Sustained nociceptive mechanical stimulation of latent myofascial trigger point induces central sensitization in healthy subjects

Effects of monopolar pulsed-capacitive dielectric radiofrequency diathermy in patients with chronic low back pain: a randomised clinical trial

Monopolar capacitive diathermy is a physiotherapy technique that uses high-frequency currents to generate heat in deep tissues. This heat can have several therapeutic effects, especially in the treatment of chronic low back pain (CLBP), however, until now there is little evidence of this type of diathermy. The purpose was to evaluate the efficacy of a pulsed monopolar dielectric radiofrequency diathermy (PRF)-capacitive type versus simulated treatment on symptomatology of patients with CLBP. A single-blind randomised controlled trial was conducted. Sixty patients with CLBP were randomly assigned to a PRF-capacitive or a simulated treatment group. All participants received 3 sessions per week for 3 weeks. Disability, pain intensity, movement phobia, lumbar anteflexion, quality of life, and sleep quality were assessed at baseline, after treatment, and at two months. The application of 9 sessions of PRF-capacitive showed significant improvements compared to simulated therapy during the entire follow-up for disability (F = 26.99, p < 0.001), pain intensity (F = 0.550, p < 0.001), the quality of life components of physical function (F = 0.780, p < 0.001), social function (F = 0.780, p < 0.001) and mental health (F = 0.858, p = 0.003) and for sleep duration (F = 0.863, p = 0.004).

The efficacy of taping on elbow proprioception in healthy individuals: A single-blinded randomized placebo-controlled study

BACKGROUND

Taping stimulates the mechanoreceptors, increases sensory information to the central nervous system, and improves sensorimotor synchronization, resulting in improved motor control. However, the efficacy of taping on elbow proprioception is not clear.

PURPOSE

This study aimed to evaluate the immediate effects of taping on elbow proprioception in healthy individuals.

STUDY DESIGN

This study was a two-arm, parallel-group, randomized, controlled, single-blinded study with a sham application.

METHODS

Fifty six healthy adults were randomized 1:1 to kinesio taping (n = 27) or sham taping (n = 29). Active joint position sense error (JPSE) was used to quantify proprioception using a universal goniometer at three-time points: baseline (BS), immediately after taping (IA), and 30 minutes after taping (30MA), with the tape still in place at 70° and 110° of elbow flexion. Participants were blinded to group assignments. The Friedman analysis assessed differences between evaluations within groups, and the Mann-Whitney U test determined differences between groups.

RESULTS

The study was completed with 56 participants and there were no dropouts. No skin reaction or adverse effect was observed in the participants and no test trial was excluded. The baseline scores of the groups were similar (p > 0.05). A significant difference was detected in the study group after kinesio taping at 70° (MD = -1.22; CI = (-2.33: -0.10; p < 0.005; d = 0.653) and 110° of elbow flexion (MD = -1.34; CI = 2,47: -0,21; p < 0.005; d = 0.73). This statistically significant difference was observed even at the 30MA evaluations at 70° (p < 0.05). Also, there was a statistically insignificant tendency to decrease in JPSE of both groups at both degrees following taping.

CONCLUSIONS

Elbow proprioception may be enhanced by kinesio taping, and this effect could last up to 30 minutes at 70° of elbow flexion. In contrast, sham taping did not produce such an improvement. Based on the differences in JPSE, kinesio taping proved more effective and had a longer-lasting impact than the sham application. The statistically insignificant tendency to decrease in JPSE may indicate that the 30-minute application period is inadequate to create a statistically significant effect on elbow proprioception. Longer usage periods can better reveal the effects of orthoses on proprioception.

Immediate effects of elbow orthoses on elbow proprioception in asymptomatic individuals: A randomized sham-controlled single-blinded study

BACKGROUND

Improving proprioception can reduce the risk of injuries, while its disruption may lead to injuries and recurrent or persistent symptoms.

PURPOSE

This study aimed to evaluate the immediate effects of elbow orthoses on elbow proprioception in asymptomatic individuals.

STUDY DESIGN

This was a randomized, controlled, single-blinded study with a sham application.

METHODS

Sixty participants were equally distributed into three orthosis groups (counterforce, sleeve, and sham). Proprioception was assessed using active joint position sense error (JPSE) at 70° and 110° of elbow flexion at three time points: baseline (BS), immediately after (IA) wearing the orthosis, and 30 minutes after (30MA) wearing the orthosis.

RESULTS

Between groups: No significant difference in JPSE was observed at 70° (p = 0.095); however, there was a significant difference at 110° (p = 0.005). Between time points: At 70°, JPSE did not exhibit a significant difference (p = 0.055), whereas a significant difference was observed at 110° (p = 0.020). Interaction of time points×groups: No significant interaction was observed either at 70° (p = 0.476) or at 110° (p = 0.346). At 70°, within the sleeve group, significant differences were identified between BS-30MA (p = 0.001) and IA-30MA (p = 0.009). At 110°, in the sleeve group, significant differences were observed between BS-30MA (p = 0.007) and IA-30MA (p = 0.007). In the counterforce group, significant differences were identified between BS-30MA time points (p = 0.001). At 70°, no difference was observed within the overall evaluation in the counterforce group (p > 0.05), whereas at 110°, a significant difference was noted (p = 0.026). At both 70° and 110°, no differences were identified within the overall evaluation in the sleeve and sham groups (p > 0.05).

CONCLUSIONS

In asymptomatic individuals, sleeve orthosis improved elbow proprioception at 70°, whereas both counterforce and sleeve orthoses were effective at 110°.

Do myofascial trigger points in masseter muscles affect the symptoms of disc displacement with reduction? A cross-sectional study

OBJECTIVE

The aim of this study was to demonstrate the effect of myofascial pain with referral from the trigger points in the masseter muscles on the clinical symptoms and functional limitations of the temporomandibular joint in participants with disc displacement with reduction.

METHODS

This prospective, cross-sectional study recruited participants aged 18-45 years with disc displacement with reduction with/without myofascial pain with referral in the masseter muscles based on the inclusion criteria. Maximum mouth opening and the presence of probable awake bruxism were assessed. The "Graded Chronic Pain Scale version 2.0" and "Jaw Function Limitation Scale-8" were used to evaluate Diagnostic Criteria for Temporomandibular Disorders Axis II. Pain levels were measured using the Visual Analog Scale.

