Understanding the vascular environment of myofascial trigger points using ultrasonic imaging and computational modeling

Assessment of the Effects of Sphingosine Kinase 1/Sphingosine-1-Phosphate on Microangiogenesis at Rat Myofascial Trigger Points Using Contrast-Enhanced Ultrasonography

Purpose

Few studies have assessed the effects of sphingosine kinase 1/sphingosine-1-phosphate (SPHK1/S1P) on microangiogenesis at rat myofascial trigger points (MTrPs) using contrast-enhanced ultrasonography (CEUS). This study aimed to address these deficiencies. Here, we investigated the effects of SPHK1/S1P on MTrP microangiogenesis and the value of CEUS in evaluating these effects.

Methods

Forty Sprague‒Dawley rats were subdivided into two groups: control and MTrP groups. MTrPs were established by 8 weeks of the strike procedure combined with eccentric motion and 4 weeks of recovery. All rats were euthanized after having undergone CEUS with an overdose of pentobarbital sodium. MTrP and control tissue samples were removed for haematoxylin and eosin (H&E) staining and transmission electron microscopy (TEM) imaging. The tissue was dehydrated, cleared, and embedded before sectioning. The sections were then incubated overnight at 4°C, and immunohistochemistry was carried out with primary antibodies including rabbit anti-CD31, rabbit anti-SPHK1and rabbit anti-S1PR1.

Results

MTrP rats exhibited spontaneous electrical activity (SEA) and a local twitch response (LTR) during electromyography (EMG) examination. The CEUS time-intensity curves (TICs) showed that the perfusion intensity in the MTrPs and surrounding tissue area was increased, with faster perfusion than in normal sites, while the TICs in the control group slowly increased and then slowly decreased. The correlation coefficient between the microvessel density (MVD) and sphingosine 1-phosphate receptor 1 (S1PR1) was 0.716 (p <0.01). Spearman correlation analysis revealed that Spearman's rho (ρ) values between the MVD and peak intensity (PI), between the MVD and area under the curve (AUC), and between the MVD and SPHK1 were > 0.5 (p <0.05), > 0.7 (p <0.01), and > 0.7 (p <0.01), respectively.

Conclusion

CEUS is valuable for detecting microangiogenesis within MTrPs, and SPHK1/S1P plays an important role in promoting MTrP tissue microangiogenesis.

Comparative Techniques of Acupuncture and Dry Needling Intersecting with Trigger Point Physiology and Diagnostics: A Cross-Discipline Narrative Review

Background

Pain management is a great burden on society; therefore, cost-effective and nonaddictive treatments for pain are urgently required. Needling of painful spots has been applied in acupuncture along with dry needling

Methods

A narrative review of the literature on TrP physiology, its associated diagnostics, and the techniques of DN and acupuncture was performed.

Results

Diagnostic imagery may benefit the study and treatment of TrPs using needling. Acupuncture and DN techniques are similar in their applications. However, the warm needling technique is established in acupuncture but not in dry needling. Additionally, translational difficulties have inhibited crossdiscipline learning.

Conclusions

Historical evidence suggests a need to examine the use of heat in needling further. Additional research should be conducted on TrP categories to determine if a relationship with the needling technique can be established. Furthermore, interdisciplinary communication would benefit both modalities.

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Key Words

• acupuncture
• dry needling
• myofascial trigger points
• trigger point physiology

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MESH Headings Collapse

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Affiliation(s)

Jordan Barber AOMA Graduate School of Integrative Medicine, Austin, TX, USA
Fabio Lodo So Wen School of Acupuncture, Milan, Italy
Andrew Nugent-Head Association for Traditional Studies, Ashville, NC, USA
Xia Zeng AOMA Graduate School of Integrative Medicine, Austin, TX, USA

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[Efficacy of kinesiotape treatment on mechanically induced neck pain: a systematic review]

BACKGROUND

This article provides a summary of the state of knowledge on the sport-specific use of a kinesiotape intervention for neck pain caused by the postural or sitting position in cycling. This review summarises the research literature on the effectiveness of kinesiotape (KTA) on pain perception, pressure pain threshold (PPT) and range of motion (ROM) in the neck muscles and trapezius muscle. The focus was specifically on studies in cycling.

