Complex regional pain syndrome is a rare, chronic, and sometimes progressive condition. It involves a severe, burning pain, inflammation, and changes in the skin. It affects one of the arms, legs, hands, or feet.
The exact cause is unclear. Symptoms may appear after an injury or surgery, but often there is no injury and no sign of neurological or physical damage to the affected area.
Treatment usually includes a combination of physical therapy and medications. It is most effective if it starts soon after symptoms appear.
People with mild symptoms may not report them, so it is unclear how many people are affected.
CRPS can affect people of any age, but it usually appears between the ages of 40 and 60 years, more commonly among females.
Contents of this article:
Types of CRPS
CRPS causes pain to the hands, feet, arms, or legs.
The severity and frequency of symptoms vary widely. Some people have repeated episodes, while for others, symptoms disappear forever after a few months.
There are two types of CRPS:
In Type 1, an apparently trivial injury, such as a fractured or sprained ankle, has occurred, but with no nerve damage. Around 90 percent of cases are Type 1.
Type 2 may emerge after breaking a bone, having surgery, or after a serious infection. There is clear evidence of nerve damage.
Symptoms of CRPS?
Symptoms include severe and continuous pain in part or all of a limb. It has been described as "burning" or a combination of burning and electrical shocks.
If CRPS happens after an injury, the pain of the injury may be unusually severe. For example an ankle sprain may trigger an unbearable burning sensation.
The affected part can become hypersensitive. Touching, bumping, or exposing the limb to temperature changes may cause severe pain.
Muscle atrophy, or wasting, can result, if the patient stops using the limb because of the pain.
There may also be:
- Changes in skin temperature, with the skin becoming sweaty at times, and cold and clammy at others
- Changes in skin color, causing blotches or streaks, ranging from very pale to pink, and perhaps even with a blue tinge
- Thin and shiny skin texture
- Unusually fast or slow nail and hair growth
- Painful, stiff and inflamed joints.
Mobility may also be reduced, as patients find it hard to move the affected part.
Stages of progression of CRPS
CRPS generally progresses in 3 stages, but not everyone will experience all three stages.
Stage 1 typically lasts from 1 to 3 months. There is a severe, burning pain in one of the limbs. There may be muscle spasms, or involuntary muscle contractions, joint stiffness, and fast-growing hair and nails. Skin color and temperature may change as blood vessels become affected.
Stage 2 usually lasts for 3 to 6 months. Pain, inflammation, and stiffness may worsen, and changes in skin texture and color become greater. Muscle tone may weaken.
By Stage 3, the changes that have happened may be irreversible. There will be significant loss of muscle tone, bones may be contorted, and the joints have become stiffer. It may be hard to use the affected limb.
Early treatment for CRPS should prevent it from reaching Stage 3.
Causes of CRPS
As mentioned above, CRPS may develop following an injury or surgery, possibly because of a reaction in the sympathetic nervous system (SNS).
The SNS is part of the autonomic nervous system (ANS). The ANS regulates heart rate, digestion, respiration rate, salivation, and perspiration. The SNS mobilizes the body's resources under stress, to trigger the "flight-or-fight" response.
When danger arises, the SNS starts to accelerate the heart rate, breathing rate, and blood pressure. Levels of certain hormones, such as adrenaline, will rise. This prepares the body for a sudden, short-term release of energy, so that the individual can either fight better or run away faster.
One theory is that trauma, such as a physical injury, causes the SNS to release the 'fight-or-flight' hormones known as catecholamines.
In some people, an unknown underlying problem may cause catecholamines to activate pain receptors, the nerve endings that send pain signals to the brain.
This could explain why patients with CRPS experience abnormal pain after a relatively minor injury. It also suggests that the injury does not cause the intense pain. The pain comes from the way the body has responded to it.
The SNS also regulates the blood vessels of the skin, so that a malfunction could lead to changes in skin color and temperature, one of the signs of CRPS.
Some cases of CRPS, however, show no evidence of SNS malfunction.
Immune system malfunction theory
Another theory is that Type 2 CRPS is linked with problem with the immune system.
When an injury occurs, the affected part may swell, as the immune system tries to stop the trigger that started this response.
Studies have shown that people with CRPS have raised levels of inflammatory chemicals, or cytokines, in their tissues.
Some experts suggest that inflammation continues after the injury has healed, irritating the nerves in that area and causing pain, redness, swelling, and warmth.
People with other inflammatory and autoimmune disorders such as asthma are more likely to have CRPS.
How is CRPS diagnosed?
If a patient seeks medical help, and they may have CRPS, the doctor will ask about the patient's medical history and will look for swollen joints and changes to skin temperature and appearance.
There are a number of diagnostic tests for CRPS.
- A bone scan uses a special camera to look for increased circulation to the joints in the affected area.
- SNS catecholamine tests can identify possible anomalies.
- A sweat test can show if the affected limb produces more sweat than an unaffected limb.
- Thermography measures skin temperature of specific parts of the body. High or low skin temperature in the affected area could indicate CRPS.
- Electrodiagnostic testing involves attaching wires to the skin and measuring the electrical activity of nerves. Abnormal readings could indicate nerve damage, and possible type 2 CRPS.
- X-rays can detect mineral loss in the bones at later stages.
- A magnetic resonance imaging (MRI) scan, a blood test or a biopsy can rule out underlying problems with bones or tissue.
Treatment options for CRPS
Early treatment is most effective, and may lead to total disappearance of signs and symptoms.
Treatment may involve a neurologist, a physical therapist and other specialists.
Physical therapy can help patients to regain their range of movement and coordination, and it helps to prevent muscle wastage and contortion of bones.
Although it may be painful at first, studies show that persisting with physical therapy can dramatically relieve symptoms.
An occupational therapist can determine how CRPS is likely to impact a patient's daily life, and they can prescribe assistive devices. A psychologist can help the patient to cope with living with a chronic, painful condition.
Pain relief for CPRS
A pain relief specialist can provide medications and other therapies. They may suggest:
NSAIDS such as ibuprofen may help relieve pain.
- Nonsteroidal anti-inflammatory drugs (NASAIDs) and over-the-counter (OTC) drugs that relieve pain and inflammation include ibuprofen, naproxen, sodium, and aspirin.
- Certain antidepressants can help reduce pain caused by a damaged nerve.
- Anticonvulsants, such as gabapentin, manage nerve pain.
- Corticosteroids, for example prednisone, may reduce inflammation.
- Bone-loss prevention medications such as alendronate (Fosamax) and calcitonin (Miacalcin) may be prescribed.
- Sympathetic nerve-blocking drugs, such as an anesthetic, may be injected to block the nerve fibers in the affected nerves.
Opioid medications, or opiates are strong painkillers that include morphine, codeine, oxycodone, and methadone. Codeine and diamorphine offer short-term pain relief for severe CRPS, but due to the risk of addiction and other side effects, they should be used with caution and only in the short term.
Other pharmaceutical options include topical analgesics, which are applied to the skin. Creams such as lidocaine, or a combination of ketamine, clonidine, and amitriptyline may reduce hypersensitivity.
Heat and cold therapy may help to reduce sweating and inflammation.
Transcutaneous electrical nerve stimulation (TENS) provides pain relief by applying electrical impulses to nerve endings.
Spinal cord stimulation involves tiny electrodes being inserted into the spinal cord, providing effective pain relief for many patients.
Complications of CRPS
Complications may result if symptoms spread to other parts of the body.
If the condition remains untreated or treatment starts late, there may muscle wasting and contracting of the hand, fingers or foot, as the muscles tighten.