Ischemic compression block attenuates mechanical hyperalgesia evoked from latent myofascial trigger points

Dry needling of the flexor digitorum brevis muscle reduces postural control in standing: A pre-post stabilometric study

There are studies that show the better balance after dry needling in lumbar pain. However, the postural control effects after foot dry needling are unknown. Our objective was to check if dry needling reduces postural control. Eighteen subjects with flexor digitorum brevis (FDB) muscle Myofascial trigger point were evaluated pre- and post-deep dry needling. We measured stabilometric variables in a pre-post study. We have found significant differences in three stabilometric variables: surface with eyes closed (29.36-53.21 mm2 ) (p = 0.000), medium speed of the laterolateral displacement with eyes closed (1.42-1.64 mm/s) (p = 0.004), and medium speed of the anteroposterior displacement with eyes closed (1.30-1.53 mm/s) (p = 0.025). Dry needling therapy application in FDB muscle reduces standing postural control with eyes closed.

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.

Ischemic Pressure vs Postisometric Relaxation for Treatment of Rhomboid Latent Myofascial Trigger Points: A Randomized, Blinded Clinical Trial

OBJECTIVE

The purpose of this study was to investigate the effects of ischemic pressure (IP) vs postisometric relaxation (PIR) on rhomboid-muscle latent trigger points (LTrPs).

METHODS

Forty-five participants with rhomboid-muscle LTrPs were randomly assigned into 3 groups and received 3 weeks of treatment-group A: IP and traditional treatment (infrared radiation, ultrasonic therapy, and transcutaneous electrical nerve stimulation); group B: PIR and traditional treatment; and group C: traditional treatment. Shoulder pain and disability, neck pain and disability, and pressure pain threshold (PPT) of 3 points on each side were measured before and after treatment.

RESULTS

Multivariate analysis of variance indicated a statistically significant Group × Time interaction (P = .005). The PPT for the right lower point was increased in group A more than in groups B or C. Neck pain was reduced in group B more than in group C. Moreover, shoulder and neck disability were reduced in both groups A and B more than in group C. The PPTs of the left lower and middle points were increased in group B compared with groups A and C. The PPT of the left upper point was increased in group A more than in group C. There were significant changes in all outcomes in the 2 experimental groups (P < .05). No changes were found in the control group except in pain intensity, shoulder disability, and PPT of the left lower point.

CONCLUSION

This study found that IP may be more effective than PIR regarding PPT, but both techniques showed changes in the treatment of rhomboid-muscle LTrPs.

Comparison of pressure release, phonophoresis and dry needling in treatment of latent myofascial trigger point of upper trapezius muscle

BACKGROUND

Latent myofascial trigger point (LMTP) is a small hypersensitive area in skeletal muscles that becomes painful under compression or stimulation. LMTPs are relevant for various musculoskeletal disorders. Although several treatments have been introduced to treat LMTP, the most efficient one is yet to be found.

OBJECTIVE

The main purpose of the present study was to compare pressure release, phonophoresis of betamethasone and dry needling on the upper trapezius latent myofascial trigger point.

METHODS

Sixty participants (mean ± SD age, 23.6 ± 2.1 y), with at least one latent myofascial trigger point in the upper trapezius muscle, participated in this study. Subjects were randomly divided into three groups (pressure release, phonophoresis with betamethasone and dry needling groups) for two weeks. Pain intensity, pain pressure threshold and active cervical range of motion were assessed.

RESULTS

Significant pain decrease, active cervical range of motion and pain pressure threshold increase were observed in the three groups (p< 0.001). The dry needling and phonophoresis groups reported more significant improvement compared to the pressure release group (p< 0.001). There was no difference between the dry needling and phonophoresis groups.

CONCLUSIONS

Considering the significant, positive effects of all three methods, dry needling and phonophoresis seem to be more effective than pressure release.

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

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

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.

Hyperexcitability to Electrical Stimulation and Accelerated Muscle Fatiguability of Taut Bands in Rats

Objective

Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats.

Methods

Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle.

Results

The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all p<0.05). The MCF at the 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those at the 1st and 5th stimuli (all p<0.01). The MCF in the frequency dependent fatigue test was significantly higher and the stimulus frequency that induced MCF was significantly lower for taut bands than for non-taut bands (both p<0.01).

Conclusions

The present study demonstrates that the muscle taut band itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.

Therapeutic effects of dry needling in patients with upper trapezius myofascial trigger points

BACKGROUND

Active myofascial trigger points (MTrPs) are major pain generators in myofascial pain syndrome. Dry needling (DN) is an effective method for the treatment of MTrPs.

OBJECTIVE

To assess the immediate neurophysiological and clinical effects of DN in patients with upper trapezius MTrPs.

METHODS

This was a prospective, clinical trial study of 20 patients with upper trapezius MTrPs and 20 healthy volunteers (matched for height, weight, body mass index and age), all of whom received one session of DN. Primary outcome measures were neuromuscular junction response (NMJR) and sympathetic skin response (SSR). Secondary outcomes were pain intensity (PI) and pressure pain threshold (PPT). Data were collected at baseline and immediately post-intervention.

