Central pain mechanisms in the rheumatic diseases: future directions

Impact of central sensitization on clinical parameters in patients with rheumatoid arthritis

OBJECTIVE

This study aimed to investigate the effects of central sensitization (CS) on pain sensitivity, disease activity, neuropathic symptoms and quality of life (QoL) in patients with rheumatoid arthritis (RA).

METHODS

Sixty patients diagnosed with RA according to the American College of Rheumatology and the European League Against Rheumatism (ACR/EULAR) 2010 classification criteria were included in the study. Patient assessment tools included visual analog scale (VAS) for pain, algometer for pain pressure threshold (PPT), disease activity score in 28 joints (DAS-28) for disease activity (DA), central sensitization inventory (CSI) for CS and rheumatoid arthritis QoL questionnaire for QoL.

RESULTS

Central sensitization was identified in 29 (48.3%) patients. Although erythrocyte sedimentation rate (ESR), C-reactive protein and swollen joint count were comparable between patients with or without CS, higher VAS, tender joint count and DAS-28 scores were observed in patients with CS (all p<0.05). Pain pressure thresholds (PPT) at the wrist (PPTW) and the trapezius muscle (PPTT) were lower in patients with CS (p=0.004, p=0.001, respectively). It was found that neuropathic pain components increased and quality of life decreased as CSI scores increased (all p=0.000).

CONCLUSION

The presence of CS leads to pain sensitivity as well as overestimation of disease activity in RA patients. The presence of CS should not be overlooked in RA patients to avoid overtreatment for inflammation and to determine the treatment need for nociplastic pain.

Characteristics of long COVID in patients with autoimmune rheumatic diseases: a systematic review and meta-analysis

Objectives

Numerous cases of long coronavirus disease (long COVID) have been reported in patients with autoimmune rheumatic diseases (ARDs). Despite the reviews on clinical manifestations of long COVID in the general population, systematic reviews on ARD patients are scarce. Herein, we conducted a systematic review and meta-analysis on the prevalence and characteristics of long COVID in ARD patients.

Methods

We searched the literature in PubMed and Embase as of 27 December 2022. Cohort, cross-sectional and case-control studies relevant to long COVID in ARD patients were collected. Stratification based on the severity of COVID infection and subtypes of rheumatic diseases [systemic autoimmune rheumatic disease (SARD) vs non-autoimmune rheumatic disease (NARD)] was also undertaken. A random-effects model was used in the meta-analysis.

Results

A total of 15 relevant studies were identified from the literature. The prevalence of long COVID was 56% (95% CI 34, 76) in 2995 patients. Hospitalized COVID patients had a higher proportion of long COVID than non-hospitalized patients. The prevalence of long COVID was similar between SARD and NARD patients. In terms of symptoms, fatigue, arthralgia and pain were commonly reported in long COVID patients with ARDs.

Conclusion

The characteristics of long COVID in ARD patients are generally similar to those in the general population despite a higher prevalence and a higher proportion of arthralgia and pain.

Description of Novel Molecular Factors in Lumbar DRGs and Spinal Cord Factors Underlying Development of Neuropathic Pain Component in the Animal Model of Osteoarthritis

Osteoarthritis (OA) is one of the most common joint disorder, with pain accompanied by functional impairment, as the most pronounced clinical symptom. Currently used pharmacotherapy involves symptomatic treatment that do not always provide adequate pain relief. This may be due to concomitance of central sensitization and development of neuropathic features in OA patients. Here we performed studies in the animal model of OA to investigate of the neuropathic component. Intraarticular injection of monoiodoacetate (MIA, 1 mg) was used to induce OA in Wistar male rats. Development of pain phenotype was assessed by behavioral testing (PAM test and von Frey's test), while corresponding changes in dorsal root ganglia (DRGs L3-L5) and spinal cord (SC) gene expression were assessed by means of qRT-PCR technique. We also performed microtomography of OA-affected knee joints to correlate the level of bone degradation with observed behavioral and molecular changes. We observed gradually developing remote allodynia after MIA treatment, indicating the presence of neuropathic component. Our results showed that, among DRGs innervating knee joint, development of central sensitization is most likely due to peripheral input of stimuli through DRG L5. In SC, development of secondary hypersensitivity correlated with increased expression of TAC1 and NPY. Our studies provided molecular records on abnormal activation of pain transmission markers in DRG and SC during development of OA that are responsible for the manifestation of neuropathic features. The obtained results increase insight into molecular changes occurring in the neuronal tissue during OA development and may contribute to readdressing treatment paradigms.

Portable Mid-Infrared Spectroscopy Combined with Chemometrics to Diagnose Fibromyalgia and Other Rheumatologic Syndromes Using Rapid Volumetric Absorptive Microsampling

The diagnostic criteria for fibromyalgia (FM) have relied heavily on subjective reports of experienced symptoms coupled with examination-based evidence of diffuse tenderness due to the lack of reliable biomarkers. Rheumatic disorders that are common causes of chronic pain such as rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis, and chronic low back pain are frequently found to be comorbid with FM. As a result, this can make the diagnosis of FM more challenging. We aim to develop a reliable classification algorithm using unique spectral profiles of portable FT-MIR that can be used as a real-time point-of-care device for the screening of FM. A novel volumetric absorptive microsampling (VAMS) technique ensured sample volume accuracies and minimized the variation introduced due to hematocrit-based bias. Blood samples from 337 subjects with different disorders (179 FM, 158 non-FM) collected with VAMS were analyzed. A semi-permeable membrane filtration approach was used to extract the blood samples, and spectral data were collected using a portable FT-MIR spectrometer. The OPLS-DA algorithm enabled the classification of the spectra into their corresponding classes with 84% accuracy, 83% sensitivity, and 85% specificity. The OPLS-DA regression plot indicated that spectral regions associated with amide bands and amino acids were responsible for discrimination patterns and can be potentially used as spectral biomarkers to differentiate FM and other rheumatic diseases.

