Nociceptor-Dependent Locomotor Dysfunction After Clinically-Modeled Hindlimb Muscle Stretching in Adult Rats with Spinal Cord Injury

Exp Neurol, 2019 · DOI: 10.1016/j.expneurol.2019.03.006 · Published: August 1, 2019

Spinal Cord Injury Pain Management Rehabilitation

Simple Explanation

This research investigates how stretching, a common therapy after spinal cord injury (SCI), affects recovery. The study found that stretching hindlimb muscles in rats with SCI dramatically reduced their ability to move. The study suggests that this negative effect is linked to nociceptors, sensory neurons that detect pain. When these neurons were depleted, the negative impact of stretching was significantly reduced. These findings suggest that while stretching is intended to help with muscle contractures and spasticity, it may unintentionally worsen locomotor function after SCI.

Study Duration

12 Weeks

Participants

24 adult female rats

Evidence Level

Not specified

Key Findings

1
Stretching-induced drops in locomotor function were observed in nociceptor-intact animals but were nearly absent in nociceptor-depleted animals.
2
Nociceptor-intact stretched animals had significantly higher levels of CGRP+ as compared to non-stretched SCI rats, suggesting that stretching promoted intraspinal CGRP+ sprouting.
3
Hindlimb stretching resulted in significant increases in the number of c-Fos positive nuclei throughout the lumbar enlargement gray matter in VEH (SCI plus stretch) animals as compared to the CON group (SCI but no stretching).

Research Summary

The study examined the effect of hindlimb stretching on locomotor function in rats with spinal cord injury (SCI), focusing on the role of nociceptive afferents. Results showed that stretching reduced locomotor function in animals with intact nociceptors, while nociceptor-depleted animals experienced minimal impact. The findings suggest that stretching after SCI may have unintended negative consequences on locomotor recovery, mediated by C-fibers and potentially warranting a reevaluation of its routine use.

Practical Implications

Re-evaluate Stretching Therapy

The routine use of stretching as a therapy after SCI should be reevaluated due to potential negative impacts on locomotor function.

Targeted Therapies

Future therapies could target specific nociceptive pathways to minimize the negative effects of stretching while retaining its benefits.

Personalized Rehabilitation

Rehabilitation programs should be personalized, considering the potential negative impact of stretching on individuals with significant spared function after SCI.

Study Limitations

1
The study was conducted on rats, and the results may not directly translate to humans.
2
The specific mechanisms by which TRPV1+ nociceptors affect locomotor function require further investigation.
3
The clinical relevance of the stretching phenomenon is uncertain.

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