Diagnosis

A visit to your health care provider is the first step to diagnosing complex regional pain syndrome (CRPS). During your visit, your health care provider will collect a detailed history and perform a physical exam.  

During the physical exam, your health care provider may touch your skin or bend the joints in your painful area. He or she may compare the color and temperature of your painful body part with its matching, healthy body part. For example, he or she may compare your CRPS-involved knee with your healthy knee. After the physical exam, your provider may order some tests.
 

Tests

There is no specific test that can show or prove that you have CRPS. Thus, your health care provider may need to use the results from a number of tests to diagnose your CRPS. You may have certain tests to help diagnose CRPS and other tests to “rule out” disorders that could be causing your pain. The choice of tests may depend on your health care provider’s experience with CRPS and the type of problems you have. CRPS signs and symptoms can vary greatly over time.
 

Infrared thermography

This test measures heat that rises from the surface of your skin. During the test, a computer screen shows a "heat map," which is a colorful picture of the surface of your skin. The picture helps health care providers see if you have a change in the blood flow to your CRPS-involved limb. Skin areas with less blood flow tend to be cooler; while areas with healthy or increased blood flow are warmer. By comparing changes in the surface skin temperatures, your health care provider can indirectly see how your nervous system is doing.

During the test, your health care provider may take side-to-side pictures to compare the healthy limb with the CRPS-involved limb. For example, if you have a painful arm, he or she may take pictures of both your healthy arm and your CRPS-involved arm.
 

Nerve conduction velocity testing (NCV)

This test measures how fast your nerves send messages to your brain. This test uses electrodes (patches) placed on the surface of the skin and usually is not painful. During the test, a tiny amount of electrical current is sent to your nerves and measured by the skin patches. Health care providers can use NCV results to learn if your CRPS-involved body part has nerve damage.

Only a few research studies have been done to judge the usefulness of NCV testing in people with CRPS. Studies that do exist show that there are nerve problems in almost half of all people with CRPS, but these problems tend to be mild. Some health care providers may make the mistake of saying that a person with CRPS has peripheral neuropathy, which is different than CRPS. The exception to this is when a person does have a definite nerve injury (CRPS-II).
 

Sympathetic Blockade

A sympathetic blockade, or “nerve block,” is an injection (shot) of medicine into a nerve. It is done to try to block or stop abnormal pain messages from going to the brain. A nerve block is sometimes done as a test. The results of a nerve block are “positive” if it relieves your pain. They are “negative” if your pain continues. The location of the shot will depend on where you are having pain. For example if you have pain in your arm, you may get a shot in an arm vein or the base of your neck (“stellate ganglion block”). If you have leg pain, you may get a shot in your lower back (“lumbar sympathetic nerve block”). If a nerve block helps relieve your pain, you may get nerve blocks as part of your regular CRPS treatment.

Nerve blocks can be more useful in diagnosing and treating certain types of people. They may be especially helpful for people with sympathetically maintained pain (SMP). Although blocks can help relieve pain in the early stages of CRPS, they may stop working after a while.
 

Tests of Sudomotor Functioning (“Sweat Tests”)

During a sweat test, a health care provider may sprinkle powder or put a small cup onto your skin. He or she will use these to measure the amount that you perspire (sweat). A body part with CRPS may sweat too much or too little compared to the healthy skin around it. Sweat tests can help diagnose CRPS only if they show positive results. Positive results prove that the involved body part sweats more or less than the healthy skin on other parts of the body. Sweat tests may be more helpful in diagnosing CRPS during the earlier stages of the disorder. This is because sweat changes tend to go away in the later stages of CRPS. Sweat tests are not done as often as other tests. They are difficult to do and are available in only a few parts of the country.
 

Three-phase Bone Scan

This test is used to look for a specific pattern of blood flow around the joint lines of your bones. Before the test, you will be given a shot with a special dye. During the test, you will keep your CRPS-involved limb still while a machine takes pictures. Bone scan results are “positive” for CRPS if they show increased blood flow around your joint line. Bone scans are positive in only about 50% of people with CRPS, usually in later stages of the disorder. Therefore, this test may not be very useful in making the diagnosis in earlier stages of CRPS.
 

X-rays

X-rays may be done to see if you have demineralization of the bone in your CRPS-involved limb. X-rays may be useful in later stages of CRPS but not as a screening tool earlier on.

Sometimes, health care providers may disagree about whether or not you have CRPS. If this occurs, you may have problems getting proper care, such as getting authorization for tests and treatment from insurance carriers.