Neural population dynamics reveal that motor-targeted intraspinal microstimulation preferentially depresses nociceptive transmission in spinal cord injury-related neuropathic pain

bioRxiv, 2023 · DOI: https://doi.org/10.1101/2023.07.27.550880 · Published: July 28, 2023

Simple Explanation

This study investigates whether stimulating the spinal cord to improve movement after spinal cord injury can also affect how the spinal cord processes pain signals. The researchers applied mild electrical stimulation to the spinal cords of rats and then tested how the rats responded to painful stimuli. They found that this stimulation reduced the transmission of pain signals in rats with spinal cord injuries and neuropathic pain. These results suggest that spinal cord stimulation could be a potential therapy for people with spinal cord injuries who experience both movement problems and chronic pain.

Study Duration

6-8 weeks

Participants

14 adult male Sprague-Dawley rats with SCI and 6 neurologically intact rats

Evidence Level

In vivo study

Key Findings

1
Motor-targeted ISMS reduced nociceptive transmission across electrodes in neurologically intact animals both during and following stimulation.
2
ISMS was not associated with altered nociceptive transmission in rats with SCI that lacked behavioral signs of neuropathic pain.
3
Nociceptive transmission was reduced both during and following motor-targeted ISMS in rats with SCI-NP, and to an extent comparable to that of neurologically intact animals.

Research Summary

The study aimed to determine if intraspinal microstimulation (ISMS) intended to enhance motor output after spinal cord injury (SCI) modulates spinal responsiveness to nociceptive sensory feedback. Motor-targeted ISMS reduced nociceptive transmission in neurologically intact rats and rats with SCI-related neuropathic pain (SCI-NP), but not in rats with SCI without neuropathic pain. The findings suggest that spinal stimulation-based therapies could be engineered to provide multi-modal rehabilitation benefits for individuals with SCI-related movement impairments and SCI-NP.

Practical Implications

Therapeutic Potential

ISMS may offer a combined approach for motor rehabilitation and pain management in SCI patients.

Personalized Treatment

The differential response to ISMS based on the presence of neuropathic pain suggests the need for personalized stimulation paradigms.

Further Research

Future studies should investigate optimal stimulation parameters and underlying mechanisms for maximizing the anti-nociceptive effects of ISMS.

Study Limitations

1
Experiments were conducted in anesthetized rats, which may affect the generalizability of the findings to awake, behaving conditions.
2
The study could not determine the specific types of neurons dominating neural transmission on each electrode channel.
3
The study was unable to determine the extent to which neural transmission on a given electrode channel was dominated by output neurons vs. local, segmental interneurons

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