Diagnosing Complex Regional Pain Syndrome (CRPS)

What is complex regional pain syndrome (CRPS)?

Complex regional pain syndrome (CRPS), also called reflex sympathetic dystrophy syndrome (RSDS), is a type of chronic pain condition. It typically occurs after an injury and affects one limb (arm, leg, hand or foot). Though complex regional pain syndrome is not yet completely understood, it is believed that CRPS develops when the central or peripheral nervous system is damaged or malfunctions. It may also be caused by an immune system response.

Complex regional pain syndrome is classified into two types. Type 1, which occurs in appoximately 90 percent of people with CRPS, occurs after an illness or injury that did not directly damage the nerves in the affected limb. Type 2 follows a direct nerve injury.

How is complex regional pain syndrome diagnosed?

Diagnosis of complex regional pain syndrome is often a lengthy process, and, in many cases, it is a diagnosis of exclusion. A singular test for CRPS does not yet exist. As complex regional pain syndrome does not have a singular cause, and it produces symptoms similar to many other conditions, diagnosis is complicated. However, medical tests are available that can indicate the possibility of CRPS and eliminate the possibility of other conditions. Early diagnosis and prompt treatment can prevent complications such as permanent loss of muscle size and strength or spread of the condition to a nearby area of the body.

Physical exam and medical history

Currently, an official diagnosis of CRPS is based on the findings of a physical exam and medical history, using the Orlando Criteria for Complex Regional Pain Syndrome and the Budapest Clinical Diagnostic Criteria for Complex Regional Pain Syndrome developed by the International Association for the Study of Pain (IASP).

CRPS diagnostic criteria include, but are not limited to, the following:

• An initial injury
• Pain
• Hyperalgesia
• Swelling
• Allodynia
• Changes in perspiration in the area
• Changes in blood flow
• No other cause for the pain or altered appearance

Medical tests

Eliminating the possibility of other medical conditions helps to determine a CRPS diagnosis. Certain medical tests can also indicate the possibility of CRPS. The following tests may be performed:

• Bone scintigraphy scan is a medical procedure used to detect bone changes. Radioactive dye is injected into a vein which allows a special camera to take detailed images of the bones.
• Sympathetic nervous system tests look for disturbances in the sympathetic nervous system. One such test compares the skin temperature and blood flow of the affected and unaffected limb. Another type of sympathetic nervous system test measures the amount of sweat on both limbs. Uneven results can indicate CRPS.
• X-rays are used to detect mineral loss in bones that may occur in the later stages of CRPS.
• Magnetic resonance imaging (MRI) is used to obtain detailed images of tissue changes.

Complex regional pain syndrome is difficult to diagnose. If an individual believes they may have CRPS, it is important to see a physician who is familiar with diagnosing and treating this condition.