Science/Tech

Amputees' Prosthetics Could Give Sense Of Touch With New Technology, Eliminate Phantom Pain

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Igor Spetic was able to discern multiple patterns using his new prosthetic technology. Photo courtesy of YouTube

Igor Spetic lost his hand nearly three years ago in an industrial accident and had resigned to the fact that he would probably never feel again. Oh, how wrong he was. Today, Spetic is one of the first recipients of an amazing new technology that allows amputees to feel.

Researchers at Case Western Reserve University and the APT Center at the Cleveland VA Medical Center have created connections between a prosthetic hand and the human brain. Unfortunately, this technology is for now limited to the lab, but so far, results are beyond promising. Exactly how the technology works will be published in the journal Science Translational Medicine, but here’s the gist of how things go.

The patient’s nerves used to relay the sense of touch to the brain are first stimulated by contact points on cuffs, which encircle major nerve bundles in the arms without penetrating them. According to a press release, this differs from other attempts of sensation restoration, which instead inserted electrodes through the nerve’s protective membranes. These implanted electrode cuffs are then electrically stimulated, which allows the patient to feel between 16 and 19 different distinct locations on their prosthetics.

“The work reactivates areas of the brain that produce the sense of touch," said Dustin Tyler, a biomedical engineer at Case Western Reserve, a lead researcher on the project. "When the hand is lost, the inputs that switched on these areas were lost."

The sensations first began as slight tingles, but after a bit of fine-tuning from the scientists and getting used by the two patients, these tingles soon became distinct sensations. A blindfolded Spetic was able to correctly identify different signal patterns as sandpaper, a smooth surface and a ridged surface. The researchers even had him touch two different textures at the same time and, amazingly, he was still able to identify each one.

To Spetic though, the highlight of his new hand was being able to correctly pull grapes off a vine without making a mess. “When the sensation's on, it's not too hard," he said. "When it's off, you make a lot of grape juice."

An unexpected but greatly appreciated side effect from the treatment was that it eliminated nearly all of the patients' phantom pains. At the moment, the effects seem to be only temporary, with Spetic’s lasting for two and a half years and the second patients lasting a year and a half. Still, this is longer than any other sense restoration therapies to date, and researchers will continue to add on to this technology.

"Our goal is not just to restore function, but to build a reconnection to the world. This is long-lasting, chronic restoration of sensation over multiple points across the hand." They believe that eventually their technology will not only help amputees who have lost hands “feel” again, but help those using prosthetic legs gain better putting and adjust to uneven gravel, control tremor, and even deep brain stimulation.

Source: Tyler DJ, Tan DW, Schiefer MA, et al. A neural interface provides long-term stable natural touch perception. Science Translational Medicine. 2014.

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