Body Position Influences Which Neural Structures Are Recruited by Lumbar Transcutaneous Spinal Cord Stimulation.
Body Position Influences Which Neural Structures Are Recruited by Lumbar Transcutaneous Spinal Cord Stimulation.
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DOI：
10.1371/journal.pone.0147479
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Minassian K
中科院分区：
文献类型：
--
作者：
Danner SM;Krenn M;Hofstoetter US;Toth A;Mayr W;Minassian K
人腰骶脊髓的经皮刺激用于引起脊髓反射和神经调节脊髓损伤后改变的感觉运动功能。这两种应用都需要可靠的刺激传入后根纤维。然而在某些情况下，传出前根纤维可以被共同激活。我们假设体位影响感觉或运动纤维的优先刺激。刺激触发的反应，经皮脊髓刺激记录使用表面肌电图从四头肌，腘绳肌，胫骨前肌，小腿三头肌肌肉在10个人与完整的神经系统在仰卧位，站立位和俯卧位。通过放置在T11和T12棘突间皮肤上的表面电极（参考腹部电极）施加单个和成对（30 ms刺激间隔）双相刺激脉冲。配对刺激被施加到评估诱发的肌电图反应的起源;跨突触反应将被抑制，而直接传出反应将几乎保持其幅度。我们发现，在仰卧位时，对第二刺激的反应降低到初始脉冲反应幅度的14%±5%，在站立位时降低到30%±5%，在俯卧位时仅降低到80%±5%。反应阈值在站立时最低，在俯卧位时最高，反应幅度在仰卧位时最大，在俯卧位时最小。在仰卧位和站立位获得的反应可能是由于感觉纤维的选择性刺激，而伴随的运动纤维刺激发生在俯卧位。我们假设，当在俯卧位时，产生的电场内的根纤维路径的变化增加了前根纤维的刺激阈值以上的后。因此，我们建议受试者仰卧或直立（如站立或踏步）进行脊髓反射或神经调节研究。
Transcutaneous stimulation of the human lumbosacral spinal cord is used to evoke spinal reflexes and to neuromodulate altered sensorimotor function following spinal cord injury. Both applications require the reliable stimulation of afferent posterior root fibers. Yet under certain circumstances, efferent anterior root fibers can be co-activated. We hypothesized that body position influences the preferential stimulation of sensory or motor fibers. Stimulus-triggered responses to transcutaneous spinal cord stimulation were recorded using surface-electromyography from quadriceps, hamstrings, tibialis anterior, and triceps surae muscles in 10 individuals with intact nervous systems in the supine, standing and prone positions. Single and paired (30-ms inter-stimulus intervals) biphasic stimulation pulses were applied through surface electrodes placed on the skin between the T11 and T12 inter-spinous processes referenced to electrodes on the abdomen. The paired stimulation was applied to evaluate the origin of the evoked electromyographic response; trans-synaptic responses would be suppressed whereas direct efferent responses would almost retain their amplitude. We found that responses to the second stimulus were decreased to 14%±5% of the amplitude of the response to the initial pulse in the supine position across muscles, to 30%±5% in the standing, and to only 80%±5% in the prone position. Response thresholds were lowest during standing and highest in the prone position and response amplitudes were largest in the supine and smallest in the prone position. The responses obtained in the supine and standing positions likely resulted from selective stimulation of sensory fibers while concomitant motor-fiber stimulation occurred in the prone position. We assume that changes of root-fiber paths within the generated electric field when in the prone position increase the stimulation thresholds of posterior above those of anterior root fibers. Thus, we recommend conducting spinal reflex or neuromodulation studies with subjects lying supine or in an upright position, as in standing or stepping.