Chronic Myofascial Pain Research Articles

Does exercise increase or decrease pain? Central mechanisms underlying these two phenomena.

Exercise is an integral part of the rehabilitation of patients suffering a variety of chronic musculoskeletal conditions, such as fibromyalgia, chronic low back pain and myofascial pain. Regular physical activity is recommended for treatment of chronic pain and its effectiveness has been established in clinical trials for people with a variety of pain conditions. However, exercise can also increase pain making participation in rehabilitation challenging for the person with pain. Animal models of exercise-induced pain have been developed and point to central mechanisms underlying this phenomena, such as increased activation of NMDA receptors in pain-modulating areas. Meanwhile, a variety of basic science studies testing different exercise protocols, show exercise-induced analgesia involves activation of central inhibitory pathways. Opioid, serotonin and NMDA mechanisms acting in rostral ventromedial medulla promote analgesia associated with exercise. This review explores and discusses current evidence on central mechanisms underlying exercised-induced pain and analgesia.

Analysis of chronic myofascial pain in the upper trapezius muscle of breast cancer survivors and women with neck pain

Myofascial trigger points are present in dysfunctioning muscles and are associated with several diseases. However, the scientific literature has not established whether myofascial trigger points of differing etiologies have the same clinical characteristics. Thus, the objective of the present study was to compare the intensity of myofascial pain, catastrophizing, and the pressure pain threshold at myofascial trigger points among breast cancer survivors and women with neck pain. This was a cross-sectional study that included women over 18 years old complaining of myofascial pain in the upper trapezius muscle region for more than 90 days, equally divided into breast cancer survivors (n = 30) and those with neck pain (n = 30). For inclusion, the presence of a bilateral, active, and centrally located trigger point with mean distance from C7 to acromion in the upper trapezius was mandatory. The measures of assessment were: pain intensity, catastrophizing, and the pressure pain threshold at the myofascial trigger points. A significant difference was observed only when comparing pain intensity (p < 0.001) between the breast cancer survivors (median score: 8.00 points, first quartile: 7.00 points, third quartile: 8.75 points) and women with neck pain (median score: 2.50 points, first quartile: 2.00 points, third quartile: 4.00 points). No significant difference was found between groups in catastrophizing and pressure pain threshold. The conclusion of this study was that breast cancer survivors have a higher intensity of myofascial pain in the upper trapezius muscle when compared to patients with neck pain, which indicates the need for evaluation and a specific intervention for the myofascial dysfunction of these women.

Patient-Specific Factors Predicting Outcome of Temporomandibular Joint Arthroscopy: A 6-Year Retrospective Study

Although indications for the surgical treatment of internal derangement of the temporomandibular joint (TMJ) and the choice of treatment are debated, arthroscopy seems generally accepted as a minimally invasive alternative. The objective of this study was to investigate various factors and their possible correlation with an unsuccessful outcome of arthroscopic lysis and lavage in patients diagnosed with chronic closed lock, arthralgia with or without concomitant osteoarthritis of the TMJ, or systemic rheumatologic disease with involvement of the TMJ. A retrospective analysis of 224 operations was conducted to identify pre-, peri-, and postoperative factors correlated with an adverse outcome. Criteria for success were maximum interincisal opening (MIO) of at least 35mm and self-graded joint pain on a 10-point visual analog scale no higher than3. Surgical outcome was graded as successful (n=150; 67%), improved (n=16; 7%), minor or no improvement (n=55; 25%), or worse (n=3; 1%). Preoperative factors that correlated with a negative outcome were the presence of psychiatric disorders (P=.0333), high self-graded global pain (P=.0320), bilateral muscle tenderness at palpation (P=.0309), and small MIO (P=.0018). For patients with systemic arthritis, younger age was correlated with an unsuccessful outcome (P=.0317). The results indicate that psychiatric comorbidities, high self-graded global pain, bilateral masticatory muscle tenderness, and small MIO predict an unsuccessful outcome after arthroscopic lysis and lavage. These factors could be indicators for chronic pain disorders, including chronic myofascial pain, increased pain sensitivity, and decreased coping abilities, associated with a poor outcome.

