Objective

To reveal the possible mechanisms underlying poststimulation block induced by high-frequency biphasic stimulation (HFBS).

Materials and Methods

A new axonal conduction model is developed for unmyelinated axons. This new model is different from the classical axonal conduction model by including both ion concentrations and membrane ion pumps to allow analysis of axonal responses to long-duration stimulation. Using the new model, the post-HFBS block phenomenon reported in animal studies is simulated and analyzed for a wide range of stimulation frequencies (100 Hz–10 kHz).

Results

HFBS can significantly change the Na⁺ and K⁺ concentrations inside and outside the axon to produce a post-HFBS block of either short-duration (<500 msec) or long-duration (>3 sec) depending on the duration of HFBS. The short-duration block is due to the fast recovery of the Na⁺ and K⁺ concentrations outside the axon in periaxonal space by diffusion of ions into and from the large extracellular space, while the long-duration block is due to the slow restoration of the normal Na⁺ concentration inside the axon by membrane ion pumps. The 100 Hz HFBS requires the minimal electrical energy to achieve the post-HFBS block, while the 10 kHz stimulation is the least effective frequency requiring high intensity and long duration to achieve the block.

Conclusion

This study reveals two possible ionic mechanisms underlying post-HFBS block of axonal conduction. Understanding these mechanisms is important for improving clinical applications of HFBS block and for developing new nerve block methods employing HFBS.

中文翻译：

---

高频双相刺激引起的刺激后阻滞的潜在机制

客观的

揭示高频双相刺激 (HFBS) 诱导的刺激后阻滞的可能机制。

材料和方法

为无髓轴突开发了一种新的轴突传导模型。这个新模型不同于经典的轴突传导模型，它包括离子浓度和膜离子泵，以允许分析轴突对长时间刺激的反应。使用新模型，针对广泛的刺激频率 (100 Hz–10 kHz) 模拟和分析动物研究中报告的后 HFBS 阻滞现象。

结果

HFBS 可以显着改变轴突内外的Na ⁺和 K ^{+浓度，根据 HFBS 的持续时间产生短期（<500 毫秒）或长期（>3 秒）的后 HFBS 阻滞。}短期阻滞是由于离子扩散进出大细胞外空间，轴突外的Na ⁺和 K ⁺浓度快速恢复，而长期阻滞是由于 Na + 和 K + 浓度恢复缓慢正常Na ⁺通过膜离子泵在轴突内浓缩。100 Hz HFBS 需要最少的电能来实现后 HFBS 阻滞，而 10 kHz 刺激是效果最低的频率，需要高强度和长持续时间才能实现阻滞。

结论

这项研究揭示了 HFBS 后轴突传导阻滞的两种可能的离子机制。了解这些机制对于改进 HFBS 阻滞的临床应用和开发采用 HFBS 的新神经阻滞方法非常重要。