Referred pain elicited by palpation and by needling of myofascial trigger points: a comparison

Singer and songwriter: Enhancing the dual functions of the electrodiagnostic report

See article on pages 620–625 in this issue.

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.

Amplified Vasodilatation within the Referred Pain Zone of Trigger Points Is Characteristic of Gluteal Syndrome-A Type of Nociplastic Pain Mimicking Sciatica

Gluteal syndrome (GS) mimicking sciatica is a new disease that has been recently recognized and included in the International Classification of Diseases, 11th Revision. The present study examines nociplastic pain involvement in GS and sciatica patients using a new Skorupska protocol (SP) test that provokes amplified vasodilatation in the area of expected muscle-referred pain. A positive test is confirmed if there is (i) a development of autonomic referred pain (AURP) and (ii) an increase in the delta of average temperature (Δ₸°) > 0.3 °C at the end of the stimulation and during the observation SP phases. Chronic GS (n = 20) and sciatica (n = 30) patients were examined. The SP test confirmed muscle-referred pain for (i) all GS patients with 90.6% positive thermograms (Δ₸° 0.6 ± 0.8 °C; maximum AURP 8.9 ± 13.6% (both p < 0.05)) and (ii) those sciatica (n = 8) patients who reported pain sensation during the test with 20.6% positive thermograms (Δ₸° 0.7 ± 0.7 °C; maximum AURP 15.1 ± 17.8% (both p < 0.05)). The remaining sciatica (n = 22) patients did not report pain during the test and presented a Δ₸° decrease and the AURP size below 1%. Conclusion: Amplified vasodilatation suggesting nociplastic pain involvement was confirmed for all GS and sciatica patients who reported painful sensations in the zone typical for gluteus minimus referred pain during the test.

Effects of deep friction massage and dry needling therapy on night pain and shoulder internal rotation in subacromial pain syndrome: 1-year follow up of a randomised controlled trial

Background/Aims

Shoulder problems are common in the general population. The aim of this research was to compare the short and long-term effects of trigger point deep friction massage and trigger point dry needling therapy on rest, activity, and the intensity of night shoulder pain and shoulder internal rotation in Subacromial Pain Syndrome.

Methods

Out of 73 outpatients diagnosed with Subacromial Pain Syndrome, 40 were selected according to agreed criteria and were randomly assigned to two groups. A total of 19 patients received trigger point deep friction massage and 21 received trigger point dry needling therapy. The trigger point deep friction massage group received treatment over 3 weeks and the trigger point dry needling therapy group received treatments over 4 weeks. Both groups received six treatment sessions and a programme of post-treatment exercises. The shoulder internal rotation angle was measured using a goniometer, and pain intensities were measured using a visual analogue scale before the first session, after six sessions and after 1 year.

Results

According to both the short- and long-term data, significant improvements were seen in both groups for all parameters. However, when the groups were compared, no significant difference was found between the two interventions, although the trigger point deep friction massage intervention showed earlier improvements as the treatments could be carried out in 3 weeks, rather than the 4 weeks required for the trigger point dry needling therapy sessions.

Conclusions

Both trigger point deep friction massage and trigger point dry needling therapy are effective in improving pain and shoulder internal rotation. Both groups maintained significant clinical improvement throughout the year. Although both interventions produced good results, trigger point deep friction massage treatments were completed in a shorter time and so demonstrated earlier improvements. Therefore, Trigger point deep friction massage may be regarded as the preferred option, particularly as no equipment is needed and is a non-invasive method of treatment.

Myofascial pain syndrome and trigger points: evaluation and treatment in patients with musculoskeletal pain

PURPOSE OF REVIEW

Myofascial pain syndrome is a chronic pain condition characterized by the presence of myofascial trigger point, a hyperirritable painful spot involving a limited number of muscle fibers. The literature suggest that myofascial trigger points should be considered peripheral pain generators and this critical review will summarize recent findings concerning the clinical evaluation and the treatment of myofascial trigger points.

RECENT FINDINGS

The clinical features of myofascial trigger points and their contribution to the patient pain and disability have been detailed in several recent studies, which support the clinical relevance of the condition. Recent studies reported that manual palpation to identify MTrPs has good reliability, although some limitations are intrinsic to the diagnostic criteria. During the last decade, a plethora of treatments have been proposed and positive effects on pain and function demonstrated.

SUMMARY

The myofascial trigger point phenomenon has good face validity and is clinically relevant. Clinicians are encouraged to consider the contribution of myofascial trigger points to the patient's pain and disability through a careful medical history and a specific manual examination. Patients with myofascial trigger points will benefit from a multimodal treatment plan including dry needling and manual therapy techniques. Internal and external validity of research within the field must be improved.

[Efficacy of dry needling in neck pain compared with other physiotherapy techniques: A systematic review]

OBJECTIVE

To determine the efficacy of dry needling (DN) in the treatment of myofascial trigger points (MTrP) compared to other methods of physical therapy in the treatment of neck pain.

METHOD

A systematic search was carried out in the MEDLINE Complete (EBSCO), Pubmed, PEDro and Scopus databases. The quality of the studies was assessed using the standard of biases of the Cochrane Collaboration.

RESULTS

Eleven articles met the eligibility criteria. The characteristics of the participants and the results of the comparison of the application of DN with ultrasound, TENS, manual therapy techniques (passive stretching, strain-counterstrain, ischaemic pressure) and kinesiotape bandage are described.

CONCLUSION

DN was a useful technique in reducing neck pain. However, its efficacy in the treatment of cervicalgia could not be determined in comparison with other physiotherapy approaches.

