Effects of Stand and Step Training with Epidural Stimulation on Motor Function for Standing in Chronic Complete Paraplegics

Abstract

Individuals affected by motor complete spinal cord injury are unable to stand, walk, or move their lower limbs voluntarily; this diagnosis normally implies severe limitations for functional recovery. We have recently shown that the appropriate selection of epidural stimulation parameters was critical to promoting full-body, weight-bearing standing with independent knee extension in four individuals with chronic clinically complete paralysis. In the current study, we examined the effects of stand training and subsequent step training with epidural stimulation on motor function for standing in the same four individuals. After stand training, the ability to stand improved to different extents in the four participants. Step training performed afterwards substantially impaired standing ability in three of the four individuals. Improved standing ability generally coincided with continuous electromyography (EMG) patterns with constant levels of ground reaction forces. Conversely, poorer standing ability was associated with more variable EMG patterns that alternated EMG bursts and longer periods of negligible activity in most of the muscles. Stand and step training also differentially affected the evoked potentials amplitude modulation induced by sitting-to-standing transition. Finally, stand and step training with epidural stimulation were not sufficient to improve motor function for standing without stimulation. These findings show that the spinal circuitry of motor complete paraplegics can generate motor patterns effective for standing in response to task-specific training with optimized stimulation parameters. Conversely, step training can lead to neural adaptations resulting in impaired motor function for standing.

Emergence of Epidural Electrical Stimulation to Facilitate Sensorimotor Network Functionality After Spinal Cord Injury

“…Stand training with EES improved standing ability in all four individuals tested. However, step training without stand training decreased EES‐enabled standing ability . Furthermore, one subject regained the ability to stand with independent knee and hip extension without EES following 3.7 years of activity‐based training with EES .…”

“…The importance of rehabilitation in recovering stepping ability has been shown to be critical in both animal models and humans following SCI. To date, all reported subjects using EES for motor recovery following paraplegia have achieved the results following months of motor training prior to implant of the device to demonstrate lack of recovery with motor training without EES followed by EES in combination with motor training . Therefore, it is difficult to separate the variables of how much the motor training and stimulation, respectively, are contributing to restoration of function.…”

Cardiovascular Autonomic Dysfunction in Spinal Cord Injury: Epidemiology, Diagnosis, and Management

“…[125][126][127][128][129][130] This approach takes advantage of sophisticated spinal networks below the level of injury to unexpectedly reactivate spared pathways, restoring supraspinal connectivity and resulting in functional recovery in those initially diagnosed clinically as motor complete. [126][127][128][129][130][131][132] During the course of some of these initial studies to restore stepping and standing using lumbosacral scES in motor complete humans, investigators discovered that individuals with cardiovascular dysfunction showed increases in SBP with stimulation. [133][134][135] This response also allowed upright standing by ameliorating orthostatic hypotension.…”

Activity-based Training on a Treadmill with Spinal Cord Injured Wistar Rats

“…LT benefits regarding autonomic functions have not been well characterized. For this reason, we implement our training paradigm with a focus on autonomic outcome measures, using four distinct groups that include two non-trained controls and a metabolic/exercise nonweight bearing group alongside an LT group that mimics the timing, session duration, manual assistance and weight support that are used in clinical studies 19,21,22,23,24 .…”