In vitro culture of muscle cells derived from myofascial trigger points.

OBJECTIVE: To examine for the in vitro existence of contractile nodules on the taut band of muscle fibers where myofascial trigger points (MTrPs) are located (using cell culture). METHODS: Sixteen male Sprague-Dawley rats (7 weeks old) were randomly divided into experimental and control groups. A blunt striking injury and eccentric exercise were applied to the gastrocnemius muscle of rats in the experimental group once a week for 8 weeks to establish an MTrP model. Subsequently, the rats were reared normally and rested for 4 weeks. After modeling, the skeletal muscles at the MTrPs (and non-MTrPs at the same anatomical position) were extracted from the two groups of rats for in vitro cell culture experiments of single muscle fibers. Potential contractile nodules in the MTrP group were exposed to different concentrations of acetylcholinesterase, whereas non-MTrP cells were exposed to acetylcholine. The morphological changes of muscle cells in each group were observed. RESULTS: By culturing MTrP cells in vitro, large contractile nodules remained in single MTrP muscle fibers, whereas some contractile nodules were twisted and deformed. After the addition of different acetylcholinesterase concentrations, no obvious morphological changes were observed in the contractile nodules in the MTrP group. After the non-MTrP cells were exposed to different acetylcholine concentrations, no significant morphological changes were observed in the single muscle fibers. CONCLUSION: MTrP cells can continue to maintain contractile morphology in vitro, but whether the recovery of such contractile nodules is related to acetylcholine remains uncertain.

Clinical observations in treatment of lower extremity varicose veins with trigger points acupuncture.

OBJECTIVES: To observe the effect of the acupuncture of myofascial trigger points (MTrPs) in the treatment of lower extremity varicose veins (LEVVs). METHODS: Overall, 260 patients with LEVVs participated in this study. LEVVs were selected based on diagnostic criteria of Clinical, Etiology, Anatomy, and Pathophysiology levels 2-5 and classified into six types on the basis of their anatomical positions. The MTrPs in the lower extremities were localized in accordance with the classification of LEVVs and treated by MTrPs acupuncture combined with self-massage and self-stretching. The interval between each treatment was 2 weeks to 1 month, depending on needling pain tolerance of each patient. An in-house evaluation was used to estimate the proportion of varicose veins in the lower limbs and their accompanying symptoms. The treatment effect was evaluated before each treatment and at 1-year follow-up. RESULTS: The mean evaluation score of LEVVs before the treatment course was 3.66 ± 1.19. After the course, this reduced to 1.18 ± 0.97, with the following response rates: 85% for excellent and good and 15% for medium. After 1-year follow-up, the mean evaluation score of all patients was 1.11 ± 0.92, with the following response rates: 87% for excellent and good, and 13% for medium. CONCLUSIONS: In some patients, MTrP acupuncture could cure LEVVs and its accompanying symptoms. These LEVVs are probably caused by fascia tension as a pre-pathology induced by the MTrPs.

Dry needling on latent and active myofascial trigger points versus oral diclofenac in patients with knee osteoarthritis: a randomized controlled trial.

BACKGROUND: Latent and active myofascial trigger points (MTrPs) in knee-associated muscles may play a key role in pain management among patients with knee osteoarthritis (KOA). The aim of this study was to investigate the effect of dry needling treatment on pain intensity, disability, and range of motion (ROM) in patients with KOA. METHODS: This randomized, single-blinded, clinical trial was carried out for 6 weeks of treatment and 6-month follow-up. A total of 98 patients met the entry criteria and were randomly assigned to the dry needling latent and active myofascial trigger point (MTrPs) with the stretching group or the oral diclofenacwith the stretching group. Numeric Pain Rating Scale (NPRS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and ROM were statistically analyzed before and after treatment and at the 6-month follow-up. RESULTS: A total of 42 patients in the dry needling group (DNG) and 35 patients in the diclofenac group (DG), respectively, completed the study, and there was no significant difference in the general data between the two groups. After treatments, both the groups showed a good effect in knee pain, function, and ROM, However, the DNG showed a significantly better result than the DG. Especially in the results of the 6-month follow-up, the DNG showed much better results than the DG. CONCLUSIONS: Dry needling on latent and active MTrPs combined with stretching and oral diclofenac combined with stretching can effectively relieve pain, improve function, and restore knee ROM affected by KOA. However, the effects of dry needling and stretching are better and longer lasting than those of oral diclofenac and stretching for at least 6 months. TRIAL REGISTRATION: Registered in the Chinese Clinical Trial Registry ( www.chictr.org.cn ) in 17/11/2017 with the following code: ChiCTR-INR-17013432.

