Myofascial Trigger Point-focused Head and Neck Massage for Recurrent Tension-type Headache: A Randomized, Placebo-controlled Clinical Trial Myofascial trigger point needling for whiplash associated pain--a feasibility study. Interrater reliability in myofascial trigger point examination High prevalence of shoulder girdle muscles with myofascial trigger points in patients with shoulder pain Bilateral Activation of Motor Unit Potentials with Unilateral Needle Stimulation of Active Myofascial Trigger Points Upper cervical mobility, posture and myofascial trigger points in subjects with episodic migraine: Case-control study. Dry Needling to a Key Myofascial Trigger Point May Reduce the Irritability of Satellite MTrPs Central Modulation of Pain Evoked From Myofascial Trigger Point Dry Needling Alters Trigger Points in the Upper Trapezius Muscle and Reduces Pain in Subjects With Chronic Myofascial Pain. Active myofascial trigger points might be more frequent in patients with cervical radiculopathy. Prevalence of myofascial trigger points in the hip in patellofemoral pain. Diagnostic utility of facet (zygapophysial) joint injections in chronic spinal pain: a systematic review of evidence. Medial branch neurotomy in management of chronic spinal pain: systematic review of the evidence. Proximal myofascial dysfunction in complex regional pain syndrome: a retrospective prevalence study. An in vivo microanalytical technique for measuring the local biochemical milieu of human skeletal muscle. The occurrence and inter-rater reliability of myofascial trigger points in the quadratus lumborum and gluteus medius: a prospective study in non-specific low back pain patients and controls in general practice. Local injection therapy in 107 patients with myofascial pain syndrome of the head and neck.
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 r and omized 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 Clinicians cl aim that myofascial trigger points ( MTrPs ) are a primary cause of pain in whiplash injured patients . Pain from MTrPs is often treated by needling , with or without injection . We conducted a placebo controlled study to test the feasibility of a phase III r and omised controlled trial investigating the efficacy of MTrP needling in patients with whiplash associated pain . Forty-one patients referred for physiotherapy with a recent whiplash injury , were recruited . Patients were r and omised to receive st and ardised physiotherapy plus either acupuncture or a sham needle control . A trial was judged feasible if : i ) the majority of eligible patients were willing to participate ; ii ) the majority of patients had MTrPs ; iii ) at least 75 % of patients provided completed self- assessment data ; iv ) no serious adverse events were reported and v ) the end of treatment attrition rate was less than 20 % . 70 % of those patients eligible to participate volunteered to do so ; all participants had clinical ly identified MTrPs ; a 100 % completion rate was achieved for recorded self- assessment data ; no serious adverse events were reported as a result of either intervention ; and the end of treatment attrition rate was 17 % . A phase III study is both feasible and clinical ly relevant . This study is currently being planned Abstract The myofascial trigger point ( MTrP ) is the hallmark physical finding of the myofascial pain syndrome ( MPS ) . The MTrP itself is characterized by distinctive physical features that include a tender point in a taut b and of muscle , a local twitch response ( LTR ) to mechanical stimulation , a pain referral pattern characteristic of trigger points of specific areas in each muscle , and the reproduction of the patient 's usual pain . No prior study has demonstrated that these physical features are reproducible among different examiners , thereby establishing the reliability of the physical examination in the diagnosis of the MPS . This paper reports an initial attempt to establish the interrater reliability of the trigger point examination that failed , and a second study by the same examiners that included a training period and that successfully established interrater reliability in the diagnosis of the MTrP. The study also showed that the interrater reliability of different features varies , the LTR being the most difficult , and that the interrater reliability of the identification of MTrP features among different muscles also varies Background Shoulder pain is reported to be highly prevalent and tends