Phrenic-to-intercostal reflex activity in response to high frequency spinal cord stimulation (HF-SCS)

Respir Physiol Neurobiol, 2022 · DOI: 10.1016/j.resp.2022.103962 · Published: December 1, 2022

Simple Explanation

The study investigates how stimulating the spinal cord can activate breathing muscles, specifically the diaphragm and intercostal muscles, in individuals with spinal cord injuries. The research focuses on the phrenic-to-intercostal reflex, which involves the interaction between nerves controlling the diaphragm (phrenic nerve) and intercostal muscles. By studying this reflex in dogs with spinal cord injuries, the researchers aim to understand how spinal cord stimulation can potentially provide respiratory support to those dependent on ventilators.

Study Duration

Not specified

Participants

5 anesthetized and C2 spinalized dogs

Evidence Level

Level 5, Animal Study

Key Findings

1
Unilateral diaphragmatic afferents reflexly inhibit motor activity to the ipsilateral EI muscles during HF-SCS.
2
The phrenic-to-intercostal reflex is mediated by neural circuitry preserved at the spinal level, independent of supraspinal input.
3
Unilateral compensatory increases in EI muscle activation were observed following ipsilateral diaphragm paralysis.

Research Summary

The study examined the phrenic-to-intercostal reflex during high-frequency spinal cord stimulation (HF-SCS) in C2 spinalized dogs to understand inspiratory muscle activation. Results showed that unilateral diaphragmatic afferents reflexly inhibit ipsilateral EI muscle activity via spinal circuitry, without requiring supraspinal input. The study also found compensatory increases in EI muscle activation following ipsilateral diaphragm paralysis, indicating the importance of spinal mechanisms in respiratory control.

Practical Implications

Respiratory Support

HF-SCS may offer respiratory support for ventilator-dependent individuals with spinal cord injury.

Spinal Circuitry

The neural circuitry mediating the phrenic-to-intercostal reflex is preserved at the spinal level.

Muscle Activation

HF-SCS technique could be utilized to maintain artificial ventilation.

Study Limitations

1
Small sample size
2
Limited muscle assessment
3
Acute preparation

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