If you are suffering from chronic pain in your limbs take a good look at yourself at a mirror -- it may help you recover, says a study that has found an unlikely source of relief.

Complex regional pain syndrome (CRPS) occurs in about one-third of people who fracture their wrists: they suffer unexplained persistent pain in their hand, arm or shoulder once the supportive plaster cast is removed.

The pain can be so bad that some patients beg for their arm to be amputated, says Candy McCabe, who developed the novel mirror therapy at Britain's University of Bath, reports the online edition of New Scientist.

McCabe and team studied eight CRPS patients who sat in front of long mirrors. These were placed so each person could see only the healthy half of their body, along with another reflection of the same half.

The result was that the side of the body with the painful arm was hidden from their view and it appeared to the patients as if they had two healthy arms.

The patients were told to concentrate hard on the image and try to believe that what they saw was a true depiction of themselves.

"Three of them were cured instantly; the others took a little longer," says McCabe. "But once the mirror was removed, the pain returned."

With continued mirror therapy, six people were completely cured. The two exceptions had conditions complicated by limb ulcers and actual physical distortions.

McCabe believes the pain results from a mismatch in the way the brain perceives the body and the actual condition of the body.

The brain is constantly sending signals to the body, predicting things like the shape and weight of the limbs, and their location. The sensory nervous system responds by sending information back, allowing the brain to refine its body image.

"When the arm is immovable in a plaster cast a mismatch occurs," McCabe says. "The brain sends out signals to the arm, but gets nothing back, so it triggers its own pain sensation in response."