Alam Monzurul, Garcia-Alias Guillermo, Shah Prithvi K, Gerasimenko Yury, Zhong Hui, Roy Roland R, Edgerton V Reggie
Department of Neurosurgery, University of California, Los Angeles, CA 90095, United States.
Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, United States.
J Neurosci Methods. 2015 May 30;247:50-7. doi: 10.1016/j.jneumeth.2015.03.012. Epub 2015 Mar 16.
Epidural spinal cord stimulation is a promising technique for modulating the level of excitability and reactivation of dormant spinal neuronal circuits after spinal cord injury (SCI). We examined the ability of chronically implanted epidural stimulation electrodes within the cervical spinal cord to (1) directly elicit spinal motor evoked potentials (sMEPs) in forelimb muscles and (2) determine whether these sMEPs can serve as a biomarker of forelimb motor function after SCI.
We implanted EMG electrodes in forelimb muscles and epidural stimulation electrodes at C6 and C8 in adult rats. After recovering from a dorsal funiculi crush (C4), rats were tested with different stimulation configurations and current intensities to elicit sMEPs and determined forelimb grip strength.
sMEPs were evoked in all muscles tested and their characteristics were dependent on electrode configurations and current intensities. C6(-) stimulation elicited more robust sMEPs than stimulation at C8(-). Stimulating C6 and C8 simultaneously produced better muscle recruitment and higher grip strengths than stimulation at one site.
COMPARISON WITH EXISTING METHOD(S): Classical method to select the most optimal stimulation configuration is to empirically test each combination individually for every subject and relate to functional improvements. This approach is impractical, requiring extensively long experimental time to determine the more effective stimulation parameters. Our proposed method is fast and physiologically sound.
Results suggest that sMEPs from forelimb muscles can be useful biomarkers for identifying optimal parameters for epidural stimulation of the cervical spinal cord after SCI.
硬膜外脊髓刺激是一种很有前景的技术，可用于调节脊髓损伤（SCI）后休眠脊髓神经回路的兴奋性水平并使其重新激活。我们研究了长期植入颈脊髓内的硬膜外刺激电极能否（1）直接诱发前肢肌肉的脊髓运动诱发电位（sMEP），以及（2）确定这些sMEP是否可作为SCI后前肢运动功能的生物标志物。
我们在成年大鼠的前肢肌肉中植入肌电图电极，并在C6和C8处植入硬膜外刺激电极。在经历背侧索挤压伤（C4）恢复后，对大鼠进行不同刺激配置和电流强度的测试，以诱发sMEP并测定前肢握力。
在所测试的所有肌肉中均诱发了sMEP，其特征取决于电极配置和电流强度。C6（-）刺激比C8（-）刺激诱发的sMEP更强。同时刺激C6和C8比单部位刺激能产生更好的肌肉募集效果和更高的握力。
选择最佳刺激配置的经典方法是针对每个受试者单独凭经验测试每种组合，并将其与功能改善情况相关联。这种方法不切实际，需要很长的实验时间来确定更有效的刺激参数。我们提出的方法快速且符合生理学原理。
结果表明，前肢肌肉的sMEP可作为有用的生物标志物，用于确定SCI后颈脊髓硬膜外刺激的最佳参数。