to be recurrent or persistent despite medical treatment . The pathophysiological mechanisms of shoulder pain are poorly understood . Furthermore , there is little evidence supporting the effectiveness of current treatment protocol s. Although myofascial trigger points ( MTrPs ) are rarely mentioned in relation to shoulder pain , they may present an alternative underlying mechanism , which would provide new treatment targets through MTrP inactivation . While previous research has demonstrated that trained physiotherapists can reliably identify MTrPs in patients with shoulder pain , the percentage of patients who actually have MTrPs remains unclear . The aim of this observational study was to assess the prevalence of muscles with MTrPs and the association between MTrPs and the severity of pain and functioning in patients with chronic non-traumatic unilateral shoulder pain . Methods An observational study was conducted . Subjects were recruited from patients participating in a controlled trial study ing the effectiveness of physical therapy on patients with unilateral non-traumatic shoulder pain .  Sociodemographic and patient-reported symptom scores , including the Disabilities of the Arm , Shoulder , and H and ( DASH ) Question naire , and Visual Analogue Scales for Pain were compared with other studies . To test for differences in age , gender distribution , and education level between the current study population and the population s from Dutch shoulder studies , the one sample T-test was used . One observer examined all subjects ( n = 72 ) for the presence of MTrPs . Frequency distributions , means , medians , st and ard deviations , and 95 % confidence intervals were calculated for descriptive purpose s. The Spearman 's rank-order correlation ( ρ ) was used to test for association between variables . Results MTrPs were identified in all subjects . The median number of muscles with MTrPs per subject was 6 ( active MTrPs ) and 4 ( latent MTrPs ) . Active MTrPs were most prevalent in the infraspinatus ( 77 % ) and the upper trapezius muscles ( 58 % ) , whereas latent MTrPs were most prevalent in the teres major ( 49 % ) and anterior deltoid muscles ( 38 % ) . The number of muscles with active MTrPs was only moderately correlated with the DASH score . Conclusion The prevalence of muscles containing active and latent MTrPs in a sample of patients with chronic non-traumatic shoulder pain was high Audette JF , Wang F , Smith H : Bilateral activation of motor unit potentialswith  unilateral needle stimulation of active myofascial trigger points . Am J Phys Med Rehabil 2004;83:368–374 . Objective : The objective of this study was to determine if there are electromyographic differences between active and latent myofascial trigger points ( MTrPs ) during trigger point needling . Design : A total of 21 subjects were recruited prospect ively . The experimental group consisted of 13 subjects who had active myofascial pain in the neck for > 6 mos . The age-matched , control group consisted of eight subjects without neck pain but with taut b and s in the cervical musculature . The active MTrPs ( or latent MTrPs in the control group ) were identified in the trapezius or levator scapulae muscles , then needle electrodes were inserted ipsilaterally into the muscle with the MTrPs and into the same muscle on the contralateral side . Electromyographic activity was recorded bilaterally with a dual-channel electromyographic machine , and local twitch responses were obtainedusinganacupuncturedryneedlingtechniqueonlyonthesideoftheactiveMTrPs . Results : We demonstrated that in subjects with active MTrPs , bilateral motor unit activation could be obtained with unilateral needle stimulation of the trigger point . In contrast , in all the subjects with latent MTrPs , only unilateral motor unit activation could be obtained in the muscle on the same side of the needle stimulation . The motor unit potentials seen on the electromyograph were similar in morphology to a fasciculation potential but more complex . Conclusion : We demonstrated bilateral or mirror-image electromyographic activity associated with unilateral needle stimulation of active MTrPs . We have found no previous mention of this phenomenon in the literature . Our study supports the concept that the perpetuation of pain and muscle dysfunction in active MTrPs may be related to abnormal central nervous system processing of sensory input at the level of the spinal cord OBJECTIVES To evaluate the association