Clinical implications of basic research
Longitudinal Performance of a Surgically Implanted Neuroprosthesis for Lower-Extremity Exercise, Standing, and Transfers After Spinal Cord Injury

Presented to the American Spinal Cord Injury Society, April 14-16, 2000, Chicago, IL.
https://doi.org/10.1016/j.apmr.2012.01.001Get rights and content

Abstract

Triolo RJ, Bailey SN, Miller ME, Rohde LM, Anderson JS, Davis JA Jr, Abbas JJ, DiPonio LA, Forrest GP, Gater DR Jr, Yang LJ. Longitudinal performance of a surgically implanted neuroprosthesis for lower-extremity exercise, standing, and transfers after spinal cord injury.

Objective

To investigate the longitudinal performance of a surgically implanted neuroprosthesis for lower-extremity exercise, standing, and transfers after spinal cord injury.

Design

Case series.

Setting

Research or outpatient physical therapy departments of 4 academic hospitals.

Participants

Subjects (N=15) with thoracic or low cervical level spinal cord injuries who had received the 8-channel neuroprosthesis for exercise and standing.

Intervention

After completing rehabilitation with the device, the subjects were discharged to unrestricted home use of the system. A series of assessments were performed before discharge and at a follow-up appointment approximately 1 year later.

Main Outcome Measures

Neuroprosthesis usage, maximum standing time, body weight support, knee strength, knee fatigue index, electrode stability, and component survivability.

Results

Levels of maximum standing time, body weight support, knee strength, and knee fatigue index were not statistically different from discharge to follow-up (P>.05). Additionally, neuroprosthesis usage was consistent with subjects choosing to use the system on approximately half of the days during each monitoring period. Although the number of hours using the neuroprosthesis remained constant, subjects shifted their usage to more functional standing versus more maintenance exercise, suggesting that the subjects incorporated the neuroprosthesis into their lives. Safety and reliability of the system were demonstrated by electrode stability and a high component survivability rate (>90%).

Conclusions

This group of 15 subjects is the largest cohort of implanted lower-extremity neuroprosthetic exercise and standing system users. The safety and efficiency data from this group, and acceptance of the neuroprosthesis as demonstrated by continued usage, indicate that future efforts toward commercialization of a similar device may be warranted.

Section snippets

System Components

A schematic and photos of the internal and external components of the neuroprosthesis are shown in figure 1. IM electrodes were implanted bilaterally at the L1-2 spinal roots to activate erector spinae for trunk extension.23 Epimysial electrodes were sutured near the motor points on the surfaces of bilateral vastus lateralis for knee extension and gluteus maximus and semimembranosus for hip extension.24, 25 These electrodes were connected to a surgically implanted pulse generator (eight-channel

Subject Pool

Characteristics of the study cohort are listed in table 2. A total of 15 subjects received the implanted standing system and completed the discharge and follow-up assessments. Most of the study cohort (14 subjects) exhibited injuries between C6 and T9: 9 were motor and sensory complete (American Spinal Injury Association [ASIA] grade A), 4 were motor complete and sensory incomplete (ASIA grade B), and 1 was motor and sensory incomplete (ASIA grade C). The 1 remaining subject had a midcervical

Discussion

Maximum standing time, body weight support, knee strength, and knee fatigue index all showed no significant change from discharge to follow-up. This indicated that subjects used the neuroprosthesis sufficiently at home in order to maintain performance levels achieved during the intensive rehabilitative training period that preceded discharge.

The subject with the C5 injury (subject no. 7) was a special case, and institutional review board approval was obtained for this exception. He received the

Conclusions

Implanted neuroprostheses for standing after SCI can be reliable, and measures of technical and clinical performance of the systems are consistent over time. Maximum standing time, body weight support, knee strength, and knee fatigue index all demonstrated no significant change from discharge to follow-up (P>.05); the technical performance of the neuroprosthesis was constant over the study interval of approximately 1 year postdischarge to home use with the system. Safety and reliability of the

Acknowledgments

We thank the investigators and staff at the satellite centers for their contributions toward the study (affiliations are listed as at the time the study was conducted): Darryl J. DiRisio, MD, and Jason P. Gagnon, PT, Albany Medical Center, Albany, NY; Susan McDowell, MD, Nancy E. Quick, MA, PT, and JoAnne Riess Resig, MS, University of Kentucky, Lexington, KY; and Julie A. Mannlein, MPT, Gianna M. Rodriguez, MD, and Melissa L. Wright, MPT, University of Michigan, Ann Arbor, MI.

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    Davis Jr is now with Tulane University Medical Center, New Orleans, LA; Abbas is now with Arizona State University, Phoenix, AZ; Gater Jr is now with Richmond Veterans Affairs Medical Center/Virginia Commonwealth University, Richmond, VA.

    Supported by the Rehabilitation Research and Development Service of the U.S. Department of Veterans Affairs (grant nos. EW66CA, B3155R); the Office of Orphan Product Development of the U.S. Food and Drug Administration (grant no. FD-R-001244); the New York State Department of Health (grant no. C-08616); and the National Center for Research Resources (NCRR) (grant no. UL1 RR024989), a component of the National Institutes of Health (NIH) and NIH roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NCRR or NIH.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

    Clinical Trial Registration No.: NCT00004445

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    Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.