Rheumatology and Long COVID: lessons from the study of fibromyalgia

Rheumatology, such as other subspecialties, has both a unique perspective to offer as well as an evolving role to play in the global COVID-19 pandemic. Our field has already contributed meaningfully to the development and repurposing of many of the immune-based therapeutics which are now standard treatments for severe forms of the disease as well as to the understanding of the epidemiology, risk factors and natural history of COVID-19 in immune-mediated inflammatory diseases. Still in evolution is our potential to contribute to burgeoning research efforts in the next phase of the pandemic: the syndrome of postacute sequelae of COVID-19 or Long COVID. While our field brings many assets to the study of Long COVID including our expertise in the investigation of chronic inflammation and autoimmunity, our Viewpoint focuses on the strong similarities between fibromyalgia (FM) and Long COVID. While one can speculate on how embracing and confident practising rheumatologists already are regarding these interrelationships, we assert that in the emerging field of Long COVID the potential lessons from the field of fibromyalgia care and research have been underappreciated and marginalised and most importantly now deserve a critical appraisal.

Pharmacokinetics, metabolite profiling, safety and tolerability of YZJ-4729 tartrate, a novel G protein-biased μ-opioid receptor agonist, in healthy Chinese subjects

Objective: YZJ-4729 is a novel G protein-biased μ-opioid receptor agonist for the treatment of acute pain in adult patients who require intravenous opioid analgesic therapy. The aim of this study was to assess the pharmacokinetics, metabolite profiling, safety and tolerability of YZJ-4729 in healthy Chinese subjects following the single intravenous doses ranged from 0.2 mg to 6 mg. Methods: This single-center, randomized, double-blind, placebo-controlled clinical study was conducted in 54 healthy male and female Chinese subjects after single ascending doses of YZJ-4729 tartrate (0.2, 0.5, 1.5, 3, 4.5, and 6 mg). Subjects in each cohort were assigned randomly to receive a single intravenous dose of YZJ-4729 tartrate injection or placebo at a ratio of 4:1. Pharmacokinetic characteristics, metabolite profiling, safety and tolerability profiles of the study drug were evaluated. Results: Overall, YZJ-4729 was safe and well tolerated in healthy Chinese subjects. The study drug reached peak plasma concentrations nearly at the end of the infusion. After administration, YZJ-4729 was eliminated rapidly with a terminal elimination half-life of 0.862-2.50 h, and excreted little in human excreta. The maximum drug concentration and area under the plasma concentration-time curve increased with dose escalation across the entire dose range. YZJ-4729 experienced extensive metabolism in human body. A total of 19 metabolites were identified and the characteristic metabolic pathways involved hydroxylation, ketone formation, N-dealkylation and glucuronide conjugation. Metabolite M10 was the most abundant circulating metabolite, and represented over 10% of total drug-related systemic exposure. Further PK and safety evaluation of M10 was necessary. Conclusion: The clinical study results laid a foundation for the further clinical studies of YZJ-4729 in patients. Clinical Trial Registration: http://www.chinadrugtrials.org.cn, identifier CTR20222574.

Efficacy of transcranial direct current stimulation in patients with knee osteoarthritis: A systematic review

OBJECTIVE

Transcranial direct current stimulation (tDCS) has demonstrated its efficacy in alleviating pain among individuals with musculoskeletal disorders. This review focuses on the application of tDCS as a therapeutic intervention for managing knee osteoarthritis (OA), a prevalent musculoskeletal condition. The primary objective is to assess the effectiveness of tDCS(add-on tDCS and /or stand-alone tDCS), whether as an add-on to existing treatments or as a standalone therapy, in reducing pain and enhancing functional capacity in patients with knee OA.

METHODS

A comprehensive search was conducted across multiple databases, including PubMed, Science Direct, OVID, MEDLINE, CINAHL, EMBASE, ProQuest, and Google Scholar, and Web of Science. The search terms employed were "Transcranial direct current stimulation" or "tDCS" in combination with "Osteoarthritis" or "OA" and "knee." After eliminating duplicates and studies that did not meet the inclusion criteria, a total of 14 relevant articles were identified for review.

RESULTS

Among the included studies, twelve reported statistically significant improvements in pain levels when comparing the active tDCS group to the sham tDCS group. Only two studies reported no significant difference in pain intensity between the active tDCS and sham tDCS groups. Findings regarding functional abilities were diverse, with some studies demonstrating a significant enhancement in functional outcomes in the active tDCS group, while others observed no statistically significant differences.

CONCLUSION

The results of this review suggest that tDCS holds promise as a pain management intervention for individuals with knee OA. Notably, anodal tDCS applied over the primary motor cortex (M1) appears to be particularly effective in alleviating pain in patients with knee OA. However, the impact of tDCS on functional performance appears to be limited.

Metabolic Fingerprinting for the Diagnosis of Clinically Similar Long COVID and Fibromyalgia Using a Portable FT-MIR Spectroscopic Combined with Chemometrics

Post Acute Sequelae of SARS-CoV-2 infection (PASC or Long COVID) is characterized by lingering symptomatology post-initial COVID-19 illness that is often debilitating. It is seen in up to 30-40% of individuals post-infection. Patients with Long COVID (LC) suffer from dysautonomia, malaise, fatigue, and pain, amongst a multitude of other symptoms. Fibromyalgia (FM) is a chronic musculoskeletal pain disorder that often leads to functional disability and severe impairment of quality of life. LC and FM share several clinical features, including pain that often makes them indistinguishable. The aim of this study is to develop a metabolic fingerprinting approach using portable Fourier-transform mid-infrared (FT-MIR) spectroscopic techniques to diagnose clinically similar LC and FM. Blood samples were obtained from LC (n = 50) and FM (n = 50) patients and stored on conventional bloodspot protein saver cards. A semi-permeable membrane filtration approach was used to extract the blood samples, and spectral data were collected using a portable FT-MIR spectrometer. Through the deconvolution analysis of the spectral data, a distinct spectral marker at 1565 cm-1 was identified based on a statistically significant analysis, only present in FM patients. This IR band has been linked to the presence of side chains of glutamate. An OPLS-DA algorithm created using the spectral region 1500 to 1700 cm-1 enabled the classification of the spectra into their corresponding classes (Rcv > 0.96) with 100% accuracy and specificity. This high-throughput approach allows unique metabolic signatures associated with LC and FM to be identified, allowing these conditions to be distinguished and implemented for in-clinic diagnostics, which is crucial to guide future therapeutic approaches.

