Prosthetic System with Electrode Cuff Restores Sense of Touch for Amputee
A prosthetic system being developed by researchers at Case Western Reserve University and the Louis Stokes Cleveland Veterans Affairs Medical Center has given amputee Igor Spetic sensation in his hand, after losing it in an industrial accident a few years ago. The system uses electrical stimulation to give the sense of feeling, but there are key differences from other reported efforts. The nerves that used to relay the sense of touch to the brain are stimulated by contact points on cuffs that encircle major nerve bundles in the arm, not by electrodes inserted through the protective nerve membranes. Three electrode cuffs are in Spetic's forearm, enabling him to feel 19 distinct points. When the researchers began the study, the sensation Spetic felt when a sensor was touched was a tingle. To provide more natural sensations, the research team has developed algorithms that convert the input from sensors taped to a patient's hand into varying patterns and intensities of electrical signals. The sensors themselves aren't sophisticated enough to discern textures, they detect only pressure. The different signal patterns, passed through the cuffs, are read as different stimuli by the brain. The system has worked for two and a half years for Spetic, whereas other research has reported sensation lasting one month and, in some cases, the ability to feel began to fade over weeks.
Transcript
00:00:01 I lost my hand approximately three years ago in an industrial accident. >> Igor Spetic of Madison, Ohio has benefited from the mechanical motion of a prosthetic limb. But he hasn't been able to feel things in his grasp. I have to visually look at whatever I'm picking up, watch that I don't over squeeze >> Over the last 2 years innovative research started to give Igor a new option >> Sandpaper. >> Good job. >> Researchers at Case Western Reserve University and the APT Center at the Cleveland VA Medical Center
00:00:37 have created connections between a prosthetic hand and the human brain. It's provided Igor with a sense of touch and most recently the ability to distinguish between textures. >> Reaches on the middle finger. >> In 19 distinct locations in his hand. >> The palm. And sand paper on the middle finger. >> What I think is fascinating about this is the perception of touch actually occurs in the brain, not in the hand itself, so losing the limb is really just losing the switch that turns that sensation on or off.
00:01:11 >> By placing electrodes on Igor's residual nerves, the team is able to send signals to his brain. Those signals create a response that's as if his prosthetic hand actually feels touch. >> So if I stimulate one position on that nerve, we can get this point on the hand. By stimulating a different position, we can get this point on the hand >> Over time, Tyler's Group has developed complext electrical patterns that correlate to certain textures. They believe they can increase the number of different textures a subject can feel and identify.
00:01:43 The key will be helping patients relearn certain stimulation patterns. >> If you watch any child, what they are doing is putting their hands in their mouth, they are feeling things, they are seeing. And they're connecting the sensation that signal is coming back with what they are seeing. This is how we learn. The research also has provided one big unexpected bonus for Egor. Relief from phantom pain. >> The way I described it was, my hand was in a vice being crushed and it kept on going and going.
00:02:14 >> Shortly after the stimulation sessions began, Egor says, his pain subsided. >> Just about, I'd say, 90, 95% gone. >> We feel that the way we've learned to stimulate the sensory system will have implications and not only limb loss. There's going to be a potential here in many other applications such as the tremor, disorders, deep brain stimulation. I think this the beginning, frankly, of a whole new era of neural interfacing. >> All are added reasons for Egor to participate in the research. >> If it happens to help me, great. If it happens to help the next person, even better.
00:02:49 I think it just gives me a sense of purpose or a sense of reasoning for. >> Tyler hopes to develop an inplantable system within five years that Egoe can test at home >> I would love to feel my wife’s hand. Just to hold hands, would be the ultimate.