Dry needling in chronic abdominal wall pain of uncertain origin

BACKGROUND

Abdominal wall pain is considered as pain that arises from the abdominal muscles rather than the underlying viscera or the spine. It is frequently overlooked and is often misdiagnosed, as these patients continue to suffer with pain. Many such patients would have even been subjected to a psychiatric evaluation in view of the absence of any ostensible clinical cause for the pain. In this study, we describe the role of myofascial trigger points in the abdominal wall pain that could be a cause of chronic pain and present our findings of pain relief by dry needling technique.

OBJECTIVES

To report the effect of dry needling treatment for patients who suffer from chronic abdominal wall pain of uncertain etiology and in whom specific myofascial trigger points were identified.

METHODS

Twelve patients diagnosed with chronic abdominal wall pain were included in the study. All patients were clinically evaluated and subjected to a combination of imaging techniques. Once categorized as patients suffering from chronic abdominal wall pain, they were subjected to a thorough palpation of the abdominal wall to identify the presence of myofascial trigger points (MTrPs) over the abdominal muscles. All had MTrPs over one or more abdominal muscles either unilaterally or bilaterally. Dry Needling using a standard technique was done based on the side and localization of the myofascial trigger points. Numerical pain rating scale (NPRS) was used to measure pain before and after treatment and at the end of four months. All patients were then seen by the primary clinician and re-evaluated.

RESULTS

Eleven out of twelve patients had significant reduction with a mean difference 5.95 in NPRS in their pain levels at four months follow up. Seven patients had complete resolution of the pain. Some patients had improvement in complaints such as Dysmenorrhea, Urinary Frequency and constipation.

CONCLUSION

Dry Needling can be a useful adjunct in treating chronic abdominal wall pain especially in those patients in whom Myofascial Trigger Points in the muscles of abdomen are identified by palpation.

LEVEL OF EVIDENCE

Level 4.

International Consensus on Diagnostic Criteria and Clinical Considerations of Myofascial Trigger Points: A Delphi Study

Objective

There is no consensus on the essential diagnostic criteria for diagnosing a trigger point (TrP). In fact, a variety of diagnostic criteria are currently being used. Our aim was to conduct a Delphi panel to achieve an international consensus on the cluster of criteria needed for the TrP diagnosis to reach a consensus on the definition of active and latent TrPs and to clarify different clinical considerations about TrPs.

Methods

Following international guidelines, an international three-round Delphi survey was conducted. Questions were created based on a systematic literature search of the diagnostic criteria for TrPs.

Results

Sixty experts from 12 countries completed all rounds of the survey. A cluster of three diagnostic criteria was proposed as essential for the TrP diagnosis: a taut band, a hypersensitive spot, and referred pain. Eighty percent of the experts agreed that the referred pain elicited by a TrP can include different sensory sensations and not just pain, that is, pain spreading to a distant area, deep pain, dull ache, tingling, or burning pain. Eighty-four percent of the international experts consistently answered that the main clinical differences between active and latent TrPs are the reproduction of any of the symptoms experienced by a patient and the recognition of pain. No specific location of the pain referral area and TrP location should be expected.

Conclusions

This Delphi panel has produced an expert-based standardized definition of a TrP with a discussion of the clinical components, including the definition of referred pain and the difference between active and latent TrPs, thereby providing a foundation for future research in MPS.

Myofascial Trigger Points: Pathophysiology and Correlation with Acupuncture Points

A review is made of recent studies on myofascial trigger points (MTrP) and their mechanism is discussed. Clinical and basic science studies have shown that there are multiple MTrP loci in a MTrP region. A MTrP locus contains a sensory component (sensitive locus) and a motor component (active locus). A sensitive locus is a point from which tenderness or pain, referred pain, and local twitch response can be elicited by mechanical stimulation. Sensitive loci (probably sensitised nociceptors) are widely distributed in the whole muscle, but are concentrated in the endplate zone. An active locus is a site from which spontaneous electrical activity can be recorded. Active loci appear to be dysfunctional endplates since spontaneous electrical activity is essentially the same as the electrical activity reported by neurophysiologists as that recorded from an abnormal endplate. A MTrP is always found in a taut band which is histologically related to contraction knots caused by excessive release of acetylcholine in abnormal endplates. Both referred pain and local twitch response are mediated through spinal cord mechanisms, as demonstrated in both human and animal studies.

The pathogenesis of MTrPs appears to be related to integration in the spinal cord of response to the disturbance of nerve endings and abnormal contractile mechanism at multiple dysfunctional endplates. There are many similarities between MTrPs and acupuncture points including their location and distribution, pain and referred pain patterns, local twitch responses (de qi), and possible spinal cord mechanism.

The local twitch response during trigger point dry needling: Is it necessary for successful outcomes?

BACKGROUND

Myofascial trigger point (MTrP) injection and trigger point dry needling (TrPDN) are widely accepted therapies for myofascial pain syndrome (MPS). Empirical evidence suggests eliciting a local twitch response (LTR) during needling is essential.

OBJECTIVE

This is the first review exploring the available literature, regardless of study design, on the neurophysiological effects and clinical significance of the LTR as it relates to reductions in pain and disability secondary to MTrP needling.

METHODS

PubMed, MEDLINE, Science Direct and Google Scholar were searched up until October 2016 using terms related to trigger point needling and the LTR.

RESULTS

and Discussion: Several studies show that eliciting a LTR does not correlate with changes in pain and disability, and multiple systematic reviews have failed to conclude whether the LTR is relevant to the outcome of TrPDN. Post needling soreness is consistently reported in studies using repeated in and out needling to elicit LTRs and increases in proportion to the number of needle insertions. In contrast, needle winding without LTRs to MTrPs and connective tissue is well supported in the literature, as it is linked to anti-nociception and factors related to tissue repair and remodeling. Additionally, the positive biochemical changes in the MTrP after needling may simply be a wash out effect related to local vasodilation. While the LTR during TrPDN appears unnecessary for managing myofascial pain and unrelated to many of the positive effects of TrPDN, further investigation is required.