Ischemic compression and kinesiotherapy on chronic myofascial pain in breast cancer survivors

Objectiveassess the effects of ischemic compression and kinesiotherapy on the rehabilitation of breast cancer survivors with chronic myofascial pain. MethodsA randomized, controlled, blinded clinical trial was performed with 20 breast cancer survivors with myofascial trigger point in the upper trapezius muscle. Patients were randomly allocated to ischemic compression + kinesiotherapy (G1, n = 10) and kinesiotherapy (G2, n = 10). Both groups were submitted to 10 sessions of treatment. The variables evaluated were: Numeric Rating Scale, Pain Related Self-Statement Scale, pressure pain threshold, Functional Assessment of Cancer Therapy-Breast and Infrared thermography. ResultsA significant reduction (p < 0.05) was observed in pain intensity after 10 sessions in Groups 1 and 2, a significant increase (p < 0.05) in pressure pain threshold in both the operated and non-operated side after 10 sessions for Group 1. ConclusionIschemic compression associated with kinesiotherapy increases the pressure pain threshold on the myofascial trigger point in the upper trapezius muscle and reduces the intensity of pain in breast cancer survivors with myofascial pain.

Efficacy and safety of botulinum toxin in treating chronic myofascial pain associated with masticatory hyperactivity

Efficacy and safety of botulinum toxin in treating chronic myofascial pain associated with masticatory hyperactivity

Somatosensory Evoked Potentials in Assessment of Pathological Autorhythmicity in Patients with Chronic Myofascial Pain

Objective: Objectivation of functional shifts in the nervous system through somatosensory evoked potentials at chronic nociceptive afferentation induced by the pathological neuronal autorhythmicity. Methods: Pre- and post-treatment assessment of evoked potential component parameters in patients with muscular pain and myofacsial trigger points with different pain severity. The active pre-treatment autorhythmicity was treated as the amplitude increase and any component latency reduction. The autorhythmicity regression was treated as the amplitude reduction and the latency increase. Results: Pain relief correlated with myofacsial trigger point transformation into the latent ones. As compared with the milder pain, the pronounced pain syndrome revealed more significant functional shifts (generators of autorhythmicity), prevailing at higher levels of the nervous system. However, in the milder pain, a number of low activity generators were detected that indicates an antinociceptive system under activity. After the treatment, the number of pathologically enhanced excitation generators decreased significantly with migration to caudal parts of the nerve system. Such shifts may serve as a neurophysiological basis for further myofascial pain exacerbations.

The benefits of the C1 and C2 vertebrae derotation in a patient with chronic cervical myofascial pain

Objective. The aim of this study was to present the case of a patient with chronic cervical pain and an elevated postural imbalance in the frontal plane. Method. The present case report was carried out in June 2017. The subjective assessment of the pain, the global postural assessment, the computerized baropodometry, the assessment of the walking and the biomechanics of the foot and functional tests (Fukuda, Romberg, VAD 2.7, Vasyli Medical and Sahrmann), were used to assess the postural imbalance. Results. The objective results were the immediate alignment of the cranium and underjaw to the central line of the body, a partial cancellation of the compensatory pathological curves from the area of the dorsal lumbar spine and the amplification of the laterality movement. The subjective result, as reported by the patient, was the absence of the previously felt discomfort at the active cranio-cervical mobility test, in the left laterality movement. Conclusion. The manual derotation of the C1 and C2 vertebrae resulted in efficient and long-term postural rehabilitation by canceling the fascial constraints and asymmetries at the base of the skull that maintained the postural syndrome, responsible in time for the onset of the symptomatology.

Efficacy of botulinum toxin therapy in treatment of myofascial pain.

The present study aimed to assess the efficacy of using botulinum toxin (BTX) in temporomandibular joint disorders, particularly pertaining to myofascial pain from masseter and temporal muscles. The study included 11 patients who were diagnosed with masseter and temporalis myofascial pain. Visual analog scale for pain and pressure algometry were conducted initially, after 1 month of conservative therapy (control group), and after 1 month of BTX type A injections (study group). Data were statistically analyzed (analysis of variance and Wilcoxon's test) to determine intergroup differences. Both conservative therapy and BTX injections showed reduction in pain scores and increase in pain threshold compared with baseline, and statistically significant differences were noted between both groups. Thus, BTX injections appear to be effective in management of chronic myofascial pain targeting masseter and temporalis muscles.

