Spinal stimulation for motor rehabilitation immediately modulates nociceptive transmission

J Neural Eng, 2022 · DOI: 10.1088/1741-2552/ac9a00 · Published: January 1, 2022

Spinal Cord Injury Neurology Pain Management

Simple Explanation

Electrical stimulation of the spinal cord is being explored to improve motor function after spinal cord injury (SCI) and to manage chronic pain. This study investigates whether stimulation intended for motor rehabilitation can also affect pain pathways. The researchers used intraspinal microstimulation (ISMS) in rats to stimulate motor areas of the spinal cord. They then measured the activity of nerve cells that transmit pain signals (nociceptive transmission) in response to touch. The study found that motor-targeted ISMS can immediately reduce the transmission of pain signals in the spinal cord, without increasing sensitivity to non-painful touch. This suggests that ISMS could offer combined benefits for both motor and pain issues in SCI patients.

Study Duration

Not specified

Participants

14 adult male Sprague-Dawley rats (~250–500 g)

Evidence Level

Level 2; Animal Study

Key Findings

1
Sub-motor threshold ISMS delivered to spinal motor pools immediately modulates concurrent nociceptive transmission
2
The magnitude of anti-nociceptive effects increases with longer durations of ISMS, including robust carryover effects
3
ISMS does not increase spinal responsiveness to non-nociceptive cutaneous transmission

Research Summary

This study investigates the potential of motor-targeted intraspinal microstimulation (ISMS) to simultaneously modulate spinal nociceptive transmission. The researchers characterized the neuromodulatory actions of ISMS on the firing dynamics of nociceptive-specific and wide dynamic range neurons in rats. The primary finding is that motor-targeted ISMS immediately and persistently modulates concurrent nociceptive transmission, decreasing the prevalence and magnitude of spinal responses to noxious peripheral stimuli.

Practical Implications

Multi-modal Therapy

ISMS may offer a new approach for managing the sensorimotor consequences of SCI, providing both motor rehabilitation and pain relief.

Reduced Hyperalgesia/Allodynia

Depression of NS and WDR neurons would be predicted to reduce hyperalgesia and allodynia, two common manifestations of below-level SCI-NP.

Avoidance of Spasticity

By not enhancing WDR responses to non-nociceptive cutaneous transmission, ISMS-based therapies may avoid exacerbating the debilitating spasms and spasticity experienced by many individuals living with SCI.