Effects of dry needling intervention on lower limb dysfunction after stroke: study protocol for a randomised controlled trial.

INTRODUCTION: Lower limb dysfunction is among the common sequelae of patients who had a poststroke and often results in the reduction of the quality of life. This study aims to assess the short and interim-term efficacy of dry needling (DN) intervention on lower extremity function, balance and gait in lower limb dysfunction after stroke. METHODS AND ANALYSIS: This protocol entails an assessor and statistician-blinded, single-centre study with a randomised controlled trial. Forty-four patients who had a poststroke will be randomly allocated (1:1) to either the conventional treatment group (n=22) or the DN group (n=22). The conventional treatment group will receive conventional rehabilitation treatment once a day for 40 min each time. The treatment will be performed five times a week for 2 weeks. In the DN group, participants will be treated with DN on the basis of the conventional treatment. The intervention will be performed thrice a week for 2 weeks. The primary outcome that determines the efficacy of lower limb dysfunction will be the change in the Fugl-Meyer Assessment of Lower Extremity scale. The secondary indicators include the range of motion of knee and ankle joints, limits of stability, modified Clinical Test of Sensory Interaction on Balance, Timed Up and Go test, Modified Ashworth Scale and Barthel Index. Results will be evaluated at baseline, at 24 hours after intervention, at 2 weeks after intervention and at 3-month follow-up. Data will be released after the completion of the study. Adverse events will be reported. ETHICS AND DISSEMINATION: The experiment was approved by the Ethical Committee of Shanghai Tong Ren Hospital in October 2021 (approval number: 202105702). The results of this study will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ChiCTR2000040754.

[Essence of acupoints and meridians based on the studies of myofascial trigger points].

Based on the modern anatomy and physiology, the referred pain of myofascial trigger points of each muscle is integrated; compared with the twelve meridians as well as conception vessel and governor vessel, the similarity of their position and running course is observed. With the current research progress of myofascial trigger points and fasciology, based on the running course of referred pain of trigger points, combined with fascia mechanics, nerve and vascular, the location of acupoints and meridians, as well as the relationship between acupoints and meridians, are discussed.

Effects of Trigger Point Dry Needling on Neuromuscular Performance and Pain of Individuals Affected by Patellofemoral Pain: A Randomized Controlled Trial.

PURPOSE: To investigate the effects of trigger point dry needling (TrP-DN) on exercise-induced patellofemoral pain syndrome (PFPS). PATIENTS AND METHODS: In this randomized, single-blind, parallel-group trial, 50 patients with PFPS were randomly allocated to the following two groups: the TrP-DN group (n = 25) and the Sham needling group (n = 25). Patients in both groups were asked to perform a stretching exercise of the quadriceps daily after needling. The needling group received a single session of TrP-DN to trigger points (TrPs) in the vastus medialis oblique (VMO), vastus lateralis (VL), and rectus femoris muscles (once a week for 6 weeks), and the Sham group received placebo needling. Visual analogue scale (VAS) for pain intensity and Kujala questionnaire for the functional status were assessed before treatment, 3 and 6 weeks after treatment, and at the 3-month follow-up. The ratio of the myoelectric amplitude of the vastus medialis oblique and vastus lateralis muscles (VMO/VL) was assessed before treatment and 6 weeks after treatment. RESULTS: There was no significant difference in the general data between the two groups. The VAS scores and Kujala scores in the TrP-DN group were significantly improved and increased at the 3-week treatment visit, 6-week treatment visit, and 3-month follow-up compared to the scores before treatment; and the scores in the Sham group were only significantly improved at the 3-week treatment visit, and 6-week treatment visit. VAS scores in the TrP-DN group were significantly lower and Kujala scores were significantly higher at the 6-week treatment visit and the 3-month follow-up compared to those in the Sham group. The VMO/VL ratio in the TrP-DN group was significantly increased at the 6-week treatment visit compared to that before treatment. CONCLUSION: TrP-DN at the quadriceps combined with stretch can reduce the pain, and improves the clinical symptoms and function, the VMO/VL ratio, and the coordination of VMO and VL in patients with PFPS.