Patients with Concomitant Chronic Neck Pain and Myofascial Pain in Masticatory Muscles Have More Widespread Pain and Distal Hyperalgesia than Patients with Only Chronic Neck Pain.

Insufficient evidence exists to compare widespread pain (WP), pain sensibility, and psychological factors that occur in patients presenting with chronic neck pain (CNP) or a combination of temporomandibular disorder (TMD) and other complaints. The present study compared the pain sensibility and psychological factors of subjects with CNP with those with TMD + CNP. Cross-sectional study. Local community. A nonprobabilistic convenience sample of 86 persons with CNP or TMD was recruited into three groups: CNP, TMD with myofascial pain in masticatory muscles with cocomitant CNP (TMD + CNP), and asymptomatic control groups consisted of 27, 29, and 30 participants, respectively. Participants underwent a clinical examination to evaluate WP with computerized assessment based on the pain drawing, pressure pain thresholds (PPT), and psychological factors, which were evaluated using the pain catastrophizing scale (PCS) and the state-trait anxiety inventory (STAI). Statistically significant differences were observed between participants with CNP and TMD + CNP for WP (t = -2.80, P < 0.01, d = -1.06). Post hoc analyses only revealed significant differences between TMD + CNP participants and asymptomatic controls for PPT at extratrigeminal areas. Pearson correlation analyses showed a moderate positive association between symptomatic groups within the WP and STAI ( P < 0.05) and a moderate negative association between PCS and PPT ( P < 0.05) at the right tibialis muscle. TMD + CNP participants had more areas of pain and also showed widespread pain hyperalgesia. Both groups of participants had psychological factors positively associated with STAI and WP; further, PCS and the PPT at the extratrigeminal region were negatively associated with each other in both groups, except for the left tibialis in the TMD + CNP group.

The Effect of the Posture of the “Hermit Doing Body Contortion” on Relief of Shoulder and Scapular Pain Caused by Chronic Myofascial Pain Syndrome: A Randomized, Parallel Group, Controlled Trial

Objective: To explore the ability of the posture of the “Hermit Doing Body Contortion” (HDBC) to relieve shoulder and scapular pain in patients with chronic myofascial pain syndrome (MPS). Methods: One hundred and thirty-six out-patients with chronic MPS were randomly assigned to one of two groups. The experimental group was advised to perform a posture of the HDBC named “posture for relieving abdominal pain, pain of the scapular blade” (PRASP) every day for two months. Both groups received Thai traditional massage treatment and hot herbal compresses once a week for four weeks. Using a numeric rating scale and dolorimeter, outcomes were assessed prior to commencing the intervention (M 0 ), and one and two months after commencing the intervention (M 1 and M 2, ). Results: The mean change in pain intensity between M 1 and M 2 differed significantly between the groups (1.32±1.45 in the experimental group and 0.47±2.26 in the control group; p = 0.039). Similarly, the mean change in pressure pain threshold between M 0 and M 2 also differed significantly between the groups (1.39±1.76 in the experimental group and 0.53±1.90 in the control group; p-value =0.027). In both cases, the experimental group achieved greater pain relief. Conclusion: In patients with chronic MPS, the posture of the HDBC combined with standard Thai traditional medicine treatments provided better ongoing relief of shoulder and scapular pain than did standard Thai traditional medicine treatments alone. Clinical trial registration no.: TCTR20151230002

Microstructural Abnormalities Were Found in Brain Gray Matter from Patients with Chronic Myofascial Pain

Myofascial pain, presented as myofascial trigger points (MTrPs)-related pain, is a common, chronic disease involving skeletal muscle, but its underlying mechanisms have been poorly understood. Previous studies have revealed that chronic pain can induce microstructural abnormalities in the cerebral gray matter. However, it remains unclear whether the brain gray matters of patients with chronic MTrPs-related pain undergo alteration. In this study, we employed the Diffusion Kurtosis Imaging (DKI) technique, which is particularly sensitive to brain microstructural perturbation, to monitor the MTrPs-related microstructural alterations in brain gray matter of patients with chronic pain. Our results revealed that, in comparison with the healthy controls, patients with chronic myofascial pain exhibited microstructural abnormalities in the cerebral gray matter and these lesions were mainly distributed in the limbic system and the brain areas involved in the pain matrix. In addition, we showed that microstructural abnormalities in the right anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) had a significant negative correlation with the course of disease and pain intensity. The results of this study demonstrated for the first time that there are microstructural abnormalities in the brain gray matter of patients with MTrPs-related chronic pain. Our findings may provide new insights into the future development of appropriate therapeutic strategies to this disease.

