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Amputee can feel and feel again thanks to the new hand prosthesis
In the future, hand amputees can hope to feel and feel again with the help of a new prosthesis. According to researchers, the Danish Dennis Aabo Sørensen is the first person in the world who can feel something again thanks to such a replacement hand.
Fireworks accident The Danish Dennis Aabo Sørensen lost his left hand in a fireworks accident about nine years ago. According to researchers, the Scandinavian is now the first person in the world who can feel and feel again without delay thanks to a new prosthesis. Sørensen is quoted in a communication from the Swiss Federal Institute of Technology in Lausanne (Switzerland): "When I held an object, I could feel whether it was soft or hard, round or square." He was enthusiastic about the new test hand: "The sensory feedback was incredible. "
Conventional prostheses work quite well. Since his accident, the Dane has been wearing a conventional prosthetic arm, which enables him to open and close the artificial hand. In the meantime, such prostheses work quite well, but still do not provide any clues as to how hard the artificial hand has to grab or how an object feels. Under the leadership of the Italian Silvestro Micera from the École Polytechnique Fédérale de Lausanne (EPFL), an international research team from several European universities and clinics has now developed the prototype of a prosthesis that can feel. They reported on their work in the journal Science Translational Medicine.
Sensations up to the pain threshold The 36-year-old Dane was operated on at the Gemelli University Hospital in Rome at the end of January 2013. The surgeons implanted electrodes on his upper arm on the median and ulnar nerves, both of which are responsible for various finger and hand movements. Less than three weeks later, the scientists attached the artificial hand and wired it to the implanted electrodes so that the tactile sensations when grasping an object can be conveyed directly to the brain. These sensations led to the pain threshold.
His children called him the cable man. In the following tests, Dennis Aabo Sørensen was blindfolded and he was put on headphones to separate him from these senses. So he had only the sense of touch. Stanisa Raspopovic of an Italian university in Pisa (Scuola Superiore Sant'Anna) said: "We feared that the sensitivity of the patient's nerves would have decreased because he had not used them for more than nine years." But the concerns turned out to be as unfounded. In a video, the Dane said: "Suddenly I could feel something that I had not felt for nine years." His children were also thrilled and called him the cable man.
"I can feel the closing of my missing hand!" During the tests, Sørensen had to feel various objects such as a tangerine, delicate plastic cups, wooden cubes or bandages. His brain quickly noticed that something was happening on his thumb, little finger and forefinger. The reaction was that he could adjust his grip because he could see what he was holding in the artificial hand. The Dane said: "And suddenly I actually felt what I was doing." The hand made it possible for him to feel the size, shape and hardness of objects. Raspopovic recalled the results of the time: "It was a very exciting moment when Dennis turned to us after endless hours with tests on the artificial hand and said incredulously: 'This is magic! I feel the closing of my missing hand! ’“
Works like a motorcycle brake Sørensen controls the fingers of the prosthesis with his muscles. "It works like a motorcycle brake," he explains the principle. “When you pull it, the hand closes. When you let go, it opens up. “He controls his fingers by watching them and adjusting his movements. The researchers made a total of more than 700 experiments with the Dane, all in the last week of the series of experiments.
Only for four weeks due to safety regulations. Because the safety regulations for clinical studies required this, Sørensen had to remove the electrodes of the new, feeling prosthesis after four weeks. However, the researchers believe that they could remain in the body for years without causing damage to the nerves. Thomas Stieglitz from the University of Freiburg im Breisgau said: "The test person would have preferred to keep the feeling hand."
Prosthesis with feeling until a few years from now The scientists are optimistic about the success that their artificial hand could help other amputees in the future. As they wrote in their professional article, the stimulation apparatus should be reduced in size in the future and then fully implanted in the arm. They now want to test their procedure on numerous patients. However, it would still be many years before the prosthesis could be available on the market with feeling. (ad)