Intraspinal microstimulation of the ventral horn has therapeutically relevant cross-modal effects on nociception

Brain Communications, 2024 · DOI: https://doi.org/10.1093/braincomms/fcae280 · Published: August 19, 2024

Spinal Cord Injury Pain Management Neurorehabilitation

Simple Explanation

This study investigates whether stimulating the spinal cord can reduce pain in rats with spinal cord injuries. The researchers used intraspinal microstimulation (ISMS) to stimulate the ventral horn of the spinal cord, an area involved in motor function. They found that ISMS, when intended to improve movement, also reduced the transmission of pain signals in the spinal cord. This suggests that spinal stimulation could be designed to address both movement and pain issues simultaneously. The reduction in pain transmission was specific to pain-related signals, with little effect on non-pain-related sensory feedback. This means spinal stimulation could potentially alleviate neuropathic pain without disrupting other important sensory functions.

Study Duration

At least 6 weeks

Participants

15 adult male Sprague–Dawley rats with moderate to severe sensorimotor deficits following a midline spinal contusion injury

Evidence Level

Not specified

Key Findings

1
Intraspinal microstimulation (ISMS) in the ventral horn reduces transmission through nociceptive specific and wide dynamic range neurons in response to pain-related sensory feedback.
2
Spinal responsiveness to non-pain-related sensory feedback is largely preserved during ISMS, indicating a modality-specific effect.
3
The depressive effects of ISMS on pain transmission appear to be more robust in animals exhibiting signs of spinal cord injury-related neuropathic pain.

Research Summary

This study demonstrates that intraspinal microstimulation (ISMS) of the ventral horn can simultaneously reduce neuropathic pain and improve movement in a rat model of spinal cord injury. The study found that ISMS reduced the transmission of pain signals while largely preserving non-pain-related sensory feedback, suggesting a modality-specific effect. The researchers suggest that spinal stimulation paradigms could be designed to offer multi-modal therapeutic benefits, addressing the diverse rehabilitation needs of individuals with spinal cord injury.

Practical Implications

Multi-modal Therapy Design

Spinal stimulation paradigms can be intentionally designed to address multiple therapeutic goals simultaneously, such as movement impairments and neuropathic pain.

Targeted Neuromodulation

Movement-targeted ISMS can selectively modulate nociceptive transmission while preserving non-nociceptive transmission, providing a more nuanced approach to pain management.

Clinical Translation Potential

Epidural spinal stimulation, a clinically available option, may also be capable of delivering multi-modal benefits, warranting further investigation and incorporation of pain and sensory assessments in ongoing studies.

Study Limitations

1
The study was conducted on a rat model of spinal cord injury, and results may not directly translate to humans.
2
The stimulation protocol was delivered in an open-loop fashion, uncorrelated with ongoing neural activity, which may limit the potential for long-lasting plasticity.
3
The study did not systematically characterize the time course of carryover effects, limiting the understanding of the durability of the observed benefits.

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