Oxidative stress may be a contributing factor in fibromyalgia patients' pain mechanisms

OBJECTIVE

The pathophysiology of fibromyalgia (FM), a continuously painful syndrome with no known origin, has been related to mitochondrial dysfunction, oxidative stress, and inflammation. Recent studies have shown that FM may be associated with an oxidative balance disorder. The objective of this study was to measure the levels of oxidative stress in FM patients and try to understand the association between FM and free radicals.

METHODS

This study was performed on 100 volunteers admitted to the University of Health Sciences, Sultan 2, Abdulhamid Han Health Application and Research Center Physical Therapy and Rehabilitation Clinic, including 50 healthy controls and 50 patients with FM. To analyze oxidative stress biomarkers, total oxidant status (TOS) and total antioxidant status (TAS) levels were measured. Total thiol (TT) and native thiol (NT) concentrations were measured to determine the relationship between thiol groups. Disulfide (DIS) and oxidative stress index (OSI) were calculated with mathematical formulas.

RESULTS

While TOS and OSI levels were statistically higher in FM patients, TAS levels were significantly lower compared to the healthy control group (p<0.001). In comparison to the healthy control group, FM patients had considerably decreased TT and NT levels. DIS levels were significantly higher in FM patients than in controls (p<0.001).

CONCLUSIONS

Reactive oxygen species have several negative impacts on the human body. As a result of the measurements we analyzed, the relationship between FM and oxidative stress should be studied in terms of disease progression and may help improve the treatment process.

Exposure time as an influencing factor among rheumatoid arthritis patients subjected to traditional Siwan therapy

Rheumatoid arthritis (RA) is a long-term autoimmune disease characterized by intra- and extra-articular manifestations. Sand therapy is traditionally indicated for RA, chronic pain, skin diseases, and musculoskeletal disorders. Many places in the world use sand therapy, including Siwa, which is a famous place in Egypt. This study investigated the exposure time to Siwan traditional therapy as a factor influencing central sensitization, pain severity, pain threshold, and kinesiophobia in RA by measuring the central sensory inventory (CSI), visual analogue scale, pressure algometer, and TAMPA kinesiophobia scale, respectively. Twenty-four patients with RA were recruited from 6 traditional healing centers, 24 RA patients were recruited and randomly assigned to 2 equal groups (GI and GII). The first received Siwan traditional therapy for 3 days, while the second received the same program for 5 days. The results revealed a significant difference in CSI between pre- and posttreatment within the GII (P = .038). The Tampa Scale score improved significantly in both groups (P = .004 and P = .014, respectively). Pain severity and pain threshold at all sites showed significant posttreatment improvements in the GII. Significant posttreatment changes were only found for GI in terms of pain severity and the most painful joint (P = .010 and P = .035, respectively). Significant changes were observed in kinesiophobia, pain severity, and pain threshold in the most painful joint 3 and 5 days after Siwan traditional therapy. Despite the nonsignificant differences in all parameters between the 2 groups, all the measured parameters produced favorable results after 5 days of treatment, suggesting the need for a long-term effect investigation.

Mapping the Design Space of Technology-Based Solutions for Better Chronic Pain Care: Introducing the Pain Tech Landscape

OBJECTIVES

Technology has substantial potential to transform and extend care for persons with chronic pain, a burdensome and costly condition. To catalyze the development of impactful applications of technology in this space, we developed the Pain Tech Landscape (PTL) model, which integrates pain care needs with characteristics of technological solutions.

METHODS

Our interdisciplinary group representing experts in pain and human factors research developed PTL through iterative discussions. To demonstrate one potential use of the model, we apply data generated from a narrative review of selected pain and technology journals (2000-2020) in the form of heat map overlays, to reveal where pain tech research attention has focused to date.

RESULTS

The PTL comprises three two-dimensional planes, with pain care needs on each x axis (measurement to management) and technology applications on the y axes according to a) user agency (user- to system-driven), b) usage time frame (temporary to lifelong), and c) collaboration (single-user to collaborative). Heat maps show that existing applications reside primarily in the "user-driven/management" quadrant (e.g., self-care apps). Examples of less developed areas include artificial intelligence and Internet of Things (i.e., Internet-linked household objects), and collaborative/social tools for pain management.

CONCLUSIONS

Collaborative development between the pain and tech fields in early developmental stages using the PTL as a common language could yield impactful solutions for chronic pain management. The PTL could also be used to track developments in the field over time. We encourage periodic reassessment and refinement of the PTL model, which can also be adapted to other chronic conditions.

Adolescents and Young Adults With Sickle Cell Disease: Nociplastic Pain and Pain Catastrophizing as Predictors of Pain Interference and Opioid Consumption

OBJECTIVES

Some patients with sickle cell disease (SCD) have features of nociplastic pain. While research suggests that many patients with nociplastic pain consume more opioids due to opioid nonresponsiveness, little is known about the impact of nociplastic pain and pain catastrophizing on opioid consumption and pain interference among adolescents and young adults (AYA) with SCD. The purpose of this study was to (1) characterize nociplastic pain and pain catastrophizing among AYA with SCD, and (2) determine whether these characterizations are associated with subsequent opioid consumption and pain interference 1 month after characterization.

METHODS

Participants completed surveys characterizing nociplastic pain and catastrophizing at a routine clinic visit (baseline). Thereafter, participants received weekly text messages that included pain interference and opioid consumption surveys. Multipredictor 2-part models were used to evaluate the predictive relationships between baseline characterizations and subsequent pain interference, and opioid consumption.

RESULTS

Forty-eight AYA aged 14 to 35 completed baseline measures. Twenty-five percent of participants had scores suggestive of nociplastic pain. Greater nociplastic pain features significantly increased the odds of consuming opioids (odds ratio=1.2) and having greater interference from pain (odds ratio=1.46). Regression analyses found that greater baseline nociplastic pain characteristics were significantly associated with opioid consumption (β=0.13) and pain interference (β=0.061); whereas higher pain catastrophizing scores predicted less opioid consumption (β=-0.03) and less pain interference (β=-0.0007).

