Prevalence and Anatomical Localization of Muscle Referred Pain from Active Trigger Points in Head and Neck Musculature in Adults and Children with Chronic Tension-Type Headache

The relationship between myofascial trigger points sensitivity, cervical postural abnormality, and clinical tension-type headache parameters

BACKGROUND

Myofascial Trigger Points (MTrPs) play a significant role in the pathogenesis of Tension Type Headache (TTH). Abnormal cranio-cervical posture has been linked to various types of headaches. However, the correlation between MTrPs sensitivity, cervical postural alignment, and clinical measures of headache has not been extensively studied in patients with TTH.

OBJECTIVES

To investigate the relationship between MTrPs sensitivity in cervical and pericranial muscles, cervical postural abnormality, and clinical headache parameters in patients with TTH. Furthermore, to investigate the effect of sex on the examined variables and their association with headache type (episodic vs chronic TTH).

METHODS

A total of 72 patients with TTH of both sexes were enrolled in this study. Headache frequency and disability as clinical measures of headache, pressure pain threshold (PPT) of bilateral upper trapezius (UT) and suboccipital (SUB) muscles, cervical lordosis angle (CA), and anterior head translation (AHT) were measured.

RESULTS

Pericranial MTrPs sensitivity did not demonstrate any correlation with clinical headache parameters or cervical postural abnormality. However, there was a significant correlation between the frequency of headaches and the level of disability (r = 0.32, P < 0.05). In addition, episodic TTH was more prevalent in females who exhibited greater AHT and MTrPs sensitivity of both bilateral UT and right SUB muscles than males.

CONCLUSIONS

There was no correlation found between the frequency of headaches and the level of disability with measures of cervical posture alignment or MTrPs sensitivity in individuals with TTH.. Based on findings, Clinicians should consider sex differences when assessing patients with TTH.

Does Tension Headache Have a Central or Peripheral Origin? Current State of Affairs

PURPOSE OF REVIEW

The aim of this narrative review is to analyze the evidence about a peripheral or central origin of a tension headache attack in order to provide a further clarification for an appropriate approach.

RECENT FINDINGS

Tension headache is a complex and multifactorial pathology, in which both peripheral and central factors could play an important role in the initiation of an attack. Although the exact origin of a tension headache attack has not been conclusively established, correlations have been identified between certain structural parameters of the craniomandibular region and craniocervical muscle activity. Future research should focus on improving our understanding of the pathology with the ultimate goal of improving diagnosis. The pathogenesis of tension-type headache involves both central and peripheral mechanisms, being the perpetuation over time of the headache attacks what would favor the evolution of an episodic tension-type headache to a chronic tension-type headache. The unresolved question is what factors would be involved in the initial activation in a tension headache attack. The evidence that favors a peripheral origin of the tension headache attacks, that is, the initial events occur outside the brain barrier, which suggests the action of vascular and musculoskeletal factors at the beginning of a tension headache attack, factors that would favor the sensitization of the peripheral nervous system as a result of sustained sensory input.

The Role of Manual Therapies in the Treatment of Headache Disorders

PURPOSE OF REVIEW

A comprehensive headache treatment plan typically requires both medication and non-medication treatment strategies. Manual therapies offer another therapeutic approach to headache treatment. This article reviews the evidence for manual therapies in the treatment of headache disorders.

RECENT FINDINGS

Current evidence shows potential benefit from myofascial trigger point injections, myofascial release, and massage for the treatment of various headache types. There is also evidence for strain counterstrain technique, ischemic compression, and spinal manipulative therapies for cervicogenic headache. Although larger randomized clinical trials are necessary for many of these modalities, recent findings show that manual therapies could be an important tool for the treatment of some headache disorders.