METHODS

The literature search was conducted in the PubMed and Google Scholar databases. The search terms used in combination were "kinesiotape" and "back pain", "neck pain", "kinesiotape" and "trapezius muscle", and "kinesiotape" and "cycling".

RESULTS

In total, the combination of keywords returned 892 results. Of these, the Powered by Editorial Manager and ProduXion Manager from Aries Systems Corporation search in the online database of PubMed returned 192 results and the search in the online database of Google Scholar returned 700 results. 874 publications were discarded due to a lack of specificity and a field of application that did not meet the requirements. Three additional studies were eliminated as "duplicate". Fifteen studies met the inclusion criteria. These were analysed in terms of content and in detail. Only one publication deals with the problem of mechanically induced neck pain during cycling. The effect of the kinesiotape refers to a reduction in pain perception and maintenance of the cervical range of motion.

CONCLUSION

Numerous studies deal with the problem of pain conditions and how these can be counteracted with the help of an appropriate KTA. Only a small number offer insights into the effectiveness of a suitable application of kinesiotape for mechanically induced neck pain.

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.

Contracture Knots vs. Trigger Points. Comment on Ball et al. Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response. Diagnostics 2022, 12, 321

A recent study published in Diagnostics attempted to visualize trigger points and contracture knots with high-definition ultrasound. Based on their findings, the authors reversed the commonly understood meaning of the two terms. However, they did so without providing any convincing evidence. The authors maintained that their sonography images represented trigger points within contracture knots, supporting the multiple loci hypothesis. On review of the paper, both conclusions seem premature and rather speculative.

Trigger Points and Contracture/Contraction Knots: What’s in a Name? Reply to Dommerholt, J.; Gerwin, R.D. Contracture Knots vs. Trigger Points. Comment on “Ball et al. Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response. Diagnostics 2022, 12, 321”

We are responding to the comment by Dommerholt and Gerwin that we have reverse-defined “myofascial trigger point” (MTrP) and “contracture/contraction knot.” In attempting to maintain philosophical agreement with specific and implied aspects of their integrated hypothesis of trigger-point formation (namely a MTrP being ischemic and hypoxic), we referred to the MTrP as the small hyperechoic signal rather than the larger hypoechoic (and therefore hyperperfused) structure surrounding it. It was never our intent to re-define nor contribute to confusion. In making this concession with respect to Dommerholt and Gerwin’s preferred nomenclature, however, we must instead now reconcile what we image as a hypoechoic (and therefore hyperperfused) MTrP with it being concurrently hypoxic.

Intrafasciomembranal Fluid Pressure: A Novel Approach to the Etiology of Myalgias

Fascia is a continuous membrane (fasciomembrane) that enables differentiation of fluid pressure on either side. Fascia membrane also enables an internal increased fluid pressure at all muscle levels (fibers, fiber bundles, skeletal muscles, compartments), and the author introduces a new unifying term for these pressures, regardless of the anatomical level - the intrafasciomembranal fluid pressure (IFMFP). Swelling, pain, and loss of tissue function are identified as common cardinal symptoms in trigger point (TrP), chronic exertional compartment syndrome (CECS), overtraining syndrome (OTS), and delayed onset muscle soreness (DOMS). Existing literature and an overall assessment indicate that intramuscular conditions related to fluid flow and pressure play a central role in different conditions, providing a common biomechanical explanation of the etiology and influence, supporting the article's theory that an increased IFMFP plays a key role in these conditions.

Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response

The literature has hypothesized that a trigger point (TrP) area consists of a hyperperfused contracture knot with smaller hypoperfused TrPs within the contracture knot. By contrast, the only published ultrasound image of a TrP has it labeled hypoechoic (i.e., hyperperfused) with no commentary regarding smaller speckles of hypoperfusion within. Furthermore, the lack of clarity in objective definition of the terms associated with the TrP (namely, the palpable “contracture knot” and smaller nonpalpable “trigger point”) has led to unnecessary communication difficulties between and among clinicians and researchers. In this case series of three muscles across two patients, by using high-definition musculoskeletal ultrasound imaging technology, we present what we believe to be the first reliable capture of palpable hypoechoic (e.g., hypoperfused) contracture knots (previously mislabeled as a hypoechoic TrP), and a visual support of the multiple loci hypothesis first proposed by Hong and Simons—the first reliable confirmation of the hyperechoic (i.e., hypoperfused) TrP within. Initially proposed by a histological study and supported by microdialysis study, this case series lends further support for the multiple loci hypothesis through visual confirmation of palpable hypoechoic contracture knots, with smaller hypoechoic TrPs “speckles” within.

Combined effectiveness of extracorporeal radial shockwave therapy and ultrasound-guided trigger point injection of lidocaine in upper trapezius myofascial pain syndrome

OBJECTIVE

Myofascial pain syndrome (MPS) is a major musculoskeletal problem and a leading cause of disability worldwide. Extracorporeal shockwave therapy (ESWT) and trigger point injection (TPI) have shown positive results for MPS but no previous study has investigated the combined effects of radial shockwave and trigger point injection of lidocaine for upper trapezius myofascial pain syndrome.

METHOD

For this purpose, forty-five participants were randomly divided into shockwave (n = 15), shockwave with ultrasound-guided trigger point injection (combined; n = 15), and control (standard care; n = 15) groups. Participants were assessed at baseline, one week and four weeks by using the visual analog scale, neck disability index, electromyography, infrared thermography, and sonoelastography.

RESULTS

Compared with control group, both shockwave and combined groups showed a statistically significant reduction in pain (P<0.01), functional disability (P<0.01), skin temperature (P<0.01), and elastic stiffness, with greater reduction in the combined group (P<0.01) than shockwave group (P<0.05) at four weeks. However, no significant difference was found in electrical activity between the groups (P>0.05). The combined group also showed significant differences in pain (P<0.05) and elastic stiffness (P<0.01) compared with shockwave group at four weeks.

CONCLUSION

Our study revealed that extracorporeal radial shockwave therapy combined with trigger point injection of lidocaine was more effective for decreasing pain and elastic stiffness in upper trapezius myofascial pain syndrome at four weeks.

Short-term effectiveness of high- and low-intensity percutaneous electrolysis in patients with patellofemoral pain syndrome: A pilot study

BACKGROUND

Unilateral patellofemoral pain syndrome (PFPS) is the most frequently diagnosed knee condition in populations aged < 50 years old. Although the treatment of myofascial trigger points (MTrPs) is a common and effective tool for reducing pain, previous studies showed no additional benefits compared with placebo in populations with PFPS. Percutaneous electrolysis is a minimally invasive approach frequently used in musculotendinous pathologies which consists of the application of a galvanic current through dry needling (DN).

AIM

To evaluate changes in sensitivity, knee pain perception and perceived pain during the application of these three invasive techniques.

METHODS

A triple-blinded, pilot randomized controlled trial was conducted on fifteen patients with unilateral PFPS who were randomized to the high-intensity percutaneous electrolysis (HIPE) experimental group, low-intensity percutaneous electrolysis (LIPE) experimental group or DN active control group. All interventions were conducted in the most active MTrP, in the rectus femoris muscle. The HIPE group received a 660 mA galvanic current for 10 s, the LIPE group 220 mA × 30 s and the DN group received no galvanic current. The MTrP and patellar tendon pain pressure thresholds (PPTs) and subjective anterior knee pain perception (SAKPP) were assessed before, after and 7 d after the single intervention. In addition, perceived pain during the intervention was also assessed.