between episodic migraines and the prevalence of myofascial trigger points ( MTrPs ) in the sternocleidomastoid and upper trapezius , forward head posture ( FHP ) , neck range of motion ( ROM ) and cervical facet joint stiffness . METHODS 20 physiotherapy students with episodic migraines and 20 age- and sex matched healthy controls were included in this observational case-control study . Demographics and headache status were evaluated through question naires . Active neck ROM , presence of MTrPs , and cervical facet joint mobility were assessed by physical examination . FHP was measured using a lateral digital photograph taken in a sitting position . RESULTS No significant differences were found in neck ROM measurements and FHP between the migraine and control groups . Significant differences were found in the prevalence of cervical facet joints stiffness in Occiput-C1 ( χ(2 ) = 4.444 , p = 0.035 ) and C1-C2 ( χ(2 ) = 10.157 , p = 0.001 ) , but not in other segments . Significant differences were found in the prevalence of active and latent MTrPs between the migraine and control subjects in the right trapezius ( χ(2 ) = 11.649 , p = 0.003 ) and right sternocleidomastoid ( χ(2 ) = 8.485 , p = 0.014 ) . CONCLUSIONS Our findings support the hypothesis that the prevalence of MTrPs in neck muscles and hypomobility in the upper cervical facet joints are associated with migraines Hsieh Y-L , Kao M-J , Kuan T-S , Chen S-M , Chen J-T , Hong C-Z : Dry needling to a key myofascial trigger point may reduce the irritability of satellite myofascial trigger points . Am J Phys Med Rehabil 2007;86:397–403 . 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 ( r and omized ) . Fourteen patients with bilateral shoulder pain and active MTrPs in bilateral infraspinatus muscles were involved . An MTrP in the infraspinatus muscle on a r and omly 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 Objectives Low-intensity low-frequency electrostimulation delivered within a myofascial trigger point ( MTP ) has been used as intervention to deactivate MTPs . The therapeutic effect has been suggested to be due to peripheral mechanisms . However , nonpainful stimuli are also known to reduce simultaneous pain through central effects . The primary objective of the present study was to assess if central pain modulation occurs after intervention with low-intensity electrostimulation within an MTP . We hypothesized that intervention induces pain inhibition via the periaqueductal gray ( PAG ) . Methods Twenty-four patients with myofascial pain syndrome participated in the study . During functional magnetic resonance scanning , painful ( high-intensity ) intramuscular electrostimulation was delivered at r and om intervals ( mean interstimulus interval=10.2 s ) within an MTP of the upper left trapezius muscle . In-between scanning sessions , intervention ( intramuscular electrostimulation , low-intensity , interstimulus interval=0.5 s ) was applied to the same area . Patients were divided into responders and nonresponders according to their change in pressure pain thresholds relative to intervention . In addition to a whole brain search , a region of interest approach was also implemented to test the effect of intervention on PAG signal change . Results The main findings were : ( 1 ) intervention modulated PAG activity to painful stimuli more in responders than in nonresponders , ( 2 ) change in PAG activity from the whole patient population correlated with change in pressure pain threshold , and ( 3 ) a network known to regulate affective qualities of the pain experience was ( subsignificantly ) engaged more in responders than in nonresponders . Discussion The applied intervention most likely involves supraspinal pain control mechanisms related to both antinociception and regulation of pain affect OBJECTIVE To determine whether dry needling of an active myofascial trigger point ( MTrP ) reduces pain and alters the status of the trigger point to either a non-spontaneously tender nodule or its resolution . DESIGN A prospect i ve , nonr and omized , controlled , interventional clinical study . SETTING University campus . PARTICIPANTS A total of 56 subjects with neck or shoulder girdle pain of more than 3 months duration and active MTrPs were recruited from a campus-wide volunteer sample . Of these , 52 completed the study ( 23 male and 33 female ) . Their mean age was 35.8 years . INTERVENTIONS Three weekly dry needling treatments of a single active MTrP. MAIN OUTCOME