Journée Sanne Lotte, Journée Henricus Louis, Reed Stephen Michael, Berends Hanneke Irene, de Bruijn Cornelis Marinus, Delesalle Cathérine John Ghislaine
Equine Diagnostics, Wyns, Netherlands.
Research Group of Comparative Physiology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Front Neurosci. 2020 Jul 17;14:652. doi: 10.3389/fnins.2020.00652. eCollection 2020.
Adhesive surface electrodes are worthwhile to explore in detail as alternative to subcutaneous needle electrodes to assess myogenic evoked potentials (MEP) in human and horses. Extramuscular characteristics of both electrode types and different brands are compared in simultaneous recordings by also considering electrode impedances and background noise under not mechanically secured (not taped) and taped conditions.
In five ataxic and one non-ataxic horses, transcranial electrical MEPs, myographic activity, and noise were simultaneously recorded from subcutaneous needle (three brands) together with pre-gelled surface electrodes (five brands) on four extremities. In three horses, the impedances of four adjacent-placed surface-electrode pairs of different brands were measured and compared. The similarity between needle and surface EMGs was assessed by cross-correlation functions, pairwise comparison of motor latency times (MLT), and amplitudes. The influence of electrode noise and impedance on the signal quality was assessed by a failure rate (FR) function. Geometric means and impedance ranges under not taped and taped conditions were derived for each brand.
High coherencies between EMGs of needle-surface pairs degraded to 0.7 at moderate and disappeared at strong noise. MLTs showed sub-millisecond simultaneous differences while sequential variations were several milliseconds. Subcutaneous MEP amplitudes were somewhat lower than epidermal. The impedances of subcutaneous needle electrodes were below 900 Ω and FR = 0. For four brands, the FR for surface electrodes was between 0 and 80% and declined to below 25% after taping. A remaining brand (27G DSN2260 Medtronic) revealed impedances over 100 kΩ and FR = 100% under not taped and taped conditions.
Subcutaneous needle and surface electrodes yield highly coherent EMGs and TES-MEP signals. When taped and allowing sufficient settling time, adhesive surface-electrode signals may approach the signal quality of subcutaneous needle electrodes but still depend on unpredictable conditions of the skin. The study provides a new valuable practical guidance for selection of extramuscular EMG electrodes. This study on horses shares common principles for the choice of adhesive surface or sc needle electrodes in human applications such as in intraoperative neurophysiological monitoring of motor functions of the brain and spinal cord.
作为皮下针电极的替代方法，粘性表面电极值得深入探索，用于评估人和马的肌源性诱发电位（MEP）。在同时记录中，比较了两种电极类型和不同品牌的肌外特性，同时考虑了未机械固定（未粘贴）和粘贴条件下的电极阻抗和背景噪声。
在五匹共济失调马和一匹非共济失调马中，同时从皮下针（三个品牌）以及四肢上的预凝胶表面电极（五个品牌）记录经颅电MEP、肌电图活动和噪声。在三匹马中，测量并比较了不同品牌的四个相邻放置的表面电极对的阻抗。通过互相关函数、运动潜伏期时间（MLT）和振幅的成对比较来评估针电极和表面肌电图之间的相似性。通过故障率（FR）函数评估电极噪声和阻抗对信号质量的影响。得出每个品牌在未粘贴和粘贴条件下的几何平均值和阻抗范围。
针 - 表面电极对的肌电图之间的高相干性在中等噪声时降至0.7，在强噪声时消失。MLT显示亚毫秒级的同时差异，而顺序变化为几毫秒。皮下MEP振幅略低于表皮MEP振幅。皮下针电极的阻抗低于900Ω，FR = 0。对于四个品牌，表面电极的FR在0至80%之间，粘贴后降至25%以下。另一个品牌（美敦力27G DSN2260）在未粘贴和粘贴条件下的阻抗超过100kΩ，FR = 100%。
皮下针电极和表面电极产生高度相干的肌电图和经颅电刺激 - MEP信号。当粘贴并给予足够的稳定时间时，粘性表面电极信号可能接近皮下针电极的信号质量，但仍取决于不可预测的皮肤状况。该研究为肌外肌电图电极的选择提供了新的有价值的实用指导。这项关于马的研究与人应用中如脑和脊髓运动功能的术中神经生理监测中粘性表面电极或皮下针电极的选择具有共同的原则。
