Central pain mechanisms in chronic pain states--maybe it is all in their head

Embodiment in Virtual Reality for the Treatment of Chronic Low Back Pain: A Case Series

Purpose

We describe two case studies that use embodiment in virtual reality as a treatment for chronic low back pain. The purpose of this case series was to determine the feasibility of a novel virtual reality-based digital therapeutic for the treatment of chronic pain.

Patients and Methods

Two patients with chronic low back pain received seven sessions, two sessions per week, of a novel digital therapeutic that combines virtual embodiment with graded motor imagery to deliver functional rehabilitation exercises using an off-the-shelf virtual reality system. Pain intensity was measured using a visual analog scale before and after each session to get an indication whether individual sessions of virtual embodiment training decrease pain intensity. Pain catastrophizing scale was assessed before the first session and after the seventh session to determine the extent to which virtual embodiment training can improve psychological symptoms of chronic low back pain.

Results

In both patients, pain intensity was improved after individual sessions of virtual embodiment training as measured by a paired t-test: (Patient A: t = 2.890, P < 0.05) and (Patient B: t = 5.346, P < 0.005). This indicates that individual sessions of virtual embodiment training decrease pain intensity. In both patients, improvements were observed in three subscales of the pain catastrophizing scale (rumination, magnification, and helplessness). This indicates that virtual embodiment training may have benefits for chronic pain symptoms such as pain intensity, pain-related mobility impairment, and disability.

Conclusion

This case series provides evidence that embodiment in virtual reality improves symptoms of persistent chronic low back pain. We propose a mechanism by which virtual embodiment may improve chronic pain symptoms by recontextualizing sensory feedback from the body as patients engage in functional rehabilitation exercises while in virtual reality.

Syrian female war refugees: preliminary fibromyalgia and insomnia screening and treatment trends

BACKGROUND

Fibromyalgia (FM) is a chronic disorder characterised by chronic widespread pain, fatigue and sleep disturbances with higher prevalence in females. Psychological factors contribute largely to FM. Although women war refugees represent a fragile population that is prone to psychological distress, FM was not studied in this population.

OBJECTIVE

The current study had three objectives: (1) to screen FM and insomnia prevalence and severity, (2) to study the correlation between FM severity and insomnia and (3) to study FM treatment trends and their concordance with the guidelines among female Syrian refugees residing in Jordan.

METHODS

A cross-sectional study design was performed. Data from 384 Syrian female were analysed from four medical centres in Jordan. The Fibromyalgia Impact Questionnaire (FIQ) was used to study FM prevalence. Structured questions were designed to explore FM pharmacotherapeutic trend, and the Insomnia Severity Index (ISI) was used to screen insomnia.

RESULTS

The prevalence of severe FM was about (30%), with a significant correlation with insomnia. Acetaminophen was used for FM relief in 60% of the study sample.

CONCLUSIONS

Fibromyalgia prevalence is high among female refugees and is associated with insomnia. The treatment is suboptimal. The early screening and raising awareness of FM diagnosis and treatments are highly recommended. Key Points Fibromyalgia is an overlooked disorder especially among female war refugees The prevalence of severe fibromyalgia was about (30%), with a significant correlation with insomnia Fibromyalgia among the Syrian female refugees is mistreated perhaps due to lack of the proper diagnosis.

Evaluating sensory profiles in nociplastic chronic low back pain: a cross-sectional validation study

BACKGROUND

Sensory profiles (SPs) may be useful in classifying patients based on sensory sensitivity and behavioral responses to stimuli to develop personalized treatments for nonspecific chronic low back pain (CLBP). The Adolescent/Adult Sensory Profile (AASP) identifies four sensitivity and behavioral response-related quadrants: Sensory Sensitive, Sensation Avoiding, Low Registration, and Sensation Seeking. It is an appropriate questionnaire for evaluating SPs; however, it has not been validated in CLBP.

OBJECTIVES

To assess the internal consistency, test-retest reliability, agreement, and construct validity of the AASP in a CLBP population with nociplastic pain in primary care physiotherapy.

DESIGN

Two evaluations were performed at a 2-week interval in this non-experimental cross-sectional study.

PARTICIPANTS

Patients with CLBP.

METHODS

Questionnaires were used to compare outcomes with the AASP. Reliability was evaluated by assessing internal consistency and test-retest reliability. Construct validity was evaluated in response to the a priori hypothesis.

RESULTS

Ninety patients with CLBP were included. Internal consistency was excellent for all SPs (Cronbach's alpha, 0.91-0.92). Test-retest reliability Intraclass Correlation Coefficient (ICC (3,2)) 0.82-0.87, for the SPs (95% CI 0.74-0.91, p< .001). Construct validity correlated positively with Low Registration, Sensory Sensitive, and Sensation Avoiding and negatively with Sensation Seeking.

CONCLUSION

The AASP is suitable for evaluating SPs in primary care CLBP patients.

Interdisciplinary Teams in Endometriosis Care

Endometriosis-associated chronic pelvic pain can at times be a complex problem that is resistant to standard medical and surgical therapies. Multiple comorbidities and central sensitization may be at play and must be recognized with the help of a thorough history and physical examination. If a complex pain problem is identified, most endometriosis expert reviews and guidelines recommend multidisciplinary care. However, there are no specific recommendations about what should be the components of this approach and how that type of team care should be delivered. There is evidence showing the effectiveness of specific interventions such as pain education, physical therapy, psychological therapies, and pharmacotherapies for the treatment of chronic pain. Interdisciplinary team models have been well studied and validated in other chronic pain conditions such as low back pain. The published evidence in support of interdisciplinary teams for endometriosis-associated chronic pain is more limited but appears promising. Based on the available evidence, a model for an interdisciplinary team approach for endometriosis care is outlined.

Tai Chi exercise can ameliorate physical and mental health of patients with knee osteoarthritis: systematic review and meta-analysis

OBJECTIVE

To systematically review the effects of Tai Chi exercise as a nonpharmacological therapeutic strategy on the physical and mental health in individuals with knee osteoarthritis.

DATA SOURCES

A systematic literature retrieval has been conducted in PubMed, Web of Science, EMbase, CENTRAL, OVID, CINAHL, Physiotherapy Evidence Database, Chinese Biomedical Database and China National Knowledge Infrastructure up to June 2020 to identify the relevant randomised controlled trials (RCTs).

METHODS

Two authors assessed independently the risk of bias using the Cochrane Collaboration's tool. Standardised mean difference (SMD) and 95% CI were calculated and data were combined using the fixed or random-effect model. The strength of evidence was rated with Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

A total of 16 RCTs involving 986 patients with knee osteoarthritis met the established inclusion criteria. The strength of evidence for the main outcomes was low or moderate. The systematic review illustrated the efficacy of Tai Chi exercise in treating and managing knee osteoarthritis. Patients' outcomes practising Tai Chi exercise were improved significantly, including pain (SMD = ‒0.69, 95%CI: ‒0.95 to ‒0.44, P < 0.001), stiffness (SMD = ‒0.59, 95%CI: ‒0.91 to ‒0.27, P < 0.001), physical function (SMD = ‒0.92, 95%CI: -1.16 to ‒0.69, P < 0.001), dynamic balance (SMD = 0.69, 95%CI: 0.38 to 0.99, P < 0.001), physiological and psychological health (SF-36 PCS: SMD = 0.48, 95%CI: 0.28 to 0.68, P < 0.001; SF-36 MCS: SMD = 0.26, 95%CI: 0.06 to 0.45, P = 0.01). No adverse events associated with Tai Chi exercise were reported.

