Neural prostheses for walking restoration

We review the state of the art of multi-channel electrical stimulation (ES) systems with surface electrodes for assistance in the standing and walking of paraplegics and hemiplegics. For the group of complete paraplegics, walking achieved with available ES systems is below their expectations, especially since these systems cannot compete with mobility provided to them by a wheelchair. However, standing and walking with ES systems are beneficial because they contribute to the improvement of physiological functions. For individuals who can stand with some arm support (e.g., paraplegics with incomplete injury and hemiplegics), the current ES systems are an effective augmentation of walking. We suggest that an ES system for walking of incomplete paraplegics and hemiplegics will be better accepted if the stimulation is regulated by a rule-based control, that is, a preprogrammed, sensor-triggered activation of several muscles resulting in normal walking. We present a method to obtain muscle activity profiles from simulation of a customized model of the patient that can be used for the synthesis of rules for control.