What is RSD?
Reflex Sympathetic Dystrophy, commonly referred to as RSD is a chronic condition that is often identified by severe pain and other symptoms. RSD patients normally experience the pain in one limb, though the pain may spread to other parts of the body. RSD is actually one form of the medical condition known as Chronic Regional Pain Syndrome (CRPS). In this regard, RSD is also known as CRPS Type 1, while the other form of the medical condition is known as CRPS Type 2 or Causalgia. RSD is the most common form occurring in a higher percentage of patients.
The pathophysiology of RSD is currently not fully understood. RSD usually results from an initiating noxious event or injuries such as sprains and amputations. However, in some cases it may be impossible to identify the precipitating cause of the condition as several noxious events may be responsible for its onset. Trauma has been identified as a predominant cause of the condition, fractures account for up to 50% of RSD cases, and other causes include immobilisation, stroke, heart attack, and iatrogenic injury such as carpal tunnel syndrome.
Most RSD symptoms begin at the site of the condition, but may spread as it progresses. If they are not treated as soon as possible, the symptoms may go from mild to severe and worsen the condition. Some believe that RSD symptoms develop in stages from acute to chronic, and the further the condition advances, the less effective the treatments used will be.
RSD is difficult to diagnose, especially given that the exact cause of the condition is unknown. A set of guidelines called the Budapest Criteria, established by the International Association for the study of Pain (IASP) is mostly used to make an RSD diagnosis. The guideline is in the form of a checklist of the signs and symptoms most common in RSD patients.
Several symptoms exist but may not always be present at the same time, making it harder to definitively diagnose a patient with the condition. RSD symptoms usually occur in the affected limb which may be a foot, hand, leg, neck, or wrist. The most common RSD symptoms and signs can be listed under four categories which are explained below along with the relevant symptoms:
- Sensory changes
These are mostly to do with changes in sensitivity. Pain is the predominant symptom in RSD patients. The severity of the pain is described as being much higher than what would be expected for the injury causing it. This severe sensation of pain is a result of the increased sensitivity to pain (hyperalgesia) that develops in all RSD patients. Some patients may also suffer from severe allodynia, which is a severe pain response to normally non-painful stimuli such as light touching and hair combing.
Tests for increased sensitivity to pain can be done with a pin prick, cotton wool, joint position, tuning fork, hot and cold roller, and other quantitative sensory tests. Some sensory abnormalities that may be indicative of RSD are:
- Spontaneous pain
- Mechanical hyperalgesia
- Thermal hyperalgesia
- Deep somatic hyperalgesia
- Autonomic changes
Vasomotor and sudomotor changes fall under autonomic changes. Vasomotor effects refer to the constriction or dilatation of blood vessels resulting from a malfunctioning sympathetic nervous system, while sudomotor changes relate to anything that stimulates the sweat glands. Some common RSD symptoms falling under this category are:
- Skin colour changes
- Skin temperature differences between affected and unaffected limbs
- Abnormal sweating
- Trophic changes
As RSD advances, trophic changes may be seen in the patient such as atrophy of the skin, hair, and nails. Demineralisation of the bone may also occur resulting in osteoporosis.
- Hair and nail changes
- Skin atrophy
- Motor changes
The pain arising from RSD is so severe that it may cause the affected individual to stop using the painful limb altogether. Prolonged immobility of the limb may result in loss of calcium from the bones of the affected part, as well as muscle atrophy in that area. Involuntary movements such as tremors and muscle spasms (dystonia) may also develop.
- Motor weakness
- Coordination deficits
- Joint stiffness
- Soft tissue
RSD may also affect the patient’s mental health due to the severity of the pain they feel. As a result, the patient may experience anxiety, depression, post-traumatic stress disorder, and emotional stress. Emotional stress usually leads to flare ups which are long-lasting periods of intense pain.
Regardless of which limb is affected, the main RSD symptom is a severe pain in one of the extremities that is disproportionate to the injury. This pain may be seen to continue even after the injury has healed. Other RSD symptoms that may be seen in all or some of the limbs typically affected by RSD are:
RSD symptoms in foot
- Skin colour may change and become blotchy, blue, purple, pale, or red.
- Change in skin texture on the affected area.
- Hyperalgesia and allodynia.
- Extreme sensitivity to touch such that even putting the foot down can feel very painful.
- Reduced mobility.
RSD symptoms in hands
- The affected hand may have limited mobility.
- Temperature changes and altered skin tone in the affected area.
- The skin may also become thin and the affected individual may be prone to infections and sores.
- Hyperalgesia and allodynia.
RSD symptoms in legs
- Affected leg may feel warmer or cooler compared to the opposite limb.
- Changes in skin colour resulting in blotchy, purple, pale, or red appearance.
- Skin texture may change such that the skin on the affected leg looks shiny and thin.
- Abnormal sweating on the affected leg.
- Hyperalgesia and allodynia.
RSD symptoms in neck
- Abnormal hair and nail growth patterns.
- Changes in skin colour and texture.
- Skin temperature changes.
- Localized swelling.
RSD symptoms in wrist
- Limited range of motion.
- Swelling in affected area.
- Skin temperature differences between affected and unaffected area.