Referred Pain Patterns of the Infraspinatus Muscle Elicited by Deep Dry Needling and Manual Palpation

OBJECTIVES

To identify the most common referred pain (ReP) pattern of the infraspinatus myofascial trigger point (MTrP) and compare its coincidence with the original ReP pattern, to verify whether there are any significant differences by sex and types of technique and to determine the observed signs and symptoms evoked by deep dry needling (DDN) and manual palpation (MPal).

DESIGN

A cohort study of patients randomized to two different examination methods (July and August 2016).

SETTINGS

Students and staff recruited from Miguel Hernandez University (Southeast Spain).

PATIENTS

One hundred thirty-three participants (70.7% women) with shoulder complaints were randomly assigned to either an MPal (n = 67) or DDN group (n = 66).

INTERVENTIONS

The same physiotherapist carried out the techniques on all participants, and the same protocol was followed for both the DDN and MPal groups. The physiotherapist did not ask participants about their pain features or other relevant issues.

OUTCOME MEASURES

Local twitch response (LTR) and ReP assessed through a visual analogue scale and features of ReP of the infraspinatus muscle.

RESULTS

The areas with the highest percentage of ReP were the front (area 3; 27.1%) and back (area 11; 21.1%) of the arm, anterior (area 4; 36.1%) and posterior (area 12; 42.1%) shoulder, and infraspinatus muscle area. DDN proved to be significantly easier than MPal in evoking an LTR (p ≤ 0.001). There were significant differences between sexes in zone 2 (p = 0.041) and no statistically significant differences were found by technique.

CONCLUSIONS

The ReP pattern of the infraspinatus muscle coincides with the original pattern described by Travell and Simons, although the neck area should be questioned. The study found no significant differences in the ReP pattern by sex and when comparing MPal with DDN of MTrP of the infraspinatus muscle. DDN proved to be significantly easier than MPal in evoking an LTR.

Turn-amplitude analysis as a diagnostic test for myofascial syndrome in patients with chronic pelvic pain

Myofascial pain syndrome of the pelvic floor is a common cause of chronic pelvic pain. The etiology of this neuromuscular pain disorder is unknown and symptoms can vary widely. Research attempting to identify an appropriate diagnostic test has, to date, not been fruitful. This study aimed to investigate the utility of turns-amplitude analysis, which involves analyzing electromyography data of the levator ani and anal sphincter muscles, as a diagnostic tool.

BACKGROUND:

Myofascial pain syndrome of the pelvic floor (MPSPF) is a common disease in the context of chronic pelvic pain (CPP); however, there is currently no gold-standard test to diagnose it.

OBJECTIVE:

To validate the turns-amplitude analysis (TAA) as a diagnostic test for MPSPF in patients with CPP.

METHODS:

A case-control study was performed, and patients were consecutively sampled within a specified period of time. A total of 128 patients were included: 64 patients with CPP (32 men and 32 women) and 64 control patients (32 men and 32 women). The same operator conducted all tests. Electromyography of the TAA is based on the collection of motor unit potentials that measure the number of changes in the signal and the mean amplitude of the changes. The electromyogram transfers the data to a graphical point cloud, which enables the patient’s results to be compared with the results of the healthy subjects.

RESULTS:

In patients and control subjects, the sensitivity and specificity of the proposed diagnostic test showed a marked clinical significance: the sensitivity was 83%, and the specificity was 100%. A positive predictive value of 1 (95% CI 1 to 1) and a negative predictive value of 0.85 (95% CI 0.77 to 0.93) were observed.

CONCLUSION:

TAA is a reliable diagnostic test to detect MPSPF. Further studies are needed to reproduce these results.

Comparison of Dry Needling versus Orthopedic Manual Therapy in Patients with Myofascial Chronic Neck Pain: A Single-Blind, Randomized Pilot Study

Objective. The aim of this study was to compare the efficacy of three interventions for the treatment of myofascial chronic neck pain. Methods. Thirty-six patients were randomly assigned to one of three intervention groups: orthopedic manual therapy (OMT), dry needling and stretching (DN-S), and soft tissue techniques (STT). All groups received two treatment sessions with a 48 h time interval. Outcome measures included neck pain intensity measured using a visual analogue scale, cervical range of motion (ROM), pressure pain threshold for measuring mechanical hyperalgesia, and two self-reported questionnaires (neck disability index and pain catastrophizing scale). Results. The ANOVA revealed significant differences for the group × time interaction for neck disability, neck pain intensity, and pain catastrophizing. The DN-S and OMT groups reduced neck disability. Only the OMT group showed decreases in mechanical hyperalgesia and pain catastrophizing. The cervical ROM increased in OMT (i.e., flexion, side-bending, and rotation) and DN-S (i.e., side-bending and rotation) groups. Conclusions. The three interventions are all effective in reducing pain intensity. Reduction in mechanical hyperalgesia and pain catastrophizing was only observed in the OMT group. Cervical ROM improved in the DN-S and OMT groups and also neck disability being only clinically relevant for OMT group.

Injecction of trigger points in the temporal muscles of patients with miofascial syndrome

Objective : The aim was to examine the effect of blocking trigger points in the temporal muscles of patients with masticatory myofascial pain syndrome, fibromyalgia and headache.Method : Seventy patients with one trigger point were randomly divided into 3 groups: injection with saline or anesthetic and non-injected (control).Results : Pain was reduced in 87.71% patients injected with saline and 100% injected with anesthetic. Similar results were obtained for headache frequency. With regard to headache intensity, the injection groups differed from the control group, but not between themselves.Conclusion : Treatment with injection at trigger points decreased facial pain and frequency and intensity of headache. Considering the injected substance there was no difference.