RESULTS

Both groups were comparable at baseline as no significant differences were found for age, height, weight, body mass index, PPTs or SAKPP. No adverse events were reported during or after the interventions. A significant decrease in SAKPP (both HIPE and LIPE, P < 0.01) and increased patellar tendon PPT (all, P < 0.001) were found, with no differences between the groups (VAS: F = 0.30; η2 = 0.05; P > 0.05; tendon PPT immediate effects: F = 0.15; η2 = 0.02; P > 0.05 and tendon PPT 7-d effects: F = 0.67; η2 = 0.10; P > 0.05). A significant PPT increase in rectus femoris MTrP was found at follow-up in both the HIPE and LIPE groups (both, P < 0.001) with no differences between the groups (immediate effects: F= 1.55; η2 = 0.20; P > 0.05 and 7-d effects: F = 0.71; η2 = 0.10; P > 0.05). Both HIPE and LIPE interventions were considered less painful compared with DN (F = 8.52; η2 = 0.587; P < 0.01).

CONCLUSION

HIPE and LIPE induce PPT changes in MTrPs and patellar tendon and improvements in SAKPP, and seem to produce less pain during the intervention compared with DN.

Impaired Lymphatic Drainage and Interstitial Inflammatory Stasis in Chronic Musculoskeletal and Idiopathic Pain Syndromes: Exploring a Novel Mechanism

A normal functioning lymphatic pump mechanism and unimpaired venous drainage are required for the body to remove inflammatory mediators from the extracellular compartment. Impaired vascular perfusion and/or lymphatic drainage may result in the accumulation of inflammatory substances in the interstitium, creating continuous nociceptor activation and related pathophysiological states including central sensitization and neuroinflammation. We hypothesize that following trauma and/or immune responses, inflammatory mediators may become entrapped in the recently discovered interstitial, pre-lymphatic pathways and/or initial lymphatic vessels. The ensuing interstitial inflammatory stasis is a pathophysiological state, created by specific pro-inflammatory cytokine secretion including tumor necrosis factor alpha, interleukin 6, and interleukin 1b. These cytokines can disable the local lymphatic pump mechanism, impair vascular perfusion via sympathetic activation and, following transforming growth factor beta 1 expression, may lead to additional stasis through direct fascial compression of pre-lymphatic pathways. These mechanisms, when combined with other known pathophysiological processes, enable us to describe a persistent feed-forward loop capable of creating and maintaining chronic pain syndromes. The potential for concomitant visceral and/or vascular dysfunction, initiated and maintained by the same feed-forward inflammatory mechanism, is also described.

Assessment of the effects of ischaemia/ hypoxia on angiogenesis in rat myofascial trigger points using colour Doppler flow imaging

Background & Aims

Myofascial pain syndrome (MPS) is a common non-articular disorder of the musculoskeletal system that is characterized by the presence of myofascial trigger points (MTrPs). Despite the high prevalence of MPS, its pathogenesis, which induces the onset and maintenance of MTrPs, is still not completely understood. To date, no studies have investigated the changes in the biochemical milieu caused by ischaemia/hypoxia in the MTrP regions of muscle that are proposed in the integrated hypothesis. Therefore, this study investigated whether ischaemic/hypoxic conditions participate in the formation of active MTrPs and affect angiogenesis using colour Doppler flow imaging (CDFI).

Methods

Twenty-five Sprague-Dawley rats were randomly divided into a model group and a normal control group. A model of active MTrPs was established by a blunt strike combined with eccentric exercise. Enzyme-linked immunosorbent assays (ELISAs) were employed to detect the levels of HIF-1α and VEGF. Microvessel density (MVD) was evaluated using immunohistochemistry. CDFI was applied to observe the blood flow signals in the MTrPs, which were classified into four grades based on their strengths.

Results

Compared with the control group, the active MTrP group exhibited significantly higher HIF-1α and VEGF levels and MVD values. These differences were accompanied by increased blood flow signals. In the active MTrP group, the blood flow signal grade was positively correlated with the MVD (P < 0.05) and independently correlated with the VEGF level (P < 0.05) but was not correlated with the expression of HIF-1α (P > 0.05).

Conclusion

Ischaemic/hypoxic conditions may be involved in the formation of MTrPs. CDFI is useful for detection of the features of angiogenesis in or surrounding MTrPs via assessment of blood flow signals.