RESULTS

A comparison between the disc displacement with reduction and disc displacement with reduction+myofascial pain with referral groups revealed statistically significant differences in Visual Analog Scale (p<0.001), the presence of awake bruxism (p=0.038), and Graded Chronic Pain Scale version 2.0 (p=0.010). However, no statistically significant difference was observed between the two groups concerning maximum mouth opening and Jaw Function Limitation Scale-8.

CONCLUSION

Participants with both disc displacement with reduction and myofascial pain with referral in the masseter muscle exhibited higher pain intensity, a higher prevalence of awake bruxism, and increased pain-related disability compared to those with disc displacement with reduction alone.

Is Dry Needling Treatment an Extra Contribution to Conventional Treatment for Hemiplegic Shoulder Pain? A Prospective, Randomized Controlled Study

Objective

This research was conducted to evaluate the effect of adding dry needling (DN) treatment to conventional rehabilitation for pain, range of motion (ROM), and functionality in patients with hemiplegic shoulder pain (HSP).

Materials and Methods

Patients with HSP (n = 38) were divided into 2 groups. A multimodal rehabilitation protocol, including physical therapy and exercise treatments, was given to both groups (5 sessions per week for 15 sessions). In addition to this rehabilitation, 3 sessions of DN therapy were given to one of the 2 groups. Measurements were a visual analogue scale; ROM; and 2 other scales (Quick Disability of the Arm, Shoulder, Hand; and the Fugl-Meyer Assessment Upper Extremity). Evaluations were made before, after, and at the third month after treatment.

Results

While a statistically significant improvement was seen in both groups in all parameters after their treatments, a statistical superiority was found in the conventional treatment+DN group (P < 0.05). However, the differences were not greater than the minimal clinically important difference values (MCID). At the 3rd month follow-up, there was no difference in pain and functionality parameters between the groups, while flexion and abduction measurements were higher in the conventional treatment+DN group (P < 0.05).

Conclusions

Adding DN treatment to conventional rehabilitation did not show any difference except in some joint ROM measurements in the subacute time. Although the changes found were statistically significant, they were not clinically significant as they did not reach MCID values.This study was registered prospectively at ClinicalTrials.gov (ref. no: NCT04790071).

Effects of Myofascial Induction Therapy on Ankle Range of Motion and Pressure Pain Threshold in Trigger Points of the Gastrocnemius-A Clinical Trial

BACKGROUND

The myofascial induction technique (MIT) has been shown to increase shoulder range of motion (ROM) in breast cancer survivors and decrease pain pressure threshold over the radial nerve in patients with epicondylalgia. To the authors' best knowledge, no study on trigger points and MIT has been published to date. The effect on ROM of latent trigger points is also unknown.

METHODS

A total of 20 twins with one latent trigger point of the gastrocnemius muscle were evaluated pre- and post-MIT in the calf. We measured static footprint variables in a pre-post study.

RESULTS

We found differences in PPT (p = 0.001) and no differences in ROM with knee flexed (p = 0.420) or stretched (p = 0.069).

CONCLUSIONS

After Calf MIT, latent myofascial trigger points improve PPT but no change in ankle dorsiflexion with knee bent or knee flexed were found in non-restriction healthy subjects.

Sensory and emotional responses to deep pressure stimulation at myofascial trigger points: a pilot study

Objective

Although manual pressure, such as that used during a massage, is often associated with pain, it can simultaneously be perceived as pleasant when applied to certain body areas. We hypothesized that stimulation of myofascial trigger points (TPs) leads to simultaneous pain and pleasure. TPs are hyperirritable points located in the taut band of the skeletal muscle.

Method

In this study, we measured the muscle tone, muscle stiffness, and pressure pain threshold of TPs and control points in the left brachioradialis muscle of 48 healthy participants. We also applied deep compression to the two points and collected subjective data on pain, pleasantness, unpleasantness, and relief.

Result

Greater muscle stiffness was observed in the TPs versus control points (t = 6.55, p < 0.001), and the pain threshold was significantly lower in the TPs (t = -6.21, p < 0.001). Unpleasantness ratings after deep compression were significantly lower in the TPs compared with control points (t = -2.68, p < 0.05). Participants experienced greater relief at the TPs compared with control points (t = 2.01, p < 0.05), although the perceived pain did not differ between the two types of points.

Conclusion

We compared the properties of TPs and control points, and found that deep compression at TPs was associated with higher muscle tone and stiffness, lower unpleasantness ratings, and higher relief ratings compared with the control points. These findings suggest that, at least for some TPs, pain and pleasantness are simultaneously elicited by deep pressure stimulation.

Immediate Effects of Mulligan Mobilization on Elbow Proprioception in Healthy Individuals: A Randomized Placebo-Controlled Single-Blind Study

OBJECTIVE

The aim of this study was to investigate the immediate effects of Mulligan's mobilization with movement (MWM) on elbow proprioception.

METHODS

The study included 26 participants in the intervention group and 30 participants in the control group. The intervention group received MWM, while the control group received a sham application. Proprioception was assessed with joint position sense error at baseline, immediately after mobilization, and 30 minutes after mobilization with 70° and 110° of elbow flexion. The hypothesis of interest was the group × time interaction.

RESULTS

At 110° of elbow flexion, group × time interaction was significant (F[2, 108] = 11.48, P = .001). In the paired comparisons, there was a statistically significant difference in favor of the control group in the first measurement (P = .003). No difference was detected in other time points (P = 1.00). At 70° of elbow flexion, there was no significant difference between the time point × group interaction (F[2, 108] = 1.37, P = .10). Therefore, no pairwise comparison was made.

CONCLUSION

In this study of healthy participants, no immediate difference was found between MWM and sham application on elbow proprioception.