MEASURES PRIMARY OUTCOMES Baseline and posttreatment evaluations of pain using a verbal analogue scale , the Brief Pain Inventory , and the status of the MTrP as determined by digital palpation . Trigger points were rated as active ( spontaneously painful ) , latent ( requiring palpation to reproduce the characteristic pain ) , or resolved ( no palpable nodule ) . SECONDARY OUTCOMES Profile of Mood States , Oswestry Disability Index , and Short Form 36 scores , and cervical range of motion . RESULTS PRIMARY OUTCOMES A total of 41 subjects had a change in trigger point status from active to latent or resolved , and 11 subjects had no change ( P < .001 ) . Reduction in all pain scores was significant ( P < .001 ) . SECONDARY OUTCOMES Significant improvement in posttreatment cervical rotational asymmetry in subjects as follows : unilateral/bilateral MTrPs ( P = .001 and P = 21 , respectively ) ; in pain pressure threshold in subjects with unilateral/bilateral MTrPs , ( P = .006 and P = .012 , respectively ) ; improvement in the SF-36 mental health and physical functioning subscale scores ( P = .019 and P = .03 ) , respectively ; and a decrease in the Oswestry Disability Index score ( P = .003 ) . CONCLUSIONS Dry needling reduces pain and changes MTrP status . Change in trigger point status is associated with a statistically and clinical ly significant reduction in pain . Reduction of pain is associated with improved mood , function , and level of disability BACKGROUND Myofascial trigger points ( MTrPs ) are commonly observed in the neck , parascapular region , and upper back muscles of patients with cervical pathology . AIM To assess the frequency of latent and active myofascial trigger point ( aMTrP ) in the neck and upper back muscles in patients with cervical radiculopathy and healthy subjects . DESIGN Controlled clinical trials . SETTING Out patients and controls . POPULATION Two hundred and forty four patients and 122 controls METHODS The patients clinical ly diagnosed as cervical radiculopathy with positive Spurling 's test and confirmed by MRI , were enrolled in this study . All subjects were examined for active and latent MTrP. In patients with cervical radiculopathy , an aMTrP was distinguished from a latent one when the referred pain elicited by exploration of the MTrP is recognized as familiar . RESULTS The patients comprised of 128 female ( 52.5 % ) and 116 male ( 47.5 % ) patients . Mean age was 44.58(20 - 65 years ) . In 125 ( 51.2 % ) of patients with cervical radiculopathy were found an aMTrP at least one muscle from upper trapezius , multifidus , splenius capitis , levator scapulae , rhomboid major , minor and deep paraspinal muscles . Number and distribution of MTrPs in patients with 244 cervical radiculopathy and in healthy controls .  aMTrPs were detected most common in levator scapula ( 16.3 % ) , splenius capitis ( 14.7 % ) , rhomboid minor ( 14.3 % ) , upper part of trapezius ( 13.5 % ) , rhomboid major ( 10.2 % ) and multifidus ( 8.6 % ) muscles . Patients with cervical radiculopathy showed latent MTrP in levator scapula ( 27 % ) , splenius capitis ( 16.8 % ) , rhomboid minor ( 24.6 % ) , upper part of trapezius ( 33.2 % ) , rhomboid major ( 9 % ) and multifidus ( 8.2 % ) muscles . There was significant difference in terms of distribution of active and latent MTrPs in patients with cervical radiculopathy ( P=0.019 ) . Number of latent MTrPs in upper trapezius muscles in patients with cervical radiculopathy was more than the expected distribution . None of the subjects of control group had aMTrP. However , healthy controls showed latent MTrP in levator scapula ( 33.6 % ) , splenius capitis ( 16.4 % ) , rhomboid minor ( 21.3 % ) , upper part of trapezius ( 40.2 % ) , rhomboid major ( 6.5 % ) and multifidus ( 17.2 % ) muscles . There was no significant difference in terms of distribution of latent MTrPs between cervical radiculopathy and control groups ( P=0.249 ) . The frequency of aMTrP was found to be significantly higher in CDH with median localization as compared to posterolateral herniations ( P=0.041 ) . After conservative treatment for two weeks , number of patients with active MTrP in cervical radiculopathy were decreased about 50 % . CONCLUSION Cervical root compression would be considered as the starting or maintaining factor of aMTrP. CLINICAL REHABILITATION IMPACT The treatment of cervical radiculopathy might be facilitated the improving in aMTrPs located in aforementioned muscles OBJECTIVES To determine the prevalence of myofascial trigger points ( MTrPs ) in the gluteus medius ( GMe ) and quadratus lumborum ( QL ) for subjects with patellofemoral pain ( PFP ) , and to examine the relationship between MTrPs and force production of the GMe after treatment . DESIGN R and omized controlled trial . SETTING A physical therapy clinic . PARTICIPANTS Subjects ( N=52 ; mean age ± SD , 30±12y ; mean height ± SD , 172±10 cm ; mean mass ± SD , 69±14 kg ) volunteered and were divided into 2 groups : a PFP group ( n=26 ) consisting of subjects with PFP , and a control group ( n=26 ) with no history of PFP .  