Dry needling: a literature review with implications for clinical practice guidelines

BACKGROUND

Wet needling uses hollow-bore needles to deliver corticosteroids, anesthetics, sclerosants, botulinum toxins, or other agents. In contrast, dry needling requires the insertion of thin monofilament needles, as used in the practice of acupuncture, without the use of injectate into muscles, ligaments, tendons, subcutaneous fascia, and scar tissue. Dry needles may also be inserted in the vicinity of peripheral nerves and/or neurovascular bundles in order to manage a variety of neuromusculoskeletal pain syndromes. Nevertheless, some position statements by several US State Boards of Physical Therapy have narrowly defined dry needling as an 'intramuscular' procedure involving the isolated treatment of 'myofascial trigger points' (MTrPs).

OBJECTIVES

To operationalize an appropriate definition for dry needling based on the existing literature and to further investigate the optimal frequency, duration, and intensity of dry needling for both spinal and extremity neuromusculoskeletal conditions.

MAJOR FINDINGS

According to recent findings in the literature, the needle tip touches, taps, or pricks tiny nerve endings or neural tissue (i.e. 'sensitive loci' or 'nociceptors') when it is inserted into a MTrP. To date, there is a paucity of high-quality evidence to underpin the use of direct dry needling into MTrPs for the purpose of short and long-term pain and disability reduction in patients with musculoskeletal pain syndromes. Furthermore, there is a lack of robust evidence validating the clinical diagnostic criteria for trigger point identification or diagnosis. High-quality studies have also demonstrated that manual examination for the identification and localization of a trigger point is neither valid nor reliable between-examiners.

CONCLUSIONS

Several studies have demonstrated immediate or short-term improvements in pain and/or disability by targeting trigger points (TrPs) using in-and-out techniques such as 'pistoning' or 'sparrow pecking'; however, to date, no high-quality, long-term trials supporting in-and-out needling techniques at exclusively muscular TrPs exist, and the practice should therefore be questioned. The insertion of dry needles into asymptomatic body areas proximal and/or distal to the primary source of pain is supported by the myofascial pain syndrome literature. Physical therapists should not ignore the findings of the Western or biomedical 'acupuncture' literature that have used the very same 'dry needles' to treat patients with a variety of neuromusculoskeletal conditions in numerous, large scale randomized controlled trials. Although the optimal frequency, duration, and intensity of dry needling has yet to be determined for many neuromusculoskeletal conditions, the vast majority of dry needling randomized controlled trials have manually stimulated the needles and left them in situ for between 10 and 30 minute durations. Position statements and clinical practice guidelines for dry needling should be based on the best available literature, not a single paradigm or school of thought; therefore, physical therapy associations and state boards of physical therapy should consider broadening the definition of dry needling to encompass the stimulation of neural, muscular, and connective tissues, not just 'TrPs'.

Clinical assessment of patients with orofacial pain and temporomandibular disorders

Accurate diagnosis of chronic pain disorders of the mouth, jaws, and face is frequently complex. It is common for patients with chronic orofacial pain to consult multiple clinicians and receive ineffective treatment before a correct diagnosis is reached. This problem is a significant public health concern. Clinicians can minimize error by starting the diagnostic procedure with a careful, accurate history and thorough head and neck examination followed by a thoughtfully constructed differential diagnosis. The possibility that the patient has symptoms of a life-threatening underlying disease rather than a more common dental, sinus, or temporomandibular disorder must always be considered.

Probable mechanisms of needling therapies for myofascial pain control

Myofascial pain syndrome (MPS) has been defined as a regional pain syndrome characterized by muscle pain caused by myofascial trigger points (MTrPs) clinically. MTrP is defined as the hyperirritable spot in a palpable taut band of skeletal muscle fibers. Appropriate treatment to MTrPs can effectively relieve the clinical pain of MPS. Needling therapies, such as MTrP injection, dry needling, or acupuncture (AcP) can effectively eliminate pain immediately. AcP is probably the first reported technique in treating MPS patients with dry needling based on the Traditional Chinese Medicine (TCM) theory. The possible mechanism of AcP analgesia were studied and published in recent decades. The analgesic effect of AcP is hypothesized to be related to immune, hormonal, and nervous systems. Compared to slow-acting hormonal system, nervous system acts in a faster manner. Given these complexities, AcP analgesia cannot be explained by any single mechanism. There are several principles for selection of acupoints based on the TCM principles: “Ah-Shi” point, proximal or remote acupoints on the meridian, and extra-meridian acupoints. Correlations between acupoints and MTrPs are discussed. Some clinical and animal studies of remote AcP for MTrPs and the possible mechanisms of remote effectiveness are reviewed and discussed.

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.

Evidence-based pain management: is the concept of integrative medicine applicable?

This article is dedicated to the concept of predictive, preventive, and personalized (integrative) medicine beneficial and applicable to advance pain management, overviews recent insights, and discusses novel minimally invasive tools, performed under ultrasound guidance, enhanced by model-guided approach in the field of musculoskeletal pain and neuromuscular diseases. The complexity of pain emergence and regression demands intellectual-, image-guided techniques personally specified to the patient. For personalized approach, the combination of the modalities of ultrasound, EMG, MRI, PET, and SPECT gives new opportunities to experimental and clinical studies. Neuromuscular imaging should be crucial for emergence of studies concerning advanced neuroimaging technologies to predict movement disorders, postural imbalance with integrated application of imaging, and functional modalities for rehabilitation and pain management. Scientific results should initiate evidence-based preventive movement programs in sport medicine rehabilitation. Traditional medicine and mathematical analytical approaches and education challenges are discussed in this review. The physiological management of exactly assessed pathological condition, particularly in movement disorders, requires participative medical approach to gain harmonized and sustainable effect.

