NEC Seminar, Friday, August 2, 9:00 AM
Speaker: Sedona Cady
Advisor: Professor D. Tyler
Title: Long-term home use of a wirelessly connected bidirectional neuroprosthesis for restoring upper limb function and somatosensation
Abstract: Percutaneous peripheral nerve stimulation using composite Flat Interface Nerve Electrodes (C-FINEs) and myoelectric sensing using Tetra Intramuscular (TIM) electrodes can restore touch and relay motor intentions for upper extremity prosthesis users. Prior home use of a 1 degree-of-freedom (DOF) surface EMG prosthesis with implanted sensory feedback improved psychosocial outcomes, including quality of life. However, functional improvements were limited. Additionally, the upkeep of the percutaneous leads, high wire count crossing the skin, and burden of using an external stimulator may deter translation. With this motivation, our team developed an implantable device with wireless communication to restore somatosensation and myoelectric control: the implanted Somatosensory Electrical Neurostimulation and Sensing (iSens®) system. The purpose of this study was to investigate how long-term use of an advanced prosthesis with iSens® affects functional and psychosocial outcomes. One study participant with a right-sided transradial amputation enrolled in the study. The home study was divided into the following phases: Baseline, Crossover 1, and Crossover 2. During Baseline and Crossover 2, the participant used his own 1 DOF surface EMG prosthesis with no sensory feedback. Crossover 1 involved using iSens® and a sensorized prosthesis with 3 DOF control and sensory feedback. Using iSens® at home revealed psychosocial improvements in perceived ability, quality of life, social interaction, and embodiment. Daily living functional performance and dexterity improved with iSens®, and function also appeared to improve across time. Phantom limb length became more aligned with the contralateral limb, and phantom position became more relaxed and open. Throughout each phase of the study, the participant favored using the sound arm over the prosthesis, and no significant change in bilateral usage was observed with iSens® compared to the participant’s own prosthesis. Results from this study support the importance of sensory feedback and high DOF control to improve both psychosocial and functional outcomes for those with upper limb loss. This case study serves as a step towards translation of iSens® technology to improve the experience of using upper limb prostheses.