DISCUSSION

In this sample of AYA with SCD, features of nociplastic pain predicted higher subsequent opioid consumption and pain interference. Being aware of nociplastic pain features in patients with SCD may better guide individualized pain management.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

High overlap in patients diagnosed with hypermobile Ehlers-Danlos syndrome or hypermobile spectrum disorders with fibromyalgia and 40 self-reported symptoms and comorbidities

Background

Joint pain is a common symptom in patients with hypermobile Ehlers-Danlos Syndrome (hEDS), hypermobility spectrum disorders (HSD) and fibromyalgia. The goal of this study was to determine whether symptoms and comorbidities overlap in patients diagnosed with hEDS/HSD and/or fibromyalgia.

Methods

We retrospectively examined self-reported data from an EDS Clinic intake questionnaire in patients diagnosed with hEDS/HSD, fibromyalgia, or both vs. controls with an emphasis on joint issues.

Results

From 733 patients seen at the EDS Clinic, 56.5% (n = 414) were diagnosed with hEDS/HSD and fibromyalgia (Fibro), 23.8% (n = 167) hEDS/HSD, 13.3% (n = 98) fibromyalgia, or 7.4% (n = 54) none of these diagnoses. More patients were diagnosed with HSD (76.6%) than hEDS (23.4%). Patients were primarily White (95%) and female (90%) with a median age in their 30s (controls 36.7 [18.0, 70.0], fibromyalgia 39.7 [18.0, 75.0], hEDS/HSD 35.0 [18.0, 71.0], hEDS/HSD&Fibro 31.0 [18.0, 63.0]). There was high overlap in all 40 symptoms/comorbidities that we examined in patients diagnosed with fibromyalgia only or hEDS/HSD&Fibro, regardless of whether they had hEDS or HSD. Patients that only had hEDS/HSD without fibromyalgia had far fewer symptoms/comorbidities than patients with hEDS/HSD&Fibro. The top self-reported issues in patients that only had fibromyalgia were joint pain, hand pain when writing or typing, brain fog, joint pain keeping from daily activities, allergy/atopy and headache. Five issues that significantly and uniquely characterized patients diagnosed with hEDS/HSD&Fibro were subluxations (dislocations in hEDS patients), joint issues like sprains, the need to stop sports due to injuries, poor wound healing, and migraine.

Conclusion

The majority of patients seen at the EDS Clinic had a diagnosis of hEDS/HSD plus fibromyalgia that was associated with more severe disease. Our findings indicate that fibromyalgia should be routinely assessed in patients with hEDS/HSD and vis-a-versa to improve patient care.

Prevalence of fatigue functional and social impairment among patients with rheumatic diseases compared to patients without: A cross-sectional comparison

Rheumatic diseases (RD) are chronic diseases that significantly affect the lives of patients. Assessing health outcomes through a patient-reported outcome measurement information system (PROMIS) is essential for RD management. Moreover, these tend to be less favorable among individuals than among the rest of the population. This study aimed to compare PROMIS between RD patients and other patients. This cross sectional study was conducted in the year 2021. Information about patients with RD was obtained from the RD registry at King Saud University Medical City. Patients without RD were recruited from family medicine clinics. Patients were contacted electronically through WhatsApp© to complete the PROMIS surveys. We compared the individual PROMIS scores between the 2 groups using linear regression, adjusting for sex, nationality, marital status, education level, employment, family history of RD, income, and chronic comorbidities. There were 1024 individuals (512 with RD and 512 without RD). The most common RD was systemic lupus erythematosus (51.6%), followed by rheumatoid arthritis (44.3%). Individuals with RD reported significantly higher PROMIS T-scores for pain [β = 6.2; 95% confidence interval (CI) = 4.76, 7.71] and fatigue (β = 2.9; 95% CI = 1.37, 4.38) compared to those without RD. Moreover, RD individuals reported lower physical functioning (β = -5.4; 95% CI = -6.50, -4.24) and social interaction (β = -4.5; 95% CI = -5.73, -3.20). Patients with RD in Saudi Arabia, particularly those with systemic lupus erythematosus and rheumatoid arthritis, have significantly greater impairment in physical functioning and social interaction and report higher levels of fatigue and pain. Addressing and ameliorating these negative outcomes is necessary to improve quality of life.

Racism exposure and trauma accumulation perpetuate pain inequities-advocating for change (RESTORATIVE): A conceptual model

Experiences of racism occur across a continuum from denial of services to more subtle forms of discrimination and exact a significant toll. These multilevel systems of oppression accumulate as chronic stressors that cause psychological injury conceptualized as racism-based traumatic stress (RBTS). RBTS has overlapping symptoms with posttraumatic stress disorder (PTSD) with the added burden that threats are constantly present. Chronic pain is a public health crisis that is exacerbated by the intersection of racism and health inequities. However, the relationship between RBTS and pain has not yet been explored. To highlight how these phenomena are interlinked, we present Racism ExpoSure and Trauma AccumulatiOn PeRpetuate PAin InequiTIes-AdVocating for ChangE (RESTORATIVE); a novel conceptual model that integrates the models of racism and pain and demonstrates how the shared contribution of trauma symptoms (e.g., RBTS and PTSD) maintains and perpetuates chronic pain for racialized groups in the United States. Visualizing racism and pain as "two halves of the same coin," in which the accumulative effects of numerous events may moderate the severity of RBTS and pain, we emphasize the importance of within-group distinctiveness and intersectionality (overlapping identities). We call on psychologists to lead efforts in applying the RESTORATIVE model, acting as facilitators and advocates for the patient's lived experience with RBTS in clinical pain care teams. To assist with this goal, we offer suggestions for provider and researcher antiracism education, assessment of RBTS in pain populations, and discuss how cultural humility is a central component in implementing the RESTORATIVE model. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Contemporary management of pain in cirrhosis: Toward precision therapy for pain

Chronic pain is highly prevalent in patients with cirrhosis and is associated with poor health-related quality of life and poor functional status. However, there is limited guidance on appropriate pain management in this population, and pharmacologic treatment can be harmful, leading to adverse outcomes, such as gastrointestinal bleeding, renal injury, falls, and hepatic encephalopathy. Chronic pain can be categorized mechanistically into three pain types: nociceptive, neuropathic, and nociplastic, each responsive to different therapies. By discussing the identification, etiology, and treatment of these three mechanistic pain descriptors with a focus on specific challenges in patients with cirrhosis, we provide a framework for better tailoring treatments, including nonpharmacologic therapies, to patients' needs.

