Motor Control and Sensory Feedback Enhance Prosthesis Embodiment and Reduce Phantom Pain After Long-Term Hand Amputation

Abstract

We quantified prosthesis embodiment and phantom pain reduction associated with motor control and sensory feedback from a prosthetic hand in one human with a long-term transradial amputation. Microelectrode arrays were implanted in the residual median and ulnar arm nerves and intramuscular electromyography recording leads were implanted in residual limb muscles to enable sensory feedback and motor control. Objective measures (proprioceptive drift) and subjective measures (survey answers) were used to assess prosthesis embodiment. For both measures, there was a significant level of embodiment of the physical prosthetic limb after open-loop motor control of the prosthesis (i.e., without sensory feedback), open-loop sensation from the prosthesis (i.e., without motor control), and closed-loop control of the prosthesis (i.e., motor control with sensory feedback). There was also a statistically significant reduction in reported phantom pain after experimental sessions that included open-loop nerve microstimulation, open-loop prosthesis motor control, or closed-loop prosthesis motor control. The closed-loop condition provided no additional significant improvements in phantom pain reduction or prosthesis embodiment relative to the open-loop sensory condition or the open-loop motor condition. This study represents the first long-term (14-month), systematic report of phantom pain reduction and prosthesis embodiment in a human amputee across a variety of prosthesis use cases.

Intuitive neuromyoelectric control of a dexterous bionic arm using a modified Kalman filter

“…1A). The first amputee (subject 6; S6) was a 57-year-old, left-hand-dominant male whose left foot and left forearm were amputated 13 years prior, after an electrocution injury [13]. The second amputee (subject 7; S7) was a 48-year-old, left-hand-dominant male, whose right forearm was amputated after Complex Regional Pain Syndrome (CRPS) and multi-year disuse [14].…”

“…Our previous publications used default values of 0.2 and 1 for the thresholds and gains respectively [13], [14], although they were often subsequently tuned on an individual DOF basis to provide optimal control [13]. Individual tuning generally involved modifying thresholds first, and then gains.…”

Long-Term Performance of Utah Slanted Electrode Arrays and Intramuscular Electromyographic Leads Implanted Chronically in Human Arm Nerves and Muscles

“…The first amputee (subject 5; S5) was a 43-year-old male whose left and right forearms were amputated 24 years prior due to trauma [9,18]. The second amputee (subject 6; S6) was a 57-year-old male whose left foot and left forearm were amputated 13 years prior due to trauma [5,6,10,12]. The third amputee (subject 7; S7) was a 48-year-old male whose right forearm was electively amputated due to chronic Complex Regional Pain Syndrome with simultaneous intraoperative implantation of the USEA and iEMG devices [4,5].…”

“…A total of 13, 65, and 46 datasets were collected for participants S5, S6, and S7, respectively. Additional experimental sessions were performed with the participants and have been reported previously [4][5][6]9,10,12].…”

“…The Utah Slanted Electrode Array (USEA) consists of a 10 × 10 grid of electrodes with depths from 0.5 to 1.5 mm that penetrate peripheral nerves to enable single-unit neural recordings and intraneural microstimulation [1]. USEAs implanted in the peripheral nerves serve as a bi-directional sensorimotor neural interface, and have now been used to reanimate motionless limbs [2,3], to provide intuitive control of and sensory feedback from bionic arms [4][5][6][7][8][9], and to alleviate neuropathic pain [10,11]. The high electrode count and intrafasicular nature of the USEA yields improved specificity [6,12].…”