Relationship between muscle spindles and myofascial trigger spots according to Hoffmann reflex pathway and tissue morphology characteristics in a rat model.

OBJECTIVES: To determine how muscle spindles are involved in the pathophysiology of chronic myofascial trigger spots (MTrSs, similar to myofascial trigger points) in a rat injury model according to the characteristics of the Hoffmann reflex (H-reflex) and the anatomical relationship between muscle spindles and MTrSs. METHODS: 16 male Sprague-Dawley rats (7 weeks old) were randomly divided into experimental and control groups. A blunt strike injury and eccentric exercise were applied to the gastrocnemius muscle of rats in the experimental group once a week for 8 weeks as a MTrS modelling intervention. Subsequently, the rats were reared normally and rested for 4 weeks. At the end of the 12th week, the rats were examined for the presence of MTrSs defined by the detection of a palpable taut band exhibiting both a local twitch response and spontaneous electrical activity. After modelling, evocation of the H-reflex and morphological examination of muscle spindles and MTrSs were conducted. RESULTS: The threshold (0.35±0.04 mA) of the H-reflex and latency (1.24±0.18 ms) of the M wave recorded at MTrSs were not significantly different to those at non-MTrSs (P>0.05). Compared with non-MTrSs, a lower Mmax (4.28±1.27 mV), higher Hmax (median (IQR) 0.95 (0.80-1.08) mV) and Hmax/Mmax (median (IQR) 0.21 (0.16-0.40)), and shorter H wave latency (4.60±0.89 ms) were recorded at MTrSs (P<0.05). Morphologically, there was a close anatomical relationship between the MTrS cells and the muscle spindles. DISCUSSION: Compared with normal muscles, the H-reflex myoelectrical activity was enhanced and some muscle spindles might have been influenced by active MTrSs. Thus, muscle spindles may play an important role in the pathological mechanism underlying myofascial trigger points.

Structural and functional abnormalities of motor endplates in rat skeletal model of myofascial trigger spots.

Myofascial trigger points (MTrPs) are defined as hyperirritable spots in a palpable taut band (TB) of skeletal muscle fibers. Knowing the formation and location of MTrPs is a great help to prevent their development and inactivate existing MTrPs. This study aimed to obtain new evidence that myofascial trigger spots (MTrSs), which are similar to human MTrPs, are found in dysfunctional motor endplates by observing the morphological characteristics of muscles and changes in biochemical substances. A total of 32 male Sprague Dawley rats were randomly divided into four groups: two control groups (i.e., C1 and C2) and two model groups (i.e., M1 and M2). C1 and M1 were used for acetylcholine (ACh) content measurement, while C2 and M2 were utilized for acetylcholinesterase (AChE) staining. In the model groups, blunt striking injury was induced and eccentric exercise was applied to the left gastrocnemius for 8 weeks. After 1 month, spontaneous electrical activity(SEA), AChE optical density (OD), muscle fiber diameter, and ACh content were measured. The results showed that extensive abnormal endplate noise (aEPN), including positive neurons, fibrillation potentials, fasciculation potential, and high amplitude (endplate spikes [EPS]), is present at MTrSs in M1. Quantitative electromyography results showed that the amplitudes of aEPN and frequency of EPS in M1 were significantly higher than those of C1. The ACh content of MTrSs in M1 was significantly higher than that in C1. The AChE OD value of M2 was significantly lower than that of C2. In addition, the diameter of the muscle fibers in the AChE-stained area was longer in M2 than in C2. In conclusion, MTrSs formed at the motor endplate with a larger diameter of muscle fibers. Excessive ACh release and decreased AChE activity at MTrSs stimulated muscle action potential and muscle contraction.

