International Consensus on Diagnostic Criteria and Clinical Considerations of Myofascial Trigger Points: A Delphi Study

Comparison of radial shockwave and dry needling therapies in the treatment of myofascial pain syndrome

Background/Aims

Myofascial pain syndrome is a frequent problem in the musculoskeletal system. As a method of treatment for myofascial pain syndrome, dry needling therapy is an effective and convenient treatment for patients because they do not need to be treated every day. However, as patients often have post-needle soreness or some patients are afraid of needles, there are limitations to this treatment. The purpose of this study is to compare the effectiveness of radial shockwave therapy with dry needling therapy to treat myofascial pain.

Methods

A total of 42 patients attending the rehabilitation department with at least one myofascial pain trigger point in their upper back muscles, were randomly assigned to receive radial shockwave therapy or dry needling therapy. Treatment was performed once a week for 3 weeks in both groups. Participants' pain pressure threshold, measured using an algometer, and pain levels, measured using a numeric pain scale, were assessed before the designated treatment was applied each week. Each patient also performed upper trapezius, rhomboid and infraspinatus muscle stretches twice a day throughout the study period.

Results

There was no difference in pain pressure threshold at the three trigger points before treatment with the different modalities commenced. At the end of the study, the radial shockwave therapy group had a significant improvement in trapezius pain pressure threshold, increasing from 11.7 at baseline to 14.8 at the end of study. There was no significant between-group difference in pain level (P=3.4 vs P=2.6) at the end of the study. Both treatments significantly reduced pain levels: from 7.2 to 3.4 in the radial shockwave group (P<0.001) and from 6.8 to 2.6 in the dry needling therapy group (P<0.001).

Conclusions

Dry needling and radial shock wave therapies are effective in reducing myofascial pain syndrome originating in the upper back muscles. Participants' pain pressure threshold increased after 3 weeks of treatment with both therapies. Radial shock therapy can be used as an alternative to dry needling in the treatment of myofascial pain syndrome in patients who have trouble attending daily physical therapy or in whom dry needling therapy is contraindicated.

Feasibility of a Support Vector Machine Classifier for Myofascial Pain Syndrome: Diagnostic Case-Control Study

OBJECTIVES

Myofascial pain syndrome (MPS) is the most common cause of chronic pain worldwide. The diagnosis of MPS is subjective, which has created a need for a robust quantitative method of diagnosing MPS. We propose that using a support vector machine (SVM) along with ultrasound (US) texture features can differentiate between healthy and MPS-affected skeletal muscle.

METHODS

B-mode US video data were collected in the upper trapezius muscle of healthy (29) participants and patients with active (21) and latent (19) MPS, using an acquisition method outlined in previous works. Regions of interest were extracted and filtered to obtain a unique set of 917 images where texture features were extracted from each region of interest to characterize each image. These texture features were then used to train 4 separate binary SVM classifiers using nested cross-validation to implement feature selection and hyperparameter tuning. The performance of each kernel was estimated on the data and validated through testing on a final holdout set.

RESULTS

The radial basis function kernel classifier had the greatest Matthews correlation coefficient performance estimate of 0.627 ± 0.073 (mean ± SD) along with the largest area under the curve of 91.0% ± 3.0%. The final holdout test for the radial basis function classifier resulted in 86.96 accuracy, a Matthews correlation coefficient of 0.724, 88% sensitivity, and 86% specificity, validating our earlier performance estimates.

CONCLUSIONS

We have demonstrated that specific US texture features that have been used in other computer-aided diagnostic literature are feasible to use for the classification of healthy and MPS muscle using a binary SVM classifier.

Electromyographic Activity Evolution of Local Twitch Responses During Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle: A Cross-Sectional Study

Objective

Trigger points (TrPs) are hypersensitive spots within taut bands of skeletal muscles that elicit referred pain and motor changes. Among the variety of techniques used for treating TrPs, dry needling is one of the most commonly applied interventions. The question of eliciting local twitch responses (LTRs) during TrP dry needling is unclear. Our main aim was to investigate the evolution of the electromyographic (EMG) peak activity of each LTR elicited during dry needling into latent TrPs of the gastrocnemius medialis muscle.

Methods

Twenty asymptomatic subjects with latent TrPs in the gastrocnemius medialis muscle participated in this cross-sectional study. Changes in EMG signal amplitude (root mean square [RMS]) with superficial EMG were assessed five minutes before, during, and five minutes after dry needling. The peak RMS score of each LTR was calculated (every 0.5 sec).