Spinal pain processing in arthritis: Neuron and glia (inter)actions

Diseases of joints are among the most frequent causes of chronic pain. In the course of joint diseases, the peripheral and the central nociceptive system develop persistent hyperexcitability (peripheral and central sensitization). This review addresses the mechanisms of spinal sensitization evoked by arthritis. Electrophysiological recordings in anesthetized rats from spinal cord neurons with knee input in a model of acute arthritis showed that acute spinal sensitization is dependent on spinal glutamate receptors (AMPA, NMDA, and metabotropic glutamate receptors) and supported by spinal actions of neuropeptides such as neurokinins and CGRP, by prostaglandins, and by proinflammatory cytokines. In several chronic arthritis models (including immune-mediated arthritis and osteoarthritis) spinal glia activation was observed to be coincident with behavioral mechanical hyperalgesia which was attenuated or prevented by intrathecal application of minocycline, fluorocitrate, and pentoxyfylline. Some studies identified specific pathways of micro- and astroglia activation such as the purinoceptor- (P2 X7 -) cathepsin S/CX3 CR1 pathway, the mobility group box-1 protein (HMGB1), and toll-like receptor 4 (TLR4) activation, spinal NFκB/p65 activation and others. The spinal cytokines TNF, interleukin-6, interleukin-1β, and others form a functional spinal network characterized by an interaction between neurons and glia cells which is required for spinal sensitization. Neutralization of spinal cytokines by intrathecal interventions attenuates mechanical hyperalgesia. This effect may in part result from local suppression of spinal sensitization and in part from efferent effects which attenuate the inflammatory process in the joint. In summary, arthritis evokes significant spinal hyperexcitability which is likely to contribute to the phenotype of arthritis pain in patients.

Involvement of Parvalbumin-Positive Neurons in the Development of Hyperalgesia in a Mouse Model of Fibromyalgia

Fibromyalgia (FM) presents as chronic systemic pain, which might be ascribed to central sensitization, in which pain information processing is amplified in the central nervous system. Since patients with FM display elevated gamma oscillations in the pain matrix and parvalbumin (PV)-positive neurons play a critical role in induction of gamma oscillations, we hypothesized that changes in PV-positive neurons are involved in hyperalgesia in fibromyalgia. In the present study, to investigate a role of PV-positive neurons in neuropathic pain, mice received reserpine administration for 3 consecutive days as an animal model of FM (RES group), while control mice received vehicle injections in the same way (VEH group). The mice were subjected to hot-plate and forced swim tests, and immuno-stained PV-positive neurons were counted in the pain matrix. We investigated relationships between PV-positive neuron density in the pain matrix and pain avoidance behaviors. The results indicated that the mice in the RES group showed transient bodyweight loss and longer immobility time in the forced swim test than the mice in the VEH group. In the hot-plate test, the RES group showed shorter response latencies and a larger number of jumps in response to nociceptive thermal stimulus than the VEH group. Histological examination indicated an increase in the density of PV-positive neurons in the primary somatosensory cortex (S1) in the RES group. Furthermore, response latencies to the hot-plate were significantly and negatively correlated with the density of PV-positive neurons in the S1. These results suggest a critical role for PV-positive neurons in the S1 to develop hyperalgesia in FM.

Systematic Review of the Use of Intravenous Ketamine for Fibromyalgia

Background: Fibromyalgia, a complex disorder that affects 1% to 5% of the population, presents as widespread chronic musculoskeletal pain without physical or laboratory signs of any specific pathologic process. The mechanism, while still being explored, suggests central sensitization and disordered pain regulation at the spinal cord and supraspinal levels, with a resulting imbalance between excitation and inhibition that may alter central nervous system nociceptive processing. Nociceptive hypersensitivity results from activity of the N-methyl-D-aspartate receptor (NMDAR)-mediated glutamatergic synaptic transmission in the spinal cord and brain. Because ketamine, an NMDAR antagonist, may reduce induction of synaptic plasticity and maintenance of chronic pain states, the study of its use in intravenous form to treat fibromyalgia has increased. Methods: We conducted a literature search with the objectives of examining the effect of intravenous ketamine administration on pain relief, identifying side effects, and highlighting the need for clinical studies to evaluate ketamine infusion treatment protocols for patients with fibromyalgia. We used the keywords "fibromyalgia," "chronic pain," "ketamine," "intravenous," and "infusion" and found 7 publications that included 118 patients with fibromyalgia who met inclusion criteria. Results: Clinical studies revealed a short-term reduction-only for a few hours after the infusions-in self-reported pain intensity with single, low-dose, intravenous ketamine infusions, likely attributable to nociception-dependent central sensitization in fibromyalgia via NMDAR blockade. Case studies suggest that increases in the total dose of ketamine and longer, more frequent infusions may be associated with more effective pain relief and longer-lasting analgesia. Another neurotransmitter release may be contributing to this outcome. Conclusion: This systematic review suggests a dose response, indicating potential efficacy of intravenous ketamine in the treatment of fibromyalgia.

Psychometric validation of the Korean version of PROMIS 29 Profile V2.1 among patients with lower extremity problems

Background

Patients with lower extremity problems (LEP) commonly experience functional loss, pain, decreased range of motion, inadequacy in daily living activities, and structural change in radiographic evaluations. However, the traditional patient-reported outcome measurement which focused on symptoms, had a limited scope of applicability. This study aimed to validate the psychometric properties of the Korean version of PROMIS-29 Profile v2.1 (K-PROMIS-29 V2.1), a multi-dimensional measure for assessing generic profile health-related quality-of-life (HRQoL) in a sample of patients with lower extremity problems (LEP).