Mechanical pain sensitivity of deep tissues in children--possible development of myofascial trigger points in children

BACKGROUND

It is still unclear when latent myofascial trigger points (MTrPs) develop during early life. This study is designed to investigate the mechanical pain sensitivity of deep tissues in children in order to see the possible timing of the development of latent MTrPs and attachment trigger points (A-TrPs) in school children.

METHODS

Five hundreds and five healthy school children (age 4- 11 years) were investigated. A pressure algometer was used to measure the pressure pain threshold (PPT) at three different sites in the brachioradialis muscle: the lateral epicondyle at elbow (site A, assumed to be the A-TrP site), the mid-point of the muscle belly (site B, assumed to be the MTrP site), and the muscle-tendon junction as a control site (site C).

RESULTS

The results showed that, for all children in this study, the mean PPT values was significantly lower (p < 0.05) at the assumed A-TrP site (site A) than at the other two sites, and was significantly lower (p < 0.05) at the assumed MTrP site (site B) than at the control site (site C). These findings are consistent if the data is analyzed for different genders, different dominant sides, and different activity levels.

CONCLUSIONS

It is concluded that a child had increased sensitivity at the tendon attachment site and the muscle belly (endplate zone) after age of 4 years. Therefore, it is likely that a child may develop an A-Trp and a latent MTrP at the brachioradialis muscle after the age of 4 years. The changes in sensitivity, or the development for these trigger points, may not be related to the activity level of children aged 7-11 years. Further investigation is still required to identify the exact timing of the initial occurrence of a-Trps and latent MTrPs.

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

The aim of the study is to test if sustained nociceptive mechanical stimulation (SNMS) of latent myofascial trigger points (MTrPs) induces widespread mechanical hyperalgesia. SNMS was obtained by inserting and retaining an intramuscular electromyographic (EMG) needle within a latent MTrP or a nonMTrP in the finger extensor muscle for 8 minutes in 12 healthy subjects. Pain intensity (VAS) and referred pain area induced by SNMS were recorded. Pressure pain threshold (PPT) was measured immediately before and after, and 10-, 20-, and 30-minutes after SNMS at the midpoint of the contralateral tibialis anterior muscle. Surface and intramuscular EMG during SNMS were recorded. When compared to nonMTrPs, maximal VAS and the area under VAS curve (VASauc) were significantly higher and larger during SNMS of latent MTrPs (both, P < .05); there was a significant decrease in PPT 10 minutes, 20 minutes, and 30 minutes postSNMS of latent MTrPs (all, P < .05). Muscle cramps following SNMS of latent MTrPs were positively associated with VASauc (r = .72, P = .009) and referred pain area (r = .60, P = .03). Painful stimulation of latent MTrPs can initiate widespread central sensitization. Muscle cramps contribute to the induction of local and referred pain.

PERSPECTIVE

This study shows that MTrPs are one of the important peripheral pain generators and initiators for central sensitization. Therapeutic methods for decreasing the sensitivity and motor-unit excitability of MTrPs may prevent the development of muscle cramps and thus decrease local and referred pain.

[Non-specific lower back pain: In search of the origin of pain]

Lower back pain is a condition considered benign and with a specific cause determined only in 15% of patients. In the past years this concept has varied, because many papers have described no benign condition leading to back pain, citing their capacity to cause disability. Through many different diagnostic techniques it is possible to identify the structures capable of producing back pain. This identification, and the level of evidence of the interventional techniques, is the aim of this paper.

Electrophysiologic effects of a therapeutic laser on myofascial trigger spots of rabbit skeletal muscles

OBJECTIVE

To better understand the mechanisms of therapeutic lasers for treating human myofascial trigger points, we designed a blinded controlled study of the effects of a therapeutic laser on the prevalence of endplate noise (EPN) recorded from the myofascial trigger spot (MTrS) of rabbit skeletal muscle.

DESIGN

In eight rabbits, one MTrS in each biceps femoris muscle was irradiated with a 660-nm, continuous-wave, gallium-aluminum-arsenate (GaAlAs) laser, at 9 J/cm2. The contralateral side of muscle was treated with a sham laser. Each rabbit received six treatments. The immediate and cumulative effects were assessed by the prevalence of EPN with electromyographic (EMG) recordings after the first and last treatments.

RESULTS

Compared with pretreatment values, the percentages of EPN prevalence in the experimental side after the first and last treatments were significantly reduced (P < 0.01 for both). The change in EPN prevalence in the experimental side was significantly greater than in the control side immediately after the first and last treatments (P < 0.05). However, no significant differences were noted between the first and last treatments (P > 0.05).

CONCLUSIONS

In our study, immediate and cumulative effects of a GaAlAs laser applied on MTrS were demonstrated on the basis of the assessment of EPN prevalence. It seems that laser irradiation may inhibit the irritability of an MTrS in rabbit skeletal muscle. This effect may be a possible mechanism for myofascial pain relief with laser therapy.

Evidence-informed management of chronic low back pain with trigger point injections

The management of chronic low back pain (CLBP) has proven very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing amongst available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to CLBP, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.

The evaluation of electrodermal properties in the identification of myofascial trigger points

OBJECTIVES

To determine whether skin resistance measurements can objectively identify the location of myofascial trigger points (MTPs) and to differentiate between 3 states.

DESIGN

Static group comparison.

