Chronic nerve health following implantation of femoral nerve cuff electrodes

Journal of NeuroEngineering and Rehabilitation, 2020 · DOI: https://doi.org/10.1186/s12984-020-00720-3 · Published: July 6, 2020

Spinal Cord Injury Rehabilitation Biomedical

Simple Explanation

This study looks at how nerve cuff electrodes, used to stimulate nerves and restore function in people with spinal cord injuries, affect the health of the nerves they're attached to over time. The researchers monitored a man with paralysis who had these electrodes implanted in his legs for a year, checking nerve function and muscle response. The results showed that while there was some minor nerve irritation immediately after surgery, the nerves remained healthy overall and even strengthened with stimulated exercise.

Study Duration

1 year

Participants

A man with bilateral lower extremity paralysis secondary to cervical SCI

Evidence Level

Level IV, Case Study

Key Findings

1
Femoral compound motor unit action potentials increased 31% in amplitude and 34% in area over 1 year of rehabilitation.
2
Evoked knee extension moments increased significantly (p < 0.01) by 79% over 1 year of rehabilitation with standing and quadriceps exercises.
3
Temporary electrodiagnostic changes suggest minor nerve irritation only intra- and peri-operatively, not continuing chronically nor impacting function.

Research Summary

This study evaluated the clinical electrodiagnostic changes due to electrode implantation acutely, chronic presence on the nerve peri- and post-operatively, and long-term delivery of electrical stimulation. Electrodiagnostics indicated preserved nerve health with strengthened responses following stimulated exercise. The outcomes demonstrate the ability to safely implant electrodes on the proximal femoral nerve close to the inguinal ligament and the electrodiagnostic findings that can be expected from implanting nerve cuff electrodes.

Practical Implications

Clinical Practice

The study suggests that electrodiagnostic studies can be used to track neurophysiological changes due to implanted nerve cuff electrodes, allowing for clinical determinations about electrode viability and nerve health.

Neuroprosthesis Design

The findings indicate that composite flat interface nerve electrodes can be implanted near joints and other technically demanding areas with minimal and temporary effects on nerve health.

Future Research

The testing protocol outlined in this study may be employed in the initial deployment of other novel nerve cuff electrode designs to reassure that they are safe and these protocols are potentially applicable to other peripheral nerves anatomies.

Study Limitations

1
Session-to-session variability in isometric moment measurements, attributed to muscle fatigue and technical factors.
2
Potential variability in calculating motor nerve conduction velocity due to approximations of distance and neuromuscular junction delay.
3
All 16 contacts of the C-FINEs were only accessible during the 6-month percutaneous phase.

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