Methods

Participants were recruited from the orthopedic outpatient clinics at the Samsung Medical Center in Seoul, South Korea from September to October 2018. Participants completed a survey questionnaire that included the K-PROMIS-29 V2.1 and the SF-36v2. Principal component analysis (PCA) and confirmatory factor analysis (CFA) and Pearson’s correlations were used to evaluate the reliability and validity of the K-PROMIS-29 V2.1.

Results

A total of 299 participants were enrolled in the study and 258 (86%) completed the study questionnaire. The mean age (SD) of the participants was 56.6 (14.5) and 32.3%, 29.8, and 25.2% of the study participants visited outpatient clinics for foot, knee, and hip problems respectively. The Cronbach’s alpha coefficients of 7 sub-domains in K-PROMIS-29 V2.1 ranged from 0.80 to 0.95, indicating satisfactory internal consistency. In CFA, the goodness-of-fit indices were high (CFI = 0.937 and SRMR = 0.061). High to moderate correlations were found between comparable subscales of the K-PROMIS-29 V2.1 and subscales of the SF-36v2 (r = 0.55–0.70).

Conclusions

The K-PROMIS-29 V2.1 is a reliable and valid measure for assessing a broad range of health-related quality-of-life domains in patients with LEP. It would reflect the real-life symptoms experienced by patients with LEP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-021-00374-1.

Residual Pain in the Context of Selecting and Switching Biologic Therapy in Inflammatory Rheumatic Diseases

For many years, inflammatory rheumatic diseases (IRDs) represented a source of disappointment in medical care caused by the mediocre efficacy of the available treatments. Some of these diseases, like Rheumatoid Arthritis (RA) or Ankylosing Spondylitis (AS), caused fear in the general population, especially due to associated joint deformities and subsequent disabilities. However, in the last 20 years, a new successful class of antirheumatic drugs has become available: biologic Disease-Modifying Antirheumatic Drugs (bDMARDs). Due to this innovative treatment, the days are over when joint and spine deformities defined the condition of a person with RA or AS. Nonetheless, expectations are higher today, and other clinical problems, (not entirely solved by bDMARDs), seem to drive the drug selection during the span of rheumatic diseases. Most of these issues are covered by the term "unmet needs." One of the most intriguing of such needs is the residual pain (RP) in patients that are otherwise in the biological remission of the disease. Present in a significant proportion of the patients that enter remission status, RP is poorly understood and managed. In recent years, new data has become available in this area and new conceptual clarifications have occurred. In this review, we explain the various nature of RP and the necessity of treatment diversification in such situations. All in all, we believe this condition is far more complex than simple pain and includes other clinical aspects, too (like fatigue or mood changes) so the terms Post-Remission Syndrome (PRS), and PRS pain might be more appropriate.

Effect of exercise training on fatigue and pain in patients with systemic autoimmune myopathies: A systematic review

Systemic autoimmune myopathies (or idiopathic inflammatory myopathies) are a wide group of rare rheumatic diseases characterized by muscle weakness due to muscle inflammation. Recent evidence has continually reinforced the relevance of the perception of pain and fatigue as parameters of notable contribution to reducing the quality of life of these patients. However, due to the multidimensional characteristic of these variables, few studies address the effects of pharmacological and non-pharmacological therapies, such as exercise training on these variables. With regard to patients with systemic autoimmune myopathies, the outcomes related to the effects of exercise training are focused on muscle strength and endurance, few explore the effects on the perception of pain and fatigue. Given this, studies that review systematically the available evidence of the effects of exercise training on these perceptions can contribute to management of this parameter in clinical practice. Given this context, the present study aims to review systematically the effectiveness of exercise training specifically on the perception of pain and fatigue.

Pain due to Ehlers-Danlos Syndrome Is Associated with Deficit of the Endogenous Pain Inhibitory Control

OBJECTIVES

Although pain is a common complication of the hypermobile type of Ehlers-Danlos syndrome, its underlying mechanisms are still an issue of controversy. In this psychophysical study, we aimed at testing small-fiber function and the endogenous pain inhibitory control in patients with pain due to Ehlers-Danlos syndrome.

METHODS

In 22 patients with pain due to Ehlers-Danlos syndrome and 22 healthy participants, matched for age and sex, we tested small-fiber function using quantitative sensory testing and the endogenous pain inhibitory control using the conditioned pain modulation (CPM) protocol. As quantitative sensory testing methods, we included thermal pain and mechanical pain thresholds and the wind-up ratio. The CPM protocol consisted of two heat painful stimuli, that is, a test stimulus and a conditioning stimulus.

RESULTS

All patients complained of widespread pain. Quantitative sensory testing revealed no small-fiber deficit; in the area of maximum pain, we found an increased wind-up ratio. Whereas in the healthy participants the CPM protocol showed that the test stimulus rating was significantly reduced during conditioning, in patients with pain due to hEDS, the test stimulus rating increased during conditioning.

CONCLUSIONS

Our psychophysical study showing that patients with pain due to hEDS have an increased wind-up ratio in the area of maximum pain and abnormal CPM protocol suggests that in this condition, pain is associated with central sensitization, possibly due to deficit of the endogenous pain inhibitory control. These data might be relevant to pharmacological treatment.

Characterizing chronic pain phenotypes in multiple sclerosis: a nationwide survey study

ABSTRACT

Chronic pain is highly prevalent in multiple sclerosis (MS). Pain heterogeneity may contribute to poor treatment outcomes. The aim of this study was to characterize pain phenotypes distributions in persons with MS and compare pain phenotypes in terms of pain intensity, frequency of chronic overlapping pain conditions, and use and analgesic effects of different classes of pain medications. Data were collected through a national web-based survey with measures of neuropathic (painDETECT) and nociplastic pain (Fibromyalgia Survey Criteria), chronic overlapping pain conditions, and pain medication use and pain relief. In a sample of N = 842 adults with chronic pain and MS, the largest proportion (41%) showed evidence of nociceptive pain, 27% had mixed neuropathic/nociplastic pain, 23% had nociplastic pain, and 9% had neuropathic pain. Nociplastic pain was associated with significantly higher pain intensity and frequency of chronic overlapping pain conditions. Across all pain types, high frequency of pain medication use along with poor-modest pain relief was reported. Cannabis use for pain was more common, and pain relief ratings were higher among those with nociplastic pain, relative to nociceptive pain. Although NSAID use was highest among those with nociplastic pain (80%), pain relief ratings for NSAIDs were highest among those with nociceptive pain. These findings underscore the need for multidimensional assessment of pain in MS with greater emphasis on the identification of pain phenotype. An improved characterization of pain as a multifaceted condition in MS could inform therapeutic approaches.