Effect of non-specific neck pain on the path of the instantaneous axis of rotation of the neck during its flexion-extension movement

Non-specific neck pain is a common musculoskeletal disorder with a high prevalence and involves impaired joint movement pattern. Therefore, this study aimed to compare the trajectory of the instantaneous axis of rotation(IAR) in flexion-extension movements of the neck between people with and without nonspecific neck pain, using functional data analysis techniques. Furthermore, possible relationships between neck kinematics and perceived pain and disability were explored. Seventy-three volunteers participated in this cross-sectional study. They were allocated in a non-specific pain group (PG, n = 28) and a control group (CG, n = 45). A cyclic flexion-extension movement was assessed by a video photogrammetry system and numerical and functional variables were computed to analyze IAR trajectory during movement. Moreover, to explore possible relationships of these variables with pain and neck disability, a visual analogue scale (VAS) and the neck disability index (NDI) were used. The instantaneous axis of rotation trajectory during the flexion-extension cyclic movement described a path like Greek letter rho both in the CG and the PG, but this trajectory was shorter and displaced upward in the PG, compared to the CG. A reduction of the displacement range and a rise in the vertical position of the IAR were related to VAS and NDI scores. Non-specific neck pain is associated with a higher location of the instantaneous axis of rotation and a decrease in length of the path traveled during the flexion-extension movement. This study contributes to a better description of neck movement in people with non-specific neck pain, which would help to plan an individualized treatment.

Location of mechanically-evoked referred sensations within the trigeminal region are not altered following a heterotopic painful stimulus

To investigate whether the location, area and frequency of referred sensations occurring during palpation of the masseter muscle can be influenced by application of a conditioning painful stimulus to the temporalis muscle. Thirty healthy participants were included in this cross-over study, performed in two sessions with > 48 h in between. At each session, palpation of the masseter muscle was performed before and after 0.2 ml of glutamate (1 mol/L) or isotonic saline (control) were injected into the anterior portion of the temporalis muscle. Palpation of the masseter muscle was done using four different forces (0.5 kg, 1 kg, 2 kg and 4 kg). Participants rated the perceived intensity of the palpation and any referred sensations on a 0-50-100 numeric rating scale, the perceived pain intensity following the injections on an electronic visual analogue scale and drew any referred sensations they experienced. No difference in referred sensations location, area and frequency was shown r during palpation either before or after injections (P > 0.05). A moderate correlation was found between perceived sensation scores and referred sensations intensity for the temporalis muscle following glutamate injection (r = 0.407, P < 0.05). Moreover, significantly more participants reported referred sensations for glutamate injections into the temporalis muscle when compared to isotonic saline (P < 0.05). Finally, a significant decrease in the perceived intensity of palpation of the masseter muscle was seen after glutamate injection in the temporalis muscle (P < 0.05). In the current study, location, area and frequency of referred sensations following mechanical stimulation of the masseter muscle were not altered by the application of a painful stimulus to the temporalis muscle. In addition, there seems to be a positive relationship between painful stimuli and referred sensations frequency and intensity elicited from the temporalis muscle.

Intramuscular Electrical Stimulation to Trigger Points: Insights into Mechanisms and Clinical Applications—A Scoping Review

Intramuscular electrical stimulation (IMES) is a modality used by clinicians to treat myofascial pain. Recent studies have shown positive results for the use of IMES on pain outcomes, yet studies investigating the potential mechanisms of IMES directly to trigger points (TrPs) are lacking. We performed a scoping review of the literature to summarize the current evidence from human and animal studies on the mechanisms of IMES to the TrP location, and to identify gaps in the existing literature. Electronic literature searches were conducted across five databases from inception to 15 August 2022, including PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Allied and Complementary Medicine Database (AMED), Scopus and Cochrane Register of Controlled Trials. Four studies met our full criteria for inclusion in this review. Three studies assessed the effects of IMES to TrPs on human subjects with MPS, and only one study used an animal model with experimentally generated TrPs. Based on the results of the included studies, IMES within a TrP region was reported to normalize muscle blood flow, decrease endplate noise of the TrP and elicit antinociceptive effects, at least partially, through engaging supraspinal descending pain inhibitory systems. At present, no clinical implications can be determined on the use of IMES to TrPs due to the limited amount and quality of the available evidence. Further studies investigating the clinical effectiveness and also underlying mechanisms of IMES to TrPs are clearly needed.