Myofascial Pain Syndrome: A Nociceptive Condition Comorbid with Neuropathic or Nociplastic Pain

Myofascial pain syndrome is featured by the presence of myofascial trigger points (TrPs). Whether TrPs are primary or secondary phenomena or if they relate to central or peripheral nervous system disorders is controversial. Referred pain, a cardinal sign of TrPs, is a central phenomenon driven by peripheral input. In 2021, the International Association for the Study of Pain (IASP) proposed a clinical criteria and grading system for classifying patients with pain on nociceptive, neuropathic, or nociplastic phenotypes. Myofascial TrP pain has been traditionally categorized as a nociceptive phenotype; however, increasing evidence supports that this condition could be present in patients with predominantly nociplastic pain, particularly when it is associated with an underlying medical condition. The clinical response of some therapeutic approaches for managing TrPs remains unclear. Accordingly, the ability to classify myofascial TrP pain into one of these phenotypes would likely be critical for producing more successful clinical treatment outcomes by a precision medicine approach. This consensus paper presents evidence supporting the possibility of subgrouping individuals with myofascial TrP pain into nociceptive, nociplastic, or mixed-type phenotype. It is concluded that myofascial pain caused by TrPs is primarily a nociceptive pain condition, is unlikely to be classified as neuropathic or nociplastic, but can be present in patients with predominantly neuropathic or nociplastic pain. In the latter cases, management of the predominant central pain problem should be a major treatment goal, but the peripheral drive from TrPs should not be ignored, since TrP treatment has been shown to reduce sensitization-associated symptomatology in nociplastic pain conditions, e.g., fibromyalgia.

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.

Time course and localization of nerve growth factor expression and sensory nerve growth during progression of knee osteoarthritis in rats

OBJECTIVES

Nerve growth factor (NGF) and sensory nerves are key factors in established osteoarthritis (OA) knee pain. We investigated the time course of NGF expression and sensory nerve growth across early and late stages of OA progression in rat knees.

DESIGN

Knee OA was induced by medial meniscectomy in rats. OA histopathology, NGF expression, and calcitonin gene-related peptide immunoreactive (CGRP-IR) nerves were quantified pre-surgery and post-surgery at weeks 1, 2, 4 and 6. Pain-related behavior was evaluated using dynamic weight distribution and mechanical sensitivity of the hind paw.

RESULTS

NGF expression in chondrocytes increased from week 1 and remained elevated until the advanced stage. In synovium, NGF expression increased only in early stages, whereas in osteochondral channels and bone marrow, NGF expression increased in the later stages of OA progression. CGRP-IR nerve density in suprapatellar pouch peaked at week 4 and decreased at week 6, whereas in osteochondral channels and bone marrow, CGRP-IR innervation increased through week 6. Percent ipsilateral weight-bearing decreased throughout the OA time course, whereas reduced paw withdrawal thresholds were observed only in later stages.

CONCLUSION

During progression of knee OA, time-dependent alterations of NGF expression and CGRP-IR sensory innervation are knee tissue specific. NGF expression increased in early stages and decreased in advanced stage in the synovium but continued to increase in osteochondral channels and bone marrow. Increases in CGRP- IR sensory innervation followed increases in NGF expression, implicating that NGF is a key driver of articular nerve growth associated with OA pain.

Analysis of Muscular Electrical Activity and Blood Perfusion of Upper Extremity in Patients with Hemiplegic Shoulder Pain: A Pilot Study

Background

Hemiplegic shoulder pain (HSP) is a common symptom for post-stroke patients, which has a severely adverse impact on their rehabilitation outcomes. However, the cause of HSP has not been clearly identified due to its complicated multifactorial etiologies. As possible causes of HSP, the abnormality of both muscular electrical activity and blood perfusion remains lack of investigations.

Objective

This study aimed to analyze the alteration of muscular electrical activity and blood perfusion of upper extremity in patients with HSP by using surface electromyography (sEMG) and laser speckle contrast imaging (LSCI) measurement techniques, which may provide some insight into the etiology of HSP.

Methods

In this observational and cross-sectional study, three groups of participants were recruited. They were hemiplegic patients with shoulder pain (HSP group), hemiplegic patients without shoulder pain (HNSP group), and healthy participants (Healthy group). The sEMG data and blood perfusion data were collected from all the subjects and used to compute three different physiological measures, the root-mean-square (RMS) and median-frequency (MDF) parameters of sEMG recordings, and the perfusion unit (PU) parameter of blood perfusion imaging.

Results

The RMS parameter of sEMG showed significant difference (p < 0.05) in the affected side between HSP, HNSP, and Healthy groups. The MDF parameter of sEMG and PU parameter of blood perfusion showed no significant difference in both sides among the three groups (p > 0.05). The RMS parameter of sEMG showed a statistically significant correlation with the pain intensity (r = -0.691, p =0.012).

Conclusion

This study indicated that the muscular electrical activity of upper extremity had a correlation with the presence of HSP, and the blood perfusion seemed to be no such correlation. The findings of the study suggested an alternative way to explore the mechanism and treatment of HSP.

Local myalgia compared to myofascial pain with referral according to the DC/TMD: Axis I and II results

BACKGROUND

The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) categorized TMD muscle disorders into 3 subgroups: local myalgia, myofascial pain with spreading and myofascial pain with referral. However, the rationale for such division into subgroups and the pathogenesis and prognosis of muscle-related TMD are still poorly understood. The aim of this study was to explore the differences between local myalgia and myofascial pain with referral by means of a biopsychosocial model based on the DC/TMD.

METHODS

This retrospective study included all consecutive TMD patients who were diagnosed according to the DC/TMD in our institution between 2015 and 2018. The Axis I and II findings of patients diagnosed with local myalgia were compared to those of patients with myofascial pain with referral. A p value < 0.05 was considered statistically significant.

RESULTS

A total of 255 patients (61 men and 194 women, mean age 37.8 ± 15.34 years) were enrolled into the study, 114 in the local myalgia group and 83 in the myofascial pain with referral group. The levels of depression and nonspecific physical symptoms, headache attributed to TMD (HAattrTMD), and characteristic pain intensity (CPI) were significantly higher in the latter group. The significant differences for depression and nonspecific physical symptoms persisted after excluding patients diagnosed with HAattrTMD, however, the levels of significance were lower (p = 0.006 compared to p = 0.033 for depression total score, and p = 0.001 compared to p = 0.046 for nonspecific physical symptoms total score). CPI levels, extent of disability, and pain duration were similar for both groups when excluding for HAattrTMD.

