Complex Regional Pain Syndrome (CRPS)
What Is Complex Regional Pain Syndrome (CRPS)/RSD?
Complex Regional Pain Syndrome (CRPS) is a chronic pain condition. A patient with CRPS has pain as well as changes in blood flow, sweating, and swelling in the painful area. Sometimes the condition leads to changes in the skin, bones and other tissues. It may also become hard for a patient with CRPS to move the painful body part.
The patient’s arms or legs are usually involved, but CRPS may affect any part of the body, such as the face or trunk. In some patients, many different areas of the body are affected. CRPS can be progressive (meaning that it gets worse at one site or spreads to other sites), or it can stay the same for a long time or even improve on its own.
CRPS usually develops after an injury. The injury may be to the skin, bone, joints or tissue. This type of CRPS has been called reflex sympathetic dystrophy. CRPS can also develop after any type of injury to major nerves. This type has been called causalgia. The injury that leads to CRPS may be only minor, and sometimes a patient cannot remember any injury or event that caused CRPS to start.
Who Gets CRPS?
Like all human beings, patients who develop CRPS have had many other injuries that did not become CRPS. Patients want to know: “Why did this injury result in my getting CRPS?” Unfortunately, no one knows the answer to this question. Experts say that it might happen because:
- The chance of getting it might run in the family
- There is some type of stress in the person’s life at the time of injury
- The injured body part is not being used for a long time (either because it is in a cast or sling, or because the person is protecting it and not moving it normally)
What Is Happening in the Body to Cause CRPS?
Until recently, doctors thought that CRPS always involved a problem in the sympathetic nervous system (a set of nerves that control the size of blood vessels, sweating, and many other bodily functions).
They now think that only some patients with CRPS have these sympathetic nervous system problems. Pain that comes from problems in the sympathetic nerves is called “sympathetically-maintained pain,” or SMP. The only way a doctor can find out if a patient has SMP is to do a sympathetic nerve block. (Sympathetic nerve blocks are injections of a numbing drug, called a local anesthetic, into different sites in the body). A person suffering from CRPS can be said to have SMP only if he or she has good pain relief from a sympathetic block.
If SMP does not explain the pain in most patients with CRPS, what is the cause of the pain? Experts agree that there are problems in the peripheral nervous system (the nerves in the body) and the central nervous system (the brain and spinal cord) of patients with CRPS, but the details are not known. There are other factors that could be involved in the development of CRPS because they directly affect the activity of the nervous system, muscles and bones. Examples of these factors are emotional issues or stress and not using a painful body part.
Diagnosing and Treating CRPS
A doctor makes the diagnosis of CRPS based on how a patient describes his or her symptoms and from what the doctor finds when he gives the patient a physical exam. The patient does not have to have a nerve block to get a diagnosis of CRPS. Laboratory tests or tests such as, X-rays or bone scans are usually not needed to make the diagnosis, either.
Symptoms Needed to Make the Diagnosis of CRPS
These are the symptoms that doctors use to decide whether or not a patient has CRPS:
Pain that is constant or almost constant, with:
- Severe pain when only a slight pain would be expected, such as when a doctor lightly pricks the skin with a pin (called “hyperalgesia”)
Having some of the following in the painful area:
- Changes in skin color (mottled, purple-bluish, red)
- Skin temperature that is not normal (either hotter or colder than other areas)
- Either more or less sweating in the area
CRPS patients also commonly experience the following symptoms:
- Problems moving the painful body part
- Tremors (“shakes”)
- Depression or anxiety (common to all chronic pain disorders)
- Sleep problems (common to all chronic pain disorders)
Some patients with CRPS have changes in the area of the pain that are known as “trophic changes.” These include:
- Wasting away of the skin, tissues, or muscle
- Thinning of the bones
- Changes in how the hair or nails grow, including thickening or thinning of hair or brittle nails
It is important to know that every patient with CRPS has different signs and symptoms. Also, a patient’s symptoms and signs can change from minute-to-minute or hour-to-hour.
No single treatment, such as a pill or nerve block, can cure CRPS, but many CRPS patients do find that their pain and other symptoms get much better with the right therapies. CRPS can improve when patients:
- Get treatments that lessen the pain (such as nerve blocks, medicines, and other treatments)
- Take part in a physical therapy program
- Get helpful psychological treatments (such as stress management skills).
Every patient with CRPS responds differently to each therapy — what works well for one patient may not work at all for another. Because of this, doctors may need to try many different medical therapies in different combinations. It is often best for patients with CRPS to see pain specialists, who are experienced in taking care of patients with difficult pain problems.
Drugs. Doctors might prescribe drugs like anti-inflammatory drugs, corticosteroids, antidepressants, anticonvulsants, calcitonin, or opioids for patients with CRPS. Patients may have to take several different drugs together to get the best pain relief.
Sympathetic Block. Sympathetic nerve blocks include stellate ganglion nerve blocks, lumbar sympathetic nerve blocks and Bier blocks. For all of these blocks, doctors inject numbing drugs (called “local anesthetics”) in different nerves. For the Bier block, a drug is injected into a vein after a cuff is inflated. The cuff keeps the drug in the painful area, so the drug only affects the tissues in that area. Doctors may also use a phentolamine infusion, in which a drug is given intravenously (through an IV). Phentolamine infusions are thought to have a similar effect as a sympathetic nerve block.
Most patients with CRPS should receive at least one sympathetic block because some patients will have dramatic pain relief. If a sympathetic block does not provide good pain relief, the patient should probably stop getting them.
Sympathectomy. Some patients with CRPS have good pain relief from sympathetic nerve blocks, but the pain relief does not last long. For these patients, doctors might suggest a sympathectomy (killing the sympathetic nerves leading to the painful body part, either by using surgery or chemicals). Some patients get longer pain relief after the sympathectomy, but others do not. Also, there is the slight chance that patients who get a sympathectomy for CRPS of the leg might develop a new pain syndrome, called post-sympathectomy syndrome.
Other Treatments. Some patients get pain relief from acupuncture and transcutaneous electrical nerve stimulation (TENS). With acupuncture, needles are placed in specific areas on the skin to help relieve pain. With TENS, patients carry a small, box-shaped device that sends electrical impulses into the body through electrodes. These electrical impulses interfere with pain signals.
Sometimes, pain specialists recommend that a patient try a treatment called spinal cord stimulation, or dorsal column stimulation. This treatment provides low-voltage electrical stimulation by placing an electrode inside the spine. Pain specialists also sometimes recommend that a patient try intraspinal infusion. Intraspinal infusion means that medications are given through a catheter going directly into the spine. Drugs that prevent or treat pain (called “analgesic medications”), such as morphine, can be given in low doses through the catheter.
Physical/Occupational Therapy. Physical and occupational therapists can help patients with CRPS begin a program of stretching, strengthening, and aerobic conditioning. The goal of this program is to help the patient get back range of motion, strength and motor control. Physical and occupational therapists might also try treatments like warm and cold baths, ultrasound, or electric stimulation.
“Desensitization” is another important treatment that can be used to help with allodynia (pain caused by things that do not normally cause pain, such as clothing, wind, cold or a light touch to the skin). The patient’s painful skin is rubbed with different materials, starting with soft, light textures and proceeding to rough, irritating surfaces. Gradually, the painful skin gets used to the rough textures, until the patient can easily deal with the touch of clothing, bed sheets, towels, etc.