Change in muscle hardness after trigger point injection and physiotherapy for myofascial pain syndrome

Assessment and treatment of masticatory myofascial pain syndrome (MPS) are not standardized and remain controversial. We examined whether muscle hardness was useful for evaluating masticatory MPS and analyzed the effectiveness of treatments such as stretching and massage (SM) and trigger point injection (TPI). Twenty healthy volunteers and 20 MPS patients were enrolled. MPS patients were divided into TPI and SM treatment groups. Hardness of masticatory muscle with a taut band (TB) and change in hardness were evaluated after SM and TPI treatments. Hardness values were significantly higher in muscle including a TB (TB point) than in the muscle of healthy controls. Visual analogue scale scores were significantly lower after SM and TPI treatments, and hardness of the TB point was significantly lower after SM but not after TPI. These results suggest that measurement of muscle hardness, including the TB, is useful for evaluating masticatory MPS. However, TPI analgesia might not be caused by change in muscle hardness. The mechanisms underlying the effects of SM and TPI on reducing pain in MPS may differ and thus warrant further research.

Electrical impedance of the torso is associated with the pressure pain threshold on myofascial trigger points in patients with chronic neck pain: A cross-sectional study

BACKGROUND

Myofascial trigger points are dysfunctional structures present in skeletal muscles and are related to sensory, motor, and autonomic changes. Despite scientific advances in recent decades in the measurement of musculoskeletal pain, evaluation of this clinical phenomenon is supported with instruments that, although valid and reliable, have a considerable degree of subjectivity.

OBJECTIVE

To correlate electrical impedance of the upper limbs and torso with pain intensity, functional capacity, catastrophizing, pressure pain threshold, and skin temperature on myofascial trigger points in the upper trapezius muscle of patients with neck pain.

METHODS

A single-blind cross-sectional study. Twenty-eight volunteers of both genders were included in the study, were aged 18-45 years, and had chronic neck pain and myofascial trigger points in the upper trapezius. The volunteers were assessed using the Numeric Rating Scale, the Neck Disability Index, the Pain-Related Self-Statement Scale, algometry, infrared thermography, and electrical bioimpedance.

RESULTS

The following significant results were observed: a negative association between the pressure pain threshold on myofascial trigger point in the right upper trapezius and electrical impedance of the torso at 5 kHz (rs=-0.392, p= 0.032), 50 kHz (rs=-0.406, p= 0.026), 250 kHz (rs=-0.388, p= 0.034), and to the frequency 500 kHz (rs=-0.444, p= 0.014).

CONCLUSION

Electrical impedance of the torso is associated with the pressure pain threshold of myofascial trigger points on the upper trapezius of individuals with neck pain. Thus, individuals with a lower pressure pain threshold have higher electrical impedance values of the torso and vice versa.

A narrative review of new trends in the diagnosis of myofascial trigger points: diagnostic ultrasound imaging and biomarkers

Myofascial pain syndrome (MPS) is one of the most common conditions of chronic musculoskeletal pain encountered by primary healthcare practitioners on a daily basis. It is generally accepted amongst the broad profile of healthcare practitioners treating MPS that the presence of discrete, palpable and tender nodules within the muscle, known as myofascial trigger points (MTrP), is necessary to confirm the diagnosis of MPS. Manual palpation is currently the most common technique used to detect MTrP, however, previous research has shown that the reliability of manual palpation for detecting MTrP is poor, and in our opinion unacceptably poor, leading to inconsistent diagnosis of MPS and poor patient outcomes. There are currently no objective accepted diagnostic criteria for the clinical detection of MTrP, nor are there standardized diagnostic criteria for MPS. Two promising areas of research with potential for enhancing the diagnosis of MPS include the use of diagnostic ultrasound and biomarkers. Further research is needed to advance the development of composite diagnostic criteria employing ultrasound imaging, biomarker assessments and physical assessment to enhance the accuracy and objectivity of MTrP detection and diagnosis of chronic MPS disorder.

