Epidural electrical stimulation effectively restores locomotion function in rats with complete spinal cord injury

Neural Regen Res, 2021 · DOI: https://doi.org/10.4103/1673-5374.290905 · Published: September 22, 2020

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

Epidural electrical stimulation (EES) can help restore movement after spinal cord injury by re-activating neural circuits. Previous studies often used single electrode sites and continuous stimulation, which can lead to tolerance declines and coordination issues. This study used rat models with complete spinal cord injury and applied EES using a flexible electrode designed to match the spinal canal. The electrode stimulation targeted specific segments of the spinal cord (L2–3 and S1). The results showed that the implanted electrode did not cause a significant inflammatory response in the spinal cord. Gait analysis revealed that burst stimulation helped rats regain coordinated locomotion, adjusting dynamically with the stimulus frequency.

Study Duration

Not specified

Participants

40 female Sprague-Dawley rats

Evidence Level

Animal study

Key Findings

1
The flexible extradural electrode exhibited good anatomical topology and matched the spinal canal shape, allowing precise stimulation of the L2–3 and S1 spinal cord segments.
2
Immunofluorescence results showed no significant differences in microglia and astrocyte numbers or morphologies, indicating minimal inflammatory response after electrode implantation.
3
Gait analysis showed coordinated gait recovery in rats with spinal cord injury under burst stimulation, with regained locomotion dynamically adjusting to stimulus frequency.

Research Summary

This study investigated the effects of a new epidural electrical stimulation (EES) model on restoring motor ability in a rat model of complete spinal cord injury (SCI). The designed flexible electrodes were compatible with rat bone morphology and had a negligible impact on the inflammatory environment of spinal cord tissue. The EES protocol, using three hotspot electrodes and burst stimulation, effectively restored locomotion reaction on the treadmill, suggesting a promising approach for SCI treatment.

Practical Implications

Therapeutic Potential

Epidural electrical stimulation using specific electrode configurations and stimulation patterns can effectively restore locomotion in spinal cord injury models, offering a potential therapeutic strategy.

Biocompatible Implants

Flexible and biocompatible electrode implants minimize inflammatory responses in the spinal cord, improving long-term functionality and reducing adverse effects.

Optimized Stimulation Parameters

The use of burst stimulation and specific current parameters (e.g., 600 μA) can optimize locomotion recovery, providing valuable insights for refining EES protocols.

Study Limitations

1
Limited range of bio-markers assessed (SMI31, neuronal markers, cleaved caspase-3) for regeneration after SCI.
2
Lack of evaluation using markers reflecting microglia and macrophage activation, such as CD68.
3
EES in humans usually needs to be combined with rehabilitation programs to recover independent, weight-bearing locomotion.

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