SETTING

Climate-controlled laboratory.

PARTICIPANTS

Forty-nine participants (age, 20.5+/-2.6 y) were assigned to 1 of 3 groups based on clinical examination result: absent (n=21), latent (n=16), or active (n=12) MTP.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Skin resistance (in kilo-ohms).

RESULTS

The 16 data points were divided into 3 categories for analysis: MTP site, surrounding tissue proximal to the MTP (first ring), and area furthest from the MTP (second ring). There was a significant increase in skin resistance between the MTP (403.64+/-124.73 kOmega), first ring (419.66+/-123.04 kOmega), and second ring (454.61+/-163.19 kOmega) (P<.01). The measurements did not differ significantly between the 3 MTP states.

CONCLUSIONS

The changes in skin resistance between the MTP and the surrounding tissue support the inclusion of this technique to help identify MTPs. The similarity between MTP states warrants investigation into the physiologic differences at specific anatomic locations.

Myofascial pain syndromes and their evaluation

Myofascial pain refers to a specific form of soft-tissue rheumatism that results from irritable foci (trigger points) within skeletal muscles and their ligamentous junctions. It must be distinguished from bursitis, tendonitis, hypermobility syndromes, fibromyalgia and fasciitis. On the other hand it often exists as part of a clinical complex that includes these other soft-tissue conditions, i.e., it is not a diagnosis of exclusion. The clinical science of trigger points can be traced to the pioneering work of Kellgren in the 1930s, with his mapping of myotomal referral patterns of pain resulting from the injection of hypertonic saline into muscle and ligaments. Most muscles have characteristic myotomal patterns of referred pain; this feature forms the basis of the clinical recognition of myofascial trigger points in the form of a tender locus within a taut band of muscle which restricts the full range of motion and refers pain centrifugally when stimulated. Although myofascial pain syndromes have been described in the medical literature for about the last 100 years, it is only recently that scientific studies have revealed objective abnormalities.

Dry needling to a key myofascial trigger point may reduce the irritability of satellite MTrPs

OBJECTIVE

To investigate the changes in pressure pain threshold of the secondary (satellite) myofascial trigger points (MTrPs) after dry needling of a primary (key) active MTrP.

DESIGN

Single blinded within-subject design, with the same subjects serving as their own controls (randomized). Fourteen patients with bilateral shoulder pain and active MTrPs in bilateral infraspinatus muscles were involved. An MTrP in the infraspinatus muscle on a randomly selected side was dry needled, and the MTrP on the contralateral side was not (control). Shoulder pain intensity, range of motion (ROM) of shoulder internal rotation, and pressure pain threshold of the MTrPs in the infraspinatus, anterior deltoid, and extensor carpi radialis longus muscles were measured in both sides before and immediately after dry needling.

RESULTS

Both active and passive ROM of shoulder internal rotation, and the pressure pain threshold of MTrPs on the treated side, were significantly increased (P < 0.01), and the pain intensity of the treated shoulder was significantly reduced (P < 0.001) after dry needling. However, there were no significant changes in all parameters in the control (untreated) side. Percent changes in the data after needling were also analyzed. For every parameter, the percent change was significantly higher in the treated side than in the control side.

CONCLUSIONS

This study provides evidence that dry needle-evoked inactivation of a primary (key) MTrP inhibits the activity in satellite MTrPs situated in its zone of pain referral. This supports the concept that activity in a primary MTrP leads to the development of activity in satellite MTrPs and the suggested spinal cord mechanism responsible for this phenomenon.

Muscle pain syndromes

This article summarizes the evidence for two major clinical syndromes of muscle pain: fibromyalgia and myofascial pain syndrome. The evidence for diagnostic and treatment approaches is reviewed.

The myofascial trigger point region: correlation between the degree of irritability and the prevalence of endplate noise

OBJECTIVE

This study was designed to investigate the correlation between the irritability of the myofascial trigger point (MTrP) and the prevalence of endplate noise (EPN) in the MTrP region of human skeletal muscle.

DESIGN

Twenty normal subjects with latent MTrPs and 12 patients with active MTrPs in the upper trapezius muscles were recruited for this study. The patients reported the subjective pain intensity of the active MTrP (0-10). The MTrP and an adjacent non-MTrP site were confirmed and marked for the measurement of pressure pain threshold (with a pressure algometer) and the prevalence of EPN (with electromyographic recordings).

RESULTS

The prevalence of EPN in the MTrP regions was significantly higher (P < 0.01) in the active MTrPs than in the latent ones. However, no EPN could be found in the non-MTrP region near either the active or the latent MTrPs. The pain intensity and the pressure pain threshold were highly correlated with the prevalence of EPN in the MTrP region (r = 0.742 and -0.716, respectively).

CONCLUSIONS

The irritability of an MTrP is highly correlated with the prevalence of EPN in the MTrP region of the upper trapezius muscle. The assessment of EPN prevalence in an MTrP region may be applied to evaluate the irritability of that MTrP.

Needle electromyographic activity of myofascial trigger points and control sites in equine cleidobrachialis muscle--an observational study

BACKGROUND

Myofascial trigger points are commonly described in humans, and many studies have shown abnormal spontaneous electrical activity, spike activity and local twitch responses at these sites. Myofascial trigger points have only rarely been described in horses, and studies of their electrophysiological characteristics have not previously been published. The objective of this study was to explore the electromyographic (EMG) and other characteristics of myofascial trigger points in equine muscle, and to compare them with normal muscle tissue.