CONCLUSION

The current study findings highlight the importance of differentiating between subgroups of myalgia according to the DC/TMD. The diagnosis of myofascial pain with referral may point to a significant Axis II component.

Cervical Myofascial Pain Is Associated with an Imbalance of Masticatory Muscle Activity

This study aimed to assess the relationship between the occurrence of cervical myofascial pain with active myofascial trigger points (MTrPs) within the upper trapezius muscle and the electromyographic asymmetry index (AsI) of masticatory muscles: temporalis anterior (TA), superficial part of the masseter muscle (MM), and anterior belly of the digastric muscle (DA). The study group comprised 100 subjects (80 women and 20 men) aged 18 to 30 years (mean 23 ± 2.6 years) reporting pain in the neck muscles, diagnosed with myofascial pain with active MTrPs only within the upper trapezius muscle. The control group comprised 60 healthy, pain-free subjects (42 women and 18 men) aged 20 to 30 years (mean 22.8 ± 2.6 years) without MTrPs in the upper trapezius muscle. The palpation measurement, based on the diagnostic criteria of Travell and Simons, was used to diagnose active MTrPs. The masticatory muscle activity was recorded using an 8-channel device for surface electromyography—BioEMG III^TM. Significant differences in electromyographic patterns between the group with MTrPs in the right side of upper trapezius muscle and the control group were observed within resting activity for the AsI TA (MTrPs: 8.64 vs. controls: −3.22; p = 0.001) and AsI MM (MTrPs: 7.05 vs. controls: −2.09; p = 0.018). Controls presented different electromyographic patterns during maximum voluntary clenching with cotton rolls between teeth within masseter muscle compared to the MTrPs group (MTrPs: 9.27 vs. controls: −0.43 vs. p = 0.041). Participants with MTrPs in the left side of upper trapezius muscle presented predomination of left-sided electromyographic patterns at rest within temporalis anterior in comparison to controls (MTrPs: −19.22 vs. controls: −3.22; p = 0.001). MTrPs within the trapezius muscle may be related to asymmetry within the masticatory muscle activity, suggesting that the presence of myofascial pain within the cervical muscles plays a role in the imbalance of the stomatognathic system. A unilateral active MTrPs within the trapezius muscle may increase the sEMG activity on the same side of the temporalis anterior and masseter muscles.

Hypoalgesic and Motor Effects of Neural Mobilisation versus Soft-Tissue Interventions in Experimental Craniofacial Hyperalgesia: A Single-Blinded Randomised Controlled Trial

Objective: The present trial aimed to compare the effects of the mobilisation of the nervous system (NS) to those of a soft-tissue intervention in subjects exposed to an experimentally induced hyperalgesia of the masticatory muscles. Methods: The study was a single-blinded randomised controlled trial. A total of 49 participants (mean ± SD age: 41 ± 11 years; 61% female) with latent myofascial trigger points (LMTrPs) in the craniofacial region were randomly assigned to one of three groups: neural mobilisation (NM), soft-tissues techniques and stretching (STT-S), and control group (CG). An initial assessment (baseline) was performed before the provocation chewing masticatory test. The pre-treatment measurements were registered 24 h later. Next, the randomised intervention was applied, and afterwards, post-treatment data were obtained. Outcome measures included pain-free maximum mouth opening (MMO), pressure pain thresholds (PPTs) in the trigeminal and cervical region, and trigeminal and cervical two-point discrimination (TPD). Results: ANOVA revealed significant differences for the time × group interaction for pain-free MMO and PPTs. The results showed an improvement in the MMO and the PPTs for NM and STT-S groups but not for the CG. There were no differences between the NM and STT-S groups. However, the effect sizes were large for the NM and medium for the STT-S. No differences were found for TDP between groups nor over time. Conclusions: The results show that with NM and STT-S techniques, we could influence motor and sensory variables in asymptomatic subjects with LMTrPs after a masticatory provocation test. Both techniques increased MMO and PPTs in the short term. These beneficial effects lead us to consider the importance of including these methods in clinical practice.

Sympathetic hyperinnervation in myofascial trigger points

OBJECTIVE

To evaluate the local distribution and activity of sympathetic nerves in myofascial trigger points (MTrPs) and explore the pathological mechanism of myofascial pain syndrome (MPS) using a rat model of disease.

METHODS

MPS was modeled in the model group (MG) by a combination of blunt trauma and eccentric exercise in Sprague-Dawley rats (n = 8). Eight rats were randomly assigned to the control group (CG). Histopathology was applied to detect the local conditions of the MTrPs. Tyrosine hydroxylase (TH), nerve growth factor (NGF), and norepinephrine (NE) were detected in the MTrPs to evaluate sympathetic remodeling.

RESULTS

Muscle fiber rupture, atrophy and shape irregularity were universally observed in the MTrPs. TH expression was significantly increased in the MG, as detected by immunofluorescence, and NGF and TH expression was also higher in MTrPs in the MG than in MTrPs in the CG, as determined by immunohistochemistry. Furthermore, the expression of NE was significantly increased in MTrPs, as determined by ELISA.

CONCLUSION

There was sympathetic hyperinnervation in MTrPs, which could partially explain the symptoms of MTrPs and is an interesting and useful new perspective regarding the diagnosis and treatment of MPS.

PERSPECTIVE

The sympathetic nerves in MTrPs are remodeled, leading to sympathetic hyperinnervation. Sympathetic hyperinnervation can partially explain the symptoms of MPS. The pathological mechanism of sympathetic hyperinnervation may be a new perspective for the diagnosis and treatment of MPS.

