Electrophysiological characteristics according to activity level of myofascial trigger points

Yu, Seong Hun; Kim, Hyun Jin

doi:10.1589/jpts.27.2841

Cited by 18 publications

(19 citation statements)

References 18 publications

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“…Dideriksen et al [22] and Falla et al [23] demonstrated that motor unit potentials reduce in amplitude following the injection of nociceptive hypertonic saline into the upper trapezius muscle. This is in line with the EMG characteristics of MTrPs cited earlier [10,11]. However, other studies, such as the study directed by Birch et al [24], present contradictory results, indicating that no signi cant differences in motor unit discharge rates were found.…”

supporting

confidence: 85%

“…Studies assessing the contractility of MTrP have found increased muscle fatigability in active and latent MTrP relative to unaffected muscles. Furthermore, it has also been demonstrated that there is increased fatigability and EMG activity in active MTrP relative to latent ones [11]. This data suggests that perturbations in the efferent system involved in muscle control is a vital component of the MTrP pathophysiology.…”

mentioning

confidence: 90%

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Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

Evans

Behr

Masani

et al. 2020

Preprint

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Background: Myofascial pain syndrome (MPS) is a prevalent chronic pain disorder primarily characterized by myofascial trigger points (MTrP). 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 vibrationsonoelastography, although there is some contradictory evidence regarding if MTrPs present as hyper or hypoechoic regions. Electromyography (EMG) investigations of MTrP have demonstrated that MTrP 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 withhyperexcitability 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.Methods: 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. Discussion: 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.Trial Registration: Name: National Institutes of Health ClinicalTrials.gov.Identifier: NCT03944889Date of Registration: May 07 2019URL: https://clinicaltrials.gov/ct2/show/NCT03944889

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supporting

confidence: 85%

mentioning

confidence: 90%

Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

Evans

Behr

Masani

et al. 2020

Preprint

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“…The intramuscular EMG activity in the upper trapezius muscle was significantly higher at rest and during contraction at latent MTrPs compared with non-MTrPs. Yu et al measured maximum voluntary isometric contraction, endurance, median frequency, and muscle fatigue index in three groups of participants: an active MTrP group, a latent MTrP group, and a control group [ 35 ]. The active MTrP group had a higher median frequency and muscle fatigue index than the control group.…”

Section: Reviewmentioning

confidence: 99%

Myofascial trigger points in migraine and tension-type headache

et al. 2018

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BackgroundA myofascial trigger point is defined as a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. It has been suggested that myofascial trigger points take part in chronic pain conditions including primary headache disorders. The aim of this narrative review is to present an overview of the current imaging modalities used for the detection of myofascial trigger points and to review studies of myofascial trigger points in migraine and tension-type headache.FindingsDifferent modalities have been used to assess myofascial trigger points including ultrasound, microdialysis, electromyography, infrared thermography, and magnetic resonance imaging. Ultrasound is the most promising of these modalities and may be used to identify MTrPs if specific methods are used, but there is no precise description of a gold standard using these techniques, and they have yet to be evaluated in headache patients.Active myofascial trigger points are prevalent in migraine patients. Manual palpation can trigger migraine attacks. All intervention studies aiming at trigger points are positive, but this needs to be further verified in placebo-controlled environments. These findings may imply a causal bottom-up association, but studies of migraine patients with comorbid fibromyalgia syndrome suggest otherwise. Whether myofascial trigger points contribute to an increased migraine burden in terms of frequency and intensity is unclear.Active myofascial trigger points are prevalent in tension-type headache coherent with the hypothesis that peripheral mechanisms are involved in the pathophysiology of this headache disorder. Active myofascial trigger points in pericranial muscles in tension-type headache patients are correlated with generalized lower pain pressure thresholds indicating they may contribute to a central sensitization. However, the number of active myofascial trigger points is higher in adults compared with adolescents regardless of no significant association with headache parameters. This suggests myofascial trigger points are accumulated over time as a consequence of TTH rather than contributing to the pathophysiology.ConclusionsMyofascial trigger points are prevalent in both migraine and tension-type headache, but the role they play in the pathophysiology of each disorder and to which degree is unclarified. In the future, ultrasound elastography may be an acceptable diagnostic test.

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“…Furthermore, it has also been demonstrated that there is increased fatigability and EMG activity in active MTrP relative to latent ones. [8] This data suggests that perturbations in the efferent system involved in muscle control is a vital component of the MTrP pathophysiology.…”

Section: Introductionmentioning

confidence: 91%

“…This is in line with the EMG characteristics of MTrPs cited earlier. [7,8] However, other studies, such as the study directed by Birch et al (2000), present contradictory results, indicating that no significant differences in motor unit discharge rates were found. Studies assessing the EMG activity of trigger points failed to locate the aberrant activity that characterizes MTrP using surface EMG but were able to demonstrate the presence of SEA, intermittent spikes in active MTrP, as well as activity associated with local twitch responses using intramuscular EMG recordings due to the method's specificity.…”

Section: Introductionmentioning

confidence: 94%

Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

Evans

Behr

Masani

et al. 2019

Preprint

View full text Add to dashboard Cite

Background: Myofascial pain syndrome (MPS) is a prevalent chronic pain disorder primarily characterized by myofascial trigger points (MTrP). 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 MTrP 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. Methods: The study conforms to the Consolidated Standards of Reporting Trials recommendations. Ethical approval will be sought 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 four treatment arms and two control treatment groups. Discussion: 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.

show abstract

Electrophysiological characteristics according to activity level of myofascial trigger points

Cited by 18 publications

References 18 publications

Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

Myofascial trigger points in migraine and tension-type headache

Quantitative Response of Healthy Muscle Following the Induction of Capsaicin: An Exploratory Randomized Controlled Trial

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