高频脊髓刺激（HF-SCS）引发的膈神经-肋间神经反射活动。
Phrenic-to-intercostal reflex activity in response to high frequency spinal cord stimulation (HF-SCS).
机构信息
Department of Physical Medicine and Rehabilitation, Case Western Reserve University, Cleveland, OH, USA; MetroHealth Research Institute, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA.
出版信息
Respir Physiol Neurobiol. 2022 Dec;306:103962. doi: 10.1016/j.resp.2022.103962. Epub 2022 Sep 5.
OBJECTIVE
HF-SCS is a novel technique of inspiratory muscle activation which results in coincident activation of the diaphragm and inspiratory intercostal muscles via spinal cord pathways and has the potential to provide respiratory support in ventilator dependent persons with spinal cord injury. The purpose of the present study was to examine the phrenic-to-intercostal reflex during HF-SCS.
METHODS
In 5 anesthetized and C2 spinalized dogs, electrical stimulation was applied via a stimulating electrode located on the ventral surface of the upper thoracic spinal cord at the T2 level. Fine wire recording electrodes were used to assess single motor unit (SMU) activity of the left and right external intercostal muscles (EI) in the 3rd interspace before and after sequential left and right phrenicotomy.
RESULTS
Mean control peak firing frequency of the right EI and left EI was 11.4 ± 0.3 Hz and 10.6 ± 0.3 Hz respectively. Following unilateral right phrenic nerve section, mean SMU peak firing frequency of right EI (ipsilateral to the section) was significantly greater when compared to control (15.9 ± 0.5 Hz vs 11.4 ± 0.3 Hz; p = 0.01). Mean SMU peak firing frequency of the contralateral left EI remained unchanged (10.2 ± 0.3 Hz vs 10.6 ± 0.3 Hz, p = 0.40). Subsequent, section of the left phrenic nerve resulted in significantly higher mean SMU peak firing frequency of the left EI (16.2 ± 0.5 Hz vs 10.2 ± 0.3 Hz) when compared to before section p = 0.01). Contralateral, right EI peak firing frequency was not different if compared to before left phrenic nerve section (16.9 ± 0.4 Hz vs. 15.9 ± 0.5 Hz; p = 0.14).
CONCLUSION
This study demonstrates that during HF-SCS: 1) unilateral diaphragmatic afferents reflexly inhibit motor activity to the ipsilateral EI muscles, 2) the neural circuitry mediating the phrenic-to-intercostal reflex is preserved at a spinal level and does not require supraspinal input and 3) unilateral compensatory increases were observed in EI muscle activation following ipsilateral diaphragm paralysis.
目的
HF-SCS 是一种新型的吸气肌激活技术，通过脊髓途径使膈神经和吸气肋间肌同时激活，有可能为脊髓损伤依赖呼吸机的患者提供呼吸支持。本研究的目的是研究 HF-SCS 期间的膈神经-肋间肌反射。
方法
在 5 只麻醉并 C2 脊髓切断的狗中，通过位于 T2 水平上胸段脊髓腹侧表面的刺激电极进行电刺激。使用细钢丝记录电极在左侧和右侧膈神经切开术之前和之后评估第 3 肋间的左侧和右侧外部肋间肌（EI）的单个运动单位（SMU）活动。
结果
右侧 EI 和左侧 EI 的平均对照峰发射频率分别为 11.4±0.3Hz 和 10.6±0.3Hz。单侧右侧膈神经切断后，与对照相比，右侧 EI（与切断侧同侧）的平均 SMU 峰发射频率显著增加（15.9±0.5Hz 与 11.4±0.3Hz；p=0.01）。对侧左侧 EI 的平均 SMU 峰发射频率保持不变（10.2±0.3Hz 与 10.6±0.3Hz，p=0.40）。随后，左侧膈神经切断导致左侧 EI 的平均 SMU 峰发射频率显著升高（16.2±0.5Hz 与 10.2±0.3Hz），与切断前相比 p=0.01）。与左侧膈神经切断前相比，对侧右侧 EI 的峰值发射频率没有差异（16.9±0.4Hz 与 15.9±0.5Hz；p=0.14）。
结论
本研究表明，在 HF-SCS 期间：1）单侧膈神经传入反射性抑制同侧 EI 肌肉的运动活动，2）介导膈神经-肋间肌反射的神经回路在脊髓水平上得以保留，并不需要中枢输入，3）在同侧膈肌无力后观察到 EI 肌肉激活的单侧代偿性增加。
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