Dry Needling Alone or in Combination with Exercise Therapy versus Other Interventions for Reducing Pain and Disability in Subacromial Pain Syndrome: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis examined the effects of dry needling alone or in combination with exercise therapy for reducing pain and disability in people with subacromial pain syndrome. Systematic searches of randomized clinical trials (RCTs) were performed in five different databases. A meta-analysis was carried out with the data obtained, and the risk of bias and quality of the studies was assessed using the Cochrane ROB 2.0 and GRADE tools. Finally, five RCTs (n = 315) were included in the meta-analysis and qualitative analysis. Our results determine that dry needling alone or combined with exercise therapy showed improvements in pain in the short-term (5RCTs: SMD: -0.27; [-0.49, -0.05]; low-quality) and mid-term (4RCTs: SMD: -0.27; [-0.51, -0.04]; low-quality) compared to a range of interventions. However, no differences were shown for disability at short-term (3 RCTs: SMD: -0.97; [-2.04, 0.11]; very-low quality) and mid-term (3 RCTs: SMD: -0.85; [-1.74, 0.04]; very-low quality). Dry needling alone or in combination with exercise therapy may result in a slight reduction in pain in the short-term and mid-term. However, the evidence about the effect of this therapy on disability in the short- or mid-term is very uncertain compared to the range of interventions analyzed in this systematic review (Registration: INPLASY202260112).

The effect of suboccipital muscle inhibition and posture correction exercises on chronic tension-type headaches

BACKGROUND

Compared with healthy people, patients with chronic tension-type headache (CTTH) are likely to have forward head postures (FHP) and a higher number of active trigger points (aTrP) on the suboccipital muscle.

OBJECTIVE

This study aims to verify how the suboccipital muscle inhibition (SMI) on aTrPs and the FHP correction exercise can effectively reduce symptoms of the CTTH patients.

METHOD

The subjects of this study were 45 individuals with CTTH, divided into three groups of 15 patients each: a) the SMI group using the myofascial release technique; b) the SMIEx group subject to both the SMI therapy and FHP correction exercises; and c) the control group. Group A and B were given the relevant interventions twice a week for four consecutive weeks, and went through the headache impact test (HIT-6) and examinations on the pressure pain threshold (PPT) of the headache areas, the type and number of myofascial trigger points (TrP), the soft tissue PPT, and the posture before and after the intervention.

RESULTS

There was a significant improvement in the HIT-6, the headache PPT, the soft tissue PPT, the TrP, and the posture in Group A and B patients to whom the SMI technique and SMIEx interventions were applied. The biggest reduction and increase in the HIT-6 and the headache PPT respectively were seen in the SMIEx group.

CONCLUSION

According to this study, the SMIEx can be an effective intervention for patients with CTTH.

Standardized palpation of the temporalis muscle evoke referred pain and sensations in individuals without TMD

OBJECTIVES

This study aimed to determine if standardized palpations of the temporalis muscle evoke referred pain and/or sensations in individuals without TMD.

MATERIALS AND METHODS

This was a randomized, single-blinded study. The mechanical sensitivity of the right temporalis muscle was assessed in 32 participants without TMD with nine different stimulations to 15 test sites using palpometers (different stimulus intensities (0.5, 1.0, and 2.0 kg) and durations (2, 5, and 10 s). After each stimulus, participants were asked to score perceived pain intensity and intensity of unpleasantness on a 0-100 numeric rating scale as an indicator of mechanical sensitivity in the temporalis muscle and to indicate any areas of referred pain/sensations on a body chart.

RESULTS

Pain intensity significantly differed between palpation durations, intensities, and test sites (P < 0.001). In contrast, unpleasantness significantly differed between palparation duration and intensities (P < 0.001), but not test sites. Participants more frequently reported referred pain/sensations evoked by the 10-s (34.4%) as opposed to the 2-s (6.3%) and 5-s (15.6%) palpation duration at the 2.0-kg stimulus intensity (P < 0.05).