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.

MiR-134-5p attenuates neuropathic pain progression through targeting Twist1.

Neuropathic pain is a kind of chronic pain because of dysfunctions of somatosensory nerve system. Recently, many studies have demonstrated that microRNAs (miRs) play crucial roles in neuropathic pain development. This study was designed to investigate the effects of miR-134-5p on the process of neuropathic pain progression in a rat model established by chronic sciatic nerve injury (CCI). First, we observed that miR-134-5p was significantly decreased in CCI rat models. Overexpression of miR-134-5p strongly alleviated neuropathic pain behaviors including mechanical and thermal hyperalgesia. Meanwhile, inflammatory cytokine expression, such as IL-6, IL-1ß and TNF-α in CCI rats were greatly repressed by upregulation of miR-134-5p. Twist1 has been widely regarded as a poor prognosis biomarker in diverse diseases. Here, by using bioinformatic analysis, 3'-untranslated region (UTR) of Twist1 was predicted to be a downstream target of miR-134-5p in our study. Here, we found that overexpression of miR-134-5p was able to suppress Twist1 dramatically. Furthermore, it was exhibited that Twist1 was increased in CCI rats time-dependently and Twist1 was inhibited in vivo. Subsequently, downregulation of Twist1 in CCI rats could depress neuropathic pain progression via inhibiting neuroinflammation. In conclusion, our current study indicated that miR-134-5p may inhibit neuropathic pain development through targeting Twist1. Our findings suggested that miR-134-5p might provide a novel therapeutic target for neuropathic pain.

Overexpression of miR-381 relieves neuropathic pain development via targeting HMGB1 and CXCR4.

MicroRNA are significant regulators of neuropathic pain development. Neuroinflammation contributes a lot to the progression of neuropathic pain. miR-381 is involved in various pathological processes. However, the role of miR-381 in neuropathic pain development remains barely understood. Therefore, in our study, we aimed to investigate the effects of miR-381 on the process of neuropathic pain progression by establishing a rat model using chronic sciatic nerve injury (CCI). Here, we observed that miR-381 was dramatically decreased in CCI rats. Up-regulation of miR-381 strongly reduced neuropathic pain behaviors including mechanical and thermal hyperalgesia. In addition, inflammatory cytokine expression, including IL-6, IL-10 and TNF-α were significantly repressed by overexpression of miR-381. High mobility group box 1 protein (HMGB1) and Chemokine CXC receptor 4 (CXCR4) participate in neuropathic pain development. In our present study, HMGB1 and CXCR4 were predicted as direct targets of miR-381 by employing bioinformatics analysis. Overexpression of miR-381 was able to restrain the expression of HMGB1 and CXCR4 greatly. The direct correlation between HMGB1 and CXCR4 and miR-381 was confirmed in our research. Furthermore, we found that HMGB1 and CXCR4 were increased in CCI rats time-dependently. Moreover, it was demonstrated that silence of HMGB1 and CXCR4 in CCI rats depressed neuropathic pain progression greatly. In conclusion, it was indicated that miR-381could inhibit neuropathic pain development through targeting HMGB1 and CXCR4.

Dry needling at myofascial trigger points mitigates chronic post-stroke shoulder spasticity.