INTERVENTIONS Patients with PFP received trigger point pressure release therapy ( TPPRT ) . MAIN OUTCOME MEASURES Hip abduction isometric strength and the presence of MTrPs . RESULTS Prevalence of bilateral GMe and QL MTrPs for the PFP group was significantly higher compared with controls ( P=.001 ) . Subjects in the PFP group displayed significantly less hip abduction strength compared with the control group ( P=.007 ) . However , TPPRT did not result in increased force production . CONCLUSIONS Subjects with PFP have a higher prevalence of MTrPs in bilateral GMe and QL muscles . They demonstrate less hip abduction strength compared with controls , but the TPPRT did not result in an increase in hip abduction strength BACKGROUND Chronic refractory spinal pain poses a peculiar diagnostic challenge because of multiple putative pain sources , overlapping clinical features , and nonspecific radiologic findings . Diagnostic injection techniques are employed to isolate the source ( s ) of pain . Facet or zygapophysial joint pain is an example of spinal pain diagnosed by local anesthetic injections of the facet joint or its nerve supply . Diagnostic facet joint injections are expected to meet the cardinal features of a diagnostic test ( i.e. , accuracy , safety and reproducibility ) . Accuracy must be compared with a " gold " or criterion st and ard that can confirm presence or absence of a disease . There is , however , no available gold st and ard , such as biopsy , to measure presence or absence of pain . Hence , there is a degree of uncertainty concerning the accuracy of diagnostic facet joint injections . OBJECTIVES To evaluate accuracy , safety and reproducibility of facet or zygapophysial joint injections in diagnosing chronic spinal pain of facet joint origin . STUDY DESIGN A systematic review of the literature for clinical studies on efficacy and utility of facet joint/nerve injections in diagnosing spinal pain from facet joints . METHODS Relevant literature on diagnostic facet injections was identified through data base search es . Excluded were abstract s , review s , book chapters , case reports and studies based on single blocks or blocks without radiologic control . Prospect i ve studies with placebo control , or controlled comparative local anesthetic blocks , were given priority over retrospective studies . Each study was grade d using AHRQ and QUADAS criteria . The level of evidence was classified as conclusive , strong , moderate , limited , or inconclusive . RESULTS Available literature pointed to strong evidence for controlled comparative local anesthetic facet joint medial branch blocks in the diagnosis of neck and low back pain . There was moderate evidence in the diagnosis of pain arising from thoracic facet joints . CONCLUSION The evidence obtained from literature review suggests that controlled comparative local anesthetic blocks of facet joint nerves ( medial branch or dorsal ramus ) are reproducible , reasonably accurate , and safe . The sensitivity , specificity , false-positive rates , and predictive values of these diagnostic tests for neck and low back pain have been vali date d and reproduced in multiple studies Zygapophysial or facet joints have been implicated as cause of low back , mid back , upper back and neck pain with referred pain . Cervical , thoracic and lumbar facet joints are innervated by the medial branches of the dorsal rami . Zygapophysial ( facet ) joints have been implicated as the source of chronic pain in 15 % to 45 % of the patients with chronic low back pain , 54 % to 60 % of the patients with chronic neck pain and 48 % of the patients with thoracic pain . A systematic review of the evidence of effectiveness of radiofrequency denervation in the management of chronic spinal pain was undertaken . This review included r and omized clinical trials , as well as non-r and omized or observational studies