CONCLUSIONS

Our present results indicate that referred pain/sensations in the orofacial region can be evoked by standardized palpation of the temporalis muscle and influenced by the palpation duration in individuals without TMD.

CLINICAL RELEVANCE

Referred pain/sensations from the temporalis muscle were duration- and intensity-dependent processes originating from local stimuli.

Pain in the temple? Headache, muscle pain or both: A retrospective analysis

AIM

Headache attributed to temporomandibular disorders and myalgia are two diagnoses included in the diagnostic criteria for temporomandibular disorders (DC/TMD). However, it is not clear if these two diagnoses are different clinical entities given their similar presentation and way in which they are diagnosed, when the myalgia is within the temporalis muscle. The purpose of this retrospective study was to assess the overlap between headache attributed to temporomandibular disorders and myalgia of the temporalis muscle.

METHODS

The charts of 671 patients seeking treatment at the Section of Orofacial Pain and Jaw Function, Aarhus University, Denmark, between January 2015 and February 2020 were screened for a diagnosis of headache attributed to temporomandibular disorders, myalgia of the temporalis muscle, or both.

RESULTS

A total of 89 patients fulfilled the DC/TMD criteria for either headache attributed to TMD, myalgia of the temporalis or both. Of these, two had a diagnosis of headache attributed to TMD, 16 of myalgia of the temporalis, and 71 were diagnosed with both. In 97.3% of the times that headache attributed to temporomandibular disorders was diagnosed, the patient was also diagnosed with myalgia of the temporalis. The Jaccard index was 0.8, indicating a substantial overlap between the two diagnoses. Finally, the overlap of pain location between the two diagnoses was substantial, with a Jaccard index of 0.9.

CONCLUSIONS

In the present study, headache attributed to temporomandibular disorders was almost exclusively diagnosed together with myalgia of the temporalis. Therefore, we propose that headache attributed to temporomandibular disorders and myalgia of the temporalis muscle have more clinical similarities than differences and as such could be considered one single clinical entity. Further studies will be needed to address the clinical consequences of this proposal.

Current advances and novel research on minimal invasive techniques for musculoskeletal disorders

The present review summarized the current advances and novel research on minimal invasive techniques for musculoskeletal disorders. Different invasive approaches were proposed in the physical therapy field for the management of musculoskeletal disorders, such as ultrasound-guided percutaneous needle electrolysis, dry needling, acupuncture and other invasive therapy techniques, discussing about their worldwide status, safety and interventional ultrasound imaging. Indeed, dry needling may be one of the most useful and studies invasive physical therapy applications in musculoskeletal disorders of different body regions, such as back, upper limb, shoulder, arm, hand, pelvis, lower limb, neck, head, or temporomandibular joint, and multiple soreness location disorders, such as fibromyalgia. In addition, the assessment and treatment by acupuncture or electro-acupuncture was considered and detailed for different conditions such as plantar fasciitis, osteoarthritis, spasticity, myofascial pain syndrome, osteoporosis and rheumatoid arthritis. As an increasing technique in physical therapy, the use of ultrasound-guided percutaneous needle electrolysis was discussed in injuries of the musculoskeletal system and entrapment neuropathies. Also, ultrasound-guided percutaneous neuromodulation was established as a rising technique combined with ultrasound evaluation of the peripheral nerve system with different clinical applications which need further studies to detail their effectiveness in different musculoskeletal conditions. Thus, invasive physical therapy may be considered as a promising approach with different novel applications in several musculoskeletal disorders and a rising use in the physiotherapy field.

