Selectivity and excitability of upper-limb muscle activation during cervical transcutaneous spinal cord stimulation in humans
Selectivity and excitability of upper-limb muscle activation during cervical transcutaneous spinal cord stimulation in humans
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DOI：
10.1152/japplphysiol.00132.2021
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发表时间：
2021-08-01
影响因子：
3.3
通讯作者：
Milosevic, Matija
中科院分区：
文献类型：
--
作者：
de Freitas, Roberto M.;Sasaki, Atsushi;Milosevic, Matija
颈经皮脊髓电刺激（tSCS）对上肢运动功能康复的疗效取决于la传入神经的募集。然而，选择性和兴奋性的电机激活与不同的电极配置仍然不清楚。在这项研究中，激活上肢运动池检查不同的阴极和阳极配置在颈部tSCS在10个健全的人。同时测量六个上肢肌肉的肌肉反应。首先，对于每个阴极配置（C6、C7和T1椎体水平），使用tSCS配对脉冲（50 ms间期）确认激活后抑制，阳极位于颈前。上肢运动池激活的选择性和兴奋性通过比较肌肉和阴极配置的第一诱发反应的募集曲线（10-100 mA）来检查。我们的研究结果表明，手的肌肉优先激活时，阴极被放置在T1与其他脊椎水平相比，而没有选择性的近端手臂肌肉。此外，需要更高的刺激强度，以激活远侧手部肌肉比近侧手臂肌肉，这表明不同的肌肉之间的兴奋性阈值。在一项单独的方案中，比较了阳极配置（前颈部、肩部、髂嵴和背部）与一种选定的阴极配置之间的反应。还评估了不适程度。最大的肌肉反应引起的阳极配置在前颈部，而没有差异的不适。因此，我们的研究结果通知电极配置的方法考虑，以帮助优化招聘的la传入在颈部tSCS.NEW &值得注意的是，我们检查了选择性和兴奋性的运动激活在多个上肢肌肉在颈部经皮脊髓刺激不同的阴极和阳极配置。与C6和C7位置相比，当阴极配置在T1椎骨上时，手部肌肉更活跃。需要更高的刺激强度，以激活远侧手部肌肉比近侧手臂肌肉。最后，与其他配置相比，前颈部的阳极配置引起更大的反应。
Cervical transcutaneous spinal cord stimulation (tSCS) efficacy for rehabilitation of upper-limb motor function was suggested to depend on recruitment of la afferents. However, selectivity and excitability of motor activation with different electrode configurations remain unclear. In this study, activation of upper-limb motor pools was examined with different cathode and anode configurations during cervical tSCS in 10 able-bodied individuals. Muscle responses were measured from six upper-limb muscles simultaneously. First, postactivation depression was confirmed with tSCS paired pulses (50-ms interval) for each cathode configuration (C6, C7, and T1 vertebral levels), with anode on the anterior neck. Selectivity and excitability of activation of the upperlimb motor pools were examined by comparing the recruitment curves (10-100 mA) of first evoked responses across muscles and cathode configurations. Our results showed that hand muscles were preferentially activated when the cathode was placed over T1 compared with the other vertebral levels, whereas there was no selectivity for proximal arm muscles. Furthermore, higher stimulation intensities were required to activate distal hand muscles than proximal arm muscles, suggesting different excitability thresholds between muscles. In a separate protocol, responses were compared between anode configurations (anterior neck, shoulders, iliac crests, and back), with one selected cathode configuration. The level of discomfort was also assessed. Largest muscle responses were elicited with the anode configuration over the anterior neck, whereas there were no differences in the discomfort. Our results therefore inform methodological considerations for electrode configuration to help optimize recruitment of la afferents during cervical tSCS.NEW & NOTEWORTHY We examined selectivity and excitability of motor activation in multiple upper-limb muscles during cervical transcutaneous spinal cord stimulation with different cathode and anode configurations. Hand muscles were more activated when the cathode was configured over the T1 vertebra compared with C6 and C7 locations. Higher stimulation intensities were required to activate distal hand muscles than proximal arm muscles. Finally, configuration of anode over anterior neck elicited larger responses compared with other configurations.