Data from: Electromyographic permutation entropy quantifies diaphragmatic denervation and reinnervation

Spontaneous reinnervation after diaphragmatic paralysis due to trauma, surgery, tumors and spinal cord injuries is frequently observed. A possible explanation could be collateral reinnervation, since the diaphragm is commonly double-innervated by the (accessory) phrenic nerve. Permutation entropy (PeEn), a complexity measure for time series, may reflect a functional state of neuromuscular transmission by quantifying the complexity of interactions across neural and muscular networks. In an established rat model, electromyographic signals of the diaphragm after phrenicotomy were analyzed using PeEn quantifying denervation and reinnervation. Thirty-three anesthetized rats were unilaterally phrenicotomized. After 1, 3, 9, 27 and 81 days, diaphragmatic electromyographic PeEn was analyzed in vivo from sternal, mid-costal and crural areas of both hemidiaphragms. After euthanasia of the animals, both hemidiaphragms were dissected for fiber type evaluation. The electromyographic incidence of an accessory phrenic nerve was 76%. At day 1 after phrenicotomy, PeEn (normalized values) was significantly diminished in the sternal (median: 0.69; interquartile range: 0.66–0.75) and mid-costal area (0.68; 0.66–0.72) compared to the non-denervated side (0.84; 0.78–0.90) at threshold p<0.05. In the crural area, innervated by the accessory phrenic nerve, PeEn remained unchanged (0.79; 0.72–0.86). During reinnervation over 81 days, PeEn normalized in the mid-costal area (0.84; 0.77–0.86), whereas it remained reduced in the sternal area (0.77; 0.70–0.81). Fiber type grouping, a histological sign for reinnervation, was found in the mid-costal area in 20% after 27 days and in 80% after 81 days. Collateral reinnervation can restore diaphragm activity after phrenicotomy. Electromyographic PeEn represents a new, distinctive assessment characterizing intramuscular function following denervation and reinnervation.

因创伤、手术、肿瘤及脊髓损伤引发的膈肌麻痹后，常可观察到自发性神经再支配现象。其潜在机制之一可能为侧支神经再支配：因膈肌通常接受（副）膈神经（accessory phrenic nerve）的双重支配。排列熵（Permutation Entropy, PeEn）作为一种时间序列复杂度测度方法，可通过量化神经与肌肉网络间的交互复杂度，反映神经肌肉传递的功能状态。在已建立的大鼠模型中，研究者通过排列熵对膈神经切断术后膈肌的肌电信号进行分析，以量化去神经支配与神经再支配过程。本研究对33只麻醉大鼠实施单侧膈神经切断术。分别于术后1、3、9、27及81天，对双侧膈肌的胸骨旁区、肋中部区及膈脚区进行在体膈肌肌电排列熵检测。处死后，取双侧半膈肌进行肌纤维分型评估。副膈神经的肌电检出率为76%。术后第1天，与非去神经支配侧（标准化值：中位数0.84，四分位距0.78~0.90）相比，胸骨旁区（中位数0.69，四分位距0.66~0.75）与肋中部区（中位数0.68，四分位距0.66~0.72）的排列熵（标准化值）显著降低（p<0.05）。而由副膈神经支配的膈脚区，其排列熵未出现明显变化（中位数0.79，四分位距0.72~0.86）。在术后81天的神经再支配过程中，肋中部区的排列熵恢复至正常水平（中位数0.84，四分位距0.77~0.86），而胸骨旁区的排列熵仍处于降低状态（中位数0.77，四分位距0.70~0.81）。作为神经再支配的组织学标志，肌纤维群组化现象于术后27天在20%的肋中部区样本中被检出，术后81天的检出率升至80%。综上，侧支神经再支配可恢复膈神经切断术后的膈肌活动；肌电排列熵可为去神经支配与神经再支配后的肌内功能评估提供一种全新且特异性的检测手段。