Reflex Sympathetic Dystrophy (RDS)
What is Reflex Sympathetic Dystrophy (RSD)?
Reflex Sympathetic Dystrophy or Complex Regional Pain Syndrome Type I (CRPS I) is a syndrome characterized by burning pain, usually in an extremity, which follows injuries not related to nerve injury. Such injuries include sprains, fractures, infections, lacerations, operations and muscle, ligament or soft tissue injuries. In contrast, Causalgia (Greek for "burning pain") or Complex Regional Pain Syndrome Type II (CRPS II) is a syndrome consisting of sustained burning pain after a traumatic nerve injury. It was originally described in soldiers following limb amputations for wounds suffered during the Civil War. The median and sciatic nerves are most commonly involved.
What are the Characteristics of RSD?
RSD and Causalgia are syndromes typified by sustained burning pain in the injured extremity, tenderness and swelling. There is abnormal vasodilatation, vasoconstriction and sweating and later skin and bone changes. In later stages "Sudecks atrophy", patchy osteoporosis and demineralization in the bone and joint areas of the affected extremity may occur. All of these changes lead to a decreased range of motion of the extremity and to disuse and atrophy. There are several distinguishing features of RSD, which make it unique among pain syndromes. There is dysesthesia, an unpleasant abnormal sensation when the extremity is touched. There is hyperesthesia, increased sensitivity to stimulation. Patients with RSD may even be sensitive to bed sheetsor to the wind blowing on their skin. There is hyperpathia, an overreaction to stimuli followed by sensations after the stimulation. Even light touch to the affected extremity may cause severe pain lasting well past the time of touch.
What are the Causes of RSD?
There is some weak evidence that RSD is caused by an inherited, genetic predisposition to an abnormal central nervous system response to nerve injury or tissue trauma. It is probably a set of abnormal responses to injury, which result in structural changes in the central nervous system or spinal cord. The exact cause of RSD is unknown. Some of the possible causes of pain in RSD include: (I) chronic irritation of sensory nerves causing increased sympathetic nervous system activity, (2) creation of artificial connections between sympathetic and sensory nerves, (3) a loss of the balance between the inputs of the large and small nerves in the peripheral nervous system, (4) hypersensitivity of small nerves following injury to the peripheral nervous system, and (5) increased sensitivity of spinal cord receptors and pain pathways.
Treatment of RSD
Since the cause of RSD is unknown, the treatment of RSD is symptomatic. In the past nerve blocks, physical therapy, pain medications, and steroids have been used to treat it. A program of physical, voactional and pyscholgical therapy combined with medication management and desensitization of the affected extremeity with the help of anesthetic nerve blocks has the best chance of relieving the pain and symptoms of RSD. Severe cases may respond to spinal cord stimulation.