Motorica, a high-tech company concerned with arm prosthetics, with the Medical Center of the Far Eastern Federal University, and Vladimir Zelman Center for Neurobiology and NeuroRehabilitation at the Skolkovo Science and Technology Institute, have made the first stage of their research on a person’s ability to sense bionic prosthetic hands including phantom pain-relieving methods. The project’s team has successfully performed a surgery implanting electrodes in patients’ peripheral nerves. The team has achieved a stable reduction of patients’ phantom pain through electrostimulation, conducting a series of sensorimotor tests using haptic communication with the invasive and noninvasive electrostimulation.
This study has confirmed the possibility of conducting invasive neurophysiological studies within domestic infrastructure and gaining positive results. The outcome will facilitate the medical dissemination of new neurotechnological treatments in phantom pain management. It will allow the patients to get used to their prostheses by simulating tactile sensations as though they were their natural limbs.
The collaborative project had gathered momentum for four years before the team began its first research study. Surgical procedures, patient rehabilitation, and follow-up studies were conducted at the Medical Center of the Far Eastern Federal University. Motorica had handled the recruitment of patients and provided the technological support for the project, while a team of scientists from Skoltech undertook the research.
The project’s first patients were two men with amputated limbs. The eligibility criteria for the patients were rather strict: 18+ adults with arm amputations and persistent phantom pain in the area of the amputated limbs.
Patient A lost his forearms because of a severe electric shock in a work accident three years ago. In addition to a partial amputation of both forearms, he had had multiple surgeries. Patient A spent three years undergoing treatment and fighting for his life. He participated in the study to find a solution to the life-interfering phantom pain he has been suffering from.
Patient B lost his forearms from a lightning strike 24 years ago. Because of the accident, Patient B has partially lost both of his forearms. His phantom pains have not receded in all the years since the accident. Although Patient B ended up getting used to them, he participated in the study not for his benefit but in the name of science and for the sake of other people in a similar situation.
On November 26, two electrodes were implanted on Patient B’s median nerve during a surgical procedure. At the same time, Patient A received three electrodes, one on the radial nerve, one on the ulnar, and one on the median. The surgery was implemented by a team of experts from the Medical Center of the Far Eastern Federal University led by ArturBiktimirov, a resident neurosurgeon at the Medical Center of the Far Eastern Federal University, an expert at the National Technological Initiative Center for Virtual and Augmented Reality. This team’s professionals had extensive experience in such breakthrough projects since high-tech treatments are carried out regularly at the university hospital, conducting their research and implementing innovative treatment methods.
On November 27, the first electrode connection and first test stimulation were conducted. The therapeutic strategy adopted by the team for phantom pain management consisted of using a series of tiny electrical impulses delivered through an electrode near the targeted peripheral nerve. The series of impulses were provided by a portable wearable device during the entire study duration, except for periods of sensorimotor studies. Patients recorded their sensations and experiences into an observation log to allow a retrospective monitoring of the phantom pain’s suppression progress.
The main stages of testing the prosthesis’ sensory feedback were: Mapping the sensitivity of the phantom limb, selecting stimulation parameters to simulate the sensation of touch and contraction of the phantom limb, and performing tests in conjunction with haptic communication in the form of electrostimulation.
In the case of Patient B, a stable suppression of phantom pain was observed from day one. At the same time, his subjective sensation of the phantom forearm developed unexpected results. At the initial suppression of the phantom pain, he could feel the touching and squeezing of his phantom hand’s fingers again. Meanwhile, Patient A’s phantom pain did not disappear entirely but decreased by 40-70%. Furthermore, Patient A also experienced a general sensation of squeezing in his fingers when clenching his hand into a fist during the application of electrical stimulation. The persistent sensation of the stimulation-induced “clenching of the hand into a fist” was used to conduct a test for assessing the size of the objects in hand. Patient A successfully determined the size of the objects held in his prosthesis while wearing a mask.
The data obtained in these tests will be analyzed by a team of scientists of the Center for Neurobiology and Neurorehabilitation at Skoltech. While there is still a lot to be done, we can say that the team is looking forward to 2022 and is planning an expansion phase for the study with an increased number of participants.
Commentaries
Ilya Chekh, co-founder and CEO of Motorica:
“Our main goal was to work out a specific technological hypothesis, which is formulated as follows: “Is it possible to induce a sensory response with invasive stimulation of the peripheral nervous system, allowing the person to feel how they pick up an object, and the approximate position of the hand’s fingers.” We have fully demonstrated that it is possible technologically and physiologically, opening huge opportunities for further research. Since this was our first attempt in the direction of invasive research, we will continue together with the Medical Center of the Far Eastern Federal University and the Russian Innovative Scientific and Technological Center located on the Russian Island in Vladivostok to develop a medical cyberspace, a special economic and legal zone for projects and companies that deal with invasive research and technology. We want to create a community of Russian developers and engineers involving development institutions and foreign partners.”
ArturBiktimirov, a functional neurosurgeon at the Medical Center of the Far Eastern Federal University and an expert of the National Technological Initiative Center for Neurotechnology and VR/AR Technology:
“In both patients, we achieved a reduction of phantom pain and obtained two types of sensation: pressure sensation and sensation perception. In other words, the patient could tell if his prosthesis was closed or open and if he was holding an object in his prosthesis. About a dozen teams worldwide work on this problem, but no one has developed any working solutions yet. The Russian team intends to pick up the pace. We are currently analyzing the results, based on which, we will build the research processes for the 2022 spring.”
