New functional electrical stimulation approaches to standing and walking

Spinal cord injury (SCI) is a devastating neurological trauma that is prevalent predominantly in young individuals. Several interventions in the areas of neuroregeneration, pharmacology and rehabilitation engineering/neuroscience are currently under investigation for restoring function after SCI. In this paper, we focus on the use of neuroprosthetic devices for restoring standing and ambulation as well as improving general health and wellness after SCI. Four neuroprosthetic approaches are discussed along with their demonstrated advantages and their future needs for improved clinical applicability. We first introduce surface functional electrical stimulation (FES) devices for restoring ambulation and highlight the importance of these devices for facilitating exercise activities and systemic physiological activation. Implanted muscle-based FES devices for restoring standing and walking that are currently undergoing clinical trials are then presented. The use of implanted peripheral nerve intraneural arrays of multi-site microelectrodes for providing fine and graded control of force during sit-to-stand maneuvers is subsequently demonstrated. Finally, intraspinal microstimulation (ISMS) of the lumbosacral spinal cord for restoring standing and walking is introduced and its results to date are presented. We conclude with a general discussion of the common needs of the neuroprosthetic devices presented in this paper and the improvements that may be incorporated in the future to advance their clinical utility and user satisfaction.