Complex Regional Pain Syndrome May Not Be Caused by Trauma

Complex Regional Pain Syndrome (CRPS) could be caused by harmful serum autoantibodies, according to research from the University of Liverpool’s Institute of Translational Medicine. The study led investigators to believe that CRPS is caused by an immune dysfunction, not abnormal brain activity after injury, as previously thought.

In cooperation with researchers from the University of Pecs in Hungary, the scientists successfully transferred antibodies from the serum of patients with CRPS to mice, where they found many of the symptoms to be replicated in the animal models. Some of the symptoms included severe pain lasting for many years, limb swelling, hair and nail growth changes, and muscle atrophy.

“CRPS is a serious condition which isn’t fully understood,” Dr. Andreas Goebel, leader of the study, said in a press release. “The findings of this study hint at a cause for it — harmful serum autoantibodies — and raise the possibility of finding a treatment.”

To determine whether CRPS stemmed from post-traumatic experiences, the researchers established a passive-transfer model via the injections. For 8 days, the mice’s mechanical hyperalgesia, paw swelling, heat and cold sensitivity, weight-bearing ability, locomotor activity, motor coordination, paw temperature, and body weight were monitored.

“It’s quite possible that CRPS is caused by a fault in the immune system,” continued Goebel. “This study seems to pinpoint the cause as autoantibodies, and by examining this area further we can look to develop a cure.”

The investigators also examined mice injected with antibodies from healthy volunteers, and noted significantly fewer CRPS symptoms. In the affected mice, the paws became significantly more sensitive to pressure as well as containing a higher concentration of the nerve-mediator Substance P.

“These results support the hypothesis that autoantibodies may contribute to the pathophysiology of CRPS, and that autoantibody-removing therapies may be effective treatments for long-standing CRPS,” the authors wrote.