Post-stroke spasticity is associated with restriction in the range of motion of the shoulder. Reducing muscular dystrophy may help relieve muscular dysfunction in patients with post-stroke shoulder spasticity. Dry needle therapy is a method of needling the trigger points using a syringe needle without the use of a drug. Dry needle therapy is commonly used for pain at the shoulder, neck, waist, and back. In this case study, a 62-year-old male patient affected with cerebral hemorrhage of the right frontal lobe had received rehabilitative treatment for 12 years. However, he still experienced shoulder spasticity. The patient received daily dry needling at the trigger points of infraspinatus, teres minor, posterior deltoid, and pectoralis major on 9 days. After the first and ninth treatment, the Modified Ashworth Scale and the passive range of motion of the shoulder was used to assess the effect of the treatment. The spasticity and range of motion of the shoulder showed obvious improvement. These results indicate that dry needling at the myofascial trigger points can effectively treat chronic post-stroke shoulder spasticity.

[Effect of Dry Needling Stimulation of Myofascial Trigger Point on Sample Entropy of Electromyography of Gastrocnemius Injured Site in Rats].

OBJECTIVE: To attempt to establish an objective quantitative indicator to characterize the trigger point activity, so as to evaluate the effect of dry needling on myofascial trigger point activity. METHODS: Twenty-four male Sprague-Dawley rats were randomly divided into blank control group, dry needling (needling) group, stretching exercise (stretching) group and needling plus stretching group (n＝6 per group). The chronic myofascial pain (trigger point) model was established by freedom vertical fall of a wooden striking device onto the mid-point of gastrocnemius belly of the left hind-limb to induce contusion, followed by forcing the rat to make a continuous downgrade running exercise at a speed of 16 m/min for 90 min on the next day which was conducted once a week for 8 weeks. Electromyography (EMG) of the regional myofascial injured point was monitored and recorded using an EMG recorder via electrodes. It was considered success of the model if spontaneous electrical activities appeared in the injured site. After a 4 weeks' recovery, rats of the needling group were treated by filiform needle stimulation (lifting-thrusting-rotating) of the central part of the injured gastrocnemius belly (about 10 mm deep) for 6 min, and those of the stretching group treated by holding the rat's limb to make the hip and knee joints to an angle of about 180°, and the ankle-joint about 90° for 1 min every time, 3 times altogether (with an interval of 1 min between every 2 times). The activity of the trigger point was estimated by the sample entropy of the EMG signal sequence in reference to Richman's and Moorman's methods to estimate the curative effect of both needling and exercise. RESULTS: After the modeling cycle, the mean sample entropies of EMG signals was significantly decreased in the model groups (needling group [0.034±0.010], stretching group [0.045±0.023], needling plus stretching group [0.047±0.034]) relevant to the blank control group (0.985±0.196, P<0.01). After the treatment, the mean sample entropy of EMG signals was evidently increased in both needling (0.819±0.088), stretching (0.532±0.25) and needling plus stretching (0.810±0.117) groups (P<0.01). The mean sample entropy of the needling and needling plus stretching groups were significantly higher than that of the stretching group (P<0.01), without remarkable difference between the two needling groups in the mean sample entropy (P>0.05), suggesting a better efficacy of dry needling in easing trigger point activity. CONCLUSION: Dry needling is able to relieve myofascial trigger point activity in rats, which is better than that of simple passive stretching therapy.

Evidence for Dry Needling in the Management of Myofascial Trigger Points Associated With Low Back Pain: A Systematic Review and Meta-Analysis.

