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Improving Neuroprosthesis-Assisted Standing with Nerve-Based Stimulating Electrodes

Fisher, Lee Erik

Abstract Details

2012, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.

Functional neuromuscular stimulation (FNS) is an important intervention in improving quality of life for individuals with spinal cord injury (SCI). For those with thoracic level injuries, FNS can restore standing and allow for significantly enhanced mobility. While these systems can facilitate short duration activities like transferring from one surface to another, their utility for longer duration standing has been inconsistent. Some users can stand for an hour or longer, while most are limited to five minutes or less, usually because of muscle fatigue and buckling at the knee joints. Multi-contact electrodes have the potential to increase muscle recruitment and improve the performance of FNS systems for standing after SCI. By selectively activating multiple populations of motor units within the quadriceps, these electrodes can more completely activate the muscle tissue, while also allowing for stimulation paradigms that delay the onset of fatigue.

In this study, we replaced the muscle-based electrode typically used to activate the knee extensors in an FNS system for standing after SCI with a four contact spiral nerve-cuff electrode wrapped around the femoral nerve. We demonstrated that these electrodes can achieve a stable interface with the nerve and produce strong contractions that are sufficient to lock the knees during standing. In one long-time user of the FNS system, we demonstrated a threefold increase in standing time by replacing the muscle-based electrode with a spiral nerve-cuff electrode.

We also demonstrated the selectivity of these electrodes in stimulating multiple independent populations of motor units within the quadriceps. We developed an efficient method for optimizing stimulation parameters for high density multi-contact stimulating electrodes to produce the strongest possible contractions with the least possible overlap between contacts. In three subjects, we demonstrated that the nerve-cuff electrodes could selectively activate independent populations of motor units within the quadriceps to produce between 11 and 43 Nm of knee extension moment. Further, we demonstrated the potential for leveraging that selectivity to reduce duty cycle or frequency of stimulation to delay the onset of fatigue.

This study demonstrates the potential for use of multi-contact nerve-cuff electrodes in improving the functionality of neuroprostheses for standing after SCI.

Ronald J. Triolo, PhD (Advisor)
Patrick E. Crago, PhD (Committee Chair)
Dustin J. Tyler, PhD (Committee Member)
Stephen M. Selkirk, MD, PhD (Committee Member)
154 p.

Recommended Citations

Citations

  • Fisher, L. E. (2012). Improving Neuroprosthesis-Assisted Standing with Nerve-Based Stimulating Electrodes [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1332536090

    APA Style (7th edition)

  • Fisher, Lee. Improving Neuroprosthesis-Assisted Standing with Nerve-Based Stimulating Electrodes. 2012. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1332536090.

    MLA Style (8th edition)

  • Fisher, Lee. "Improving Neuroprosthesis-Assisted Standing with Nerve-Based Stimulating Electrodes." Doctoral dissertation, Case Western Reserve University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1332536090

    Chicago Manual of Style (17th edition)