CONCLUSION

Tai Chi exercise was beneficial for ameliorating physical and mental health of patients with knee osteoarthritis and should be available as an alternative non-pharmacological therapy in rehabilitation programmes.

Complaints of neuropathic pain, noxious cervical plexus neuropathy and neck tightness are reported by patients who undergo neck dissection: an institutional study and narrative review

There exists a subgroup of patients who undergo neck dissection (ND) who postoperatively complain of either neuropathic pain, dysaesthesia and/or discomfort that is located within the dermatomal distribution of the cervical plexus. The purpose of our study was to determine the prevalence, characteristic, and demographics of these symptoms in our patient cohort. We undertook a retrospective randomised observational cohort study of 105 patients who had undergone ND. The primary predictor variable was the undertaking of a ND. The secondary outcome variable was the complaint of either neuropathic pain or a noxious neuropathy, at a minimum of twelve months after surgery. A recognised symptom questionnaire and a visual analogue score was employed for the purpose of the study. A descriptive and statistical analysis was applied to the assembled data. Twenty patients (19%) complained of either spontaneous (n=9) or evoked (n=11) neuropathic pain that occurred within the surgical site. In addition, 71 patients (68%) described an altered sensation in the dermatomal distribution of the great auricular or tranverse cervical nerves while 70 patients (67%) described the feeling of 'neck tightness'. There were no characteristics of the study cohort that underpinned these results. Neuropathic pain can occur following ND. This can cause distress to a small but defined group of patients. Despite its importance, we found a paucity of studies in the literature that have investigated neuropathic pain following ND. We believe this condition requires more research attention and clinical awareness.

The Overactive Pelvic Floor (OPF) and Sexual Dysfunction. Part 2: Evaluation and Treatment of Sexual Dysfunction in OPF Patients

INTRODUCTION

The assessment of pelvic floor muscle (PFM) overactivity is part of a comprehensive evaluation including a detailed history (medical, gynecological history/antecedent), appraisal of the psychosocial contexts of the patient, as well as a musculoskeletal and a neurological examination.

OBJECTIVES

The aims of this article are to review (i) the assessment modalities evaluating pelvic floor function in women and men with disorders associated with an overactive pelvic floor (OPF), and (ii) therapeutic approaches to address OPF, with particular emphases on sexual pain and function.

METHODS

We outline assessment tools that evaluate psychological and cognitive states. We then review the assessment techniques to evaluate PFM involvement including digital palpation, electromyography, manometry, ultrasonography, and dynamometry, including an overview of the indications, efficacy, advantages, and limitations of each instrument. We consider each instrument's utility in research and in clinical settings. We next review the evidence for medical, physiotherapy, and psychological interventions for OPF-related conditions.

RESULTS

Research using these assessment techniques consistently points to findings of high PFM tone among women and men reporting disorders associated with OPF. While higher levels of evidence are needed, options for medical treatment include diazepam suppositories, botulinum toxin A, and other muscle relaxants. Effective psychological therapies include cognitive behavioral therapy, couple therapy, mindfulness, and educational interventions. Effective physiotherapy approaches include PFM exercise with biofeedback, electrotherapy, manual therapy, and the use of dilators. Multimodal approaches have demonstrated efficacy in reducing pain, normalizing PFM tone, and improving sexual function. Multidisciplinary interventions and an integrative approach to the assessment and management of OPF using a biopsychosocial framework are discussed.

CONCLUSION

Although the efficacy of various intervention approaches has been demonstrated, further studies are needed to personalize interventions according to a thorough assessment and determine the optimal combination of psychological, physical, and behavioral modalities. Padoa A, McLean, L, Morin M, et al. The Overactive Pelvic Floor (OPF) and Sexual Dysfunction. Part 2: Evaluation and Treatment of Sexual Dysfunction in OPF Patients. Sex Med 2021;9:76-92.

Comorbidity of Fibromyalgia in Primary Knee Osteoarthritis: Potential Impact on Functional Status and Quality of Life

BACKGROUND

Knee osteoarthritis (OA) is a painful condition with peripheral and central pain transmission. Fibromyalgia (FM) is the role model of central sensitization of pain perception.

AIM

To assess the frequency of FM in knee OA patients and evaluate the impact of FM on mental health and the quality of life in knee OA patients.

PATIENTS AND METHODS

A total of 121 female patients were recruited and divided into 3 groups: group I of 59 patients with knee OA only, group II of 32 patients with knee OA and FM, and group III of 30 FM patients. Patients underwent history taking, examination, investigations, and radiological evaluation of both knees. The assessment of visual analog scale (VAS), Pittsburgh Sleep Quality Index (PSQI), Pain Anxiety Symptom Scale Short Form 20 (PASS20), Beck Depression Inventory (BDI-II), and PCASEE questionnaire were done for all patients. Lequesne index of knee OA and radiological Kellgren and Lawrence score severity were done for all OA patients. Fibromyalgia Impact Questionnaire (FIQ) was assessed for all FM patients.

RESULTS

FM was diagnosed in 35.5% of knee OA patients. Group II patients had higher VAS, PASS-20, PSQI, and lower quality of life than either groups I and III, elevated Lequesne index score than group I, significant correlation between VAS and BMI (p=0.002), Lequesne index score (p<0.001), PASS20 (p=0.006), BDI-II score (p=0.002), and FIQ (P<0.001), and a negative correlation was found between VAS and physical (p<0.001), anxiety (p=0.046), and social (p=0.026) QoL parameters. Univariable regression analysis showed a higher age, VAS, PSQI, PASS20, and FIQ were associated with lower QoL in group II. A higher PASS20 was the only predictor of lower QoL in multivariable analysis.

CONCLUSION

Fibromyalgia coexists frequently in knee OA patients and has implications on their mental health, functional activity, and quality of life.

Why are assumptions passed off as established knowledge?

In this paper we attempt to explain the problems that can arise when assumptions made by experts in their respective fields of Medicine become widely accepted as established knowledge. Our hypothesis is that these problems are in large part attributable to a failure of the experts to follow the principles of logical argument. Empirical data to evaluate our hypothesis derives from an analysis of the reasoning processes employed in the generation of three syndromes drawn from the clinical discipline of Pain Medicine: myofascial pain, shoulder impingement and central sensitisation. We demonstrate a failure by the proponents of these syndromes to structure their scientific arguments in a logically valid fashion, which lead them to promote assumptions to the status of facts. In each instance those in relevant scientific journals responsible for content review accepted - and thereby promulgated - this fundamental error in reasoning. The wide acceptance of each of these assumptions as established knowledge affirms our hypothesis. Furthermore, we show that such uncritical acceptance has had significant consequences for many patients.

Fibromyalgia

Fibromyalgia is characterized by generalized pain, specific sites of musculoskeletal tenderness, fatigue, sleep disturbance, headaches, and many other visceral and cognitive maladies. The epidemiology is not well-elucidated and the diagnoses and management can be difficult. Surgery may not be the most appropriate management of some of these pain conditions like fibromyalgia. It may even be more difficult to discern some surgical conditions from points of heightened sensitivity in the fibromyalgia patient. Close attention to the current and past medical history in such patients should aid the surgeon in his attempt to rid the patient of painful conditions through surgery.

