Optimal peripheral nerve stimulation intensity for paired associative stimulation with high‑frequency peripheral component in healthy subjects

Scientific Reports, 2022 · DOI: 10.1038/s41598-022-16811-1 · Published: July 15, 2022

Simple Explanation

This study investigates the ideal intensity of peripheral nerve stimulation (PNS) when combined with transcranial magnetic stimulation (TMS) in a technique called paired associative stimulation (PAS). The goal is to enhance brain plasticity and improve muscle function. The researchers tested different intensities of PNS to see how they affected the response of muscles in healthy individuals. They found that using an intensity just sufficient to elicit a minimal F-wave response, or slightly lower, was most effective in enhancing muscle activity. These findings suggest that applying too much or too little PNS can hinder the benefits of PAS. Further research is needed to confirm these results in patients with spinal cord injuries.

Study Duration

Not specified

Participants

2 experiments with 10 healthy subjects each

Evidence Level

Level 2: Experimental study

Key Findings

1
PAS with PNS intensity defined as the level required to achieve 7/10 F-response persistence did not produce significant MEP potentiation.
2
PAS with PNS intensity at the 1/10 F-response persistence level (“baseline”) and 25% lower produced significant MEP potentiation.
3
PNS intensities 25% higher or 50% lower than the 1/10 F-response persistence level did not result in significant MEP potentiation.

Research Summary

This study aimed to refine the definition of optimal peripheral nerve stimulation (PNS) intensity in paired associative stimulation (PAS) protocols using high-frequency PNS, called “high-PAS”. Two experiments were performed on healthy subjects, measuring motor-evoked potential (MEP) amplitude change after PAS at different PNS intensities. The results indicate that PNS intensity required to achieve 1/10 F-response persistence, or 25% lower, produces significant MEP potentiation in healthy subjects, suggesting that excessively high PNS intensities are not beneficial.

Practical Implications

Optimizing PNS Intensity

The study suggests that using the minimal intensity required to elicit F-responses or slightly lower (25% reduction) may be optimal for PAS protocols.

Clinical Translation

The findings provide insights for refining PAS protocols in clinical settings, potentially improving the effectiveness of rehabilitation interventions for spinal cord injury patients.

Further Research

The authors recommend dose-response studies in patients with SCI to confirm whether the findings translate to clinical populations with compromised connectivity between upper and lower motor neurons.

Study Limitations

1
The study was conducted only on healthy subjects, and the results may not directly translate to patients with spinal cord injuries.
2
The sample size in each experiment was relatively small (10 subjects), which may limit the generalizability of the findings.
3
The study only investigated the acute effects of PAS on MEP potentiation, and further research is needed to determine the long-term effects of different PNS intensities.

Your Feedback

Was this summary helpful?

Back to Physiology