Complex regional pain syndrome is a chronic pain condition that is as complex as it is rare. When a person sustains an injury, sometimes the nerves are damaged, causing the central and peripheral nervous systems to send and receive confusing or incorrect signals to the brain. The result is pain and swelling in the arms and/or legs. For 92% of patients, this pain may start in one arm or leg and then spread to others.
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This condition has been classified as one of the most painful chronic pain conditions, scoring 42 out of 50 on the McGill Pain Index. This makes complex regional pain syndrome more painful than childbirth or amputation.
In complex regional pain syndrome, the body is reacting to nerve damage or trauma in an amplified way. Symptoms can be minor or severe and can sometimes resolve themselves or worsen over time for no apparent reason.
Symptoms of complex regional pain syndrome
In addition to pain and swelling, other symptoms of complex regional pain syndrome include:
- Tight, shiny skin. The swelling of the arms and legs can cause skin to appear thin, tight, and shiny. This may eventually cause cracks to appear if the skin is not properly cared for.
- Muscle spasms. Uncontrollable movement in the affected limb is present in most cases.
- Sensitivity to touch. Even things like water and vibrations can be painful for patients with complex regional pain syndrome.
- Variations in thermoregulation. Because the nerves are not able to consistently regulate body temperature, skin may feel hot or cold in response to abnormal, inconsistent blood flow. Skin may also appear blotchy or turn bright red or blue.
- Bone issues. Bones in the affected limb mat soften and become weaker, and the patient may experience joint stiffness and decreased range of motion.
Symptoms that are seen less frequently include dizziness and fainting. Patients will also occasionally report problems with vision and osteoporosis.
Stages of complex regional pain syndrome
Patients may move through several stages before being diagnosed with the condition. Stage one is when burning pain at the site of injury begins. Patients may also experience sweating and change in color of the limb due to fluctuations in thermoregulation. This stage can last for several weeks.
Pain increases, as does swelling, when a patient progress to stage two. Hair growth stops, and nails may also grow brittle and develop cracks and ridges. The joints stiffen, and muscles become weaker and atrophy.
Stage three brings about irreversible changes in skin and bones. Pain increases to a level that is unbearable, and may begin to involve not only the whole limb but also spread to the rest of the body. Movement is severely limited, and occasionally bones are moved around in the affected limb due to softening. The tendons that are responsible for moving the limb begin to contract, pulling the foot or hand towards the body.
Types of complex regional pain syndrome
Complex regional pain syndrome is usually divided into two types.
In CRPS-I, there is no obvious trauma or injury to the nerves. This indicates that the condition may have originated internally, or that the body has sustained an infection that may have caused damage. CRPS-II is originated from obvious injury or trauma. Because both types have the same symptoms and treatments, some researchers are not in agreement that this division is valid or that a division is necessary at all.
Regardless, 90% of patients have clear evidence of trauma or injury. These injuries can be fractures, sprains, strains, bruises, burns, or cuts. They can also occur as a result of being in a cast or undergoing surgery. While most people sustain a broken ankle or a huge bruise and then go on to recover without developing CRPS, some have a severe reaction to the injury and begin to move through the three stages of the condition. There is limited connection to genetic history as a cause of CRPS, but those with autoimmune disorders or other inflammatory responses have a higher incidence of CRPS than those without those conditions.
Those with CRPS have a high level of cytokines, inflammatory chemicals released in reaction to some stimulus (physical or chemical). The extreme response to injury is almost like the body’s defense mechanism to the injury and seems to function in the same manner as an allergy.
Complex regional pain syndrome involves the small fibers in the nerves. It can cause blood vessels to open wide to leak fluid into the surrounding muscle and tissue. This response causes swelling, redness, and pain. When the small fibers cause constriction, blood vessels cut off the flow of blood and cause the affected limb to feel cold and become white or blue in tone. Those patients who have conditions that affect the blood vessels may be particularly susceptible to this response.
Diagnosing and treating complex regional pain syndrome
Patients who have nerve abnormalities in the small nerve fibers seem to develop this condition more frequently.
The ends of the small nerve fibers are densely packed and very sensitive. They contribute to inflammation and abnormalities in the blood. In extreme cases, these abnormal small peripheral nerves can trigger abnormalities within the larger central nervous system, which can lead to neurological issues in brain function.
There is not a single test that indicates complex regional pain syndrome. When a patient presents for diagnosis, it is usually due to an extreme painful reaction to a light stimulus. Doctors then rely on patient reporting and history as well as their own observation to begin initial diagnostics. Thermography and X-rays can be used, as well as sympathetic nerve blocks to see if nerve damage is the cause of pain.
Treatments for complex regional pain syndrome
Once a diagnosis is reached, both types are treated in the same manner. Anticonvulsant and anti-depressant drugs seem to work well to alleviate the pain. This may have to do with the way that these drugs work on the pain receptors in the brain. Anti-inflammatory drugs and corticosteroids are utilized to reduce swelling, and doctors may prescribe opioids in extreme cases.
Physical therapy and counseling have been proven to work well in conjunction with one another, possibly even more effectively than any other treatment. For children and adolescents, this approach has been shown to be very effective, with one study reporting an 88% success rate in long-term pain reduction. This is good news as it allows doctors to avoid prescription drugs for younger patients.
While the chances of developing complex regional pain syndrome are slim, it is important to recognize the signs of this condition. For more information and to find out the latest research, visit the National Institute of Neurological Disorders and Stroke.
Image by Keirsten Marie via Flickr