Results

Analysis of variance revealed a significant effect (F = 29.069, P &lt;0.001) showing a significant decrease of RMS peak amplitude after each subsequent LTR. Differences were significant (P &lt;0.001) during the first three LTRs, and stable until the end of the procedure. No changes (P =0.958) were found for mean RMS data at rest before (mean = 65.2 mv, 95% confidence interval [CI] = 47.3–83.1) and after (61.0 mv, 95% CI = 42.3–79.7) dry needling.

Conclusions

We found that, in a series of LTRs elicited during the application of dry needling over latent TrPs in the medial gastrocnemius muscle, the RMS peak amplitude of each subsequent LTR decreased as compared with the initial RMS peak amplitude of previous LTRs. No changes in superficial EMG activity at rest were observed after dry needling of latent TrPs of the gastrocnemius medialis muscle.

Repetitive Peripheral Magnetic Stimulation (rPMS) in Subjects With Migraine-Setup Presentation and Effects on Skeletal Musculature

Purpose: Repetitive peripheral magnetic stimulation (rPMS) has been successfully applied recently in migraineurs to alleviate migraine symptoms. Symptom relief has been achieved by stimulating myofascial trigger points (mTrPs) of the trapezius muscles, which are considered part of the trigemino-cervical complex (TCC). However, effects on musculature have not been assessed in detail, and the specificity of effects to muscles considered part of the TCC yet has to be elucidated. Against this background, this study presents the setup of rPMS in migraine and evaluates effects on skeletal musculature. Materials and Methods: Thirty-seven adults (mean age: 25.0 ± 4.1 years, 36 females) suffering from migraine and presenting mTrPs according to physical examination underwent rPMS either to mTrPs in the trapezius muscles (considered part of the TCC; n = 19) or deltoid muscles (considered not part of the TCC; n = 18) during six sessions over the course of 2 weeks. Standardized questionnaires were filled in to assess any adverse events and experience with rPMS as well as satisfaction and benefits from stimulation. Algometry was performed to evaluate changes in pressure pain thresholds (PPTs). Results: All stimulation sessions were successfully performed without adverse events, with 84.2% of subjects of the trapezius group and 94.4% of subjects of the deltoid group describing rPMS as comfortable (p = 0.736). Muscular pain or tension improved in 73.7% of subjects of the trapezius group and in 61.1% of subjects of the deltoid group (p = 0.077). PPTs of the trapezius muscles clearly increased from the first to the last stimulation sessions-regardless of the stimulated muscle (rPMS to the trapezius or deltoid muscles). However, depending on the examined muscles the increase of PPTs differed significantly (subjects with stimulation of trapezius muscles: p = 0.021; subjects with stimulation of deltoid muscles: p = 0.080). Conclusion: rPMS is a comfortable method in migraineurs that can improve local muscular pain or tension. Furthermore, it is able to increase directly and indirectly the PPTs of the trapezius muscles (considered part of the TCC) when applied over mTrPs, supporting the role of the TCC in migraineurs.

Reversible tactile hypoesthesia associated with myofascial trigger points: a pilot study on prevalence and clinical implications

Introduction:

Tactile hypoesthesia observed in patients with myofascial pain syndrome (MPS) is sometimes reversible when pain is relieved by trigger point injections (TPIs). We aimed to investigate the prevalence of such reversible hypoesthesia during TPI therapy and topographical relations between areas of tactile hypoesthesia and myofascial trigger points (MTrP) in patients with MPS.

Methods:

Forty-six consecutive patients with MTrP were enrolled in this study. We closely observed changes in areas of tactile hypoesthesia in patients who had tactile hypoesthesia at the first visit, and throughout TPI therapy. Tactile stimulation was given using cotton swabs, and the areas of tactile hypoesthesia were delineated with an aqueous marker and recorded in photographs.

Results:

A reduction in the size of hypoesthetic area with TPI was observed in 27 (58.7%) patients. All the 27 patients experienced a reduction in pain intensity by more than 50% in a numerical rating scale score through TPI therapy. In 9 patients, the reduction in the sizes of hypoesthetic areas occurred 10 minutes after TPI. Complete disappearance of tactile hypoesthesia after TPI therapy was observed in 6 of the 27 patients. Myofascial trigger points were located in the muscles in the vicinity of ipsilateral cutaneous dermatomes to which the hypoesthetic areas belonged.

Conclusion:

Our results indicate a relatively high prevalence of reversible tactile hypoesthesia in patients with MPS. Mapping of tactile hypoesthetic areas seems clinically useful for detecting MTrP. In addition, treating MTrP with TPI may be important for distinguishing tactile hypoesthesia associated with MPS from that with neuropathic pain.

