Ng Karen B, Guiu Hernandez Esther, Haszard Jillian, Macrae Phoebe, Huckabee Maggie-Lee, Cakmak Yusuf O
Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
University of Canterbury Rose Centre for Stroke Recovery and Research, Christchurch, New Zealand.
Front Neurosci. 2024 Feb 8;18:1265894. doi: 10.3389/fnins.2024.1265894. eCollection 2024.
Transcutaneous auricular vagus nerve stimulation (taVNS) is considered a safe and promising tool for limb rehabilitation after stroke, but its effect on cough has never been studied. It is known that the ear and larynx share vagal afferent pathways, suggesting that stimulating the ear with taVNS might have effects on cough sensitivity. The specific stimulation parameters used can influence outcomes.
To investigate the effect of various stimulation parameters on change in cough sensitivity, compared to the reference parameter of 25 Hz stimulation at the left concha (most commonly-used parameter for stroke rehabilitation). Design, setting, and participants: Randomized, single-blind, active-controlled, eight-period cross-over design conducted March to August 2022 at a New Zealand research laboratory with 16 healthy participants.
All participants underwent eight stimulation conditions which varied by stimulation side (right ear, left ear), zone (ear canal, concha), and frequency (25 Hz, 80 Hz). Main outcome measures: Change in natural and suppressed cough threshold (from baseline to after 10 min of stimulation) assessed using a citric acid cough reflex test.
When compared to the reference parameter of 25 Hz stimulation at the left concha, there was a reduction in natural cough threshold of -0.16 mol/L for 80 Hz stimulation at the left canal ( = 0.004), indicating increased sensitivity. For the outcome measure of suppressed cough threshold, there was no significant effect of any of the stimulation conditions compared to the active reference.
Since stroke patients often have cough hyposensitivity with resulting high risk of silent aspiration, using 80 Hz taVNS at the left canal may be a better choice for future stroke rehabilitation studies than the commonly used 25 Hz taVNS at the left concha. Treatment parameters should be manipulated in future sham-controlled trials to maximize any potential treatment effect of taVNS in modulating cough sensitivity.
ACTRN12623000128695.
经皮耳迷走神经刺激（taVNS）被认为是中风后肢体康复的一种安全且有前景的工具，但其对咳嗽的影响从未被研究过。已知耳朵和喉部共享迷走神经传入通路，这表明用taVNS刺激耳朵可能会对咳嗽敏感性产生影响。所使用的具体刺激参数会影响结果。
与左侧耳甲25赫兹刺激的参考参数（中风康复最常用的参数）相比，研究各种刺激参数对咳嗽敏感性变化的影响。设计、设置和参与者：2022年3月至8月在新西兰一家研究实验室对16名健康参与者进行随机、单盲、活性对照、八周期交叉设计。
所有参与者接受了八种刺激条件，这些条件因刺激侧（右耳、左耳）、区域（耳道、耳甲）和频率（25赫兹、80赫兹）而异。主要结局指标：使用柠檬酸咳嗽反射试验评估自然咳嗽阈值和抑制咳嗽阈值从基线到刺激10分钟后的变化。
与左侧耳甲25赫兹刺激的参考参数相比，左侧耳道80赫兹刺激的自然咳嗽阈值降低了-0.16摩尔/升（P = 0.004），表明敏感性增加。对于抑制咳嗽阈值这一结局指标，与活性对照相比，任何刺激条件均无显著影响。
由于中风患者常伴有咳嗽低敏，导致隐性误吸风险高，因此在未来的中风康复研究中，与常用的左侧耳甲25赫兹taVNS相比，左侧耳道80赫兹taVNS可能是更好的选择。在未来的假对照试验中应调整治疗参数，以最大限度地发挥taVNS在调节咳嗽敏感性方面的任何潜在治疗效果。
ACTRN12623000128695。