Impact of clinical and psychological factors associated with depression in patients with rheumatoid arthritis: comparative study between Germany and Brazil

OBJECTIVE

To investigate the prevalence of depressive symptoms and its association with clinical and psychological factors in patients with rheumatoid arthritis (RA) in Germany and in Brazil.

METHOD

A convenience sample of 267 RA patients, 176 from Germany (age 62.4 ± 12.3 years) and 91 from Brazil (age 56.3 ± 12.6 years), was used in this cross-sectional study. The following questionnaires were used: Beck Depression Inventory (BDI), painDETECT test, Perceived Stress Questionnaire, fatigue questionnaire (FACIT), Health Assessment Questionnaire Disability Index (HAQ-DI), and the SF-36 questionnaires (Short-Form 36 Health Survey). Disease activity score (DAS 28-CRP) and visual analogue scale (VAS) for pain were also evaluated. Statistical analysis is based on comparison of means and proportions. Statistical significance for non-normal data was evaluated by non-parametrical tests.

RESULTS

Depressive symptoms were more prevalent in the Brazilian sample (44% vs 22.9%, p = 0.025). Compared to German patients, the Brazilian ones also experienced more pain (current pain status on VAS: 4.67 ± 3.4 vs 3.67 ± 2.31 respectively, p < 0.01), were physically more limited (1.89 ± 1.85 vs 1.01 ± 0.75, p = 0.012), and had higher C-reactive protein levels (7.78 ± 18.3 vs 5.82 ± 10.45, p = 0.028). Despite receiving a more intensive treatment, German patients presented similar disease activity when compared to Brazilian patients (DAS28-CRP: Brazil 3.4 ± 1.5 vs Germany 3.3 ± 1.3, p = 0.307).

CONCLUSION

Depressive symptoms are frequent in RA patients from different countries and interact with psychological disorders and the experience of pain. They contribute negatively to their well-being suggesting the need for psychoeducational strategies. Key Points • New psychoeducational strategies for RA management.• Higher inflammation marker in rheumatoid arthritis patients is associated with depression.• Medical treatment in RA influences depressive symptoms.• Depressive symptoms are dependent on population group.• High disease activity is related to depression.

The PROMISⓇ-Plus-Osteoarthritis of the Knee (OAK) profile measure integrates generic and condition-specific content to enhance relevance and efficiency

OBJECTIVE

The Patient-Reported Outcomes Measurement Information System (PROMIS)-Plus-Osteoarthritis of the Knee (OAK) profile integrates universal PROMIS items with knee-specific items across 13 domains. We evaluated the psychometric properties of a subset of six domains associated with quality of life in people with OAK.

STUDY DESIGN AND SETTING

In a cross-sectional study of OAK patients (n=600), we estimated reliability using Pearson and Spearman correlations with Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores and known-groups validity with PROMIS Global Health. Measure responsiveness was tested via paired t-tests in a longitudinal study (n=238), pre/post total knee replacement.

RESULTS

Across the six domains, internal consistency reliability (Cronbach's alpha) was 0.77-0.95 and test-retest reliability (intraclass correlation coefficients) was ≥0.90. Correlations with Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores and PROMIS Global supported convergent and divergent validity. Known-groups validity testing revealed better scores in all domains for high vs. low global status groups, and knee-specific items added value in physical function and pain. All domains reflected (p<0.001) better health status scores at follow up.

CONCLUSION

The six PROMIS-Plus-OAK profile domains demonstrated good psychometric characteristics. The measure integrates universal and knee-specific content to provide enhanced relevance, measurement precision and efficient administration for patient care and clinical research.

Dorsal horn disinhibition and movement-induced behaviour in a rat model of inflammatory arthritis

OBJECTIVES

Alterations beyond joint inflammation such as changes in dorsal horn (DH) excitability contribute to pain in inflammatory arthritis (IA). More complete understanding of specific underlying mechanisms will be important to define novel targets for the treatment of IA pain. Pre-clinical models are useful, but relevant pain assays are vital for successful clinical translation. For this purpose, a method is presented to assess movement-induced pain-related behaviour changes that was subsequently used to investigate DH disinhibition in IA.

METHODS

IA was induced by intra-articular injection of complete Freund's adjuvant (CFA) in male rats, and weight distribution was assessed before and after walking on a treadmill. To confirm increased activity in nociception-related pathways, fos expression was assessed in the superficial DH, including in nociceptive neurons, identified by neurokinin 1 (NK1) immunoreactivity, and interneurons. Inhibitory terminal density onto NK1+ neurons was assessed and lastly, a cohort of animals was treated for 3 days with gabapentin.

RESULTS

At 4 weeks post-CFA, walking reduced weight distribution to the affected joint and increased DH fos expression, including in NK1+ neurons. Neuronal activity in inhibitory cells and inhibitory terminal density on NK1+ neurons were decreased in CFA-treated animals compared with controls. Treatment with gabapentin led to recovered behaviour and DH neuronal activity pattern in CFA-treated animals.

CONCLUSION

We describe an assay to assess movement-induced pain-related behaviour changes in a rodent IA model. Furthermore, our results suggest that disinhibition may contribute to pain related to movement in IA.

Chemical Mediators' Expression Associated with the Modulation of Pain in Rheumatoid Arthritis

BACKGROUND

The management of pain in patients with rheumatoid arthritis (RA) is a complex subject due to the autoimmune nature of the pathology. Studies have shown that chemical mediators play a fundamental role in the determination, susceptibility and modulation of pain at different levels of the central and peripheral nervous system, resulting in interesting novel molecular targets to mitigate pain in patients with RA. However, due to the complexity of pain physiology in RA cand the many chemical mediators, the results of several studies are controversial.