OBJECTIVE: To evaluate the current evidence of the effectiveness of dry needling of myofascial trigger points (MTrPs) associated with low back pain (LBP). DATA SOURCES: PubMed, Ovid, EBSCO, ScienceDirect, Web of Science, Cochrane Library, CINAHL, and China National Knowledge Infrastructure databases were searched until January 2017. STUDY SELECTION: Randomized controlled trials (RCTs) that used dry needling as the main treatment and included participants diagnosed with LBP with the presence of MTrPs were included. DATA EXTRACTION: Two reviewers independently screened articles, scored methodologic quality, and extracted data. The primary outcomes were pain intensity and functional disability at postintervention and follow-up. DATA SYNTHESIS: A total of 11 RCTs involving 802 patients were included in the meta-analysis. Results suggested that compared with other treatments, dry needling of MTrPs was more effective in alleviating the intensity of LBP (standardized mean difference [SMD], -1.06; 95% confidence interval [CI], -1.77 to -0.36; P=.003) and functional disability (SMD, -0.76; 95% CI, -1.46 to -0.06; P=.03); however, the significant effects of dry needling plus other treatments on pain intensity could be superior to dry needling alone for LBP at postintervention (SMD, 0.83; 95% CI, 0.55-1.11; P<.00001). CONCLUSIONS: Moderate evidence showed that dry needling of MTrPs, especially if associated with other therapies, could be recommended to relieve the intensity of LBP at postintervention; however, the clinical superiority of dry needling in improving functional disability and its follow-up effects still remains unclear.

MiR-150 alleviates neuropathic pain via inhibiting toll-like receptor 5.

MicroRNAs (miRNAs) are reported as vital participators in the pathophysiological course of neuropathic pain. However, the underlying mechanisms of the functional roles of miRNAs in neuropathic pain are largely unknown. This study was designed to explore the potential role of miR-150 in regulating the process of neuropathic pain in a rat model established by chronic sciatic nerve injury (CCI). Overexpression of miR-150 greatly alleviated neuropathic pain development and reduced inflammatory cytokine expression, including COX-2, interleukin IL-6, and tumor necrosis factor (TNF)-α in CCI rats. By bioinformatic analysis, 3'-untranslated region (UTR) of Toll-like receptor (TLR5) was predicted to be a target of miR-150. TLR5 commonly serves as an important regulator of inflammation. Overexpression of miR-150 significantly suppressed the expression of TLR5 in vitro and in vivo. Furthermore, upregulation of TLR5 decreased the miR-150 expression and downregulation of TLR5 increased miR-150, respectively. Overexpression of TLR5 significantly reversed the miR-150-induced suppressive effects on neuropathic pain. In conclusion, our current study indicates that miR-150 may inhibit neuropathic pain development of CCI rats through inhibiting TLR5-mediated neuroinflammation. Our findings suggest that miR-150 may provide a novel therapeutic target for neuropathic pain treatment.

Histopathological nature of myofascial trigger points at different stages of recovery from injury in a rat model.

OBJECTIVE: To investigate the histopathological nature of myofascial trigger points (MTrPs) or spots (MTrSs) at different stages of recovery from injury in a rat model. METHODS: Forty Sprague-Dawley rats were randomly divided into two groups: a control group (CG) and experimental group (EG). The CG was further randomly subdivided into CG1 and CG2 subgroups. The CG2 was used for palpating the taut band and CG1 as a blank. EG was subdivided into three groups according to recovery times: 4 weeks (4W), 8 weeks (8W) and 12 weeks (12W); these groups consisted of eight rats each. All CG rats received no intervention, whereas the intervention in EG rats was by a blunt strike to the vastus medialis and eccentric exercise for 8 weeks. The taut bands with spontaneous electrical activity were then detected in the muscle to guide a muscle biopsy. The histopathological findings were investigated under optical and electron microscopes in all groups. RESULTS: Under optical microscopy, the differently augmented sizes of round fibres (contracture knots) with deep staining in the transverse section and fusiform shapes in a longitudinal view were clearly seen in CG2 and EGs with a large diameter; the number of contracture knots was significantly more in EGs than in CGs. Under an electron microscope, the mitochondria in EGs significantly decreased with abnormal structures. The sarcomeres were significantly shortened in the 8W and 12W EGs. CONCLUSION: An injury can cause activation of MTrSs in a muscle and an activated level of MTrPs depending on the number of contracture knots in muscle with impaired energy production.