Muscle Fatigue Post-stroke Elicited From Kilohertz-Frequency Subthreshold Nerve Stimulation
Muscle Fatigue Post-stroke Elicited From Kilohertz-Frequency Subthreshold Nerve Stimulation
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千赫兹频率阈下神经刺激引起的中风后肌肉疲劳
DOI：
10.3389/fneur.2018.01061
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发表时间：
2018
影响因子：
3.4
通讯作者：
Xiaogang Hu
中科院分区：
文献类型：
--
作者：
Yang Zheng;Henry Shin;Xiaogang Hu
目的：快速肌肉疲劳限制了功能性电刺激（FES）在运动障碍患者中的临床应用。本研究旨在描述一种新的经皮神经刺激技术引起的肌肉力的可持续性。方法：本病例研究招募了一名偏瘫慢性中风幸存者。采用高频模式（高频模式，HF）将60 μs的阈下脉冲经皮传递至中/尺神经束近端，以评估卒中幸存者两侧手指屈肌疲劳情况。常规神经刺激技术以600 μs脉冲30 Hz（低频模式，LF）为对照条件。间歇给予3-s刺激，1-s休息，可引起疲劳。为了公平比较，初始收缩力（约为最大自主收缩的30%）在高频和低频模式之间匹配。通过引起的手指屈曲力（振幅和波动）和高密度肌电图（EMG）量化的肌肉激活模式来评估肌肉疲劳。结果：与LF刺激相比，HF刺激对侧和患侧的诱导力下降更慢，力平台更高，在更高的水平上产生更可持续的力输出。同时，与LF刺激相比，HF刺激下的力波动增加更慢，连续刺激训练后的力波动较小，说明肌纤维的同步激活较少。以力肌电比测量的肌肉激活效率在高频刺激模式下也更高。结论：我们的研究结果表明，与LF刺激相比，HF神经刺激技术可以通过保持更高的肌肉激活效率来减轻脑卒中幸存者的肌肉疲劳。该技术有助于提高基于电刺激的神经康复方法的性能，并促进FES在临床人群中的应用。
Purpose: Rapid muscle fatigue limits clinical applications of functional electrical stimulation (FES) for individuals with motor impairments. This study aimed to characterize the sustainability of muscle force elicited with a novel transcutaneous nerve stimulation technique. Method: A hemiplegic chronic stroke survivor was recruited in this case study. Clustered subthreshold pulses of 60-μs with kilohertz (12.5 kHz) carrier frequency (high-frequency mode, HF) were delivered transcutaneously to the proximal segment of the median/ulnar nerve bundles to evaluate the finger flexor muscle fatigue on both sides of the stroke survivor. Conventional nerve stimulation technique with 600-μs pulses at 30 Hz (low-frequency mode, LF) served as the control condition. Fatigue was evoked by intermittently delivering 3-s stimulation trains with 1-s resting. For fair comparison, initial contraction forces (approximately 30% of the maximal voluntary contraction) were matched between the HF and LF modes. Muscle fatigue was evaluated through elicited finger flexion forces (amplitude and fluctuation) and muscle activation patterns quantified by high-density electromyography (EMG). Result: Compared with those from the LF stimuli, the elicited forces declined more slowly, and the force plateau was higher under the HF stimulation for both the affected and contralateral sides, resulting in a more sustainable force output at higher levels. Meanwhile, the force fluctuation under the HF stimulation increased more slowly, and, thus, was smaller after successive stimulation trains compared with the LF stimuli, indicating a less synchronized activation of muscle fibers. The efficiency of the muscle activation, measured as the force-EMG ratio, was also higher in the HF stimulation mode. Conclusion: Our results indicated that the HF nerve stimulation technique can reduce muscle fatigue in stroke survivors by maintaining a higher efficiency of muscle activations compared with the LF stimulation. The technique can help improve the performance of neurorehabilitation methods based on electrical stimulation, and facilitate the utility of FES in clinical populations.