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A New Test to Assess Severity of Complex Regional Pain Syndrome

Some of the best minds in the world of rehabilitation have come together to formulate a scoring system for complex regional pain syndrome (CRPS). Until now, patients were diagnosed with this condition as either "yes you have CRPS" or "no, you don't have CRPS". [That's what is called a dichotomous diagnosis]. Until now, there has been no way to give it a description such as mild, moderate, or severe that conveyed to everyone just what the condition looked like.

Like its name, complex regional pain syndrome (CRPS) is a complex problem. CRPS is a disorder that can cause severe pain and disability. However, as painful and disabling as the condition is, there is not a lot that doctors know about it. More women get it than men. It occurs after about one to two percent of all bone fractures. It is most common (up to 35 percent) after certain types of wrist fractures.

Complex regional pain syndrome more commonly affects the hand or foot, but may spread further up the affected limb and even into the opposite limb. The common symptoms of CRPS are unrelenting burning or aching pain, skin sensitivity, swelling, discoloration, sweating, and temperature changes. If the condition becomes chronic, dystrophy or deterioration of the bones and muscles in the affected body part may occur.

What they don't know is why it happens, who it will happen to, and how severe it will be. And, because treatment of CRPS depends on the symptoms, a severity scoring system like this Complex Regional Pain Syndrome Severity Score (CSS) may help.

The CSS is a simple test that can be given easily yet still reflects diagnostic features of CRPS (e.g., pain, sweating, skin color changes). It was put together and tested by experts from well-known rehabilitation centers such as Rehabilitation Institute of Chicago, Vanderbilt University School of Medicine, Trauma Related Neuronal Dysfunction Consortium in The Netherlands, Rush University Medical Center in Chicago, Stanford Medical Center (California), and two universities in Germany.

It was tested on 114 people with a known diagnosis of CRPS and compared with 41 patients with nerve pain that was not caused by CRPS. Most of the CRPS patients had a history of fracture or crush injury leading to the development of CRPS.

The test consisted of a checklist of signs and symptoms common with this condition. Self-reported symptoms included differences in temperature, skin color, sweating, and swelling from one side (involved side) to the other (uninvolved side). A second section of the test evaluates signs observed by the examiner such as exaggerated levels of pain with pinprick test, differences in skin temperature felt by the examiner, and decreased range-of-motion of the involved part (hand, foot).

Higher test scores meant more severe pain and other symptoms. Patients with CRPS had much higher test scores than the patients in the nerve pain but non CRPS group. Statistical analysis showed that this new scoring system for severity of CRPS is reliable and valid. In other words, it can be used dependably to identify people with CRPS and provide a picture of the severity of their condition. Used over time, it can also show changes or fluctuations in individual cases.

The authors conclude that this type of tool will help health care professionals plan and modify treatment for patients with CRPS. Having a consistent severity score will help improve communication among all the health care professionals working with people who have CRPS.

Researchers involved in this project do not see this tool as a replacement for current pain scales in use to measure treatment outcomes. But the scoring system may be helpful when conducting research on this condition as it can show changes in symptoms with treatment. It may even function as a predictor of who will get better with different types of treatment.

Reference: R. Norman Harden, et al. Development of a Severity Score for CRPS. In Pain. December 2010. Vol. 151. No. 3. Pp. 870-876.

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