Electromyographic Patterns of Masticatory Muscles in Relation to Active Myofascial Trigger Points of the Upper Trapezius and Temporomandibular Disorders

The presented study aimed to analyze and compare the electromyographic patterns of masticatory muscles in subjects with active myofascial trigger points (MTrPs) within upper trapezius, patients with temporomandibular disorders (TMDs) and healthy adults. Based on the diagnostic criteria of MTrPs according to Travell & Simons and the Research Diagnostic Criteria for Temporomandibular Disorders, 167 people were qualified for the study. Subjects were divided into 3 groups: with active MTrPs in the upper trapezius, with diagnosed temporomandibular disorders (TMDs) and healthy adults. Measurements of the bioelectric activity of the temporalis anterior (TA) and masseter muscle (MM) were carried out using the BioEMG III ™. Based on statistical analysis, significantly lower values of TA resting activity were observed among controls in comparison to MTrPs (1.49 μV vs. 2.81 μV, p = 0.00) and TMDs (1.49 μV vs. 2.97 μV, p = 0.01). The POC index values at rest differed significantly between MTrPs and TMDs (86.61% vs. 105%, p = 0.04). Controls presented different electromyographic patterns within AcI in comparison to both MTrPs (4.90 vs. −15.51, p = 0.00) and TMDs (4.90 vs. −16.49, p = 0.00). During clenching, the difference between MTrPs and TMDs was observed within MVC TA (91.82% vs. 116.98%, p = 0.02). TMDs showed differences within AcI in comparison to both MTrPs group (−42.52 vs. 20.42, p = 0.01) and controls (−42.52 vs. 3.07, p = 0.00). During maximum mouth opening, differences between MTrPs and TMDs were observed within the bioelectric activity of masseter muscle (16.45 μV vs. 10.73 μV, p = 0.01), AsI MM (0.67 vs. 11.12, p = 0.04) and AcI (13.04 vs. −3.89, p = 0.01). Both the presence of MTrPs in the upper trapezius and TMDs are related to changes in electromyographic patterns of masticatory muscles.

Headache and musculoskeletal pain in school children are associated with uncorrected vision problems and need for glasses: a case-control study

Musculoskeletal pain and headache are leading causes of years lived with disability, and an escalating problem in school children. Children spend increasingly more time reading and using digital screens, and increased near tasks intensify the workload on the precise coordination of the visual and head-stabilizing systems. Even minor vision problems can provoke headache and neck- and shoulder (pericranial) pain. This study investigated the association between headaches, pericranial tenderness, vision problems, and the need for glasses in children. An eye and physical examination was performed in twenty 10–15 year old children presenting to the school health nurse with headache and pericranial pain (pain group), and twenty age-and-gender matched classmates (control group). The results showed that twice as many children in the pain group had uncorrected vision and needed glasses. Most children were hyperopic, and glasses were recommended mainly for near work. Headache and pericranial tenderness were significantly correlated to reduced binocular vision, reduced distance vision, and the need for new glasses. That uncorrected vision problems are related to upper body musculoskeletal symptoms and headache, indicate that all children with these symptoms should have a full eye examination to promote health and academic performance.

Dry needling strategies for musculoskeletal conditions: Do the number of needles and needle retention time matter? A narrative literature review

Acupuncture and dry needling are both minimally invasive procedures that use thin, filiform needles without injectate for the management of a variety of neuromusculoskeletal pain conditions. While the theoretical constructs underlying the use of acupuncture and dry needling are unique, both appear to have the ability to elicit biochemical, biomechanical, endocrinological and neurovascular changes associated with reductions in pain and disability. However, optimal treatment dosage has yet to be determined, and there is a lack of consistency in the literature on the number of needles that should be inserted and the needle retention time. Therefore, the purpose of this narrative review is to further explore the importance of these two variables. While trigger point dry needling advocates single needle insertions via repetitive, quick in-and-out pistoning, most acupuncture and dry needling clinical trials have incorporated multiple needles for five to 40 min. Notably and to date, using a single needle to repeatedly prick trigger points one at a time with fast-in and fast-out pistoning maneuvers has not yet been shown to produce significant and clinically meaningful long term improvements in pain and disability in a wide array of musculoskeletal conditions. Insertion of multiple needles for typically 20-30 min durations has been shown to produce larger treatment effect sizes and longer-lasting outcomes than brief, single-needle strategies. Moreover, the number of needles and needle retention time are two variables associated with treatment dosage and must be carefully matched with specific musculoskeletal conditions and the patient's goals.

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.