Myofascial Trigger Points Then and Now: A Historical and Scientific Perspective

The intent of this article is to discuss the evolving role of the myofascial trigger point (MTrP) in myofascial pain syndrome (MPS) from both a historical and scientific perspective. MTrPs are hard, discrete, palpable nodules in a taut band of skeletal muscle that may be spontaneously painful (i.e., active) or painful only on compression (i.e., latent). MPS is a term used to describe a pain condition that can be acute or, more commonly, chronic and involves the muscle and its surrounding connective tissue (e.g. fascia). According to Travell and Simons, MTrPs are central to the syndrome-but are they necessary? Although the clinical study of muscle pain and MTrPs has proliferated over the past two centuries, the scientific literature often seems disjointed and confusing. Unfortunately, much of the terminology, theories, concepts, and diagnostic criteria are inconsistent, incomplete, or controversial. To address these deficiencies, investigators have recently applied clinical, imaging (of skeletal muscle and brain), and biochemical analyses to systematically and objectively study the MTrP and its role in MPS. Data suggest that the soft tissue milieu around the MTrP, neurogenic inflammation, sensitization, and limbic system dysfunction may all play a role in the initiation, amplification, and perpetuation of MPS. The authors chronicle the advances that have led to the current understanding of MTrP pathophysiology and its relationship to MPS, and review the contributions of clinicians and researchers who have influenced and expanded our contemporary level of clinical knowledge and practice.

Skin Resistivity Value of Upper Trapezius Latent Trigger Points

Introduction. The skin resistivity (SkR) measurement is commonly recommended for acupoints measurement, but for trigger points (TrPs) only one study is available. The purpose of the study was to evaluate SkR for latent TrPs compared to non-TrPs and the surrounding tissue. Material and Methods. Forty-two healthy volunteers with unilateral latent upper trapezius TrPs (12 men, 30 women) aged 21–23 (mean age: 22.1 ± 0.6 y) participated in the study. Keithley electrometer 610B was used for measuring SkR (Ag/AgCl self-adhesive, disposable ground electrode: 30 mm diameter). SkR was measured for latent TrPs and compared to opposite non-TrPs sites and the surrounding tissue. Results. The SkR decrease of TrPs-positive sites as compared to TrPs-negative sites and the surrounding tissue was confirmed. However, no statistically significant difference in the SkR value occurred when all data were analyzed. The same was confirmed after gender division and for TrPs-positive subjects examined for referred pain and twitch response presence. Conclusion. SkR reactive changes at latent TrPs are possible but the results were not consistent with the previous study. Thus, caution in applying SkR to latent TrPs isolation is recommended and its clinical use should not be encouraged yet. Further studies, especially on active TrPs, are yet required.

Reliability of different methodologies of infrared image analysis of myofascial trigger points in the upper trapezius muscle

BACKGROUND:

Infrared thermography is recognized as a viable method for evaluation of subjects with myofascial pain.

OBJECTIVE:

The aim of the present study was to assess the intra- and inter-rater reliability of infrared image analysis of myofascial trigger points in the upper trapezius muscle.

METHOD:

A reliability study was conducted with 24 volunteers of both genders (23 females) between 18 and 30 years of age (22.12±2.54), all having cervical pain and presence of active myofascial trigger point in the upper trapezius muscle. Two trained examiners performed analysis of point, line, and area of the infrared images at two different periods with a 1-week interval. The intra-class correlation coefficient (ICC_2,1) was used to assess the intra- and inter-rater reliability.

RESULTS:

With regard to the intra-rater reliability, ICC values were between 0.591 and 0.993, with temperatures between 0.13 and 1.57 °C for values of standard error of measurement (SEM) and between 0.36 and 4.35 °C for the minimal detectable change (MDC). For the inter-rater reliability, ICC ranged from 0.615 to 0.918, with temperatures between 0.43 and 1.22 °C for the SEM and between 1.19 and 3.38 °C for the MDC.

CONCLUSION:

The methods of infrared image analyses of myofascial trigger points in the upper trapezius muscle employed in the present study are suitable for clinical and research practices.