METHODS

Four horses with chronic pain signs and impaired performance were examined. They had previously been examined at the second author's practice, and showed signs compatible with the diagnosis of myofascial trigger points in their cleidobrachialis (brachiocephalic) muscle, ie localised tender spots in a taut band of skeletal muscle which produced a local twitch response on snapping palpation. They had therefore been selected for treatment with acupuncture. Needle EMG activity and twitch responses were recorded at 25 positions at the trigger point and at a nearby control point during the course of each horse's acupuncture treatment.

RESULTS

All subjects demonstrated objective signs of spontaneous electrical activity, spike activity and local twitch responses at the myofascial trigger point sites within taut bands. The frequency of these signs was significantly greater at myofascial trigger points than at control sites (P<0.05).

CONCLUSION

Equine myofascial trigger points can be identified, and have similar objective signs and electrophysiological properties to those documented in human and rabbit skeletal muscle tissue. The important differences from findings in human studies are that referred pain patterns and the reproduction of pain profile cannot be determined in animals.

Electrophysiological Assessment of Acupuncture Points

OBJECTIVE

This study was designed to assess the occurrence of end plate noise (EPN) in an acupuncture point (AcP).

DESIGN

Ten male and 10 female normal volunteers were included in this study. For each subject, mapping of the distribution of EPN loci in an AcP region of Stomach-36 in one leg selected randomly, and also in a nearby non-AcP region in the other leg as a control, was performed with electromyographic recordings.

RESULTS

There were significantly more EPN loci in the AcP region of Stomach-36 than in the non-AcP region near this AcP. Whenever the searching needle approached an EPN locus, the subjects always felt pain, soreness, or an unpleasant sensation. This feeling was rarely reported when no EPN was recorded from any site in either an AcP region or a non-AcP region. After electromyographic study, every AcP was confirmed as a myofascial trigger point.

CONCLUSIONS

Similar to the distribution of EPN loci in an MTrP region, significantly more EPN loci can be identified in an AcP region of Stomach-36 than in a nearby non-AcP site. This study provides additional support to the hypothesis that some AcPs are also myofascial trigger points.

Referred pain pattern of the pronator quadratus muscle

Pain patterns of the myofascial trigger points (TrP) for most muscles of the forearm have been documented. However, there are no published reports on the referred pain patterns for the pronator quadratus (PQ) muscle. The purpose of this study was to determine the referred pain pattern of the TrP in the PQ. Thirty-five arms of 35 healthy adult volunteers with no history of neck pain, arm pain or paresthesia were studied. Following skin sterilization, a Teflon-coated syringe needle was inserted into the PQ of the non-dominant forearm under electromyographic guidance, and 0.3mL of 6% hypertonic saline was injected. Subjects drew in their pain areas on a pain diagram, and this drawing was transferred into the Pain Chart System for analysis. Two main pain patterns were observed. The most common pattern involved pain spreading both distally and proximally from the injection site, along the medial aspect of the forearm (57%). In half of these cases, the pain area extended to the medial epicondyle proximally and the fifth digit distally. The second main pattern revealed pain spreading distally to the third and/or fourth finger (29%). The pain patterns originating from the PQ resemble the C8-T1 dermatomes, and ulnar and median nerve sensory distributions. Thus, myofascial pain of the PQ should be considered as a possible cause of pain in the medial forearm and hand, especially when no other neurological abnormalities are present.

Referred Pain Pattern of the Abductor Pollicis Longus Muscle

OBJECTIVE

To determine the referred pain pattern of the abductor pollicis longus muscle.

DESIGN

Intramuscular hypertonic saline was injected into the abductor pollicis longus of 15 healthy adults to induce muscle pain. Subjects completed pain drawings depicting the pain distribution. The drawings were transferred into the Pain Chart System for analysis.

RESULTS

Referred pain distributions were as follows: the radial aspect of the wrist (61.9%), the dorsal aspects of the third and fourth fingers (14.3%), and a combination of the two distribution patterns (23.8%).

CONCLUSION

Referred pain patterns of the abductor pollicis longus resemble the C6, 7, and 8 dermatomes, the superficial radial sensory nerve distribution, and are very similar to the area of pain experienced in de Quervain's tenosynovitis. Thus, identification of the abductor pollicis longus trigger point should be considered in pain of the radial aspect of the wrist and thumb, especially when no other neurologic abnormalities or inflammatory conditions are present.

Comparison of lidocaine injection, botulinum toxin injection, and dry needling to trigger points in myofascial pain syndrome

BACKGROUND

Myofascial pain syndrome (MPS) is one of the most common causes of chronic musculoskeletal pain. Several methods have been recommended for the inactivation of trigger points (TrP).

OBJECTIVES

This prospective, single-blind study was proposed to compare TrP injection with botulinum toxin type A (BTX-A) to dry needling and lidocaine injection in MPS.

METHODS

Eighty-seven trigger points (cervical and/or periscapular regions) in 23 female and six male patients with MPS were treated and randomly assigned to three groups: lidocaine injection (n=10, 32 TrP), dry needling (n=10, 33 TrP), and BTX-A injection (n=9, 22 TrP).

OUTCOME MEASURES

Clinical assessment including cervical range of motion, TrP pain pressure threshold (PPT), pain scores (PS), and visual analog scales for pain, fatigue, and work disability were evaluated at entry and the end of the 4th week. Additionally, depression and anxiety were evaluated with the Hamilton depression and anxiety rating scales, and quality of life was assessed using the Nottingham health profile (NHP). The subjects were also asked to describe side effects. INJECTION PROCEDURE: One milliliter of 0.5% lidocaine was administered to each TrP in the lidocaine injection group, 10-20 IU of BTX-A to each TrP in the BTX-A group, and dry needling to each TrP in the last group, followed by stretching of the muscle groups involved. The patients were instructed to continue their home exercise programs.