Effectiveness of Dry Needling, Manual Therapy, and Kinesio Taping® for Patients with Chronic Myofascial Neck Pain: A Single-Blind Clinical Trial

Background: Chronic neck pain (CNP) is a common disorder associated with substantial morbidity. Different methods of rehabilitation are used to manage chronic myofascial neck pain. Objectives: The present study aims to assess the effects of dry needling (DN), manual therapy (MT) and Kinesio Taping® (KT) methods on the treatment of patients with chronic myofascial neck pain. Methods: Thirty-nine individuals (mean ± standard deviation (SD): Age 35 ± 10.1 years; height 178.6 ± 7.5 cm; body mass 86.9 ± 7.7 kg) out of 57 patients (age range: 18 - 55 years) were included in the current single-blinded randomized clinical trial. The subjects were assigned into 3 groups (N = 13 subjects in each group) including DN, MT, and KT. Pain intensity, pain catastrophizing scale (PCS), neck disability index (NDI), and cervical spine range of motion (CROM) in different directions were evaluated by self-reported questionnaires and cervical goniometer at baseline and following 5 treatment sessions. Following the evaluation of the normal distribution of variables by Shapiro-Wilk test, the paired-samples t-test and one-way analysis of variance (ANOVA) were used to analyze the data. Results: Pain intensity and catasrophizing, neck disability, and CROM in all directions significantly improved following the 3 interventions (P 0.05). Conclusions: It is assumed that DN, MT, and KT can improve pain and neck disability and increase CROM in patients with myofascial CNP. The MT techniques are more effective in increasing CROM for rotation compared to the other 2 methods.

WITHDRAWN: Acupuncture for neck disorders.

Neck pain is one of the three most frequently reported complaints of the musculoskeletal system. Treatments for neck pain are varied, as are perceptions of benefit. Acupuncture has been used as an alternative to more conventional treatment for musculoskeletal pain. This review summarises the most current scientific evidence on the effectiveness of acupuncture for acute, subacute and chronic neck pain. This update replaces our 2006 Cochrane review update on this topic. To determine the effects of acupuncture for adults with neck pain, with focus on pain relief, disability or functional measures, patient satisfaction and global perceived effect. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, the Manual, Alternative and Natural Therapy Index System (MANTIS), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and the Index to Chiropractic Literature (ICL) from their beginning to August 2015. We searched reference lists, two trial registers and the acupuncture database Traditional Chinese Medical Literature Analysis and Retrieval System (TCMLARS) in China to 2005. We included published trials that used random assignment to intervention groups, in full text or abstract form. We excluded quasi-randomised controlled trials (RCTs). Two review authors made independent decisions for each step of the review: article inclusion, data abstraction and assessment of quality of trial methods. We assessed study quality by using the Cochrane Back Review Group 'Risk of bias' tool. We used consensus to resolve disagreements, and when clinical heterogeneity was absent, we combined studies by using random-effects meta-analysis models. Of the 27 included studies, three represented individuals with whiplash-associated disorders (WADs) ranging from acute to chronic (205 participants), five explored chronic myofascial neck pain (186 participants), five chronic pain due to arthritic changes (542 participants), six chronic non-specific neck pain (4011 participants), two neck pain with radicular signs (43 participants) and six subacute or chronic mechanical neck pain (5111 participants).For mechanical neck pain, we found that acupuncture is beneficial at immediate-term follow-up compared with sham acupuncture for pain intensity; at short-term follow-up compared with sham or inactive treatment for pain intensity; at short-term follow-up compared with sham treatment for disability; and at short-term follow-up compared with wait-list control for pain intensity and neck disability improvement.Statistical pooling was appropriate for acupuncture compared with sham for short-term outcomes due to statistical homogeneity (P value = 0.83; I2 = 20%).Results of the meta-analysis favoured acupuncture (standardised mean difference (SMD) -0.23, 95% confidence interval (CI) -0.20 to -0.07; P value = 0.0006). This effect does not seem sustainable over the long term.Whether subsequent repeated sessions would be successfulwas not examined by investigators in our primary studies.Acupuncture appears to be a safe treatment modality, as adverse effects are minor. Reported adverse effects include increased pain, bruising, fainting, worsening of symptoms, local swelling and dizziness. These studies reported no life-threatening adverse effects and found that acupuncture treatments were cost-effective.Since the time of our previous review, the quality of RCTs has improved, and we have assessed many of them as having low risk of bias. However, few large trials have provided high-quality evidence. Moderate-quality evidence suggests that acupuncture relieves pain better than sham acupuncture, as measured at completion of treatment and at short-term follow-up, and that those who received acupuncture report less pain and disability at short-term follow-up than those on a wait-list. Moderate-quality evidence also indicates that acupuncture is more effective than inactive treatment for relieving pain at short-term follow-up.