in the analysis . Literature search included MEDLINE , EMBASE , systematic review s , narrative review s , cross-references to the review s and various published trials ; and peer review ed abstract s from scientific meetings during the past two years . An algorithmic approach was followed in study evaluation with a description of inclusion and exclusion criteria . A set of high-performing scales or checklists pertaining to r and omized clinical trials and observational trials derived from the Agency for Healthcare Research and Quality ( AHRQ ) was utilized ; Systems to Rate the Strength of Scientific Evidence . Qualitative analysis was conducted , using five levels of evidence for effectiveness of medial branch neurotomy . Our search strategy identified over 1,000 citations as the result of electronic and manual screening . A total of 7 r and omized trials of radiofrequency neurotomy for spinal pain were identified . However , only 4 related to medial branch neurotomy . Two of the four met the inclusion criteria . Among the multiple observational studies considered for inclusion , 4 prospect i ve evaluations were included in the systematic review . In addition , 3 retrospective evaluations were also included . Two r and omized trials comprised of 27 patients receiving active treatment . The first study consisted of cervical facet joint pain and the second consisted of lumbar facet joint pain . Both studies showed positive results . Similar to r and omized trials , prospect i ve , as well as retrospective evaluations showed positive evidence , both in short-term and long-term . The results of this systematic review of 2 well- design ed r and omized trials , 4 prospect i ve well- design ed trials without r and omization and 3 retrospective evaluations provided strong evidence that radiofrequency denervation offers short-term relief and moderate evidence of long-term pain relief of facet joint origin OBJECTIVE To assess the prevalence of clinical ly evident myofascial dysfunction ( MD ) and its relationship to motor neglect ( MN ) in Complex Regional Pain Syndrome ( CRPS ) . DESIGN Retrospective chart review . PATIENTS Forty-one consecutively evaluated CRPS patients . OUTCOME MEASURES ( a ) Prevalence of trigger points in the proximal musculature of the CRPS limb . ( b ) Prevalence of MN in a subset ( n = 34 ) . RESULTS MD was detected in 61 % of CRPS patients . It was more prevalent in the upper limb ( 70 % ) than in the lower limb ( 47 % ) . MN was more common in those who also had MD . CONCLUSION MD is common in CRPS patients , especially in the upper limb and in those patients with MN . Prospect i ve trials are needed to confirm these intriguing findings , which may have important implication s regarding CRPS pathophysiology and treatment Myofascial pain associated with myofascial trigger points ( MTrPs ) is a common cause of nonarticular musculoskeletal pain . Although the presence of MTrPs can be determined by soft tissue palpation , little is known about the mechanisms and biochemical milieu associated with persistent muscle pain . A microanalytical system was developed to measure the in vivo biochemical milieu of muscle in near real time at the subnanogram level of concentration . The system includes a microdialysis needle capable of continuously collecting extremely small sample s ( approximately 0.5 microl ) of physiological saline after exposure to the internal tissue milieu across a 105-microm-thick semi-permeable membrane . This membrane is positioned 200 microm from the tip of the needle and permits solutes of < 75 kDa to diffuse across it . Three subjects were selected from each of three groups ( total 9 subjects ) : normal ( no neck pain , no MTrP ) ; latent ( no neck pain , MTrP present ) ; active ( neck pain , MTrP present ) . The microdialysis needle was inserted in a st and ardized location in the upper trapezius muscle . Due to the extremely small sample size collected by the microdialysis system , an established microanalytical laboratory , employing immunoaffinity capillary electrophoresis and capillary electrochromatography , performed analysis of selected analytes . Concentrations of protons , bradykinin , calcitonin gene-related peptide , substance P , tumor necrosis factor-alpha , interleukin-1beta , serotonin , and norepinephrine were found to be significantly higher in the active group than either of the other two groups ( P < 0.01 ) . pH was significantly lower in the active group than the other two groups ( P < 0.03 ) . In conclusion , the described microanalytical technique enables continuous sampling of extremely small quantities of substances directly from soft tissue , with minimal system perturbation and without harmful effects on subjects . The measured levels of analytes can be used to distinguish clinical ly distinct groups The presence of a trigger point is essential to the myofascial pain syndrome . This study centres on identifying clearer criteria for the presence of trigger points in the quadratus lumborum and gluteus medius muscle by investigating the occurrence and inter-rater reliability of trigger point symptoms . Using the symptoms and signs as described by Simons ' 1990 definition and two other former sets of criteria , 61 non-specific low back pain patients and 63 controls were examined in general practice by 5 observers , working in pairs . From the two major criteria of Simons ' 1990 definition only ' localized tenderness ' has good discriminative ability and inter-rater reliability ( kappa > 0.5 ) . This study does not find proof for the clinical usefulness of ' referred pain ' , which has neither of these two abilities . The criteria ' jump sign ' and ' recognition ' , on the condition that localized tenderness is present , also have good discriminative ability and inter-rater reliability . Trigger points defined by the criteria found eligible in this study allow significant distinction between non-specific low back pain patients and controls . This is not the case with trigger points defined by Simons ' 1990 criteria . Concerning reliability there is also a significant difference between the two different criteria sets . This study suggests that the clinical usefulness of trigger points is increased when localized tenderness and the presence of either jump sign or patient 's recognition of his pain complaint are used as criteria for the presence of trigger points in the M. quadratus lumborum and the M. gluteus medius Myofascial pain syndrome of the head and neck is a frequent cause of facial pain and is characterized by tender trigger points . In a double-blind study of 107 patients , local injection therapy using one of three solutions was applied at the trigger points by intracutaneous injection of 0.3 ml solution followed by deep infiltration of the site . Results using bupivacaine 0.25 % , lignocaine 1 % and saline 0.9 % were compared . There was no significant difference among groups with respect to reduction of pain and overall rating by patients of the therapeutic benefits . Fifty-three patients ( 49 % ) were free of symptoms after treatment , 40 patients ( 38 % ) reported substantial relief and in 14 patients ( 13 % ) symptoms remained unchanged . The findings suggest that relief of pain is mainly due to reflex mechanisms rather than to the pharmacological effects of the injected solutions . Physiological saline solution is recommended for use in local injection therapy
Within spinal pain , patients with neck pain were found to have the highest prevalence rates of MTrPs .
The trapezius descendens , levator scapulae , and suboccipitales muscles were the most prevalent locations for active MTrPs in patients with neck pain .
Latent MTrPs were present in asymptomatic people , but no significant differences were found in the prevalence rate of latent MTrPs between patients with spinal ( neck ) pain and healthy controls .
The only study investigating prevalence of MTrPs in different localizations of the same muscle reported no significant differences in prevalence between active and latent MTrPs within the trapezius descendens muscle .
Studies examining pathophysiological mechanisms underlying MTrPs demonstrated an acidic environment , high concentration of algogenic/inflammatory substances , stiffer muscle tissue , retro grade diastolic blood flows , spontaneous muscle activity at rest , and loss of muscle contractibility in muscles with MTrPs .
Altered central processing was also found to play a role in the development of MTrPs .
Myofascial trigger points are a prevalent clinical entity , especially in patients with neck pain .
Evidence was not found to support or deny the role of MTrPs in other spinal pain .
Compelling evidence supports local mechanisms underlying MTrPs .
OBJECTIVE A systematic review was performed to evaluate the existing evidence related to the prevalence , incidence , localization , and pathophysiology of myofascial trigger points ( MTrPs ) in patients with spinal ( back and neck ) pain .