Amputees' phantom limbs return in virtual reality

Lost limbs are reappearing in a Lawnmower Man-style virtual reality world designed to help amputees rid themselves of phantom limb pain

Scientists are helping amputees to experience their lost limbs once again. Using 3D computer graphics and a virtual reality headset, the lost limb can be 'restored'. What might at first sound like a tasteless Lawnmower Man sequel is claimed to be an extremely promising therapy for patients struggling to come to terms with amputation.

The machine is designed to combat phantom limb pain (PLP) -- a sensation of pain experienced by an amputee that appears to originate in the missing limb. Intriguingly, researchers have discovered that if a person's brain can be tricked into believing they can see and move a 'phantom limb', this motion reduces the perception of pain in PLP.

The virtual reality system, developed at the University of Manchester, gives the illusion that a person's amputated limb is still there, in three dimensions, in full colour. It immerses amputees in a life-size virtual reality world where the errant limb is still attached. The remaining limb/s can be used to control the movement of the virtually restored limb.

Users can make complex gestures and move their fingers, hands, arms, feet and legs. The virtual limb can also play ball games.

Project leader Dr Craig Murray said, "Many people who undergo an amputation experience a phantom limb. These are often very painful for the person concerned. They can persist for many years, and are very difficult to treat."

The small-scale study has seen impressive results already, with four out of the five participating patients showing improvement. "One patient felt that the fingers of her amputated hand were continually clenched into her palm, which was very painful for her," said Murray. "However, after just one session using the virtual system she began to feel movement in her fingers and the pain began to ease."

Dr Stephen Pettifer, of the School of Computer Science said: "Most people know about 3D graphics and virtual reality from their use in the entertainment industry, in computer games and special effects in films.

"It's very satisfying being able to apply the same technology to something that may have a real positive impact on someone's health and well-being." -CS

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