Artificial motor control for electrically stimulated upper limbs of plegic or paretic people

Abstract

Introduction: Functional Electrical Stimulation (FES) is a technique used in the restoration and generation of movements performed by subjects with neuromuscular disorders such as spinal cord injury (SCI). The purpose of this article is to outline the state of the art and perspectives of the use of FES in artificial motor control of the upper limbs in paretic or plegic people. Methods: The databases used in papers selection were Google Scholar and Capes' Portals as well as proceedings of the Annual Conference of the International Functional Electrical Stimulation Society (IFESS). Results: Approximately 85% of the reviewed studies showed FES profile with pulse duration ranging from 1 to 300 μs and modulating (burst) frequency between 10 and 40 Hz.Regarding the type of electrodes, 88% of the studies employed transcutaneous electrodes. Conclusion: We concluded that FES with closed-loop feedback and feedforward are the most used and most viable systems for upper limbs motor control, because they perform self-corrections slowing neuromuscular adaptation, allowing different planes and more range of movement and sensory-motor integration. One of the difficulties found in neuroprosthesis systems are electrical wires attached to the user, becoming uninteresting in relation to aesthetics and break. The future perspectives lead to a trend to miniaturization of the stimulation equipment and the availability of wireless networks, which allow the attachment of modules to other components without physical contact, and will become more attractive for daily use.

Closed-loop functional optogenetic stimulation

“…FES of nerve has been used to modulate respiration, bowel, bladder, and sexual function in spinal cord injury patients 1 . FES of muscle has been performed to improve muscle conditioning in patients with muscular degenerative diseases to aid walking and/or upper extremity function 2–4 . In all cases, electrical stimulation performs reverse order recruitment, activating large motor units (large-diameter axons innervating large, fast-twitch, oxidative, and glycolytic muscle fibers) before small motor units (small-diameter axons innervating slow, fatigue-resistant muscle fibers) 5–7 .…”

“…Despite the body of work performed in the peripheral nervous system, no closed-loop (CL) studies utilizing optogenetics for motor control have been carried out. Commonly used to control paralyzed 2,12,13 and prosthetic limbs 14,15 , CL systems provide greater functionality and practicality for users compared to their open-loop counterparts 16 .…”

The Supernumerary Dorsal Grasper for people with C5-C7 spinal cord injury

“…Functional electrical stimulation (FES) [13] is a non-invasive method that artificially stimulates peripheral nerves to restore contraction of the paralyzed muscle [14]. However, FES faces several ongoing challenges, such as skin discomfort [15], low muscle selectivity [16], and muscle fatigue [17]. More invasive approaches have included nerve transfer [18] and tendon transfer [19].…”

A Wirelessly Powered 4-Channel Neurostimulator for Reconstructing Walking Trajectory

“…Memberg et al implanted neuroprostheses to restore arm and hand function of humans for more than 7 years [ 3 ]. In these studies, the muscle motion could be generated by the FES after the spinal injury because the lower motor neurons had kept their characteristics and still maintained excitability to the electrical stimulation [ 4 ]. Thus, the FES is one of the effective treatments for patients with spinal cord injury to reconstruct the functional motion of their limbs.…”