carpal tunnel syndrome and cervical radiculopathy; surgical procedures; radiation therapy; and infection.

The physiological events leading to the manifestation of severe pain and other symptoms are not known, it is hypothesized that the initial injury triggers an abnormal and exaggerated response by the sympathetic nervous system. This may in turn send an abnormal pattern of communication to the central nervous system (brain and spinal cord) and thus to appropriate anatomical structures, which ultimately triggers the ongoing problems.

Diagnosis

The diagnosis of RSD/CRPS is often difficult and often a diagnosis of exclusion. When all of the symptoms are present, diagnosis is obvious, but when they are not, it may be a long time before the diagnosis is made and treatment begun. A thorough history and neurological examination is of utmost importance. Evaluation of the appearance of the limb, the temperature, color, signs of swelling and vascular reactivity is documented. During the exam, the clinician may notice that the response to mild sensory stimuli produces severe pain. There may be changes in the hair, nails, joints, and muscles; that is, the nails may be overgrown, the joints may be swollen and stiff, and the muscles may be weak and atrophied (wasted).

Often other diagnoses 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 limb.

Treatment

Once the diagnosis of RSD/CRPS is made, an individualized treatment plan should be formulated in which the goals are to control pain and to maintain normal mobility of the limb. Treatment often combines physical therapy with a therapist familiar with the disorder, medications, nerve blocks, and psychosocial support.

Physical therapy should include daily range of motion exercises. Patients should be advised to avoid activities that may accelerate osteoporosis or joint injury.

Medications that treat other forms of chronic pain are often prescribed, including NSAIDS (nonsteroidal anti-inflammatory drugs), central acting agents such as tramadol (Ultram®), tricyclic antidepressants (amytriptyline), anticonvulsants (Neurontin®, Topamax®), and opioids (oxycodone, morphine). Medications that block selected actions of the sympathetic nervous system, such as Clonodine® (available in oral and patch formulations), can be useful in some cases. Zanaflex®, Baclofen®, and Klonopin® are medications for muscle stiffness that can be useful.

The most helpful type of nerve block, the sympathetic block, is used to block the transmission of overactivity from the ganglion (group of nerve cell bodies). When performed in the upper extremity, it is called a stellate ganglion block, and when performed in the lower extremity, a lumbar sympathetic block. The procedure, 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 are candidates for a permanent procedure called sympathectomy, the aim of which is to suppress the activity of the sympathetic nervous system in the affected area.

A TENS (transcutaneous electrical nerve stimulation) 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.

Psychosocial support (counseling, support groups, and chronic pain center programs) is very important for people living with chronic pain, many of whom are significantly disabled both physically and mentally and thus have difficulty performing everyday activities.