Awake behaving electrophysiological correlates of forelimb hyperreflexia, weakness and disrupted muscular synchronization following cervical spinal cord injury in the rat

Behav Brain Res, 2016 · DOI: 10.1016/j.bbr.2016.03.042 · Published: July 1, 2016

Simple Explanation

This study investigates how cervical spinal cord injury (cSCI) affects forelimb function in rats. The researchers recorded muscle activity (EMG) in the biceps and triceps muscles of the impaired forelimb during both voluntary movements and reflexive responses to a thermal stimulus. The results showed that cSCI reduced voluntary forelimb strength despite rehabilitation. There was also an increase in biceps muscle activity during reflexive withdrawal from the thermal stimulus, indicating hyperreflexia. The study suggests that both biceps hyperreflexia and reduced voluntary drive contribute to forelimb strength deficits after cSCI. The use of quantitative measures of forelimb dysfunction in rats can aid in the development of treatments for spinal cord injury.

Study Duration

4 weeks post-injury

Participants

8 adult female Sprague Dawley rats

Evidence Level

Not specified

Key Findings

1
C5/C6 hemicontusion reduced volitional forelimb strength by more than 50% despite weekly rehabilitation for one month post-injury.
2
Triceps EMG during volitional strength assessment was reduced by more than 60% following injury, indicating reduced descending drive.
3
Biceps EMG during reflexive withdrawal from a thermal stimulus was increased by 500% following injury, indicating flexor withdrawal hyperreflexia.

Research Summary

The study assessed muscular dysfunction following unilateral cSCI using awake behaving electromyography (EMG) simultaneously recorded from the biceps and triceps of the impaired forelimb. Volitional forelimb strength was significantly reduced following cSCI. Reflexive and volitional EMG activation of the biceps, but not triceps, was significantly correlated with residual forelimb strength after cSCI. The results support the hypothesis that biceps hyperreflexia and descending volitional drive both significantly contribute to forelimb strength deficits after cSCI.

Practical Implications

Treatment Development

The study's findings on the electrophysiological correlates of forelimb dysfunction after cSCI can inform the development of targeted regenerative, pharmacological, and neuroprosthetic treatments for spinal cord injury.

Rehabilitation Strategies

Understanding the contribution of biceps hyperreflexia and reduced descending drive to forelimb weakness can lead to more effective rehabilitation strategies that address these specific factors.

Assessment Tool

The automated quantitative measures of forelimb dysfunction used in this study can be adopted as a reliable tool for assessing the efficacy of potential therapies in preclinical research.

Study Limitations

1
The study only included female rats, limiting the generalizability of the findings to males.
2
The study focused on a specific type of cervical spinal cord injury (C5/C6 hemicontusion), which may not represent the full spectrum of cSCI in humans.
3
The study only assessed muscle activity in the biceps and triceps, neglecting other muscles involved in forelimb function, potentially missing a broader picture of muscular dysfunction.

Your Feedback

Was this summary helpful?

Back to Spinal Cord Injury