Configuration of electrical spinal cord stimulation through real-time processing of gait kinematics

Abstract

Epidural electrical stimulation (EES) of the spinal cord and real-time processing of gait kinematics are powerful methods for the study of locomotion and the improvement of motor control after injury or in neurological disorders. Here, we describe equipment and surgical procedures that can be used to acquire chronic electromyographic (EMG) recordings from leg muscles and to implant targeted spinal cord stimulation systems that remain stable up to several months after implantation in rats and nonhuman primates. We also detail how to exploit these implants to configure electrical spinal cord stimulation policies that allow control over the degree of extension and flexion of each leg during locomotion. This protocol uses real-time processing of gait kinematics and locomotor performance, and can be configured within a few days. Once configured, stimulation bursts are delivered over specific spinal cord locations with precise timing that reproduces the natural spatiotemporal activation of motoneurons during locomotion. These protocols can also be easily adapted for the safe implantation of systems in the vicinity of the spinal cord and to conduct experiments involving real-time movement feedback and closed-loop controllers.

Current Principles of Motor Control, with Special Reference to Vertebrate Locomotion

“…Intrathecal electric stimulation of afferents and particularly the dorsal columns or peripheral stimulation have been shown to promote locomotor activity or facilitate other movements (19,88,89,241,243,330,404,405,462). Currently, this approach seems to be the most promising way to elevate the excitability in the spinal cord networks of spinal cord injury patients to a degree so that the remaining brain stem fibers from LGPi can initiate the locomotor activity, particularly if combined with locomotor training.…”

Recruitment of Upper-Limb Motoneurons with Epidural Electrical Stimulation of the Primate Cervical Spinal Cord

“…Details on muscle implantation can be found in ref. 72 . Laminectomies were performed at the T1/T2 and C3/C4 junctions to provide access to the cord and allow insertion of the spinal implants.…”

“…Detailed protocols for the implantation and placement of the spinal implant are provided in ref. 72 .…”

Realistic Anatomically Detailed Open-Source Spinal Cord Stimulation (RADO-SCS) Model

“…Finite element analysis has been widely implemented in two-dimensional (2D) and threedimensional (3D) spinal cord current flow models. Although multitude computational SCS models of rodent and non-human primates had been developed and implemented for motor control following spinal cord injury 7,32,33 , here we specifically focused on human SCS modelling studies (minimally invasive or non-invasive) for pain management. We categorized prior SCS models based on tissue compartments (considered vs. not considered/absent) and anatomical precision (limited, basic precision, moderate precision, and enhanced precision) (see Table 1).…”