T1ρ-Mapping for Musculoskeletal Pain Diagnosis: Case Series of Variation of Water Bound Glycosaminoglycans Quantification before and after Fascial Manipulation® in Subjects with Elbow Pain

Diagnosis and management of musculoskeletal pain is a major clinical challenge. Following this need, the first aim of our study was to provide an innovative magnetic resonance technique called T_1ρ to quantify possible alterations in elbow pain, a common musculoskeletal pain syndrome that has not a clear etiology. Five patients were recruited presenting chronic elbow pain (>3 months), with an age between 30 and 70 years old. Patients underwent two T_1ρ-mapping evaluations, one before and one after the series of Fascial Manipulation^® (FM) treatments. After the first MRI evaluation, a Disability of the Arm, Shoulder and Hand (DASH) questionnaire was administered to quantify the symptoms and pain intensity. Patients then received three sessions of FM, once a week for 40 min each. A statistically significant difference was found between bound and unbound water concentration before and after FM treatment. Our preliminary data suggest that the application of the manual method seems to decrease the concentration of unbound water inside the deep fascia in the most chronic patients. This could explain the change in viscosity perceived by many practitioners as well as the decrease of symptoms due to the restoration of the normal property of the loose connective tissue. Being able to identify an altered deep fascial area may better guide therapies, contributing to a more nuanced view of the mechanisms of pain.

A MAPP Network Case-control Study of Urological Chronic Pelvic Pain Compared With Nonurological Pain Conditions

OBJECTIVES

Limited research suggests commonalities between urological chronic pelvic pain syndromes (UCPPS) and other nonurological chronic overlapping pain conditions (COPCs) including fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome. The goal of this case-control study was to examine similarities and differences between UCPPS and these other COPCs.

MATERIALS AND METHODS

As part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research (MAPP) Network, we examined 1039 individuals with UCPPS (n=424), nonurological COPCs (n=200), and healthy controls (HCs; n=415). Validated standardized measures were used to assess urological symptoms, nonurological pain symptoms, and psychosocial symptoms and traits.

RESULTS

Participants with UCPPS had more urological symptoms than nonurological COPCs or HCs (P<0.001); nonurological COPC group also had significantly worse urological symptoms than HCs (P<0.001). Participants with nonurological COPCs reported more widespread pain than those with UCPPS (P<0.001), yet both groups had similarly increased symptoms of anxiety, depression, negative affect, perceived stress, neuroticism, and lower levels of extraversion than HCs (P<0.001). Participants with UCPPS with and without COPCs reported more catastrophizing than those with nonurological COPCs (P<0.001).

DISCUSSION

Findings are consistent with the hypothesis of common underlying biopsychosocial mechanisms and can guide the comprehensive assessment and treatment of these conditions regardless of the primary site of pain or diagnosis. Heightened catastrophizing in UCPPS should be examined to inform psychosocial interventions and improve patient care.

Relationship Between Pain Alleviation and Disease-specific Health-related Quality of Life Measures in Patients With Chronic Low Back Pain Receiving Duloxetine: Exploratory Post Hoc Analysis of a Japanese Phase 3 Randomized Study

This post hoc analysis of a Japanese phase 3 randomized study (ClinicalTrials.gov identifier: NCT01855919) investigated relationships between pain severity (assessed by the Brief Pain Inventory [BPI]) and disease-specific health-related quality of life (assessed by the 24-item Roland-Morris Disability Questionnaire [RDQ-24]) in duloxetine-treated patients with chronic low back pain (CLBP).

Novel Characterization Of Thermal Temporal Summation Response By Analysis Of Continuous Pain Vs Time Curves And Exploratory Modeling

Background

Temporal summation (TS) refers to the increased perception of pain with repetitive noxious stimuli. While thermal TS is generally considered a behavioral correlate of spinal windup, noxious heat pulses also trigger additional sensory processes which were modeled in this study.

Methods

Nineteen healthy volunteers (9 females, mean age 29.2, SD 10.5) underwent two identical TS experiments, spaced a week apart. The TS paradigm consisted of 10 identical heat pulses with individualized temperatures at the thenar eminence (0.5Hz). We extracted 3 features from continuous TS response curves: Lag, time to first feel pain; Slope, the rate of pain increase between the first and most painful heat pulse; and Delta, the maximum drop in pain after peak pain is reached. We then examined the within-individual stability of these features, followed by the Pearson’s correlations among these features and between the features and negative affect.

Results

All 3 features were stable over 1 week. Lag and Delta were negatively correlated (r = −0.5, p = 0.042). Slope did not correlate with Lag or Delta, but strongly correlated with a traditional TS measure, first pulse pain and peak pain difference (r = 0.91, p < 0.0001). Negative affects such as trait and state anxiety were negatively correlated with baseline (r = −0.49, p = 0.031) and peak stimulating temperature (r = −0.48, p = 0.039), respectively, suggesting an association between anxiety and greater pain sensitivity.

Conclusion

We were able to decouple spinal windup from other perceptual processes generated by phasic thermal TS paradigms and demonstrate temporal stability of these curve features. These curve features may help better characterize the complex sensory response to noxious heat pulses and serve as biomarkers to profile patients with chronic pain.

Psychological factors are associated with local and generalized pressure pain hypersensitivity, pain intensity, and function in people with chronic shoulder pain: A cross-sectional study

OBJECTIVES

To explore the association between psychological factors and shoulder pain intensity, function, as well as local and generalized pressure pain hypersensitivity.

DESIGN

a cross-sectional study.

METHODS

90 participants with chronic shoulder pain were included. Pressure pain thresholds determined the presence of pain hypersensitivity. Pain intensity, function, pain self-efficacy, emotional distress, and pain catastrophizing were also assessed. Analyses were adjusted for gender and age.

RESULTS

The diagnosis of depression (yes/no answer) was associated with both greater local (standardized β = -0.19[95%CI -0.37 to -0.00]) and generalized (standardized β = -0.20[95%CI -0.39 to -0.01]) pressure pain hypersensitivity. Greater pain self-efficacy was associated with lower local pressure pain hypersensitivity (standardized β = 0.19[95%CI 0.04 to 0.38]). The standardized beta coefficient for the diagnosis of depression indicated that this variable showed the strongest association with pressure pain hypersensitivity. Additionally, greater pain self-efficacy was associated with lower pain intensity (standardized β = -0.34[95%CI -0.51 to -0.17]) and better function (standardized β = -0.47[95%CI -0.63 to -0.30]). Greater pain catastrophizing was associated with more pain intensity (standardized β = 0.35[95%CI 0.18 to 0.52]) and worse function (standardized β = 0.26[95%CI 0.10 to 0.43]). The standardized beta coefficients for pain catastrophizing and pain self-efficacy indicated that both variables showed the strongest association with shoulder pain intensity and function, respectively CONCLUSION: Psychological factors were associated with local and generalized pressure pain hypersensitivity, pain intensity, and function in people with chronic shoulder pain.

