Spinal cord stimulation attenuates below-level mechanical hypersensitivity in rats after thoracic spinal cord injury

Neuromodulation, 2021 · DOI: 10.1111/ner.13248 · Published: January 1, 2021

Spinal Cord Injury Neurology Pain Management

Simple Explanation

This study investigates the effectiveness of spinal cord stimulation (SCS) in reducing pain below the injury level in rats with spinal cord injury (SCI). Two types of SCS were tested: conventional SCS and high-frequency SCS. The researchers measured the rats' sensitivity to touch on their hind paws before, during, and after SCS treatment. They also examined the activity of specific nerve cells in the spinal cord related to pain processing. The results showed that both conventional and high-frequency SCS modestly reduced the rats' sensitivity to touch, but this effect was temporary. The study also found that conventional SCS did not significantly change the activity of the pain-related nerve cells examined.

Study Duration

6-8 weeks post-SCI

Participants

Male Sprague-Dawley rats (220–280 g)

Evidence Level

Animal Study

Key Findings

1
Both conventional SCS (50 Hz, 80% MoT) and high-frequency SCS (1200 Hz, 40% MoT) attenuated hind paw mechanical hypersensitivity in SCI rats.
2
The inhibitory effects from both SCS paradigms in SCI rats were rather modest as compared to those reported for nerve-injured rats in previous studies.
3
Conventional SCS (50 Hz, 0.2 msec, Ab1, 10 min) did not significantly attenuate S-R functions or inhibit windup in lumbar WDR neurons of SCI rats, as compared to pre-SCS level.

Research Summary

The study evaluated the effects of conventional and high-frequency spinal cord stimulation (SCS) on below-level mechanical hypersensitivity in rats with spinal cord injury (SCI). Both SCS paradigms modestly attenuated mechanical hypersensitivity, but the effects were short-lived. The conventional SCS did not significantly inhibit the response of wide-dynamic range (WDR) neurons in the lumbar spinal cord. The findings suggest that while SCS may have some potential for managing SCI pain, further research is needed to optimize stimulation parameters and understand the underlying mechanisms.

Practical Implications

Potential for SCI Pain Management

Both conventional and 1200 Hz, low-intensity SCS may have the potential to attenuate below-level mechanical hypersensitivity caused by incomplete thoracic SCI.

Need for Optimization

Studies for optimizing stimulation parameters will be needed to improve the efficacy of SCS for SCI pain.

Further Research

Further investigation is warranted to determine the benefit of different SCS paradigms on other pain modalities and categories.

Study Limitations

1
The study examined only mechanical hypersensitivity.
2
No post-mortem histological quantification of the location and extent of injury was performed.
3
The mechanisms of SCI pain involve both spinal and supraspinal mechanisms and may differ in the development and maintenance phases.

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