Comparison of masseter muscle referred sensations after mechanical and glutamate stimulation: a randomized, double-blind, controlled, cross-over study

Referred sensations (RS) are commonly found in various musculoskeletal pain conditions. Experimental studies have shown that RS can be elicited through glutamate injection and mechanical stimulation. Despite this, differences and similarities between these modalities in RS outcomes remain unclear. The aim of this study was to assess differences between mechanical-induced and glutamate injection-induced RS in the trigeminal region. The present randomized, double-blind, controlled, cross-over study recruited 60 healthy participants who were assessed in 2 different sessions. In both sessions, pressure was applied to the masseter muscle with 4 different forces (0.5, 1, 2, and 4 kg), and glutamate (1 mol/L or 0.25 mol/L) was injected into the same area. Participants rated their perceived masseter sensations and rated and drew any RS they experienced. No difference was found in number of participants reporting RS after glutamate injection compared with mechanical stimulation. More participants reported RS when the stimulus was painful compared with a nonpainful stimulus. Furthermore, it was shown that the more intense the stimulus, the higher the frequency of RS. Finally, RS centre-of-gravity location was similar between the 2 sessions. In summary, RS was elicited in healthy individuals through both modalities, and no differences in frequency of RS were observed in the orofacial region. Hence, RS does not seem to be modality-dependent, and only the painfulness of the stimulus caused an increase in frequency of RS. Finally, RS location for each participant was similar in both sessions possibly indicating a preferred location of referral. These findings may have implications for our understanding of RS in craniofacial pain conditions.

Myofascial trigger points in migraine and tension-type headache

BACKGROUND

A myofascial trigger point is defined as a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. It has been suggested that myofascial trigger points take part in chronic pain conditions including primary headache disorders. The aim of this narrative review is to present an overview of the current imaging modalities used for the detection of myofascial trigger points and to review studies of myofascial trigger points in migraine and tension-type headache.

FINDINGS

Different modalities have been used to assess myofascial trigger points including ultrasound, microdialysis, electromyography, infrared thermography, and magnetic resonance imaging. Ultrasound is the most promising of these modalities and may be used to identify MTrPs if specific methods are used, but there is no precise description of a gold standard using these techniques, and they have yet to be evaluated in headache patients. Active myofascial trigger points are prevalent in migraine patients. Manual palpation can trigger migraine attacks. All intervention studies aiming at trigger points are positive, but this needs to be further verified in placebo-controlled environments. These findings may imply a causal bottom-up association, but studies of migraine patients with comorbid fibromyalgia syndrome suggest otherwise. Whether myofascial trigger points contribute to an increased migraine burden in terms of frequency and intensity is unclear. Active myofascial trigger points are prevalent in tension-type headache coherent with the hypothesis that peripheral mechanisms are involved in the pathophysiology of this headache disorder. Active myofascial trigger points in pericranial muscles in tension-type headache patients are correlated with generalized lower pain pressure thresholds indicating they may contribute to a central sensitization. However, the number of active myofascial trigger points is higher in adults compared with adolescents regardless of no significant association with headache parameters. This suggests myofascial trigger points are accumulated over time as a consequence of TTH rather than contributing to the pathophysiology.

CONCLUSIONS

Myofascial trigger points are prevalent in both migraine and tension-type headache, but the role they play in the pathophysiology of each disorder and to which degree is unclarified. In the future, ultrasound elastography may be an acceptable diagnostic test.

Comparison of Pressure Pain Thresholds in Upper Trapezius and Temporalis Muscles Trigger Points Between Tension Type Headache and Healthy Participants: A Case-Control Study

OBJECTIVE

To date, the minimum clinical differences (MCDs) in the pressure pain thresholds (PPTs) of the upper trapezius and temporalis muscles have not yet been established in participants with tension-type headache (TTH). The purpose of the study was to evaluate the MCDs of the PPTs of the upper trapezius and temporalis in participants with TTH and those without TTH.

METHODS

The sample comprised 120 participants with TTH (n = 60; mean [standard deviation] years = 38.30 [10.05]) and without TTH (n = 60; 34 [8.20]). The participants were recruited from an outpatient clinic in Spain from 2014 to 2016. The PPTs of the most hyperalgesic trigger points of the upper trapezius and temporalis were assessed.

