Virtual massage could relieve phantom limb pain for amputees

The Daily Mail of London, England, reported that amputees who experience phantom limb pain could find relief in a surprisingly simple way - by watching someone else rub their hands together.

The treatment seems to fool the brain that it is their missing hand being massaged, according to the American researchers, who worked with combat veterans. Phantom limbs occur when an amputee feels the often painful sensation of touch arising from a limb that is no longer present.

Lead researcher Vilayanur Ramachandran from the Centre for Brain and Cognition at the University of California, used newly discovered properties of mirror neurons to soothe the ache. Mirror neurons fire when a person performs an intentional action - such as waving - and also when they observe someone else performing the same action. They are thought to help us predict the intentions of others by creating a "virtual reality" simulation of the action in our minds.

"You also find cells like this for touch," says Ramachandran. "They fire when you touch yourself and when you watch someone else being touched in the same location."

Ramachandran and his colleague and wife Diane Rogers-Ramachandran used a "mirror box" - a tool that creates the visual illusion of two hands for people who actually only have one. By placing an amputee's arms either side of a mirror - with the missing limb on the non-reflective side, the amputee sees the reflection of their normal hand superimposed on the location of their missing hand.

Two amputees watched their normal hand being prodded, and both felt the remarkable sensation of "being prodded" in their missing hand. In another experiment, when the amputees watched a volunteer's hand being stroked, they too began to experience a stroking sensation arising from their missing limb.
The amputees "felt" the actions of others because their missing limb provided no feedback to partially inhibit their mirror neurons, no longer telling them that they were not "literally" being touched, says Ramachandran.

One woman reported that watching a volunteer rubbing her hand caused the cramping sensation within the phantom limb to cease for 10 to 15 minutes. "If you do it often enough perhaps this pain will go away for good," suggests Ramachandran. "If an amputee experiences pain in their missing limb, they could watch a friend or partner rub their hand to get rid of it."

Massaging the skin helps relieve a painful sensation by restoring blood flow and activating sensory fibres, which inhibit pain messages to the brain. By watching another person rubbing their hand, these amputees are apparently tapping into this latter mechanism, says Ramachandran.

"If performed early enough, this type of therapy may also be used to help stroke patients regain movements by watching others perform their lost actions," he concluded.