- Hyperalgesia and allodynia.
Stages of RSD Symptoms
There are three clinical stages of RSD; namely acute, subacute, and chronic.
1. Acute RSD
This stage lasts approximately 3 months. A burning pain is usually the first symptom followed by swelling, hyperhidrosis, coolness to the touch, and redness with vasomotor instability which results in increased dependency. Another physical change that can occur in this stage is demineralisation of the underlying bony skeleton as a result of disuse of the limb.
2. Subacute RSD
If treatment of RSD does not begin in the acute phase, the condition may progress to the second stage which can last up to 9 months. In this subacute stage, the patient develops persistent, severe pain in the affected limb, and fixed edema. Loss of function increases because of the enhanced pain, as well as thickening and scarring of connective tissue in the joints as a result of chronic inflammation. Skin and subcutaneous tissues begin to atrophy and demineralisation of the underlying bony skeleton that began in the acute stage becomes pronounced.
The chronic stage is the last stage that may develop approximately 1 year after the onset of the disease. This stage may last for several years or become permanent. During the chronic stage, the pain level varies and may subside or continue undiminished. Edema may subside over time and the skin will be dry, pale, cool, and shiny. Stiffness of the affected area, as well as loss of function are more pronounced.
Identifying RSD Symptoms
As mentioned before, there are no clear methods, tests, or tools to diagnose RSD. Most diagnoses are made on the basis of the appearance of symptoms related to the condition. In general, a patient must meet the following criteria for diagnosis:
- The patient must have experienced some noxious event such as a contusion, crush, laceration, surgery, sprain, fracture, or dislocation.
- Pain, allodynia, and/or hyperalgesia must be present. Allodynia refers to central pain sensitisation following a repetitive stimulation that is normally not painful, for example if the patient feels pain from a light touch or when brushing their hair. Hyperalgesia is a similar condition of an enhanced pain response where a person develops an increased sensitivity to pain.
- Individuals with RSD may feel pain that is constant and disproportionate to the injury. The pain usually begins locally but may progress to involve the entire extremity.
- Symptoms associated with sympathetic nervous system dysfunction such as edema, changes in skin blood flow, and sudomotor activity must be present for a patient to be diagnosed with RSD.
RSD Symptoms tests
Other tests can be used to aid in the diagnosis by eliminating other conditions that may exhibit signs and symptoms similar to RSD.
- Magnetic Resonance Imaging Scans
A Magnetic Resonance Imaging (MRI) scan uses magnets and radio waves to capture images of the body’s internal structure, allowing the physician to see the patient’s bones as well as soft tissues of their body. MRIs use strong magnetism to highlight tissue irregularities in the affected limb. A magnetic field that temporarily aligns the water molecules in the body is generated during an MRI scan. The radio waves then use these aligned particles to produce faint signals which are recorded as images by the machine.
A localised loss of bone density occurs in the affected limb only. This bone loss is identifiable on plain radiographs, so X-ray imagery can be used to check for broken bones and loss of bone minerals. X-rays can be used to detect changes in the bone as early as two weeks after the onset of RSD so treatment can begin as soon as possible, offering a better chance for managing the disease.
- Bone Scan
A bone scan is a nuclear imaging test that helps diagnose several types of bone disease. The test is very sensitive to any difference in bone metabolism. RSD is characterised by bone changes such as demineralization and loss of bone density. The bone scans find such changes through the use of a radioactive substance that’s injected into the patient’s vein. A triple phase bone scan can even help distinguish between RSD and CRPS Type 2 since it has the best sensitivity compared to MRI and plain film radiographs.
- Thermography tests
A thermography test is a sympathetic nervous system test that checks for skin temperature and blood flow differences between injured and non-injured limbs or the amount of sweat on both limbs. Any variation between the two is usually indicative of RSD. The reliability of this test with regards to RSD diagnosis is conditional as many other factors can also contribute to a variance in thermographic readings. These include factors such as smoking habits, certain skin lotions that the patient uses, prior history of trauma to the affected area, and recent physical activity. In addition, not all patients who have RSD exhibit an altered thermographic reading, especially when tested in the later stages of the disease.
RSD Symptoms in Infants
Although RSD symptoms in infants have rarely been observed, a few cases have been reported in children. Children with RSD may have bone or soft tissue edema that are visible on MRI scans and can be mistaken for stress fractures or injury. RSD diagnosis in children is established by studying the patient’s history and through physical examination. RSD symptoms in infants may vary but the most common is prolonged pain. Children with RSD may also developed an increased sensitivity to touch and pain in the affected limb, changes in temperature, skin colour and swelling of the affected limb, stiffness in the affected joint, and problems coordinating muscle movements.
RSD symptoms in infants can occur in more than one area of the body due to the spreading of the pain that may even involve the entire body. Children may have localized pain to the affected limbs and experience RSD symptoms in hands, neck, wrist, and feet. The stages of RSD symptoms described above are not normally seen in children and the duration of RSD symptoms in infants does not affect or influence their response to treatment. Intense physical and occupational therapy have proven to be more effective in treatment of children with RSD, and these RSD treatment options are relatively side effect free.
RSD has a better prognosis in children than in adults and most children have been seen to recover faster than adults.