T156. Restoration of somatosensory feedback and bidirectional real-time control of a prosthetic hand using peripheral nervous system signals

Abstract

Hand amputation is a highly disabling event, which significantly affects quality of life. Effective hand replacement can be achieved if the user, in addition to motor functions, is provided with the rich sensations that are naturally perceived while grasping and moving. We already demonstrated with promising results the possibility to restore, for a short period of 30 days, the somatosensory feedback from the lost hand in an amputee by implanting four transverse intrafascicular multichannel electrodes (TIMEs) into the residual nerves of the stump. However, the long-term usability and clinical relevance of intraneural sensory feedback have not yet been clearly demonstrated. To this aim, we performed a six-month clinical study with two trans-radial amputees who received implants of four TIMEs in their median and ulnar nerves. After calibration, electrical stimulation was delivered through the TIMEs connected to artificial sensors in the digits of a prosthesis to generate sensory feedback, which was then used by the subjects while performing different grasping tasks. The subjects reported stimulation-induced sensations from the phantom hand for the whole duration of the trial. They also successfully integrated the sensory feedback into their motor control strategies while performing experimental tests resembling realistic tasks (with and without the support of vision).The results also demonstrate that a high complexity of perception can be obtained, allowing the subjects to identify the stiffness and shape of different objects. The results achieved with the two subjects show the feasibility of longterm use of intraneural stimulation and improve the knowledge about the new type of bidirectional hand prostheses, for a more near-natural replacement as possible of missing hands.