Effect of trigger point injection on lumbosacral radiculopathy source

Background:

Active muscular trigger points (aMTPs) presenting with radiating pain can interfere in diagnosis and treatment of patients suffering from lumbosacral radiculopathy.

Objectives:

We aimed to diagnose and evaluate the trigger point therapy on the outcome of pain in patients with lumbosacral radiculopathy.

Materials and Methods:

A total of 98 patients were enrolled suffered with chronic pain andlumbosacral radiculopathy at L4-L5 and L5-S1 who were candidates of non-surgical management. All patients received conservative modalities, including bed rest, non-steroidal anti-inflammatory agents (NSAID), and physiotherapy. These treatments continued for a week. Patients were examined for the presence of trigger points in their lower extremities. Those who had trigger points were divided into 2 groups (TP and N). Patients in TP group underwent trigger point injection therapy. No further therapy was done for the N group. Pain scores and straight leg raise (SLR) test in both groups were collected and analyzed on the seventh and 10th days of the therapy. Results were analyzed by paired t test and chi-square test.

Results:

Out of 98 patients, 64 had trigger points. Thirty-two patients were assigned to each group. Pain scores (Mean ± SD) in TP group was 7.12 ± 1.13 and in N group was 6.7 ± 1.16, P = 0.196. Following the treatment, pain scores were 2.4 ± 1.5 in TP group and 4.06 ± 1.76 in N group P = 0.008. SLR test became negative in all patients in TP group but only in 6 (19%) patients in N group, P = 0.001.

Conclusions:

Results show that trigger point injection therapy in patients suffering from chronic lumbosacral radiculopathy with trigger points can significantly improve their recovery, and conservative therapy may not be adequate.

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.

Dry needling - peripheral and central considerations

Dry needling is a common treatment technique in orthopedic manual physical therapy. Although various dry needling approaches exist, the more common and best supported approach targets myofascial trigger points. This article aims to place trigger point dry needling within the context of pain sciences. From a pain science perspective, trigger points are constant sources of peripheral nociceptive input leading to peripheral and central sensitization. Dry needling cannot only reverse some aspects of central sensitization, it reduces local and referred pain, improves range of motion and muscle activation pattern, and alters the chemical environment of trigger points. Trigger point dry needling should be based on a thorough understanding of the scientific background of trigger points, the differences and similarities between active and latent trigger points, motor adaptation, and central sensitize application. Several outcome studies are included, as well as comments on dry needling and acupuncture.

Etiology of myofascial trigger points

Myofascial pain syndrome (MPS) is described as the sensory, motor, and autonomic symptoms caused by myofascial trigger points (TrPs). Knowing the potential causes of TrPs is important to prevent their development and recurrence, but also to inactivate and eliminate existing TrPs. There is general agreement that muscle overuse or direct trauma to the muscle can lead to the development of TrPs. Muscle overload is hypothesized to be the result of sustained or repetitive low-level muscle contractions, eccentric muscle contractions, and maximal or submaximal concentric muscle contractions. TrPs may develop during occupational, recreational, or sports activities when muscle use exceeds muscle capacity and normal recovery is disturbed.

[Trigger points - Diagnosis and treatment concepts with special reference to extracorporeal shockwaves]

The 70-year-old trigger point theory has experienced a growing scientific confirmation and clinical significance as a consequence of recent muscle pain research. The trigger point pain formation is caused by high levels of vasoneuroactive substances. Depending on intensity and duration of the muscle stimulus the central pain processing is modified and leads to characteristic referred pain patterns. The most effective conventional forms of treatment are aimed at a direct mechanical manipulation of the trigger point as are new forms of therapy with focused and radial shockwaves. By using high pressures the focused shockwaves in particular are suitable to provoke local and referred pain and thus simplify the trigger point diagnosis. The empirically found therapeutic effect of shockwaves on muscles is hypothetical and can be explained in analogy with validated reactions of shockwaves in non-muscle tissues. Overall, the shockwave therapy on muscles represents a confirmation and extension of the existing trigger point therapy. It seems to be suitable for treating functional muscular disorders and myofascial pain syndromes within the locomotor system.