Trigger point dry needling for the treatment of myofascial pain syndrome: current perspectives within a pain neuroscience paradigm

Myofascial pain syndrome is a pain condition characterized by the presence of trigger points. Current evidence, mostly experimental studies, clearly supports a role of trigger points on peripheral and central sensitization since they are able to contribute to sensitization of peripheral nociceptors, spinal dorsal horn neurons, and the brainstem. Several interventions are proposed for treating trigger points, dry needling being one of the most commonly used by clinicians. There is no consensus on the clinical application of trigger point dry needling: some authors propose that local twitch responses should be elicited during the needling intervention to be effective, whereas others do not. The application of trigger point dry needling is able to reduce the excitability of the central nervous system by reducing peripheral nociception associated to the trigger point, by reducing dorsal horn neuron activity, and by modulating pain-related brainstem areas. However, the effects are mainly observed in the short-term, and effect sizes are moderateto small. Therefore, the current review proposes that the application of trigger point dry needling should be integrated into current pain neuroscience paradigm by combining its application with pain neuroscience education, graded exercise and manual therapy. Additionally, patient’s expectations, beliefs, previous experiences and patient–clinician interaction should be considered when integrating trigger point dry needling into a comprehensive treatment approach.

Immediate effects of variable durations of pressure release technique on latent myofascial trigger points of the levator scapulae: a double-blinded randomised clinical trial

OBJECTIVE

Latent myofascial trigger points (MTrPs) of the levator scapulae have a high prevalence and may influenceconditions of the neck and shoulder. The pressure release technique is one of the most recommended manual therapy techniques. The aim of this study was to determine the effect of varying durations of the pressure release technique application on latent MTrPs of the levator scapulae.

METHODS

In a three-arm (1:1:1 ratio), double-blinded, parallel, randomised clinical trial, 60 healthy university students (23 men, 37 women) with a mean±SD age of 20.0±2.67 years were recruited. Subjects were assigned to receive pressure release in one latent MTrP of the levator scapulae lasting 30s (T_30s; n=17), 60s (T_60s; n=22) or 90s (T_90s; n=21). Active cervical range of movement (CROM), strength, pressure pain threshold (PPT) and neck pain intensity at full stretch were measured immediately before and after treatment.

RESULTS

Mixed-model analyses of variance showed statistically significant differences for PPT (P=0.045; partial Eta²=0.103), comparing T_60s versus T_30s (P=0.009; Cohen's d=1.044) and T_90s versus T_30s groups (P=0.001; Cohen's d=1.253), and for left side bending strength (P=0.043; partial Eta²=0.105), comparing T_90s versus T_30s (P=0.023; Cohen's d=0.907). The rest of the comparisons did not present any significant differences (P⩾0.05).

CONCLUSIONS

The 60 s and 90 s applications of the pressure release technique may be recommended to increase PPT and strength, respectively, in latent MTrPs of the levator scapulae in the short term.

TRIAL REGISTRATION NUMBER

NCT03006822.

Prevalence of Myofascial Trigger Points in Poststroke Patients With Painful Shoulders: A Cross-Sectional Study

BACKGROUND

In patients with stroke, hemiplegic shoulder pain can be a major problem. One source of shoulder pain can be myofascial trigger points (MTrPs).

OBJECTIVE

To determine the prevalence of myofascial trigger points (MTrPs) and the correlation between MTrPs and pain and function in patients presenting with shoulder pain following a stroke.

DESIGN

Cross-sectional study.

SETTING

Department of Physical Therapy.

PATIENTS

Fifty patients with stroke with shoulder pain.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASUREMENTS

The prevalence of the MTrPs located in infraspinatus, supraspinatus, teres minor, and upper trapezius was studied, using the diagnosis criteria recommended by Simons et al. The pressure pain threshold was also evaluated. Pain and function were assessed with the Visual Analogue Scale (VAS) and the Disability of the Arm, Shoulder and Hand (DASH) scale, respectively.

RESULTS

The prevalence of latent MTrPs was 68%, 92%, 40%, and 62% for supraspinatus, infraspinatus, teres minor, and upper trapezius muscle, respectively. The prevalence of active MTrPs was 34%, 50%, 12%, and 20% for supraspinatus, infraspinatus, teres minor, and upper trapezius muscle, respectively. Pain was moderately correlated with the prevalence of latent MTrPs (r = 0.35; P = .01) and active MTrPs (r = 0.31; P = .03) in the supraspinatus muscle. Disability was measured with the DASH scale and was moderately correlated with latent MTrPs in the infraspinatus (r = 0.31; P = .03) and active MTrPs of the supraspinatus (r = 0.32; P = .02).

