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Sunday, August 22, 2010

Curing phantom pain

Thomas Weiss from the Friedrich-Schiller-University Jena and his team have developed a hand prosthesis that they hope will eliminate phantom hand pain.

Phantom pain is the phenomenon in which a person feels persistent pain or itching coming from a limb that has been amputated. Sufferers will sometimes insist that the missing hand or foot is extremely painful to them. Understandably, this has been difficult for physicians to treat, since there is no hand or foot. Painkillers can be ineffective, and the discomfort can last years or even a lifetime.

At first, phantom pain was thought to be triggered by crushed or damaged nerves at the amputation site. Now, it is known that the discomfort originates directly in the brain. The part of the brain responsible for the missing limb now has no job, and begins to fire when other parts of the body are stimulated. In some cases, stroking part of a patient’s face will create the sensation of touching a missing limb.

Weiss’s idea was to create a prosthesis that sends precise sensory information from pressure sensors in an artificial hand to nerves in the upper arm. Hopefully, the brain will interpret the sensations as originating in the prosthetic hand, just as it would from a real hand. This should give the hand-control part of the brain its job back, preventing the re-organization of the brain that causes the phantom limb pain.

So far, the device has been tested on only a few patients, but with promising results.

The new development from Jena provides the upper arm with sensory information which is then transmitted to the brain. This reduces phantom pain.

Credit: Sandra Preissler/FSU