"Phantom limb syndrome" affects almost everyone who has lost a limb. The imagined limb often becomes painful when apparently distorted in a cramped position.
Professor Vilayanuas Ramachandran, director of the centre for brain and cognition at the University of California, said mirrors were proving more effective than powerful pain-killing drugs at relieving the discomfort of the syndrome.
He places a mirror on the side of the lost limb and asks the patient to look at the reflection. "If they look inside the mirror they see the reflection of their normal hand and it looks as if you have given them their phantom back," he said.
Patients frequently complain that their phantom arm has become curled up into a painful position and Professor Ramachandran asks them to put their intact arm into the same position and then to uncurl it so that it becomes normal again.
"If the phantom is in a painful `cramped' position, we find that merely viewing the reflection of the normal hand in a mirror causes the phantom hand to spring to life and start moving. For many the pain and cramping is instantly relieved."
Professor Ramachandran has also tried mirror therapy on "neglect syndrome" patients who have suffered a stroke or some sort of brain damage to one half of the brain, which causes them to be oblivious to one side of their visual field.
The mirror treatment could help scientists to unravel some of the complex mysteries of the brain, he said. "This has implications for understanding how the brain handles space and how we react to object in mirrors and how your beliefs about objects in the world are affected by this attention deficit."Reuse content