Cause of Complex Regional Pain Syndrome Further Examined

Researchers at the University of Liverpool in the United Kingdom and University of Pecs in Hungary have provided further insight into the source of chronic pain for Complex Regional Pain Syndrome (CRPS) sufferers.

The researchers reported recent discoveries indicated there is an “autoimmune contribution,” to the condition, which often occurs after a small accident or surgery and causes pain that persists for several years.

For their study published in PAIN, the investigators removed serum IgG with antibodies from chronic CRPS patients and injected it into mice. This process allowed them to replicate the symptoms in the mice. The researchers also followed the same procedure for healthy patients.

The researchers also created a passive-transfer trauma model and submitted the mice to hind-limb skin and muscle incisions to cause a mild tissue injury.

For an 8-day period, investigators observed the mice’s “mechanical hyperalgesia, paw swelling, heat and cold sensitivity, weight-bearing ability, locomotor activity, motor coordination, paw temperature, and body weight.” Proinflammatory sensory neuropeptides and cytokines were also monitored in the paw tissues.

The mice injected with IgG serum from CRPS sufferers developed significant swelling of limbs and paws and signs of experiencing pain when put under pressure.

The authors established that “plantar incision induced a remarkable elevation of substance P immunoreactivity on day 8, which was significantly increased by CRPS-IgG.” Substance P acts as nerve-mediator and is secreted during inflammation and pain, according to the statement from the University of Liverpool.

“It’s quite possible that CRPS is caused by a fault in the immune system,” Andreas Goebel, MD, study leader and a consultant in Pain Medicine at The Walton Centre National Health Service Foundation Trust, said in a statement. “This study seems to pinpoint the cause as autoantibodies, and by examining this area further we can look to develop a cure.”