Quantitative sensory testing and predicting outcomes for musculoskeletal pain, disability, and negative affect: a systematic review and meta-analysis

Hypersensitivity due to central pain mechanisms can influence recovery and lead to worse clinical outcomes, but the ability of quantitative sensory testing (QST), an index of sensitisation, to predict outcomes in chronic musculoskeletal disorders remains unclear. We systematically reviewed the evidence for ability of QST to predict pain, disability, and negative affect using searches of CENTRAL, MEDLINE, EMBASE, AMED, CINAHL, and PubMed databases up to April 2018. Title screening, data extraction, and methodological quality assessments were performed independently by 2 reviewers. Associations were reported between baseline QST and outcomes using adjusted (β) and unadjusted (r) correlations. Of the 37 eligible studies (n = 3860 participants), 32 were prospective cohort studies and 5 randomised controlled trials. Pain was an outcome in 30 studies, disability in 11, and negative affect in 3. Meta-analysis revealed that baseline QST predicted musculoskeletal pain (mean r = 0.31, 95% confidence interval [CI]: 0.23-0.38, n = 1057 participants) and disability (mean r = 0.30, 95% CI: 0.19-0.40, n = 290 participants). Baseline modalities quantifying central mechanisms such as temporal summation and conditioned pain modulation were associated with follow-up pain (temporal summation: mean r = 0.37, 95% CI: 0.17-0.54; conditioned pain modulation: mean r = 0.36, 95% CI: 0.20-0.50), whereas baseline mechanical threshold modalities were predictive of follow-up disability (mean r = 0.25, 95% CI: 0.03-0.45). Quantitative sensory testing indices of pain hypersensitivity might help develop targeted interventions aiming to improve outcomes across a range of musculoskeletal conditions.

Translation and cross-cultural adaptation of the Polish Central Sensitization Inventory

Objectives

The Central Sensitization Inventory (CSI) is a new, simple clinimetric instrument intended to help doctors who deal with pain of unclear origin. It may be particularly useful when there is a large component of neuropathic pain and to assess non-specific symptoms associated with the phenomenon of central sensitization known under the common name of the central sensitization syndrome. The aim of this study is to perform translation of the CSI into Polish, its cultural adaptation and its preparation for further validation. The proposed adaptation of the scale may be applied both at the clinical level and at the level of primary care.

Material and methods

The CSI translation process took place in several stages. Firstly, the text of the questionnaire was translated from English to Polish by five independent translators. Secondly, the optimal version of the text was determined and, at the third stage, it was submitted to a linguist in order to assess it in the context of the idiomatic and semantic clarity. Thirdly, the translation was passed on to a native speaker who verified the congruence of the Polish translation with its original version. At a later stage, the effect of translating the scale and its usefulness were discussed by a group of experts in order to adapt a cultural tool. The final step was to provide it to be completed and evaluated by twenty anonymous patients with the aim of pre-assessing the level of its understanding.

Results

The final result of the undertaken activities is the Polish version of the CSI ready for validation.

Conclusions

After the multistage preparation and thorough verification of the Polish questionnaire at conceptual, empirical, semantic and idiomatic levels, necessary due to numerous cultural and linguistic differences, the Polish translation of the CSI seems to be a product ready for further validation and introduction to clinical practice.

Effectiveness of Tai Chi on fibromyalgia patients: A meta-analysis of randomized controlled trials

OBJECTIVE

To identify empirical evidence on the effectiveness of Tai Chi in treating fibromyalgia (FM).

METHOD

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to compare the effectiveness of Tai Chi and standard care or conventional therapeutic exercise in patients with FM. PubMed, Medline, and Physiotherapy Evidence Database were searched for relevant studies published before May 2019. Treatment effectiveness was evaluated using the fibromyalgia impact questionnaire (FIQ), and the total score, pain score, sleep quality index, fatigue, depression, and quality of life were assessing among the patients.

RESULTS

Six RCTs with 657 patients were included. Results of our meta-analysis indicated that Tai Chi exerts significant positive effects on reducing the total FIQ score at 12-16 weeks (standard mean difference [SMD]: -0.61; 95% confidence interval [CI]: -0.90 to -0.31) and pain score (SMD: -0.88; 95% CI: -1.58 to -0.18), improving sleep quality (SMD: -0.57; 95% CI: -0.86 to -0.28), relieving fatigue (SMD: -0.92; 95% CI: -1.81 to -0.04), alleviating depression (SMD: -0.49; 95% CI: -0.97 to -0.01), and enhancing quality of life physically (SMD: 6.21; 95% CI: 3.18-9.24) and psychologically (SMD: 5.15; 95% CI: 1.50-8.81).

CONCLUSION

Tai Chi exerts significantly greater effects on patients with FM than standard care; therefore, we suggest that Tai Chi can be used as an alternative treatment. However, more large-scale, high-quality, and multicenter trials are required to provide stronger evidence on the effectiveness of Tai Chi, as an alternative to aerobic exercise, compared with conventional therapeutic exercise.

Machine learning-based prediction of clinical pain using multimodal neuroimaging and autonomic metrics

Although self-report pain ratings are the gold standard in clinical pain assessment, they are inherently subjective in nature and significantly influenced by multidimensional contextual variables. Although objective biomarkers for pain could substantially aid pain diagnosis and development of novel therapies, reliable markers for clinical pain have been elusive. In this study, individualized physical maneuvers were used to exacerbate clinical pain in patients with chronic low back pain (N = 53), thereby experimentally producing lower and higher pain states. Multivariate machine-learning models were then built from brain imaging (resting-state blood-oxygenation-level-dependent and arterial spin labeling functional imaging) and autonomic activity (heart rate variability) features to predict within-patient clinical pain intensity states (ie, lower vs higher pain) and were then applied to predict between-patient clinical pain ratings with independent training and testing data sets. Within-patient classification between lower and higher clinical pain intensity states showed best performance (accuracy = 92.45%, area under the curve = 0.97) when all 3 multimodal parameters were combined. Between-patient prediction of clinical pain intensity using independent training and testing data sets also demonstrated significant prediction across pain ratings using the combined model (Pearson's r = 0.63). Classification of increased pain was weighted by elevated cerebral blood flow in the thalamus, and prefrontal and posterior cingulate cortices, and increased primary somatosensory connectivity to frontoinsular cortex. Our machine-learning approach introduces a model with putative biomarkers for clinical pain and multiple clinical applications alongside self-report, from pain assessment in noncommunicative patients to identification of objective pain endophenotypes that can be used in future longitudinal research aimed at discovery of new approaches to combat chronic pain.

Genome-wide association study of multisite chronic pain in UK Biobank

Chronic pain is highly prevalent worldwide and represents a significant socioeconomic and public health burden. Several aspects of chronic pain, for example back pain and a severity-related phenotype 'chronic pain grade', have been shown previously to be complex heritable traits with a polygenic component. Additional pain-related phenotypes capturing aspects of an individual's overall sensitivity to experiencing and reporting chronic pain have also been suggested as a focus for investigation. We made use of a measure of the number of sites of chronic pain in individuals within the UK general population. This measure, termed Multisite Chronic Pain (MCP), is a complex trait and its genetic architecture has not previously been investigated. To address this, we carried out a large-scale genome-wide association study (GWAS) of MCP in ~380,000 UK Biobank participants. Our findings were consistent with MCP having a significant polygenic component, with a Single Nucleotide Polymorphism (SNP) heritability of 10.2%. In total 76 independent lead SNPs at 39 risk loci were associated with MCP. Additional gene-level association analyses identified neurogenesis, synaptic plasticity, nervous system development, cell-cycle progression and apoptosis genes as enriched for genetic association with MCP. Genetic correlations were observed between MCP and a range of psychiatric, autoimmune and anthropometric traits, including major depressive disorder (MDD), asthma and Body Mass Index (BMI). Furthermore, in Mendelian randomisation (MR) analyses a causal effect of MCP on MDD was observed. Additionally, a polygenic risk score (PRS) for MCP was found to significantly predict chronic widespread pain (pain all over the body), indicating the existence of genetic variants contributing to both of these pain phenotypes. Overall, our findings support the proposition that chronic pain involves a strong nervous system component with implications for our understanding of the physiology of chronic pain. These discoveries may also inform the future development of novel treatment approaches.

