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J Neurotrauma. 2019 May 1;36(9):1451-1460. doi: 10.1089/neu.2018.5921. Epub 2018 Dec 15.

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

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1 Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, Minnesota.
2 Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.
3 Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Mayo Clinic, Rochester, Minnesota.
4 Department of Integrative Biology and Physiology University of California Los Angeles, Los Angeles, California.
12 Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, Texas.
5 Pavlov Institute of Physiology, St. Petersburg, Russia.
6 Department of Neurobiology, University of California Los Angeles, Los Angeles, California.
7 Department of Neurosurgery, University of California Los Angeles, Los Angeles, California.
8 Brain Research Institute, University of California Los Angeles, Los Angeles, California.
9 Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, Badalona, Spain.
10 Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia.
11 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota.


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.


electrically evoked spinal motor potentials; epidural electrical stimulation, spinal cord injury; neuromodulation; spinal cord intraoperative electrophysiology

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