RESULTS

Pain pressure thresholds and PS significantly improved in all three groups. In the lidocaine group, PPT values were significantly higher than in the dry needle group, and PS were significantly lower than in both the BTX-A and dry needle groups. In all, visual analog scores significantly decreased in the lidocaine injection and BTX-A groups and did not significantly change in the dry needle group. Disturbance during the injection procedure was lowest in the lidocaine injection group. Quality of life scores assessed by NHP significantly improved in the lidocaine and BTX-A groups but not in the dry needle group. Depression and anxiety scores significantly improved only in the BTX-A-injected group.

CONCLUSIONS

Injection is more practical and rapid, since it causes less disturbance than dry needling and is more cost effective than BTX-A injection, and seems the treatment of choice in MPS. On the other hand, BTX-A could be selectively used in MPS patients resistant to conventional treatments.

Interventional approaches to the management of myofascial pain syndrome

Interventional therapies are a valuable addition to our armamentarium when treating myofascial pain syndromes. When combined with other therapies, interventional techniques can be an effective adjunct in the multidisciplinary management of pain. This article describes current interventional therapies that are employed in treating myofascial pain syndromes. The mainstay of injection therapies, the myofascial trigger point injection, is emphasized. More recent advances, such as the use of botulinum toxin, are also discussed. In addition, other techniques such as acupuncture and the use of laser therapy are mentioned.

Referred craniofacial pain patterns in patients with temporomandibular disorder

BACKGROUND

Referred pain is prevalent in the craniofacial region, and it would be helpful for dental practitioners to have drawings delineating regions with a high probability for a patient's referred pain source.

METHODS

The author applied firm pressure for approximately five seconds to trigger points, nodules of spot tenderness, and selected masticatory structures within the head and neck region on 230 patients with temporomandibular disorder, or TMD. As firm pressure was being applied, subjects were asked whether pain was developing or intensifying in a location different than that being palpated.

RESULTS

One hundred ninety-six subjects (85 percent) reported that referred pain was being generated. The cheek area, ear and forehead were the most frequently reported sites of referred pain generation; palpation over the trapezius muscle, lateral pterygoid area and masseter muscle were the most common sources of referred pain to the craniofacial region. The author provides figures displaying common referred pain sites and their sources.

CONCLUSIONS

Patients with TMD often report referred craniofacial pain arising from palpation of the head and neck region. The author found that the pattern between referred pain source and site was consistent and predictable.

PRACTICE IMPLICATIONS

Practitioners should consider craniofacial pain's propensity for referral when treating patients with TMD. Practitioners can use the figures presented to determine regions of high probability for a patient's referred pain source.

Signs and symptoms of the myofascial pain syndrome: a national survey of pain management providers

OBJECTIVE

The goal of this study was to assess clinical consensus regarding whether myofascial pain syndrome (MPS) is a legitimate and distinct diagnosis as well as the signs and symptoms characterizing MPS.

DESIGN

A standardized mailed survey with return postage provided.

SUBJECTS

A total of 1,663 American Pain Society members in medically related disciplines listed in the 1996/1997 directory.

OUTCOME MEASURES

A standardized survey assessing clinical opinion regarding whether MPS is a legitimate diagnosis, whether MPS is a clinical entity distinct from fibromyalgia, and the signs and symptoms believed to be "essential to," "associated with," or "irrelevant to" to the diagnosis of MPS.

RESULTS

Of the 403 surveys returned, 88.5% respondents reported that MPS was a legitimate diagnosis, with 81% describing MPS as distinct from fibromyalgia. The only signs and symptoms described as essential to the diagnosis of MPS by greater than 50% of the sample were regional location, presence of trigger points, and a normal neurologic examination. Regarding the signs and symptoms considered to be essential or associated with MPS, more than 80% of respondents agreed on regional location, trigger points, normal neurologic examination, reduced pain with local anesthetic or "spray and stretch," taut bands, tender points, palpable nodules, muscle ropiness, decreased range of motion, pain exacerbated by stress, and regional pain described as "dull," "achy," or "deep." Sensory or reflex abnormalities, scar tissue, and most test results were considered to be irrelevant to the diagnosis of MPS by a large proportion of the respondents.

CONCLUSIONS

There was general agreement across specialties that MPS is a legitimate diagnosis distinct from fibromyalgia. There was a high level of agreement regarding the signs and symptoms essential or associated with a diagnosis of MPS. Differences across specialties are discussed. This survey provides a first step toward the development of consensus-based diagnostic criteria for MPS, which can then be validated empirically.

Pathophysiologic and electrophysiologic mechanisms of myofascial trigger points

OBJECTIVE

To review recent clinical and basic science studies on myofascial trigger points (MTrPs) to facilitate a better understanding of the mechanism of an MTrP.

DATA SOURCES

English literature in the last 15 years regarding scientific investigations on MTrPs in either humans or animals.

STUDY SELECTION

Research works, especially electrophysiologic studies, related to the pathophysiology of MTrP.

DATA SYNTHESIS

(1) Studies on an animal model have found that a myofascial trigger spot (MTrS) in a taut band of rabbit skeletal muscle fibers is similar to a human MTrP in many aspects. (2) An MTrP or an MTrS contains multiple minute loci that are closely related to nerve fibers and motor endplates. (3) Both referred pain and local twitch response (characteristics of MTrPs) are related to the spinal cord mechanism. (4) The taut band of skeletal muscle fibers (which contains an MTrP or an MTrS in the endplate zone) is probably related to excessive release of acetylcholine in abnormal endplates.

CONCLUSION

The pathogenesis of an MTrP appears to be related to integrative mechanisms in the spinal cord in response to sensitized nerve fibers associated with abnormal endplates.