Central nociceptive sensitization vs. spinal cord training: opposing forms of plasticity that dictate function after complete spinal cord injury

Frontiers in Physiology, 2012 · DOI: 10.3389/fphys.2012.00396 · Published: October 4, 2012

Spinal Cord Injury Neurology Pain Management

Simple Explanation

This research investigates how spinal cord training interacts with central sensitization (increased pain sensitivity) after a complete spinal cord injury. The study found that spinal training can change how the spinal cord responds to pain signals. Also, inducing pain sensitivity can impair future spinal learning. These findings suggest that pain and learning in the spinal cord are opposing processes, which has implications for designing better rehabilitation strategies for spinal cord injury patients.

Study Duration

Not specified

Participants

119 adult male Sprague-Dawley rats

Evidence Level

Original Research Article

Key Findings

1
Spinal training history influences future nociceptive responsiveness to formalin. Specifically, uncontrollable stimulation enhances tactile hyper-reactivity.
2
Intradermal formalin disrupts future spinal learning on the contralateral paw for at least 24 hours, indicating a lasting central change.
3
Direct activation of spinal NMDA receptors generates a lasting impairment in spinal learning, suggesting central sensitization undermines spinal cord learning.

Research Summary

The experiments were designed to test for cross-talk between spinal training and nociceptive plasticity in complete SCI. The results indicate that spinal training history can inﬂuence future nociceptive responsiveness in the formalin test. Taken together the ﬁndings indicate that central sensitization and adaptive spinal learning are opposing forms of spinal plasticity.

Practical Implications

Rehabilitation Strategies

Care must be taken in designing rehabilitative strategies for SCI patients to avoid therapies that might produce uncontrolled nociceptive input.

Pain Management

Nociceptive input to the spinal cord may promote a maladaptive plasticity that undermines future spinal cord training and rehabilitation potential, even in complete SCI.

Therapeutic Targets

Therapies should promote adaptive spinal plasticity while limiting central pain to improve recovery after SCI.

Study Limitations

1
The main focus of the work with this spinal learning model has been behavioral and pharmacological, rather than strictly physiological.
2
Direct electrophysiological conﬁrmation for the recruitment of ﬁber types and muscle group activation following stimulation of the tibialis anterior represents an important area for further research.
3
The relative role of different nociceptive populations remains an open question for further research.

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