Amputee patients suffering from “phantom pain” may get relief from a modified prosthesis that can convince the brain the body part still exists, researchers say. Scientists from Friedrich-Schiller-University at Jena, Germany, together with trauma surgeons at Jena University Hospital, Germany, and supported by German Social Accident Insurance (Deutsche Gesetzliche Unfallversicherung, DGVU), have produced a modified prosthetic hand than can reduce phantom pain following amputation by using a stimulation unit that is connected to the remaining part of the upper arm by a cuff.
After an individual has a limb amputation, brain structures responsible for processing sensory information coming from the lost body part are “out of work” and try to reorganize themselves, explained Thomas Weiss, psychologist and professor at Friedrich-Schiller-University department for biological and clinical psychology. “These areas take over the processing of sensory stimuli from other body parts, especially the arm stump and the face,” Weiss said. This results in intensified and sometimes painful sensations-otherwise known as phantom pain.
Modern prosthetic hands have pressure sensors meant to regulate grip strength depending on what the wearer is trying to pick up, such as a raw egg or a hammer. The stimulation unit in the modified hand takes feedback from these sensors and “talks” to the wearer’s brain, Gunther Hofmann, MD, director of the Jena University Hospital department for trauma, hand, and reconstructive surgery explained.
“Our system is now able to transmit this sensory information from the hand to the upper arm,” Hoffman said.
“Thus the brain picks up the feedback from the prosthesis as if it was one’s own hand,” Weiss added.
By giving the appropriate brain structure sensory input from the “hand” it is meant to control, the reorganization that causes phantom pain can be prevented or reversed, they say.
Hoffman reports that the first patients who have tested the Jena system were “very positive about it,” and the researchers now want to test the system “on as many patients as possible.”
“We would like to know if the transmission of sensory information from the hand is helpful to only a few people or if it is a therapeutic for all wearers of artificial limbs,” Weiss concluded.
