Taylor Rachael L, Schulin Mikael, Goonetilleke Samanthi, Welgampola Miriam S
Equal contribution; Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Central Clinical School, University of Sydney, Sydney, Australia.
Equal contribution; Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Central Clinical School, University of Sydney, Sydney, Australia; Department of Neuroscience and Locomotion, Division of Otorhinolaryngology, Faculty of Health Sciences, Linköping University, Linköping Sweden.
J Am Acad Audiol. 2014 Nov-Dec;25(10):969-74. doi: 10.3766/jaaa.25.10.5.
In evoked potential testing, it is common practice to abrade the skin surface as a means of reducing and balancing electrode impedance. The effects of skin preparation and electrode impedance on ocular vestibular-evoked myogenic potential (oVEMP) prevalence and amplitudes are not known.
We sought to determine whether comparable oVEMP waveforms could be recorded without excessive skin preparation.
This was a prospective study with a repeated-measures (within-subjects) design.
The study group comprised 20 healthy participants (12 females and 8 males) ages 21-57 yr.
oVEMP reflexes were recorded in response to air-conducted and bone-conducted (AC and BC) stimuli in three conditions. In the first condition (no skin preparation), electrodes were simply placed over the skin surface. For the second condition (moderate skin preparation), oVEMP testing was repeated after the skin had been prepared with 70% isopropyl alcohol swabs. oVEMPs recorded in these two conditions were then compared with those recorded using a third conventional protocol whereby the skin was abraded with skin preparation gel until electrode impedances were low and balanced. For BC stimuli, reflex amplitudes and latencies were compared using a repeated-measures general linear model. For AC stimuli, rates of reflex detection were analyzed using a generalized estimating equation. Nonparametric Friedman tests were used to compare AC oVEMP amplitudes across the three conditions.
There was no significant effect of electrode impedance on reflex amplitudes, latencies, or rates of detection (p > 0.05). The results indicated significant stimulus-related artifact (≥3 μV) in 25 of 40 recordings under the high-impedance condition in response to BC stimulation. The stimulus artifact was detectable in 12 of 40 recordings after moderate skin preparation and in 5 recordings after skin abrasion.
Comparable rates of reflex detection and oVEMP amplitudes were recorded in the three conditions, implying that rigorous rubbing of the facial skin is largely unnecessary in clinical oVEMP testing. However, for oVEMPs recorded in response to a single-polarity stimulus, reducing and balancing electrode impedances with either isopropyl alcohol wipes or skin abrasion may help reduce unwanted stimulus artifact.
在诱发电位测试中，磨损皮肤表面是降低和平衡电极阻抗的常用方法。皮肤准备和电极阻抗对眼前庭诱发肌源性电位（oVEMP）的发生率和波幅的影响尚不清楚。
我们试图确定在不过度进行皮肤准备的情况下是否能够记录到可比的oVEMP波形。
这是一项采用重复测量（受试者内）设计的前瞻性研究。
研究组包括20名年龄在21至57岁之间的健康参与者（12名女性和8名男性）。
在三种情况下记录oVEMP反射，以响应气导和骨导（AC和BC）刺激。在第一种情况（未进行皮肤准备）下，电极直接放置在皮肤表面。在第二种情况（适度皮肤准备）下，用70%异丙醇棉签擦拭皮肤后重复进行oVEMP测试。然后将这两种情况下记录的oVEMP与使用第三种传统方案记录的结果进行比较，即使用皮肤准备凝胶磨损皮肤直至电极阻抗低且平衡。对于骨导刺激，使用重复测量一般线性模型比较反射波幅和潜伏期。对于气导刺激，使用广义估计方程分析反射检测率。使用非参数Friedman检验比较三种情况下气导oVEMP波幅。
电极阻抗对反射波幅、潜伏期或检测率没有显著影响（p>0.05）。结果表明，在高阻抗条件下，40次骨导刺激记录中有25次存在显著的刺激相关伪迹（≥3μV）。适度皮肤准备后，40次记录中有12次可检测到刺激伪迹，皮肤磨损后5次记录中可检测到刺激伪迹。
三种情况下记录的反射检测率和oVEMP波幅相当，这意味着在临床oVEMP测试中，面部皮肤的严格摩擦在很大程度上是不必要的。然而，对于响应单极性刺激记录的oVEMP，用异丙醇擦拭或皮肤磨损来降低和平衡电极阻抗可能有助于减少不必要的刺激伪迹。