RESULTS

There were statistically significant differences, mean (standard deviation) kg/cm², for the right upper trapezius PPT (P < .001; 1.52 [0.35] vs 2.37 [0.49]), the left upper trapezius PPT (P < .001; 1.53 [0.36] vs 2.29 [0.49]), the right temporalis PPT (P = .008; 1.56 [0.31] vs 1.72 [0.33]), and the left temporalis PPT (P = .001; 1.57 [0.27] vs 1.74 [0.30]) between participants with and without TTH, respectively.

CONCLUSIONS

The PPT MCDs for the right and left upper trapezius and the right and left temporalis were 0.85, 0.76, 0.16, and 0.17 kg/cm², respectively, for the clinical management of trigger points in participants with TTH.

The prevalence of myofascial trigger points in neck and shoulder-related disorders: a systematic review of the literature

Background

Neck and shoulder disorders may be linked to the presence of myofascial trigger points (MTrPs). These disorders can significantly impact a person’s activities of daily living and ability to work. MTrPs can be involved with pain sensitization, contributing to acute or chronic neck and shoulder musculoskeletal disorders. The aim of this review was to synthesise evidence on the prevalence of active and latent MTrPs in subjects with neck and shoulder disorders.

Methods

We conducted an electronic search in five databases. Five independent reviewers selected observational studies assessing the prevalence of MTrPs (active or latent) in participants with neck or shoulder disorders. Two reviewers assessed risk of bias using a modified Downs and Black checklist. Subject characteristics and prevalence of active and latent MTrPs in relevant muscles was extracted from included studies.

Results

Seven articles studying different conditions met the inclusion criteria. The prevalence of MTrPs was compared and analysed. All studies had low methodologic quality due to small sample sizes, lack of control groups and blinding. Findings revealed that active and latent MTrPs were prevalent throughout all disorders, however, latent MTrPs did not consistently have a higher prevalence compared to healthy controls.

Conclusions

We found limited evidence supporting the high prevalence of active and latent MTrPs in patients with neck or shoulder disorders. Point prevalence estimates of MTrPs were based on a small number of studies with very low sample sizes and with design limitations that increased risk of bias within included studies. Future studies, with low risk of bias and large sample sizes may impact on current evidence.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2157-9) contains supplementary material, which is available to authorized users.

Retrospective study to identify trigeminal-cervical ocular referred pain as a new causative entity of ocular pain

Purpose

To determine the prevalence and clinical characteristics of trigeminal–cervical (TC) ocular referred pain.

Methods

A retrospective study of 1,680 patients seen during 2002–2010 was performed in an ocular surface specialty center to identify patients with or without TC pain defined as ocular pain with ipsilateral trigger points located at the occipital region. Patients with refractory TC pain despite topical anesthetics and conventional treatments received interventional injection to each trigger point.

Results

A total of 81 (4.8%) patients (study group) with TC pain and 241 patients (control group) without TC pain were identified out of the 1,680 patients over an 8 year period. There was no difference in age, gender, prior surgeries, medications, non-pain symptoms, pain laterality, and concomitant ocular diseases between the 2 groups. Multivariate regression analysis showed that patients with TC pain had a significant correlation with persistent deep ocular pain, ipsilateral trigger points (f²=99, p<0.001) but not headaches (f²=0.09, p=0.5). Injection at the trigger points achieved complete or partial pain resolution with a low recurrence rate in 43 of 45 (96%) patients with TC pain.

Conclusion

TC pain defined herein may be a different entity of ocular pain and can indeed be differentiated from other ocular pain by the referral character so that one may avoid mislabeling it as undetermined or as a reason to unnecessarily overtreat concomitant ocular diseases.

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.

Myofascial trigger point-focused head and neck massage for recurrent tension-type headache: a randomized, placebo-controlled clinical trial

OBJECTIVE

Myofascial trigger points (MTrPs) are focal disruptions in the skeletal muscle that can refer pain to the head and reproduce the pain patterns of tension-type HA (TTH). The present study applied massage focused on MTrPs of patients with TTH in a placebo-controlled, clinical trial to assess efficacy on reducing headache (HA) pain.