Short-Term Effects of Kinesio Taping in the Treatment of Latent and Active Upper Trapezius Trigger Points: two Prospective, Randomized, Sham-Controlled Trials

The presence of myofascial trigger points (MTrPs) is one of the most common causes of musculoskeletal problems and may lead to limited professional activity. Among the various treatment methods proposed for MTrPs, Kinesio Taping (KT) is a non-invasive, painless, and less time-consuming method with fewer side effects that has become widely used as a therapeutic tool in a variety of prevention and rehabilitation protocols. The aim of the study was to evaluate the immediate and short-term efficacy of the space correction KT technique in patients with latent or active MTrPs in the upper trapezius muscle. Two parallel randomized sham-controlled trials were simultaneously executed: in trial A, ninety-seven participants with latent MTrPs were randomly assigned to either the KT (n = 51) or sham (n = 46) group; in trial B, thirty-seven participants with active MTrPs were assigned to the KT (n = 20) or sham (n = 17) group. The primary outcome was pressure pain threshold (PPT) in the upper trapezius muscle, measured with algometry. Secondary outcomes included the active range of motion (ROM) of the cervical spine (lateral flexion and rotation), measured with a cervical ROM goniometer. In each trial, two-way ANOVA tests were used to compare the study effects on the outcome measures between the groups, with time serving as the intra-group factor (baseline, immediately, and 72 h after the application) and the intervention type (KT and sham) as the between-group factor. At 72 h, participants receiving KT did not show significant differences in PPT (trial A: mean difference −1.8 N; 95% CI: [−8.1, 4.4], trial B: mean difference −1.2 N; 95% CI: [−7.4, 5.1]), cervical lateral flexion (trial A: mean difference 0.2 degrees; 95% CI: [−2.7, 3.1], trial B: mean difference −2.4 degrees; 95% CI: [−8.4, 3.6]), and cervical rotation (trial A: mean difference 3.7 degrees; 95% CI: [−0.1, 7.5], trial B: mean difference 1.4 degrees; 95% CI: [−5.7, 8.4]), compared to the sham groups. Thus, the results of this study do not support the use of the space correction KT technique to treat patients with latent or active myofascial trigger points in the upper trapezius muscle.

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.

Immediate effects of self-myofascial release on latent trigger point sensitivity: a randomized, placebo-controlled trial

Latent myofascial trigger points (MTrP) have been linked to several impairments of muscle function. The present study was conducted in order to examine whether a single bout of self-myofascial release using a foam roller is effective in reducing MTrP sensitivity. Fifty healthy, pain-free subjects (26.8±6 years, 21 men) with latent MTrP in the lateral gastrocnemius muscle were included in the randomized, controlled trial. One week after a familiarization session, they were randomly allocated to three groups: (1) static compression of the most sensitive MTrP using a foam roll, (2) slow dynamic foam rolling of the lateral calf and (3) placebo laser acupuncture of the most sensitive MTrP. Treatment duration in each group was 90 seconds. The pressure pain threshold (PPT) of the most sensitive MTrP was assessed using a handheld algometer prior to and after the intervention. A repeated measures analysis of variance (3x2) did not reveal significant between-group interactions (p>.05) but showed a significant time effect (F=7.715, p<.05). While placebo and dynamic self-myofascial release did not change MTrP sensitivity (p>.05), static compression of MTrP increased the PPT (2.6±0.8 to 3.0±1.1, d=.35; p<.05). Static self_myofascial release using a foam roller might represent an alternative to reduce pressure pain of latent MTrP. Additional research should aim to extend these findings to patients and athletes with myofascial pain syndromes.

Involvement of neutrophils and interleukin-18 in nociception in a mouse model of muscle pain

Muscle pain is a common condition that relates to various pathologies. Muscle overuse induces muscle pain, and neutrophils are key players in pain production. Neutrophils also play a central role in chronic pain by secreting interleukin (IL)-18. The aim of this study was to investigate the involvement of neutrophils and IL-18 in a mouse model of muscle pain. The right hind leg muscles of BALB/c mice were stimulated electrically to induce excessive muscle contraction. The left hind leg muscles were not stimulated. The pressure pain threshold, number of neutrophils, and IL-18 levels were investigated. Furthermore, the effects of the IL-18-binding protein and Brilliant Blue G on pain were investigated. In stimulated muscles, pressure pain thresholds decreased, and neutrophil and IL-18 levels increased compared with that in non-stimulated muscles. The administration of IL-18-binding protein and Brilliant Blue G attenuated hyperalgesia caused by excessive muscle contraction. These results suggest that increased IL-18 secretion from larger numbers of neutrophils elicits mechanical hyperalgesia.

Friction massage versus kinesiotaping for short-term management of latent trigger points in the upper trapezius: a randomized controlled trial

Background

Latent trigger points in the upper trapezius muscle may disrupt muscle movement patterns and cause problems such as cramping and decreased muscle strength. Because latent trigger points may spontaneously become active trigger points, they should be addressed and treated to prevent further problems. In this study we compared the short-term effect of kinesiotaping versus friction massage on latent trigger points in the upper trapezius muscle.

Methods

Fifty-eight male students enrolled with a stratified sampling method participated in this single-blind randomized clinical trial (Registration ID: IRCT2016080126674N3) in 2016. Pressure pain threshold was recorded with a pressure algometer and grip strength was recorded with a Collin dynamometer. The participants were randomly assigned to two different treatment groups: kinesiotape or friction massage. Friction massage was performed daily for 3 sessions and kinesiotape was used for 72 h. One hour after the last session of friction massage or removal of the kinesiotape, pressure pain threshold and grip strength were evaluated again.

Results

Pressure pain threshold decreased significantly after both friction massage (2.66 ± 0.89 to 2.25 ± 0.76; P = 0.02) and kinesiotaping (2.00 ± 0.74 to 1.71 ± 0.65; P = 0.01). Grip strength increased significantly after friction massage (40.78 ± 9.55 to 42.17 ± 10.68; P = 0.03); however there was no significant change in the kinesiotape group (39.72 ± 6.42 to 40.65 ± 7.3; P = 0.197). There were no significant differences in pressure pain threshold (2.10 ± 0.11 & 1.87 ± 0.11; P = 0.66) or grip strength (42.17 ± 10.68 & 40.65 ± 7.3; P = 0.53) between the two study groups.

Conclusions

Friction massage and kinesiotaping had identical short-term effects on latent trigger points in the upper trapezius. Three sessions of either of these two interventions did not improve latent trigger points.

Trial registration

Registration ID in IRCT: IRCT2016080126674N3.

