Electrophysiological Guidance of Epidural Electrode Array Implantation over the Human Lumbosacral Spinal Cord to Enable Motor Function after Chronic Paralysis

Abstract

Epidural electrical stimulation (EES) of the spinal cord has been shown to restore function after spinal cord injury (SCI). Characterization of EES-evoked motor responses has provided a basic understanding of spinal sensorimotor network activity related to EES-enabled motor activity of the lower extremities. However, the use of EES-evoked motor responses to guide EES system implantation over the spinal cord and their relation to post-operative EES-enabled function in humans with chronic paralysis attributed to SCI has yet to be described. Herein, we describe the surgical and intraoperative electrophysiological approach used, followed by initial EES-enabled results observed in 2 human subjects with motor complete paralysis who were enrolled in a clinical trial investigating the use of EES to enable motor functions after SCI. The 16-contact electrode array was initially positioned under fluoroscopic guidance. Then, EES-evoked motor responses were recorded from select leg muscles and displayed in real time to determine electrode array proximity to spinal cord regions associated with motor activity of the lower extremities. Acceptable array positioning was determined based on achievement of selective proximal or distal leg muscle activity, as well as bilateral muscle activation. Motor response latencies were not significantly different between intraoperative recordings and post-operative recordings, indicating that array positioning remained stable. Additionally, EES enabled intentional control of step-like activity in both subjects within the first 5 days of testing. These results suggest that the use of EES-evoked motor responses may guide intraoperative positioning of epidural electrodes to target spinal cord circuitry to enable motor functions after SCI.

Regenerative Therapies for Spinal Cord Injury

“…For example, smallscale clinical studies have demonstrated that the use of epidural electrical stimulation, in particular in conjunction with dynamic, task-specific training, can restore voluntary, coordinated motor activity in previously paralyzed individuals following SCI. [204][205][206][207] It is envisioned that combining proregenerative drugs, biomolecules, and/or cells with electrical stimulation and/or rehabilitative training will lead to better results. This type of approach would be expected to create a proregenerative environment supportive of axonal growth and plasticity, which would then be guided to form and maintain relays for different bodily functions via direct neuromuscular stimulation.…”

Rehabilitation of patients in late period after spinal cord injury: a meta-analysis of literature data

“…Проведенные эксперименты свидетельствуют о том, что двигательный паттерн при ЭЭС требует сочетания с сенсорной информацией. Восстановление функции ходьбы должно обязательно сочетаться с вертикальной нагрузкой на конечности, этот фактор играет критическую роль в реабилитации людей с травмой спинного мозга методом ЭЭС [46][47][48][49].…”

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

“…In addition, this subject was able to take independent steps while walking on a treadmill and with minimal support while walking over ground after a year of multimodal rehabilitation and optimization of EES parameters . In a follow‐up study, two subjects were able to perform intentional, coordinated leg movements while positioned on their side within the first five sessions of testing with EES . These studies provided additional evidence that EES with rehabilitation has the potential to restore intentional control of motor function following severe damage to the central nervous system .…”

“…Although EES has been demonstrated to enable function in individuals with chronic SCI, limitations still remain and must be addressed before successful translation to clinical use can be achieved. The surgical procedure required to place the EES array requires a laminectomy or laminotomy , which results in permanent removal of the lamina portion of the vertebral bone. This procedure has inherent risks associated with removing a portion of the spine including spinal deformity and instability .…”