Economic Impact of Adherence to Pain Treatment Guidelines in Chronic Pain Patients

Objectives

This research compared health care resource use (HCRU) and costs for pharmacotherapy prescribing that was adherent vs nonadherent to published pain management guidelines. Conditions included osteoarthritis (OA) and gout (GT) for nociceptive/inflammatory pain, painful diabetic peripheral neuropathy (pDPN) and post-herpetic neuralgia (PHN) for neuropathic pain, and fibromyalgia (FM) for sensory hypersensitivity pain.

Methods

This retrospective cohort study used claims from MarketScan Commercial and Medicare Databases identifying adults newly diagnosed with OA, GT, pDPN, PHN, or FM during July 1, 2006, to June 30, 2013, with 12-month continuous coverage before and after initial (index) diagnosis. Patients were grouped according to their pharmacotherapy pattern as adherent, nonadherent, or “unsure” according to published pain management guidelines using a claims-based algorithm. Adherent and nonadherent populations were compared descriptively and using multivariate statistical analyses for controlling bias.

Results

Final cohort sizes were 441,465 OA, 76,361 GT, 10,645 pDPN, 4,010 PHN, and 150,321 FM, with adherence to guidelines found in 51.1% of OA, 25% of GT, 59.5% of pDPN, 54.9% of PHN, and 33.5% of FM. Adherent cohorts had significantly (P < 0.05) fewer emergency department (ED) visits and lower proportions with hospitalizations or ED visits. Mean health care costs increased following diagnosis across all conditions; however, adherent cohorts had significantly lower increases in adjusted costs pre-index to postindex (OA $5,286 vs $9,532; GT $3,631 vs $7,873; pDPN $9,578 vs $16,337; PHN $2,975 vs $5,146; FM $2,911 vs $3,708; all P < 0.001; adherent vs nonadherent, respectively).

Conclusions

Adherence to pain management guidelines was associated with significantly lower HCRU and costs compared with nonadherence to guidelines.

Bidirectional association between migraine and fibromyalgia: retrospective cohort analyses of two populations

OBJECTIVE

Fibromyalgia (FM) and migraine are common pain disorders that tend to coexist. This study determined whether these two conditions exhibited any mutual influences.

SETTING

Cohort study.

PARTICIPANTS

A retrospective, longitudinal cohort study was conducted using data obtained from a nationwide healthcare database. This study had two arms. Arm 1 comprised 33 216 patients with FM and arm 2 consisted of 7420 patients with migraine; all of these patients were diagnosed between 2000 and 2010. Using the aforementioned database, control subjects who had neither FM nor migraine and were matched with the FM and migraine patients by sex, age and index date of diagnosis were recruited. Each control cohort was four times the size of the corresponding study cohort. Follow-up for the control and study cohorts was conducted until the end of 2011.

RESULTS

The incidence rates of FM and migraine were calculated in arms 1 and 2, respectively. The overall incidence of migraine was greater in the FM cohort than in the corresponding control cohort (4.39 vs 2.07 per 1000 person-years (PY)); crude HR=2.12, 95% CI=1.96 to 2.30; adjusted HR (aHR)=1.89, 95% CI=1.75 to 2.05). After adjustment for sex, age and comorbidities, the overall incidence of FM in the migraine cohort was 1.57 times greater than that in the corresponding control cohort (7.01 vs 4.49 per 1000 PY; aHR=1.52, 95% CI=1.39 to 1.65).

CONCLUSIONS

The present study revealed a bidirectional link between FM and migraine.

Kappa opioid signaling in the central nucleus of the amygdala promotes disinhibition and aversiveness of chronic neuropathic pain

Chronic pain is associated with neuroplastic changes in the amygdala that may promote hyper-responsiveness to mechanical and thermal stimuli (allodynia and hyperalgesia) and/or enhance emotional and affective consequences of pain. Stress promotes dynorphin-mediated signaling at the kappa opioid receptor (KOR) in the amygdala and mechanical hypersensitivity in rodent models of functional pain. Here, we tested the hypothesis that KOR circuits in the central nucleus of the amygdala (CeA) undergo neuroplasticity in chronic neuropathic pain resulting in increased sensory and affective pain responses. After spinal nerve ligation (SNL) injury in rats, pretreatment with a long-acting KOR antagonist, nor-binaltorphimine (nor-BNI), subcutaneously or through microinjection into the right CeA, prevented conditioned place preference (CPP) to intravenous gabapentin, suggesting that nor-BNI eliminated the aversiveness of ongoing pain. By contrast, systemic or intra-CeA administration of nor-BNI had no effect on tactile allodynia in SNL animals. Using whole-cell patch-clamp electrophysiology, we found that nor-BNI decreased synaptically evoked spiking of CeA neurons in brain slices from SNL but not sham rats. This effect was mediated through increased inhibitory postsynaptic currents, suggesting tonic disinhibition of CeA output neurons due to increased KOR activity as a possible mechanism promoting ongoing aversive aspects of neuropathic pain. Interestingly, this mechanism is not involved in SNL-induced mechanical allodynia. Kappa opioid receptor antagonists may therefore represent novel therapies for neuropathic pain by targeting aversive aspects of ongoing pain while preserving protective functions of acute pain.

Association between musculoskeletal pain at multiple sites and objectively measured physical activity and work capacity: Results from UK Biobank study

OBJECTIVES

To describe the cross-sectional association between musculoskeletal pain at multiple sites and physical work capacity (PWC) and objectively measured physical activity (PA).

DESIGN

Observational study.

METHODS

Data from a subsample of the UK Biobank were utilised (n=9856; mean age 58.5 years, mean body mass index 30.2kg/m2, 62% female). PWC was measured by a bicycle ergometer and PA by an accelerometer. Pain experienced in hip, knee, back and neck/shoulder was collected by questionnaire. Linear regression modelling was used with adjustment for potential confounders to estimate the association between pain and PWC and PA.

RESULTS

Increase in number of painful sites was associated with lower PWC, moderate and vigorous PA and increased low intensity PA in a dose-response relationship (all p-values for trend ≤0.001) before and after adjustment for confounders. In site specific analyses, hip pain was associated with an increased low intensity PA (β 52.8min/week, 95% CI 2.3-103.2) and reduced moderate PA (β -50.1min/week, 95% CI -98.5 to -1.8). Knee pain was only associated with vigorous PA (β -5.7min/week, 95% CI -10.0 to -1.3). Pain at neck/shoulder pain and back were not independently associated with PWC and PA.

CONCLUSIONS

Greater number of painful sites is consistently associated with poorer PWC, increased low intensity PA and reduced moderate to vigorous PA. Clinicians should address the critical role of being physically active in managing chronic musculoskeletal pain and interventions targeting musculoskeletal pain may be needed to increase PA levels.

Fatiguing Trunk Flexor Exercise Decreases Pain Sensitivity in Postpartum Women

Background

Low back pain (LBP) is common in the general population and among postpartum women. Abdominal muscle exercise is often used to treat LBP, but it is unknown if fatiguing abdominal muscle exercise can produce exercise-induced hypoalgesia (EIH).

Objectives

To assess pressure pain thresholds (PPTs) at rest and following fatiguing trunk flexor exercise (EIH) in (1) nulligravid and postpartum women to evaluate the impact of pregnancy and childbirth and (2) nulligravid women and men to examine sex differences.