Treatment of Myofascial Triggerpoints: A Comparison of “Spray and Stretch” and “Postisometric Relaxation”

Purpose: Referred pain from myofascial trigger points (MTrP) frequently can be found as the underlying condition in patients presenting with back pain, joint pain, or headache. The purpose of this trial was to compare the pain reduction of postisometric relaxation therapy (PIR) and spray and stretch therapy (SAS). Materials and Methods: Outpatients (24 female and 3 male) with at least one active MTrP were randomised to either SAS or PIR therapy. In both groups, every participant received 3 treatment sessions. The pressure pain threshold (PPT) was measured. Additionally, the pain level was rated by the patient using a visual analogue scale (VAS). The primary outcome was the difference in PPT at follow up after 3–4 weeks (t4) and time of randomisation (t0). As an exploratory data analysis PPT values and VAS ratings before and after each treatment session and VAS ratings at t0 and t4 have been evaluated. Results: The mean change in PPT was +22.1 kPa (SD 70.3 kPa) in the SAS group and −25.6 kPa (SD 80.5 kPa) in the PIR group. There was no significant difference between these mean values (p=0.1146). Hence no difference between these treatment options could be found. Also, the exploratory data analysis of PPT and VAS values did not suggest a difference between SAS and PIR treatments. In both groups, some patients worsened and some improved. In some cases PPT measurements and VAS ratings were inconsistent. Discussion: No difference was found between SAS and PIR, but the number of patients evaluated may have been too small to show an existing difference between the 2 treatment options. We included patients with acute myofascial pain as well as patients with chronic myofascial pain. They may react differently to treatment and should probably be evaluated separately. There may be a bias due to the change of the examiner in our trial. We can not explain the majority of women presenting with myofascial pain but this is consistent with former studies. Conclusions: Further research is necessary to reveal if either PIR or SAS therapy is more appropriate in terms of pain reduction. Patients with chronic pain and those with acute pain should be evaluated separately.

Effectiveness of botulinum toxin type A for the treatment of chronic masticatory myofascial pain: A case series

BackgroundThe aim of this study is to evaluate the effectiveness of botulinum toxin type A (BTX-A) for the treatment of chronic masticatory myofascial pain (MMP) over 12 months and to test a standardized protocol. MethodsThis is a prospective case series of consecutive adult patients with chronic MMP treated with injection of BTX-A into the bilateral temporalis and masseter muscles. The authors used the same anatomic landmarks and dosage and followed each patient for 12 months. The primary outcome variables were reduction in pain measured with visual analog scale (VAS) and Physician Global Assessment (PGA). Secondary outcome variables were change in maximum pain-free opening, change in palpatory pain points in the face and oral cavity, and change in results from a questionnaire measuring disability, dysfunction, and psychosocial effects of the disease. ResultsThe authors included 15 women and 4 men (mean [standard deviation] age, 32.7 [6.9] years) in the study. Pain decreased significantly as measured with the VAS (P < .0001) and PGA (P < .0001). Maximum pain-free opening increased significantly (P = .010), but maximum voluntary opening did not change significantly (P = .837). The number of palpatory pain points (P < .0001) and the symptom questionnaire score decreased over time (P < .0001). ConclusionsThe results of this case series suggest that injecting BTX-A into the bilateral temporalis and masseter muscles may be a safe and effective treatment for chronic MMP. Practical ImplicationsControlled clinical trials are needed to confirm whether administration of BTX-A is effective in treating facial pain.