CONCLUSIONS

This study shows that the prevalence of MTrPs is high in patents following a stroke. MTrPs in this population are moderately associated with pain and function.

LEVEL OF EVIDENCE

II.

Widespread Pressure Pain Sensitivity and Referred Pain from Trigger Points in Patients with Upper Thoracic Spine Pain

Objectives

The presence of trigger points (MTrPs) and pressure pain sensitivity has been well documented in subjects with neck and back pain; however, it has yet to be examined in people with upper thoracic spine pain. The purpose of this study was to investigate the presence of MTrPs and mechanical pain sensitivity in individuals with upper thoracic spine pain.

Methods

Seventeen subjects with upper thoracic spine pain and 17 pain-free controls without spine pain participated. MTrPs were examined bilaterally in the upper trapezius, rhomboid, iliocostalis thoracic, levator scapulae, infraspinatus, and anterior and middle scalene muscles. Pressure pain thresholds (PPTs) were assessed over T2, the C5-C6 zygapophyseal joint, the second metacarpal, and the tibialis anterior.

Results

The numbers of MTrPs between both groups were significantly different (P < 0.001) between patients and controls. The number of MTrPs for each patient with upper thoracic spine pain was 12.4 ± 2.8 (5.7 ± 4.0 active TrPs, 6.7 ± 3.4 latent TrPs). The distribution of MTrPs was significantly different between groups, and active MTrPs within the rhomboid (75%), anterior scalene (65%), and middle scalene (47%) were the most prevalent in patients with upper thoracic spine pain. A higher number of active MTrPs was associated with greater pain intensity and longer duration of pain history.

Conclusions

This study identified active MTrPs and widespread pain hypersensitivity in subjects with upper thoracic spine pain compared with asymptomatic people. Identifying proper treatment strategies might be able to reduce pain and improve function in individuals with upper thoracic spine pain. However, future studies are needed to examine this.

Localization of Muscle Edema and Changes on Muscle Contractility After Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle

In this article, we aimed to describe what happens in skeletal muscle after dry needling intervention using magnetic resonance imaging (to show if there is edema) and tensiomyography (to measure contractile properties). At the same time, we describe the relationship between pain, edema, and contractility. Our results suggest that in asymptomatic patients, the application of dry needling over latent trigger points produce intra-muscular edema, an increase in muscle stiffness and an improved muscle contraction time.

Comparison of intravenous NSAIDs and trigger point injection for low back pain in ED: A prospective randomized study

INTRODUCTION

Low back pain (LBP) is a common complaint originating from muscles Myofascial pain syndrome (MPS) is mainly associated with trigger points (TrP) in the muscle tissue. We compared the intravenously administered non-steroidal anti-inflammatory drug (NSAID) and trigger point injection (TPI) in the treatment of LBP patients admitted to the emergency department due to pain caused by TrPs.

MATERIAL AND METHOD

After randomization, NSAID was administered intravenously in group 1 and TPIs were performed as specified by Travell and Simons in group 2. The TrPs were identified with the anamnesis and physical examination Demographic characteristics and vital signs of the patients were recorded. Pain scores were measured with the Visual Analogue Scale (VAS) at admission; and in minutes 5, 10, 15, 30, and 60.

RESULTS

There were 32 patients in group 1 and 22 patients in group 2. The demographics, vital signs, and pain scores at admission were not statistically significantly different between the groups. The pain scores decreased significantly in the TPI group. During the 60 min' follow-up period, the mean VAS pain score decreased by 0.41 ± 1.30 in the TPI group and by 2.59 ± 2.37 in the NSAID group (p < 0.001). Respond the treatment was significantly higher group TPI than Group NSAID (21/22 vs 20/32 respectively, p = 0.008).

CONCLUSION

In this small randomized study with several methodological limitations, TPI was superior to the intravenous NSAIDs in the treatment of acute LBP due to TrPs. TPI can be used in the emergency departments for the acute treatment of LBP in selected patients.

Quantitative proteomics analysis to identify biomarkers of chronic myofascial pain and therapeutic targets of dry needling in a rat model of myofascial trigger points

Background

Proteomics analysis may provide important information regarding the pathogenesis of chronic myofascial pain and the mechanisms underlying the treatment effects of dry needling.