Methods

Seventy healthy adults (31 postpartum women, 23 nulligravid women, 16 men) participated. Postpartum and nulligravid women were tested twice (16-18 weeks apart) to identify changes in EIH with postpartum recovery. PPTs were measured at the nailbed and superior rectus abdominis before and after exercise to investigate systemic and local EIH, respectively. Rectus abdominis muscle thickness was assessed with ultrasound.

Results

Postpartum women reported lower PPTs than nulligravid women at the abdomen (p < 0.05) whereas postpartum women had lower PPTs at the nailbed during the first session only. Men reported higher nailbed PPTs (p = 0.047) and similar PPTs at the abdomen than women (p = 0.294). All groups demonstrated EIH at the abdomen (p < 0.05). Systemic EIH was absent in postpartum and nulligravid women (p > 0.05), while men demonstrated hyperalgesia. Local EIH was positively associated with muscle thickness for men and women, which was not significant at the second timepoint.

Limitations

Acute exercise response may not reflect changes that occur with exercise training.

Conclusion

Fatiguing trunk flexor exercise produced local EIH for all groups including postpartum and nulligravid women. Clinically, trunk exercises may be useful for acute pain relief for clinical populations that are characterized by pain and/or weakness in the abdominal region muscles in populations with abdominal pain syndromes.

Thymulin treatment attenuates inflammatory pain by modulating spinal cellular and molecular signaling pathways

Thymulin is a peptide hormone which is mainly produced by thymic epithelial cells and it has immune-modulatory and anti-inflammatory effects. In this study, we investigated the effects of different doses and various timings of thymulin intraperitoneal administration on spinal microglial activity and intracellular pathways in an inflammatory rat model of Complete Freund's adjuvant (CFA). Thymulin treatment was implemented following CFA-induced inflammation for 21 days. After conducting behavioral tests (edema and hyperalgesia), the cellular and molecular aspects were examined to detect the thymulin effect on inflammatory factors and microglial activity. We demonstrated that thymulin treatment notably reduced thermal hyperalgesia and paw edema induced by CFA. Furthermore, molecular investigations showed that thymulin reduced CFA-induced activation of microglia cells, phosphorylation of p38 MAPK and the production of spinal pro-inflammatory cytokines (TNF-α, IL-6) during the study. Our results suggest that thymulin treatment attenuates CFA-induced inflammation. This effect may be mediated by inhibition of spinal microglia and production of central inflammatory mediators which seems to be associated with the ability of thymulin to reduce p38 MAPK phosphorylation. These data provide evidence of the anti-hyperalgesic effect of thymulin on inflammatory pain and characterize some of the underlying spinal mechanisms.

The juvenile fibromyalgia syndrome (JFMS): a poorly defined disorder

Juvenile fibromyalgia syndrome (JFMS) is a chronic condition characterized by symptoms of chronic diffuse musculoskeletal pain and multiple painful tender points on palpation. It is often accompanied by fatigue, disorders of sleep, chronic headaches, irritable bowel syndrome, and subjective soft tissue swelling. The complexity of the presenting clinical picture in JPFS has not been sufficiently defined in the literature. Similarities to adult fibromyalgia syndrome in JFMS are often difficult to compare, because many of the symptoms are "medically unexplained" and often overlap frequently with other medical conditions. However, a valid diagnosis of JFMS often decreases parents' anxiety, reduces unnecessary further investigations, and provides a rational framework for a management plan. The diagnostic criteria proposed by Yunus and Masi in 1985 to define JFMS were never validated or critically analyzed. In most cases, the clinical diagnosis is based on the history, the physical examination that demonstrates general tenderness (muscle, joints, tendons), the absence of other pathological conditions that could explain pain and fatigue, and the normal basic laboratory tests. Research and clinical observations defined that JFMS may have a chronic course that impacts the functional status and the psychosocial development of children and adolescents. This paper briefly reviews the existing knowledge on JFMS focusing on the diagnosis, clinical and the epidemiological characteristics in children and adolescents for better understanding of this disorder.

Physiological Response to Opioids

The clinical setting in which women's health physicians practice, whether as generalist, obstetricians and gynecologists, or subspecialists, dictates our frequent clinical interaction with "pain." Opioid-containing medications are frequently prescribed within our specialty as a means of immediate pain relief. Opioid-containing medication causes a deep physiological alteration of several systems resulting in potential harm to acute and chronic opioid users. This article includes a thorough system-based review of opioid-containing medications on physiological systems. Women's health providers should have an in-depth understanding of such reverberations on patients' wellbeing to maintain the safest level of care. A solid grasp of physiological repercussions of opioid use would encourage physicians to seek alternative treatment options. Such practice is essential in curbing the opioid epidemic our patients are facing.

Lower Urinary Tract Symptoms in a Chronic Pelvic Pain Population

OBJECTIVES

This study aimed to characterize the prevalence of lower urinary tract symptoms in a chronic pain population.

METHODS

In this observational cohort study, patients referred to a female pelvic pain clinic completed several validated questionnaires assessing bladder symptoms, central sensitization, pain symptoms, depression, anxiety, and neuropathic pain. Patients diagnosed as having interstitial cystitis were excluded. Patient demographic characteristics and survey responses were compared across American Urological Association Symptom Index (AUA-SI) severity categories. Multivariable logistic regression was performed to identify independent predictors of moderate-to-severe AUA-SI scores.

RESULTS

A total of 177 patients were included in the analysis. American Urological Association Symptom Index data showed that 48.8% of patients had mild, 31.2% had moderate, and 20.0% had severe symptoms. Patients reporting moderate or severe AUA-SI scores had higher mean Central Sensitization Inventory (CSI) scores (46.7 ± 16.0 vs 32.9 ± 13.8, P < 0.0001), McGill scores (median, 25 [interquartile range, 16-38] vs 13 [5-27]; P = 0.0003), Patient-Reported Outcomes Measurement Information System depression T-scores (median, 53.9 [interquartile range, 46.2-61.6] vs 51.2 [37.1-55.3]; P = 0.009), Pelvic Pain and Urgency/Frequency Symptoms Scale scores (18.4 ± 6.2 vs 12.5 ± 5.4, P < 0.0001), and Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs scores (median, 10.5 [interquartile range, 3.0-16.5] vs 6.0 [1.0-12.0]; P = 0.02). The odds of moderate-to-severe AUA-SI symptoms were higher with a positive PUF and CSI score and were lower with a diagnosis of vestibular pain.

CONCLUSIONS

There is a high prevalence of lower urinary tract symptoms among patients with chronic pelvic pain. Vestibulodynia was associated with lower odds of bladder symptoms. High PUF and CSI scores were significantly associated with moderate-to-severe bladder symptoms.

The clinical utility of repetitive transcranial magnetic stimulation in reducing the risks of transitioning from acute to chronic pain in traumatically injured patients

Pain is a multifaceted condition and a major ongoing challenge for healthcare professionals having to treat patients in whom pain put them at risk of developing other conditions. Significant efforts have been invested in both clinical and research settings in an attempt to demystify the mechanisms at stake and develop optimal treatments as well as to reduce individual and societal costs. It is now universally accepted that neuroinflammation and central sensitization are two key underlying factors causing pain chronification as they result from maladaptive central nervous system plasticity. Recent research has shown that the mechanisms of action of repetitive transcranial magnetic stimulation (rTMS) make it a particularly promising avenue in treating various pain conditions. This review will first discuss the contribution of neuroinflammation and central sensitization in the transition from acute to chronic pain in traumatically injured patients. A detailed discussion on how rTMS may allow the restoration from maladaptive plasticity in addition to breaking down the chain of events leading to pain chronification will follow. Lastly, this review will provide a theoretical framework of what might constitute optimal rTMS modalities in dealing with pain symptoms in traumatically injured patients based on an integrated perspective of the physiopathological mechanisms underlying pain.