Selenium and Zinc Status in Chronic Myofascial Pain: Serum and Erythrocyte Concentrations and Food Intake.

IntroductionNutritional disorders have been reported to be important causal factors that can intensify or cause a painful response in individuals with chronic musculoskeletal pain.AimTo assess the habitual intake of and the serum and erythrocyte levels of selenium and zinc in patients with chronic myofascial pain.Materials and MethodsA case-control study of 31 patients with chronic myofascial pain (group I) and 31 subjects without pain (group II). Dietary record in five days for assessing food intake were used. The serum and erythrocyte concentrations of selenium and zinc were analyzed using an atomic absorption spectrophotometry. Pain intensity was assessed using a visual analog scale.ResultsThe group of patients with chronic myofascial pain, compared with the control group, showed a lower erythrocyte concentration of selenium (79.46 ± 19.79 μg/L vs. 90.80 ± 23.12 μg/L; p = 0.041) and zinc (30.56 ± 7.74 μgZn/gHb vs. 38.48 ± 14.86 μgZn/gHb, respectively; p = 0.004). In this study, a compromised food intake of zinc was observed in the majority of the subjects in both groups. The selenium intake was considered to be safe in 80% of the subjects in both groups; however, the likelihood of inadequate intake of this mineral was twice as high in group I (49.5% vs. 24.4%, respectively). In the logistic regression analysis, the erythrocyte concentration of zinc was associated with the presence of pain. In each additional 1 mg of Zn2+ per gram of hemoglobin, a reduction of 12.5% was observed in the risk of the individual having chronic myofascial pain (B = -0.133; adjusted OR = 0.875, 95% CI = 0.803 to 0.954, Wald = 9.187, standard error = 0.044, p = 0.002). Physical inactivity and obesity were noted more commonly in group I compared with the control group.ConclusionIn this study, patients with chronic myofascial pain showed lower intracellular stores of zinc and selenium and inadequate food intake of these nutrients.

Change in Health-Related Quality-of-Life at Group and Individual Levels Over Time in Patients Treated for Chronic Myofascial Neck Pain

This study evaluated change in health-related quality of life at the group and individual levels in a consecutive series of patients with chronic myofascial neck pain. Fifty patients with chronic neck pain self-administered the Short Form-36 Version 2 (SF-36 v2) before treatment and 6 weeks later. Internal consistency reliability was estimated for the 8 scale scores and Mosier's formula was used to estimate reliability of the physical and mental health composite scores. Significance of group-level change was estimated using within-group t statistics. Significance of individual change was evaluated by reliable change index. Statistically significant ( P < .05) group mean improvement over time was found for all SF-36 scores. At the individual level, 20% of the possible changes were statistically significant (17% improvement, 3% decline). Estimating the significance of individual change in health-related quality of life adds important information in comparing different treatment modalities for chronic myofascial neck pain.

Brain structural changes in patients with chronic myofascial pain.

Myofascial trigger points (MTrPs) are a highly prevalent source of musculoskeletal pain. Prolonged ongoing nociceptive input from MTrPs may lead to maladaptive changes in the central nervous system. It remains, however, unknown whether pain from MTrPs is associated with brain atrophy. In addition, stress, which may contribute to the formation of MTrPs, is also known to affect brain structures. Here, we address whether structural brain changes occur in patients with chronic pain originating from MTrPs and whether such changes are related to pain or stress. Voxel-based morphometry was used to compare grey-matter (GM) volumes in 21 chronic pain patients, with MTrPs in the bilateral upper trapezius muscles, with 21 healthy controls. Hyperalgesia was assessed by pressure pain thresholds, and stress was assessed by cortisol levels and anxiety questionnaires. Patients exhibited normal stress levels but lowered pain thresholds. GM atrophy was found in dorsal and ventral prefrontal regions in patients. The GM density of the right dorsolateral prefrontal cortex correlated with pain thresholds in patients, i.e. the more atrophy, the lower pain threshold. GM atrophy was also found in the anterior hippocampus, but the atrophy was neither related to pain nor stress. Patients with chronic myofascial pain exhibit GM atrophy in regions involved in top-down pain modulation and in processing of negative affect. The relationship between the dorsolateral prefrontal cortex and pain thresholds suggests the presence of pain disinhibition. No evidence was found for the involvement of stress. It remains unclear whether the observed atrophy contributes to the development of the chronic pain state or is caused by the ongoing nociceptive input. Chronic myofascial pain, caused by myofascial trigger points, is associated with localized brain atrophy in areas involved in pain processing and modulation, among others. These findings extend previous knowledge about peripheral and spinal changes to the supraspinal level.