[Migraine prophylaxis with trigger point therapy and lymphatic drainage : A pilot study]

Migraine is a complex, multifactorial, neurovascular disorder of the brain. Patients frequently have pericranial trigger points, but trigger point (TP) therapy for migraine has not yet been adequately studied. In contrast, lymphatic drainage (LD) has been studied in patients with migraine. The multifactorial origin of migraine suggests using a combination of approaches such as TP therapy and lymphatic drainage. The present study evaluated the effectiveness of TP therapy alone and in combination with LD in preventing migraine during treatment period and over an 8‑week period after completion of treatment. A wait list control group served as a control group. Patients completed a headache calendar. The results of this pilot study suggest a beneficial effect for TP alone and TP combined with LD for migraine prophylaxis for 8 weeks after completion of treatment.

Predictors of upper trapezius pain with myofascial trigger points in food service workers: The STROBE study

Shoulder pain occurs commonly in food service workers (FSWs) who repetitively perform motions of the upper limbs. Myofascial trigger points (MTrPs) on the upper trapezius (UT) are among the most common musculoskeletal shoulder pain syndromes. This study determined the psychological, posture, mobility, and strength factors associated with pain severity in FSWs with UT pain due to MTrPs.In this cross-sectional study, we measured 17 variables in 163 FSWs with UT pain due to MTrPs: a visual analog scale (VAS) pain score, age, sex, Borg rating of perceived exertion (BRPE) scale, beck depression inventory, forward head posture angle, rounded shoulder angle (RSA), shoulder slope angle, scapular downward rotation ratio, cervical lateral-bending side difference angle, cervical rotation side difference angle, glenohumeral internal rotation angle, shoulder horizontal adduction angle, serratus anterior (SA) strength, lower trapezius (LT) strength, bicep strength, and glenohumeral external rotator strength, in 163 FSWs with UT pain due to MTrPs.The model for factors influencing UT pain with MTrPs included SA strength, age, BRPE, LT strength, and RSA as predictor variables that accounted for 68.7% of the variance in VAS (P < .001) in multiple regression models with a stepwise selection procedure. The following were independent variables influencing the VAS in the order of standardized coefficients: SA strength (β = -0.380), age (β = 0.287), BRPE (β = 0.239), LT strength (β = -0.195), and RSA (β = 0.125).SA strength, age, BRPE, LT strength, and RSA variables should be considered when evaluating and intervening in UT pain with MTrPs in FSWs.

Microstructural Abnormalities Were Found in Brain Gray Matter from Patients with Chronic Myofascial Pain

Myofascial pain, presented as myofascial trigger points (MTrPs)-related pain, is a common, chronic disease involving skeletal muscle, but its underlying mechanisms have been poorly understood. Previous studies have revealed that chronic pain can induce microstructural abnormalities in the cerebral gray matter. However, it remains unclear whether the brain gray matters of patients with chronic MTrPs-related pain undergo alteration. In this study, we employed the Diffusion Kurtosis Imaging (DKI) technique, which is particularly sensitive to brain microstructural perturbation, to monitor the MTrPs-related microstructural alterations in brain gray matter of patients with chronic pain. Our results revealed that, in comparison with the healthy controls, patients with chronic myofascial pain exhibited microstructural abnormalities in the cerebral gray matter and these lesions were mainly distributed in the limbic system and the brain areas involved in the pain matrix. In addition, we showed that microstructural abnormalities in the right anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) had a significant negative correlation with the course of disease and pain intensity. The results of this study demonstrated for the first time that there are microstructural abnormalities in the brain gray matter of patients with MTrPs-related chronic pain. Our findings may provide new insights into the future development of appropriate therapeutic strategies to this disease.

Presence of Latent Myofascial Trigger Points and Determination of Pressure Pain Thresholds of the Shoulder Girdle in Healthy Children and Young Adults: A Cross-sectional Study

OBJECTIVE

The primary objective of this study was to compare the number of myofascial trigger points (MTPs) and the pressure pain thresholds (PPTs) in the shoulder girdle, on the dominant and nondominant sides, between healthy children and adults. The secondary aim was to assess the correlations between the number of MTPs and the PPTs in these populations.

METHODS

A cross-sectional study was performed. Thirty-five children (aged 9.1 ± 1.7 years) and 35 adults (aged 23.4 ± 3.4 years) with no history of shoulder or cervical pathology were included. All participants were examined for MTPs in the shoulder muscles and assessed for PPTs in the neck, shoulder, and tibialis anterior. Parametric and nonparametric tests, effect sizes, and odds ratios were used to determine the differences between groups and sides. Spearman's σ test was used to assess correlations between latent MTPs (LTPs) and PPTs in each group.

RESULTS

Children had fewer LTPs than adults did (P = .03). The upper trapezius was the muscle with the largest number of LTPs, affecting 13 adults on the dominant side. Children had lower PPTs compared with adults (P < .05). Correlations between the number of LTPs (on both sides and in total) and PPTs were observed only in adults.

CONCLUSIONS

Healthy children have fewer LTPs and lower PPTs in the shoulder girdle than healthy adults. A relationship was observed between sensitivity to pressure and the presence of LTPs in adults, in whom lower PPT was associated with more LTPs. This relationship was not detected in children.

Trigger points are associated with widespread pressure pain sensitivity in people with tension-type headache

Objective

To investigate the association between trigger points (TrPs) and widespread pressure pain sensitivity in people with tension-type headache (TTH) and to determine if this association is different between frequent episodic (FETTH) or chronic (CTTH) headache.

Design

A cross-sectional study.

Methods

One hundred and fifty-seven individuals (29% male) with TTH participated. Clinical features of headache, i.e., intensity, duration, and frequency, were recorded in a headache diary. Active and latent TrPs were bilaterally explored in the temporalis, masseter, suboccipital, upper trapezius, sternocleidomastoid, and splenius capitis muscles. Pressure pain thresholds (PPT) were assessed over the trigeminal area (i.e., temporalis muscle), extra-trigeminal (i.e., C5/C6 zygapophyseal joint), and two distant pain-free points (i.e., second metacarpal and tibialis anterior muscle).