Efficacy of duloxetine by prior NSAID use in the treatment of chronic osteoarthritis knee pain: A post hoc subgroup analysis of a randomized, placebo-controlled, phase 3 study in Japan

BACKGROUND

A previously conducted placebo-controlled, randomized, phase 3 study of 353 Japanese patients with knee osteoarthritis (OA) showed significant improvements for duloxetine vs placebo in pain and health-related quality of life (HRQoL) (ClinicalTrials.gov Identifier: NCT02248480). Reported here are post hoc subgroup analyses evaluating the efficacy of duloxetine according to the pattern of prior nonsteroidal anti-inflammatory drug (NSAID) use.

METHODS

Patients with knee OA pain received once-daily duloxetine or placebo for 14 weeks. Pain was evaluated using the Brief Pain Inventory (BPI) and HRQoL was evaluated using the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Patients were divided into four subgroups based on their prior NSAID use: (i) no prior NSAID use; (ii) low-frequency NSAID use (<14 days/month); (iii) high-frequency transdermal NSAID use (transdermal NSAIDs only; ≥14 days/month for the 3 months before study entry); and (iv) high-frequency other NSAID use (eg, oral NSAIDs only, both oral and transdermal NSAIDs; ≥14 days/month for the 3 months before study entry).

RESULTS

In each of the four prior NSAID use subgroups, there were greater reductions in BPI average pain severity score for duloxetine vs placebo at all timepoints during the 14-week treatment period; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, the proportion of patients achieving a ≥50% reduction in BPI average pain severity score was higher for duloxetine vs placebo. In each subgroup, there were greater reductions in WOMAC total score for duloxetine vs placebo at all timepoints; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, there were greater reductions at Week 14 in WOMAC pain, stiffness, physical function, and total scores for duloxetine vs placebo.

CONCLUSIONS

Duloxetine was consistently effective with respect to pain relief and HRQoL in Japanese patients with knee OA pain, regardless of the pattern of prior NSAID use.

Effects of Mantra Meditation versus Music Listening on Knee Pain, Function, and Related Outcomes in Older Adults with Knee Osteoarthritis: An Exploratory Randomized Clinical Trial (RCT)

OBJECTIVE

Disease-modifying treatments for OA remain elusive, and commonly used medications can have serious side effects. Although meditation and music listening (ML) have been shown to improve outcomes in certain chronic pain populations, research in OA is sparse. In this pilot RCT, we explore the effects of two mind-body practices, mantra meditation (MM) and ML, on knee pain, function, and related outcomes in adults with knee OA.

METHODS

Twenty-two older ambulatory adults diagnosed with knee OA were randomized to a MM (N=11) or ML program (N=11) and asked to practice 15-20 minutes, twice daily for 8 weeks. Core outcomes included knee pain (Knee Injury and Osteoarthritis Outcome Score [KOOS] and Numeric Rating Scale), knee function (KOOS), and perceived OA severity (Patient Global Assessment). Additional outcomes included perceived stress (Perceived Stress Scale), mood (Profile of Mood States), sleep (Pittsburgh Sleep Quality Index), and health-related quality of life (QOL, SF-36). Participants were assessed at baseline and following completion of the program.

RESULTS

Twenty participants (91%) completed the study (9 MM, 11 ML). Compliance was excellent; participants completed an average of 12.1±0.83 sessions/week. Relative to baseline, participants in both groups demonstrated improvement post-intervention in all core outcomes, including knee pain, function, and perceived OA severity, as well as improvement in mood, perceived stress, and QOL (Physical Health) (p's≤0.05). Relative to ML, the MM group showed greater improvements in overall mood and sleep (p's≤0.04), QOL-Mental Health (p<0.07), kinesiophobia (p=0.09), and two domains of the KOOS (p's<0.09).

CONCLUSIONS

Findings of this exploratory RCT suggest that a simple MM and, possibly, ML program may be effective in reducing knee pain and dysfunction, decreasing stress, and improving mood, sleep, and QOL in adults with knee OA.

Learning and Unlearning of Pain

This review provides an overview of learning mechanisms and memory aspects for the development of chronic pain. Pain can be influenced in important ways by an individual's personality, by family, and by the sociocultural environment in which they live. Therefore, learning mechanisms can explain why pain experience and pain behavior can increase or decrease. Linking pain with positive consequences or removing negative consequences can contribute significantly to the chronification of pain. We will provide an overview of treatment options that use the characteristics of extinction. Operant extinction training and cognitive behavioral approaches show promising results for the treatment of chronic pain.

A Mechanism-Based Approach to Physical Therapist Management of Pain

Pain reduction is a primary goal of physical therapy for patients who present with acute or persistent pain conditions. The purpose of this review is to describe a mechanism-based approach to physical therapy pain management. It is increasingly clear that patients need to be evaluated for changes in peripheral tissues and nociceptors, neuropathic pain signs and symptoms, reduced central inhibition and enhanced central excitability, psychosocial factors, and alterations of the movement system. In this Perspective, 5 categories of pain mechanisms (nociceptive, central, neuropathic, psychosocial, and movement system) are defined, and principles on how to evaluate signs and symptoms for each mechanism are provided. In addition, the underlying mechanisms targeted by common physical therapist treatments and how they affect each of the 5 categories are described. Several different mechanisms can simultaneously contribute to a patient's pain; alternatively, 1 or 2 primary mechanisms may cause a patient's pain. Further, within a single pain mechanism, there are likely many possible subgroups. For example, reduced central inhibition does not necessarily correlate with enhanced central excitability. To individualize care, common physical therapist interventions, such as education, exercise, manual therapy, and transcutaneous electrical nerve stimulation, can be used to target specific pain mechanisms. Although the evidence elucidating these pain mechanisms will continue to evolve, the approach outlined here provides a conceptual framework for applying new knowledge as advances are made.

Lateralized kappa opioid receptor signaling from the amygdala central nucleus promotes stress-induced functional pain

The response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.

The Association Between Headaches and Temporomandibular Disorders is Confounded by Bruxism and Somatic Symptoms

OBJECTIVES

The objective of this observational study was to establish the possible presence of confounders on the association between temporomandibular disorders (TMD) and headaches in a patient population from a TMD and Orofacial Pain Clinic.

MATERIALS AND METHODS

Several subtypes of headaches have been diagnosed: self-reported headache, (probable) migraine, (probable) tension-type headache, and secondary headache attributed to TMD. The presence of TMD was subdivided into 2 subtypes: painful TMD and function-related TMD. The associations between the subtypes of TMD and headaches were evaluated by single regression models. To study the influence of possible confounding factors on this association, the regression models were extended with age, sex, bruxism, stress, depression, and somatic symptoms.

RESULTS

Of the included patients (n=203), 67.5% experienced headaches. In the subsample of patients with a painful TMD (n=58), the prevalence of self-reported headaches increased to 82.8%. The associations found between self-reported headache and (1) painful TMD and (2) function-related TMD were confounded by the presence of somatic symptoms. For probable migraine, both somatic symptoms and bruxism confounded the initial association found with painful TMD.