RESULTS

At baseline, SSR amplitude was higher in patients versus healthy volunteers (p<0.003). With respect to NMJR, a clinically abnormal increment and normal reduction was observed in patients and healthy volunteers, respectively. Moreover, PPT of patients was less than healthy volunteers (p<0.0001). After DN, SSR amplitude decreased significantly in patients (p<0.01), but did not change in healthy volunteers. A clinically important reduction in the NMJR of patients and increment in healthy volunteers was demonstrated after DN. PPT increased after DN in patients, but decreased in healthy volunteers (p<0.0001). PI improved after DN in patients (p<0.001).

CONCLUSIONS

The results of this study showed that one session of DN targeting active MTrPs appears to reduce hyperactivity of the sympathetic nervous system and irritability of the motor endplate. DN seems effective at improving symptoms and deactivating active MTrPs, although further research is needed.

TRIAL REGISTRATION NUMBER

IRCT20130316128.

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.

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.

Myelinated Afferents Are Involved in Pathology of the Spontaneous Electrical Activity and Mechanical Hyperalgesia of Myofascial Trigger Spots in Rats

Myofascial trigger points (MTrPs) are common causes for chronic pain. Myelinated afferents were considered to be related with muscular pain, and our clinical researches indicated they might participate in the pathology of MTrPs. Here, we applied myofascial trigger spots (MTrSs, equal to MTrPs in human) of rats to further investigate role of myelinated afferents. Modified pyridine-silver staining revealed more nerve endings at MTrSs than non-MTrSs (P < 0.01), and immunohistochemistry with Neurofilament 200 indicated more myelinated afferents existed in MTrSs (P < 0.01). Spontaneous electrical activity (SEA) recordings at MTrSs showed that specific block of myelinated afferents in sciatic nerve with tetrodotoxin (TTX) led to significantly decreased SEA (P < 0.05). Behavioral assessment showed that mechanical pain thresholds (MPTs) of MTrSs were lower than those of non-MTrSs (P < 0.01). Block of myelinated afferents by intramuscular TTX injection increased MPTs of MTrSs significantly (P < 0.01), while MPTs of non-MTrSs first decreased (P < 0.05) and then increased (P > 0.05). 30 min after the injection, MPTs at MTrSs were significantly lower than those of non-MTrSs (P < 0.01). Therefore, we concluded that proliferated myelinated afferents existed at MTrSs, which were closely related to pathology of SEA and mechanical hyperalgesia of MTrSs.

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.

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.

Clinical implication of latent myofascial trigger point

Myofascial trigger points (MTrPs) are hyperirritable points located within a taut band of skeletal muscle or fascia, which cause referred pain, local tenderness and autonomic changes when compressed. There are fundamental differences between the effects produced by the two basic types of MTrPs (active and latent). Active trigger points (ATrPs) usually produce referred pain and tenderness. In contrast, latent trigger points (LTrPs) are foci of hyperirritability in a taut band of muscle, which are clinically associated with a local twitch response, tenderness and/or referred pain upon manual examination. LTrPs may be found in many pain-free skeletal muscles and may be "activated" and converted to ATrPs by continuous detrimental stimuli. ATrPs can be inactivated by different treatment strategies; however, they never fully disappear but rather convert to the latent form. Therefore, the diagnosis and treatment of LTrPs is important. This review highlights the clinical implication of LTrPs.

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.

Latent myofascial trigger points

A latent myofascial trigger point (MTP) is defined as a focus of hyperirritability in a muscle taut band that is clinically associated with local twitch response and tenderness and/or referred pain upon manual examination. Current evidence suggests that the temporal profile of the spontaneous electrical activity at an MTP is similar to focal muscle fiber contraction and/or muscle cramp potentials, which contribute significantly to the induction of local tenderness and pain and motor dysfunctions. This review highlights the potential mechanisms underlying the sensory-motor dysfunctions associated with latent MTPs and discusses the contribution of central sensitization associated with latent MTPs and the MTP network to the spatial propagation of pain and motor dysfunctions. Treating latent MTPs in patients with musculoskeletal pain may not only decrease pain sensitivity and improve motor functions, but also prevent latent MTPs from transforming into active MTPs, and hence, prevent the development of myofascial pain syndrome.

Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation

Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activity at myofascial trigger point originates from the extrafusal motor endplate. The spontaneous electrical activity represents focal muscle fiber contraction and/or muscle cramp potentials depending on trigger point sensitivity. Local pain and tenderness at myofascial trigger points are largely due to nociceptor sensitization with a lesser contribution from non-nociceptor sensitization. Nociceptor and non-nociceptor sensitization at myofascial trigger points may be part of the process of muscle ischemia associated with sustained focal muscle contraction and/or muscle cramps. Referred pain is dependent on the sensitivity of myofascial trigger points. Active myofascial trigger points may play an important role in the transition from localized pain to generalized pain conditions via the enhanced central sensitization, decreased descending inhibition and dysfunctional motor control strategy.