A Framework for Understanding the Relationship between Descending Pain Modulation, Motor Corticospinal, and Neuroplasticity Regulation Systems in Chronic Myofascial Pain.

Myofascial pain syndrome (MPS) is a leading cause of chronic musculoskeletal pain. However, its neurobiological mechanisms are not entirely elucidated. Given the complex interaction between the networks involved in pain process, our approach, to providing insights into the neural mechanisms of pain, was to investigate the relationship between neurophysiological, neurochemical and clinical outcomes such as corticospinal excitability. Recent evidence has demonstrated that three neural systems are affected in chronic pain: (i) motor corticospinal system; (ii) internal descending pain modulation system; and (iii) the system regulating neuroplasticity. In this cross-sectional study, we aimed to examine the relationship between these three central systems in patients with chronic MPS of whom do/do not respond to the Conditioned Pain Modulation Task (CPM-task). The CPM-task was to immerse her non-dominant hand in cold water (0−1°C) to produce a heterotopic nociceptive stimulus. Corticospinal excitability was the primary outcome; specifically, the motor evoked potential (MEP) and intracortical facilitation (ICF) as assessed by transcranial magnetic stimulation (TMS). Secondary outcomes were the cortical excitability parameters [current silent period (CSP) and short intracortical inhibition (SICI)], serum brain-derived neurotrophic factor (BDNF), heat pain threshold (HPT), and the disability related to pain (DRP). We included 33 women, (18–65 years old). The MANCOVA model using Bonferroni's Multiple Comparison Test revealed that non-responders (n = 10) compared to responders (n = 23) presented increased intracortical facilitation (ICF; mean ± SD) 1.43 (0.3) vs. 1.11 (0.12), greater motor-evoked potential amplitude (μV) 1.93 (0.54) vs. 1.40 (0.27), as well a higher serum BDNF (pg/Ml) 32.56 (9.95) vs. 25.59 (10.24), (P < 0.05 for all). Also, non-responders presented a higher level of DRP and decreased HPT (P < 0.05 for all). These findings suggest that the loss of net descending pain inhibition was associated with an increase in ICF, serum BDNF levels, and DRP. We propose a framework to explain the relationship and potential directionality of these factors. In this framework we hypothesize that increased central sensitization leads to a loss of descending pain inhibition that triggers compensatory mechanisms as shown by increased motor cortical excitability.

Impact of Needle Diameter on Long-Term Dry Needling Treatment of Chronic Lumbar Myofascial Pain Syndrome

To investigate the impact of diameter of needles on the effect of dry needling treatment of chronic lumbar myofascial pain syndrome. Forty-eight patients with chronic lumbar myofascial pain syndrome were randomly allocated to 3 groups. They received dry needling with needles of diameter 0.25 (group A), 0.5 (group B), and 0.9 mm (group C). Visual analog scale evaluation and health survey were conducted at baseline and 3 months after the treatment. Visual analog scale scores were significantly different in all groups from baseline to 3 months. Visual analog scale scores at 3 months showed differences between group C and the other 2 groups. When baseline and 3 months after treatment (0 day and 3 months) in each of the 3 groups was compared, there was a difference between group C and group B. The Short Form (36) Health Survey scores from baseline to 3 months were different within the treatment groups. Visual analog scale score evaluations at 3 months showed efficacy in all groups. Results of 3 months showed that efficacy of treatment with larger needles (0.9-mm diameter) was better than that of smaller ones (0.5-mm diameter). The Short Form (36) Health Survey scores at 3 months indicated that treatments with needles of varying diameters were all effective, and when the results of 3 months were compared, there was no difference between the 3 groups.