DISCUSSION

The findings of this study imply that there is a central working mechanism overlapping TMD and headache. Health care providers should not regard these disorders separately, but rather look at the bigger picture to appreciate the complex nature of the diagnostic and therapeutic process.

A novel fluorescent biosensor for adrenaline detection and tyrosinase inhibitor screening

In this work, a novel simple fluorescent biosensor for the highly sensitive and selective detection of adrenaline was established. Firstly, water-soluble CuInS₂ quantum dots (QDs) capped by L-Cys were synthesized via a hydrothermal synthesis method. Then, the positively charged adrenaline was assembled on the surface of CuInS₂ QDs due to the electrostatic interactions and hydrogen bonding, which led to the formation of adrenaline-CuInS₂ QD (Adr-CuInS₂ QD) electrostatic complexes. Tyrosinase (TYR) can catalyze adrenaline to generate H₂O₂, and additionally oxidize the adrenaline to adrenaline quinone. Both the H₂O₂ and the adrenaline quinone can quench the fluorescence of the CuInS₂ QDs through the electron transfer (ET) process. Thus, the determination of adrenaline could be facilely achieved by taking advantage of the fluorescence "turn off" feature of CuInS₂ QDs. Under the optimum conditions, the fluorescence quenching ratio I_f/I_f0 (I_f and I_f0 were the fluorescence intensity of Adr-CuInS₂ QDs in the presence and absence of TYR, respectively) was proportional to the logarithm of adrenaline concentration in the range of 1 × 10^-8-1 × 10^-4 mol L^-1 with the detection limit of 3.6 nmol L^-1. The feasibility of the proposed biosensor in real sample assay was also studied and satisfactory results were obtained. Significantly, the proposed fluorescent biosensor can also be utilized to screen TYR inhibitors. Graphical abstract Schematic illustration of the fluorescent biosensor for adrenaline detection (A) and tyrosinase inhibitor screening (B).

Effect of tai chi versus aerobic exercise for fibromyalgia: comparative effectiveness randomized controlled trial

OBJECTIVES

To determine the effectiveness of tai chi interventions compared with aerobic exercise, a current core standard treatment in patients with fibromyalgia, and to test whether the effectiveness of tai chi depends on its dosage or duration.

DESIGN

Prospective, randomized, 52 week, single blind comparative effectiveness trial.

SETTING

Urban tertiary care academic hospital in the United States between March 2012 and September 2016.

PARTICIPANTS

226 adults with fibromyalgia (as defined by the American College of Rheumatology 1990 and 2010 criteria) were included in the intention to treat analyses: 151 were assigned to one of four tai chi groups and 75 to an aerobic exercise group.

INTERVENTIONS

Participants were randomly assigned to either supervised aerobic exercise (24 weeks, twice weekly) or one of four classic Yang style supervised tai chi interventions (12 or 24 weeks, once or twice weekly). Participants were followed for 52 weeks. Adherence was rigorously encouraged in person and by telephone.

MAIN OUTCOME MEASURES

The primary outcome was change in the revised fibromyalgia impact questionnaire (FIQR) scores at 24 weeks compared with baseline. Secondary outcomes included changes of scores in patient's global assessment, anxiety, depression, self efficacy, coping strategies, physical functional performance, functional limitation, sleep, and health related quality of life.

RESULTS

FIQR scores improved in all five treatment groups, but the combined tai chi groups improved statistically significantly more than the aerobic exercise group in FIQR scores at 24 weeks (difference between groups=5.5 points, 95% confidence interval 0.6 to 10.4, P=0.03) and several secondary outcomes (patient's global assessment=0.9 points, 0.3 to 1.4, P=0.005; anxiety=1.2 points, 0.3 to 2.1, P=0.006; self efficacy=1.0 points, 0.5 to 1.6, P=0.0004; and coping strategies, 2.6 points, 0.8 to 4.3, P=0.005). Tai chi treatment compared with aerobic exercise administered with the same intensity and duration (24 weeks, twice weekly) had greater benefit (between group difference in FIQR scores=16.2 points, 8.7 to 23.6, P<0.001). The groups who received tai chi for 24 weeks showed greater improvements than those who received it for 12 weeks (difference in FIQR scores=9.6 points, 2.6 to 16.6, P=0.007). There was no significant increase in benefit for groups who received tai chi twice weekly compared with once weekly. Participants attended the tai chi training sessions more often than participants attended aerobic exercise. The effects of tai chi were consistent across all instructors. No serious adverse events related to the interventions were reported.

CONCLUSION

Tai chi mind-body treatment results in similar or greater improvement in symptoms than aerobic exercise, the current most commonly prescribed non-drug treatment, for a variety of outcomes for patients with fibromyalgia. Longer duration of tai chi showed greater improvement. This mind-body approach may be considered a therapeutic option in the multidisciplinary management of fibromyalgia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01420640.

Relationships between psychological state, abuse, somatization and visceral pain sensitivity in irritable bowel syndrome

BACKGROUND AND OBJECTIVE

Psychological states may interfere with visceral sensitivity. Here we investigate associations between psychosocial factors and visceral sensitivity in irritable bowel syndrome (IBS).

METHODS

Two IBS patient cohorts (Cohort 1: n = 231, Rome II; Cohort 2: n = 141, Rome III) underwent rectal barostat testing, and completed questionnaires for anxiety, depression, somatization, and abuse. The associations between questionnaire measures and visceral sensitivity parameters were analyzed in three-step general linear models (step1: demographic and abuse variables; step 2: anxiety and depression; step 3: somatization).

RESULTS

Cohort 1. Pain threshold was positively associated with age and female gender, and negatively with adult sexual abuse and somatization. Pain referral area was negatively associated with age and positively with somatization and GI-specific anxiety, the latter effect mediated by somatization. Cohort 2. Pain threshold was positively associated with age and male gender, and negatively with adult sexual abuse. Pain intensity ratings were positively associated with somatization, female gender and depression, the latter effect mediated by somatization.

CONCLUSION

Somatization is associated with most visceral sensitivity parameters, and mediates the effect of some psychological factors on visceral sensitivity. It may reflect a psychobiological sensitization process driving symptom generation in IBS. In addition, abuse history was found to independently affect some visceral sensitivity parameters.

Do We Pay Enough Attention to Neuropathic Pain in Knee Osteoarthritis Patients?

SUMMARY – The aim of the study was to determine the prevalence of neuropathic pain in knee osteoarthritis patients using painDETECT questionnaire, and to evaluate correlations between pain intensity, gender, age and types of treatment, and the presence of neuropathic pain. The study included 122 patients. All participants completed a questionnaire on sociodemographic data, duration of symptoms, types of treatment and preventable risk factors (body mass index and waist circumference). The presence of neuropathic pain was assessed by painDETECT, according to which subjects were classified into three groups (neuropathic pain likely, possible, or unlikely). Neuropathic pain was likely in 18 (14.8%), possible in 30 (24.6%) and unlikely in 74 (60.7%) subjects. A significant positive correlation was found between visual analog scale for pain and painDETECT score. There was no statistically significant difference in gender, age, waist circumference and body mass index among three groups of participants according to painDETECT score. In conclusion, knee osteoarthritis patients with neuropathic pain component were experiencing higher levels of pain, implicating poorer pain control with common analgesics. Recognizing these patients as a distinct subgroup would allow clinicians to improve their treatment by using unconventional analgesics with central activity.