Ehrenbrusthoff Katja, Ryan Cormac G, Martin Denis J, Milnik Volker, Dinse Hubert R, Grüneberg Christian
Department of Applied Health Sciences, Hochschule für Gesundheit, Bochum, Germany.
School of Health & Life Sciences, Teesside University, Middlesbrough, United Kingdom.
Front Hum Neurosci. 2022 Aug 23;16:898759. doi: 10.3389/fnhum.2022.898759. eCollection 2022.
In people with chronic low back pain (CLBP), maladaptive structural and functional changes on a cortical level have been identified. On a functional level, somatosensory cortical excitability has been shown to be reduced in chronic pain conditions, resulting in cortical disinhibition. The occurrence of structural and/or functional maladaptive cortical changes in people with CLBP could play a role in maintaining the pain. There is currently no measurement protocol for cortical excitability that employs stimulation directly to the lower back. We developed a protocol for the measurement of single pulse somatosensory evoked potential (SEP) waveforms and paired-pulse behavior (PPB) generated from sensory nerves of the lower back and quantified its test-retest reliability in a sample of 30 healthy individuals to gain insights into the normal variability of cortical responses, which could then be compared to results from people with CLBP. We investigated cortical excitability by measuring SEPs and PPB. PPB was defined as the ratio of the amplitude of the second cortical response (A2s) divided by the first cortical response (A1). A2s was determined by subtracting the response to single-pulse stimuli from the paired pulse stimuli response to account for linear superposition effects. The test-retest reliability of the protocol was very poor with no evidence of systematic bias but a high amount of random variability between sessions. There was no significant difference in the right side PPB for session 1 (Mean ratio A2s/A1 = 0.66, SD = 0.54) and session 2 (Mean ratio A2s/A1 = 0.94, SD = 1.56); mean session difference [(95% CI) = -0.44 (-1.23 to 0.34); (22) = -1.17, = 0.26]. The ICC. (absolute agreement) for the outlier-removed right side PPB were 0.19 (95% CI: -0.84 to 0.66) and 0.43 for left side PPB (95% CI: -0.37 to 0.76). This finding potentially has wider implications for PPB protocols. If these findings were replicated in other groups and other nerves, it would question the validity of this measure more generally. However, these findings are restricted to healthy people and sensory nerves of the lower back and may not be generalizable.
在慢性下腰痛（CLBP）患者中，已发现皮层水平存在适应性不良的结构和功能变化。在功能层面，体感皮层兴奋性在慢性疼痛状态下已被证明会降低，导致皮层去抑制。CLBP患者中结构和/或功能适应性不良的皮层变化的发生可能在维持疼痛中起作用。目前尚无直接对下背部进行刺激来测量皮层兴奋性的方案。我们开发了一种用于测量由下背部感觉神经产生的单脉冲体感诱发电位（SEP）波形和配对脉冲行为（PPB）的方案，并在30名健康个体的样本中量化了其重测可靠性，以深入了解皮层反应的正常变异性，然后可将其与CLBP患者的结果进行比较。我们通过测量SEP和PPB来研究皮层兴奋性。PPB定义为第二个皮层反应（A2s）的幅度除以第一个皮层反应（A1）的比率。A2s通过从配对脉冲刺激反应中减去单脉冲刺激的反应来确定，以考虑线性叠加效应。该方案的重测可靠性非常差，没有系统偏差的证据，但各次测量之间存在大量随机变异性。第一次测量（平均比率A2s/A1 = 0.66，标准差 = 0.54）和第二次测量（平均比率A2s/A1 = 0.94，标准差 = 1.56）的右侧PPB没有显著差异；平均测量差异[（95%置信区间）= -0.44（-1.23至0.34）；（22）= -1.17，P = 0.26]。去除异常值后的右侧PPB的组内相关系数（绝对一致性）为0.19（95%置信区间：-0.84至0.66），左侧PPB为0.43（95%置信区间：-0.37至0.76）。这一发现可能对PPB方案有更广泛的影响。如果这些发现在其他群体和其他神经中得到重复，将更普遍地质疑该测量方法的有效性。然而，这些发现仅限于健康人群和下背部的感觉神经，可能无法推广。