METHODS

Fifty-six patients with TTH were randomized to receive 12 massage or placebo (detuned ultrasound) sessions over 6 weeks, or to wait-list. Trigger point release massage focused on MTrPs in cervical musculature. HA pain (frequency, intensity, and duration) was recorded in a daily HA diary. Additional outcome measures included self-report of perceived clinical change in HA pain and pressure-pain threshold at MTrPs in the upper trapezius and suboccipital muscles.

RESULTS

From diary recordings, group differences across time were detected in HA frequency (P=0.026), but not for intensity or duration. Post hoc analysis indicated that HA frequency decreased from baseline for both massage (P<0.0003) and placebo (P=0.013), but no difference was detected between massage and placebo. Patient report of perceived clinical change was greater reduction in HA pain for massage than placebo or wait-list groups (P=0.002). Pressure-pain threshold improved in all muscles tested for massage only (all P's<0.002).

DISCUSSION

Two findings from this study are apparent: (1) MTrPs are important components in the treatment of TTH, and (2) TTH, like other chronic conditions, is responsive to placebo. Clinical trials on HA that do not include a placebo group are at risk for overestimating the specific contribution from the active intervention.

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.

Evaluation of myofascial trigger points using infrared thermography: a critical review of the literature

OBJECTIVE

The aim of this study was to review recent studies published on the use of infrared thermography for the assessment of myofascial trigger points (MTrPs).

METHODS

A search of the MEDLINE, CINAHL, PEDro, and SciELO databases was carried out between November 2012 and January 2013 for articles published in English, Portuguese, or Spanish from the year 2000 to 2012. Because of the nature of the included studies and the purpose of this review, the analysis of methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

The search retrieved 11 articles, 2 of which were excluded based on language (German and Chinese). Three were duplicated in different databases, 1 did not use infrared thermography for diagnostic purposes, and the other did not use infrared thermography to measure the skin temperature. Thus, the final sample was made up of 4 observational investigations: 3 comparative studies and 1 accuracy study.

CONCLUSION

At present, there are few studies evaluating the accuracy and reliability of infrared thermography for the diagnosis and assessment of MTrPs. Of the few studies present, there is no agreement on skin temperature patterns in the presence of MTrPs.

Changes in blood flow and cellular metabolism at a myofascial trigger point with trigger point release (ischemic compression): a proof-of-principle pilot study

OBJECTIVE

To demonstrate proof-of-principle measurement for physiologic change within an active myofascial trigger point (MTrP) undergoing trigger point release (ischemic compression).

DESIGN

Interstitial fluid was sampled continuously at a trigger point before and after intervention.

SETTING

A biomedical research clinic at a university hospital.

PARTICIPANTS

Subjects (N=2) from a pain clinic who had chronic headache pain.

INTERVENTIONS

A single microdialysis catheter was inserted into an active MTrP of the upper trapezius to allow for continuous sampling of interstitial fluid before and after application of trigger point therapy by a massage therapist.

MAIN OUTCOME MEASURES

Procedural success, pain tolerance, feasibility of intervention during sample collection, and determination of physiologically relevant values for local blood flow as well as glucose and lactate concentrations.

RESULTS

Both patients tolerated the microdialysis probe insertion into the MTrP and treatment intervention without complication. Glucose and lactate concentrations were measured in the physiologic range. After intervention, a sustained increase in lactate was noted for both subjects.

CONCLUSIONS

Identifying physiologic constituents of MTrPs after intervention is an important step toward understanding pathophysiology and resolution of myofascial pain. The present study forwards that aim by showing that proof-of-concept for collection of interstitial fluid from an MTrP before and after intervention can be accomplished using microdialysis, thus providing methodological insight toward treatment mechanism and pain resolution. Of the biomarkers measured in this study, lactate may be the most relevant for detection and treatment of abnormalities in the MTrP.