Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, Canada.
Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada.
Trials. 2020 Dec 11;21(1):1020. doi: 10.1186/s13063-020-04937-4.
Myofascial pain syndrome (MPS) is a prevalent chronic pain disorder primarily characterized by myofascial trigger points (MTrPs). There is limited knowledge on the pathophysiology and mechanisms underlying MTrP and its development. Research has previously demonstrated the identification of MTrPs using ultrasound and vibration sonoelastography, although there is some contradictory evidence regarding if MTrPs present as hyper or hypoechoic regions. Electromyography (EMG) investigations of MTrP have demonstrated that MTrPs are usually located proximal to innervation zones where the peak surface EMG signals are obtained from. Central sensitization has been proposed as the primary mechanism underlying MTrP development. Central sensitization is associated with hyperexcitability of neuronal responses to normal or noxious stimuli. There is a need for a study that measures ultrasound image textural changes and motor unit activity responses in the muscle following sensitization. The purpose of this study is to determine whether sensitizing healthy muscle using capsaicin induces a regional change in image texture variables within the specific and surrounding muscles, as well as the motor unit frequency and amplitude changes that accompany them. This is an exploratory trial that aims to provide preliminary evidence on whether central sensitization is a direct cause of taut band and MTrP development.
Ethical approval was obtained from the University Health Network (UHN) Research Ethics Board. This proposed study is a single centered, factorial, randomized placebo-controlled trial with two independent variables, depth of capsaicin application and dose of capsaicin, for a total of six treatment arms and three control treatment groups.
This will be the first study that assesses the B-mode ultrasound image texture of induced sensitized muscles and will provide more evidence on muscle motor unit activity and regional changes of central sensitization. Findings from this study may support one of few hypotheses proposed delineating the involvement of central sensitization in the development of trigger points.
National Institutes of Health ClinicalTrials.gov NCT03944889 . Registered on May 07, 2019.
肌筋膜疼痛综合征（MPS）是一种常见的慢性疼痛障碍，主要表现为肌筋膜触发点（MTrP）。目前对于 MTrP 及其发展的病理生理学和机制知之甚少。先前的研究已经证明可以使用超声和振动超声弹性成像来识别 MTrP，尽管关于 MTrP 是否表现为高回声或低回声区域存在一些相互矛盾的证据。MTrP 的肌电图（EMG）研究表明，MTrP 通常位于神经支配区域的近端，可从这些区域获得表面 EMG 信号的峰值。中枢敏化被认为是 MTrP 发展的主要机制。中枢敏化与神经元对正常或有害刺激的反应过度兴奋有关。因此，需要一项研究来测量敏化后的肌肉中超声图像纹理变化和运动单位活动的反应。本研究的目的是确定使用辣椒素敏化健康肌肉是否会引起特定肌肉和周围肌肉的图像纹理变量区域性变化，以及伴随这些变化的运动单位频率和幅度变化。这是一项探索性试验，旨在提供关于中枢敏化是否是紧张带和 MTrP 发展的直接原因的初步证据。
该研究获得了多伦多大学健康网络（UHN）伦理审查委员会的批准。这项研究是一项单中心、双因素、随机安慰剂对照试验，有两个独立变量，即辣椒素的应用深度和剂量，共 6 个治疗组和 3 个对照组。
这将是第一项评估诱导性敏化肌肉 B 型超声图像纹理的研究，并将提供更多关于肌肉运动单位活动和中枢敏化区域变化的证据。这项研究的结果可能支持少数几个假设之一，这些假设描述了中枢敏化在触发点发展中的作用。
美国国立卫生研究院临床试验.gov NCT03944889。于 2019 年 5 月 7 日注册。
