Sudden stop detection and automatic seating support with neural stimulation during manual wheelchair propulsion

Abstract

Objective: Wheelchair safety is of great importance since falls from wheelchairs are prevalent and often have devastating consequences. We developed an automatic system to detect destabilizing events during wheelchair propulsion under real-world conditions and trigger neural stimulation to stiffen the trunk to maintain seated postures of users with paralysis.

Design: Cross-over intervention

Setting: Laboratory and community settings

Participants: Three able-bodied subjects and three individuals with SCI with previously implanted neurostimulation systems

Interventions: An algorithm to detect wheelchair sudden stops was developed. This was used to randomly trigger trunk extensor stimulation during sudden stops events

Outcome Measures: Algorithm success and false positive rates were determined. SCI users rated each condition on a seven-point Usability Rating Scale to indicate safety.

Results: The system detected sudden stops with a success rate of over 93% in community settings. When used to trigger trunk neurostimulation to ensure stability, the implant recipients consistently reported feeling safer (P<.05 for 2/3 subjects) with the system while encountering sudden stops as indicated by a 1–3 point change in safety rating.

Conclusion: These preliminary results suggest that this system could monitor wheelchair activity and only apply stabilizing neurostimulation when appropriate to maintain posture. Larger scale, unsupervised and longer-term trials at home and in the community are indicated. This system could be generalized and applied to individuals without an implanted stimulation by utilizing surface stimulation, or by actuating a mechanical restraint when necessary, thus allowing unrestricted trunk movements and only restraining the user when necessary to ensure safety.

Trial Registration: NCT01474148

Keywords:

• Spinal cord injury
• Electrical stimulation
• Wheelchairs
• Mobility
• Safety

Acknowledgments

The authors would like to acknowledge the contributions of our study participants, the Motion Study Laboratory at the Louis Stokes Cleveland Veterans Affairs Medical Center, and the Cleveland APT Center. The contents do not represent views of the U.S. Department of Veterans Affairs or the U.S. Government.

Disclaimer statements

Contributors None.

Funding This material was based on work supported in part by the National Institutes of Health (Grant 1R01NS101043-01) and the Department of Defense, SCIR Program (Grant W81XWH-17-1-0240).

Conflicts of interest The authors have no conflict of interest to declare.