Results

Eighty (51%) patients were classified as FETTH, whereas 77 (49%) were classified as CTTH. No differences in the number of either active or latent TrPs (all p > 0.171) or widespread pressure pain sensitivity (all p > 0.351) were observed between FETTH and CTTH groups. The number of active and latent TrPs was significantly and negatively associated with PPTs: The higher the number of active or latent TrPs, the lower the widespread PPT, and the more generalized sensitization. This association was stronger within the FETTH group than the CTTH group.

Conclusions

This study found that the number of TrPs in head and neck/shoulder muscles was associated with widespread pressure hypersensitivity independently of the frequency of headache.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

The immediate effect of multiple mechanical impulses on electromyography and pressure pain threshold of lumbar latent trigger points: an experimental study

BACKGROUND

Myofascial pain is a common syndrome, which has not been studied extensively in the low back. Despite a variety of manual and instrument assisted interventions available, little work has targeted the possible effects of fast mechanical impulses on myofascial trigger points (MTrPs) on its sensitivity and electrical activity. The purpose of this experimental study was to quantify the immediate effect of one session of mechanical impulses to lumbar latent MTrPs and to normal muscle tissue with pressure pain threshold (PPT) and surface electromyography (sEMG) as outcome measures.

METHODS

During the autumn of 2009, in 41 asymptomatic subjects between 17-40 years of age the lumbar musculature was searched for a latent MTrP by a trained clinician. Using 3 disposable pre-gelled electrodes bilaterally, sEMG was recorded continuously from muscle containing either latent or no MTrP. Both the trigger point group and control group received the intervention and were blinded to group allocation. The immediate effects of mechanical impulses were assessed by sEMG and PPT before and after intervention using Wilcoxon matched-pairs signed-ranks test, Mann-Whitney U test and paired t-tests.

RESULTS

The PPT increased significantly across both groups (p < 0.01) after intervention. The proportionate increase (14.6 %) was comparable in both MTrP and control groups. The electrical activity on the MTrP side was not significantly higher in the MTrP group compared to the contralateral side. The decrease of resting electrical activity after intervention was significant in the MTrP group on the side of the latent MTrP (P = 0.001) as well as the contralateral side (p=0.022), and not significant in the control group on either side (p=0.33 and p=0.93).

CONCLUSION

In this study, the immediate effect of one session of mechanical impulses was associated with a significant increase in PPT for both groups and a significant decrease in the resting electrical activity of the lumbar muscles only in the MTrP group. It is unknown if these effects have clinical significance.

Myofascial pain and fibromyalgia: two different but overlapping disorders

There is good evidence supporting that people with fibromyalgia syndrome (FMS) exhibit central sensitization. The role of peripheral nociception is under debate in FMS. It seems that widespread pain experienced in FMS is considered multiple regional pains; therefore, several authors proposed that muscles play a relevant role in FMS. Trigger points (TrPs) have long been a contentious issue in relation to FMS. Preliminary evidence reported that the overall spontaneous pain is reproduced by referred pain from active TrPs, suggesting that FMS pain is largely composed of pain arising, at least partially, from TrPs. Finally, there is preliminary evidence suggesting that management of TrPs is able to modulate the CNS and is effective for reducing pain in FMS, although results are conflicting and future studies are clearly needed.

Effect of cervical mobilization and ischemic compression therapy on contralateral cervical side flexion and pressure pain threshold in latent upper trapezius trigger points

Studies have shown a clinical relationship between trigger points and joint impairments. However the cause-and effect relationship between muscle and joint dysfunctions in trigger points could not be established. The purpose of this study was to investigate effects of mobilization and ischemic compression therapy on cervical range of motion and pressure pain sensitivity in participants with latent trigger point in the upper trapezius muscle. Ninety asymptomatic participants with upper trapezius latent trigger point were randomized in to 3 groups: mobilization, ischemic compression and a control. The outcomes were measured over a 2 week period. Repeated measures ANOVA showed statistically and clinically significant pre to post improvement in both the interventional groups compared to control (p < 0.05). However the effect sizes between the intervention groups were small (<0.3) revealing minimal clinical detectable difference.

Short-Term Effects of Kinesio Taping and Cross Taping Application in the Treatment of Latent Upper Trapezius Trigger Points: A Prospective, Single-Blind, Randomized, Sham-Controlled Trial

Kinesio taping (KT) may be a new treatment in patients with myofascial trigger points (MTrPs). A new method available for taping practitioners is cross taping (CT). The main objective was to determine how CT, KT, and medical adhesive tape (sham group) affect the subjective assessment of resting bioelectrical activity and pain of the upper trapezius muscle (UT) in patients with MTrPs. 105 volunteers were recruited to participate. The primary outcome was resting bioelectrical activity of UT muscle as assessed by surface electromyography (sEMG) in each group and pain intensity on a visual analog scale (VAS). Assessments were collected before and after intervention and after the 24-hours follow-up. No significant differences were observed in bioelectrical activity of UT between pre-, post-, and follow-up results. In three groups patients had significantly lower pain VAS score after the intervention (CT—p < 0.001, KT—p < 0.001, and sham—p < 0.01). The Kruskal-Wallis ANOVA showed no significant differences in almost all measurements between groups. The application of all three types of tapes does not influence the resting bioelectrical activity of UT muscle and may not lead to a reduction in muscle tone in the case of MTrPs.

Altered Central Sensitization and Pain Modulation in the CNS in Chronic Joint Pain

Musculoskeletal pain disorders are the second largest contributor to global disability underlining the significance of effective treatments. However, treating chronic musculoskeletal pain, and chronic joint pain (osteoarthritis (OA)) in particular, is challenging as the underlying peripheral and central pain mechanisms are not fully understood, and safe and efficient analgesic drugs are not available. The pain associated with joint pain is highly individual, and features from radiological imaging have not demonstrated robust associations with the pain manifestations. In recent years, a variety of human quantitative pain assessment tools (quantitative sensory testing (QST)) have been developed providing new opportunities for profiling patients and reaching a greater understanding of the mechanisms involved in chronic joint pain. As joint pain is a complex interaction between many different pain mechanisms, available tools are important for patent profiling and providing the basic knowledge for development of new drugs and for developing pain management regimes.