Materials and methods

This study used a rat model of myofascial trigger points (MTrPs) to perform a proteomics analysis. Three biological replicate experiments were used to compare the proteomes of healthy control rats, a rat model of MTrP, MTrP model rats following dry needling of MTrPs, and MTrP model rats following dry needling of non-MTrPs. Tandem mass tag (TMT) labeling technology based on nanoscale liquid chromatography-tandem mass spectrometry was used. Hierarchical clustering, gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and protein–protein interaction network analysis were performed to characterize the proteins. To validate the TMT results, three candidate biomarker proteins were verified using parallel reaction monitoring and Western blot analysis.

Results

A total of 2,635 proteins were identified. GO and KEGG enrichment analyses showed that the glycolysis/gluconeogenesis pathways played dominant roles in the pathogenesis of chronic myofascial pain. The three candidate biomarker proteins were the pyruvate kinase muscle isozyme (encoded by the PKM gene), the muscle isoform of glycogen phosphorylase (encoded by the PYGM gene), and myozenin 2 (encoded by the MYOZ2 gene). The validation results were consistent with the TMT results.

Conclusion

This is the first proteomics study that has investigated the pathogenesis of chronic myofascial pain and the mechanisms underlying the treatment effects of dry needling in an in vivo rat model of MTrPs, which might promote our understanding of the molecular mechanisms underlying chronic myofascial pain.

Effect of Local Anesthetic Versus Botulinum Toxin-A Injections for Myofascial Pain Disorders: A Systematic Review and Meta-Analysis

OBJECTIVE

Myofascial pain is a chronic pain disorder characterized by the presence of painful localized regions of stiff muscle and/or myofascial trigger points. Intramuscular myofascial trigger point injections are considered first-line treatments for myofascial pain. Common injectates include local anesthetics and botulinum toxin-A (BTX-A). The objective of this systematic review was to compare the effectiveness of local anesthetics and BTX-A on pain intensity in patients with myofascial pain.

METHODS

A comprehensive systematic search of 3 databases, EMBASE, CENTRAL, and Medline was conducted. The search was comprised of words to describe "myofascial pain" and "injections." We performed a meta-analysis comparing local anesthetic and BTX-A injections across these follow-up week periods: 0 (immediately following the injection), 1 to 2, 3 to 4, 5 to 6, 7 to 8, 9 to 10, 11 to 12, 16, 18, 24 weeks with local anesthetics and BTX-A as subgroups. We also performed subgroup analyses comparing the effectiveness of local anesthetic injections and BTX-A injections at various muscle locations and comparing the effectives of single versus multiple injection sessions.

RESULTS

In total, 33 studies were included. A qualitative analysis suggested that local anesthetics and BTX-A were inconsistently effective at mitigating pain across all follow-up periods. The meta-analyses revealed that local anesthetic injections were more effective than BTX-A at mitigating pain intensity. Multiple injection sessions of local anesthetics were more beneficial than a single session.

CONCLUSIONS

Additional studies are needed to determine sources of heterogeneity mediating the observed differences in effectiveness of local anesthetic and BTX-A injections among the studies. Additional replicative studies are also needed to delineate the relative efficacy and effectiveness of local anesthetic and BTX-A injection. The quantitative results of this study suggest that patients overall experience more pain relief with local anesthetic injections.

Evidence of Generalized Muscle Stiffness in the Presence of Latent Trigger Points Within Infraspinatus

OBJECTIVE

To evaluate stiffness of infraspinatus muscle tissue, both with and without latent trigger points, using ultrasound shear wave elastography (SWE). The primary hypothesis is that muscle with a latent trigger point will demonstrate a discrete region of increased shear wave speed. The secondary hypothesis is that shear wave speed (SWS) in the region with the trigger point will be higher in patients compared with controls, and will be similar between the two groups in the uninvolved regions.

DESIGN

Case-control.

SETTING

Hospital-based outpatient physical therapy center.

PARTICIPANTS

Convenience sample (N=18) of patients (6 female, 3 male, mean age=44) (range=31-61y) diagnosed with latent trigger points in infraspinatus and matched controls without trigger points.

MAIN OUTCOME MEASURES

Shear wave speed (m/s).

RESULTS

SWS of the latent trigger point (mean=4.09±SD1.4 m/s) did not differ from the adjacent muscle tissue (3.92±1.6 m/s, P>.05), but was elevated compared to corresponding tissue in controls (2.8±0.75 m/s, P=.02). SWS was generally greater in patients' uninvolved tissue (3.83±1.6 m/s) when compared to corresponding tissue in controls (2.62±0.2 m/s, P=.05).

CONCLUSION

Although discrete regions of increased SWS corresponding to the trigger point were not observed in patients, evidence of generally increased muscle stiffness in infraspinatus was exhibited compared to healthy controls. Further study of additional muscles with SWE is warranted.