Association between muscle trigger points, ongoing pain, function, and sleep quality in elderly women with bilateral painful knee osteoarthritis

OBJECTIVE

The objectives of this study were to investigate if referred pain elicited by active trigger points (TrPs) reproduced the symptoms in individuals with painful knee osteoarthritis (OA) and to determine the relationship between the presence of active TrPs, intensity of ongoing pain, function, quality of life, and sleep quality in individuals with painful knee OA.

METHODS

Eighteen women with bilateral painful knee OA, aged 79 to 90 years, and 18 matched controls participated. Muscle TrPs were bilaterally explored in several muscles of the lower extremity. Trigger points were considered active if the elicited referred pain reproduced knee symptoms, and TrPs were considered latent if the elicited pain did not reproduce symptoms. Pain was collected with a numerical pain rate scale (0-10), function was assessed with Western Ontario and McMaster Universities, quality of life was assessed with the Medical Outcomes Study Short Form 36 questionnaire, and sleep quality was determined with the Pittsburgh Sleep Quality Index.

RESULTS

Women with knee OA exhibited a greater number of active TrPs (mean, 1 ± 1; P < .001) but similar number of latent TrPs (mean, 4 ± 2) than healthy women (mean, 4 ± 3; P = .613). A greater number of active TrPs were associated with higher intensity of ongoing pain (r = 0.605; P = .007). Higher intensity of ongoing knee pain was associated with lower physical function (P < .05).

CONCLUSIONS

The referred pain elicited by active TrPs in the lower extremity muscles contributed to pain symptoms in painful knee OA. A higher number of active TrPs was associated with higher intensity of ongoing knee pain.

A critical evaluation of Quintner et al: missing the point

The objective of this article is to critically analyze a recent publication by Quinter, Bove and Cohen, published in Rheumatology, about myofascial pain syndrome and trigger points (Quintner et al., 2014). The authors concluded that the leading trigger point hypothesis is flawed in reasoning and in science. They claimed to have refuted the trigger point hypothesis. The current paper demonstrates that the Quintner et al. paper is a biased review of the literature replete with unsupported opinions and accusations. In summary, Quintner et al. have not presented any convincing evidence to believe that the Integrated TrP Hypothesis should be laid to rest.

Central sensitization in humans: assessment and pharmacology

It is evident that chronic pain can modify the excitability of central nervous system which imposes a specific challenge for the management and for the development of new analgesics. The central manifestations can be difficult to quantify using standard clinical examination procedures, but quantitative sensory testing (QST) may help to quantify the degree and extend of the central reorganization and effect of pharmacological interventions. Furthermore, QST may help in optimizing the development programs for new drugs.Specific translational mechanistic QST tools have been developed to quantify different aspects of central sensitization in pain patients such as threshold ratios, provoked hyperalgesia/allodynia, temporal summation (wind-up like pain), after sensation, spatial summation, reflex receptive fields, descending pain modulation, offset analgesia, and referred pain areas. As most of the drug development programs in the area of pain management have not been very successful, the pharmaceutical industry has started to utilize the complementary knowledge obtained from QST profiling. Linking patients QST profile with drug efficacy profile may provide the fundamentals for developing individualized, targeted pain management programs in the future. Linking QST-assessed pain mechanisms with treatment outcome provides new valuable information in drug development and for optimizing the management regimes for chronic pain.

Additional effects of transcranial direct-current stimulation and trigger-point injection for treatment of myofascial pain syndrome: a pilot study with randomized, single-blinded trial

BACKGROUND

Chronic pain caused by myofascial pain syndrome (MPS) results in generalized and debilitating conditions. Trigger-point injection (TPI) is the mainstay of MPS management to reduce acute and localized pain. Other adjunctive intervention to modulate the central pain pathway might be helpful if they are combined with TPI. Transcranial direct-current stimulation (tDCS), which is a form of neurostimulation, has been reported to be safe and effective in treating chronic pain by changing cortical excitability.

OBJECTIVES

To determine whether there is an additional effect of tDCS and TPI to reduce pain in patients with MPS.

PATIENTS

Twenty-one patients with newly diagnosed MPS of shoulder girdle muscles.

INTERVENTIONS

Patients were randomly assigned into 1 of 3 groups (2 active and 1 sham stimulation groups) and received TPI. Immediately after TPI, tDCS (2 mA for 20 minutes on 5 consecutive days) was administered. For the active stimulation groups, tDCS was applied over 2 different locations (primary motor cortex and dorsolateral prefrontal cortex [DLPFC]).

OUTCOME MEASURES

Visual analogue scale (VAS), Pain Threshold Test, and short form of the McGill Pain Questionnaire were measured before and immediately after stimulation for 5 consecutive days.

RESULTS

The mean VAS values were decreased in all three groups after 5 days. There was a significant change between before and after stimulation only in the DLPFC group. The significant change in the mean VAS value was shown from after the second stimulation session (p=0.031), and this remained significant until the last stimulation session (p=0.027).

CONCLUSION

This study suggests that tDCS over DLPFC may have additional effects with TPI to reduce pain in patients with MPS. tDCS over DLPFC can be used to reverse central pain pathway by modulating cortical plasticity.

Myofascial trigger points: peripheral or central phenomenon?

Trigger points (TrP) are hyperirritable spots in a taut band of a skeletal muscle, which usually have referred pain. There is controversy over whether TrP are a peripheral or central nervous system phenomenon. Referred pain, the most characteristic sign of TrP, is a central phenomenon initiated and activated by peripheral sensitization, whereby the peripheral nociceptive input from the muscle can sensitize dorsal horn neurons that were previously silent. TrP are a peripheral source of nociception, and act as ongoing nociceptive stimuli contributing to pain propagation and widespread pain. Several studies support the hypothesis that TrP can induce central sensitization, and appropriate TrP treatment reduces central sensitization. In contrast, preliminary evidence suggests that central sensitization can also promote TrP activity, although further studies are needed. Proper TrP management may prevent and reverse the development of pain propagation in chronic pain conditions, because inactivation of TrP attenuates central sensitization.