OBJECTIVE

The aim of this study was to identify the chemical mediators that are able to modulate pain in RA.

METHOD

In this review, a search was conducted on PubMed, ProQuest, EBSCO, and the Science Citation index for studies that evaluated the expression of chemical mediators on the modulation of pain in RA.

RESULTS

Few studies have highlighted the importance of the expression of some chemical mediators that modulate pain in patients with rheumatoid arthritis. The expression of TRPV1, ASIC-3, and TDV8 encode ionic channels in RA and modulates pain, likewise, the transcription factors in RA, such as TNFα, TGF-β1, IL-6, IL-10, IFN-γ, IL-1b, mTOR, p21, caspase 3, EDNRB, CGRPCALCB, CGRP-CALCA, and TAC1 are also directly involved in pain perception.

CONCLUSION

The expression of all chemical mediators is directly related to RA and the modulation of pain by a complex intra and extracellular signaling pathway, however, transcription factors are involved in modulating acute pain, while the ionic channels are involved in chronic pain in RA.

The Impact of Tinnitus on Fibromyalgia

Objective

Fibromyalgia (FM) is a disorder characterized by chronic diffuse pain and enhanced pain response to stimuli and is caused by central sensitization Tinnitus also is related to central sensitization So we investigated the impact of tinnitus on FM.

Methods

We included 22 FM patients with tinnitus and 25 FM patients without tinnitus We assessed a range of symptoms using the Widespread Pain Index; Symptom Severity Score scale; Visual Analogue Scale of pain; and the Korean versions of the Fibromyalgia Impact Questionnaire (FIQ), the Insomnia Severity Index, and the Short-form Health Survey (SF-36) Information about the severity of tinnitus in FM patients was evaluated using the Korean version of the Tinnitus Handicap Questionnaire (THQ-K).

Results

There were significant differences between the group that had mild tinnitus (THQ<38) and the group that had moderate-to-severe tinnitus (THQ≥38) for FIQ score (p=0025) and for the physical functioning (p=0003), social functioning (p=0035), and mental health (p=0017) components of the SF-36 Also, after dividing patients into 2 groups according to insomnia severity, significant differences were observed in FIQ score (p=0002) and in body pain (p=0001), general health (p=0008), vitality (p=0003), social functioning (p=0003), role limitation due to emotional condition (p=0001), and mental health (p<0001) components of the SF-36.

Conclusion

The FM patients with severe tinnitus had more functional impairments and lower quality of life than those with mild tinnitus Severe insomnia also was accompanied by worse health status and lower quality of life.

Assessing our approach to diagnosing Fibromyalgia

Introduction: Fibromyalgia represents the most prevalent of the group of conditions that are known as central sensitivity syndromes. Approximately 2-5% of the adult population in the United States is affected by Fibromyalgia. This pain amplification syndrome has an enormous economic impact as measured by work absenteeism, decreased work productivity, disability and injury compensation, and over-utilization of healthcare resources. Multiple studies have shown that early diagnosis of this condition can improve patient outlook, and redirect valuable health care resources toward more appropriate targeted therapy. Efforts have been made toward improving diagnostic accuracy through updated criteria. Areas Covered: Reviewed here are 1) reasons for the need for more accurate diagnosis of Fibromyalgia, (2) a review of the evolution of Fibromyalgia to current times, and (3) the proliferation of currently available diagnostic criteria and problems related to each of them. From initial literature review until October 2020, PubMed, Embase, and Scopus were searched for applicable literature. Expert Opinion: A discussion of ongoing efforts to obtain a biomarker to enhance diagnostic accuracy concludes this review. A need to include rheumatologists as part of the care team of patients with Fibromyalgia is emphasized.

Fibromyalgia in patients with psoriatic arthritis: Relationship with enthesopathy, sleep, fatigue and quality of life

OBJECTIVES

To evaluate the relationship of fibromyalgia with enthesopathy, sleep, fatigue and quality of life in patients with psoriatic arthritis.

METHODS

The psoriatic arthritis patients according to CASPAR criteria were included in the study. The diagnosis of fibromyalgia was based on 2016 ACR criteria. Demographic and clinical parameters were noted. Disease activity and enthesopathy were evaluated with Disease Activity Score-28 (DAS-28) and Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), respectively. Functional assessment scales in this study were Psoriatic Arthritis Quality of Life (PsAQoL), Pittsburgh Sleep Quality Index (PSQI), Multidimensional Assessment of Fatigue (MAF). Fibromyalgia Impact Questionnaire (FIQ) was used to assess the functional status of fibromyalgia. The Mann-Whitney U test and Spearman correlation coefficient (ρ) were used. Hierarchical multiple regression analysis used to examine the differential contributions to FIQ score. P < .05 was accepted as significant.

RESULTS

We enrolled 50 PsA patients (31 female, 19 male) with a mean age of 49.5 years (SD: 10.2) and mean disease duration 7.5 years (SD: 7.5). Thirty-two patients (64% of PsA patients) fulfilled ACR criteria for fibromyalgia. The mean scores of MASES, PSQI, MAF and PsAQoL were significantly higher in patients with fibromyalgia (P < .05). The correlations between FIQ and other functional parameters were as follows; MASES (ρ = 0.71, P < .0005), PSQI (ρ = 0.62, P < .0005), MAF (ρ = 0.60, P < .0005), PsAQoL (ρ = 0.61, P < .0005). A moderate correlation was existing between FIQ and DAS-28 (ρ = 0.42, P = .03).

CONCLUSIONS

Coexistence of fibromyalgia in PsA patients is associated with the presence of enthesopathy, poor quality of life, sleep disturbance and fatigue.

Randomized clinical trial comparing of transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) in knee osteoarthritis

BACKGROUND

Due to the limitations of pharmacological and surgical management of knee osteoarthritis (OA), several non-pharmacologic approaches including transcutaneous electrical nerve stimulation (TENS) and transcranial direct current stimulation (tDCS) have been introduced, with promising results.

OBJECTIVE

We aimed to investigate and compare the therapeutic effects of TENS and tDCS for the treatment of patients with knee OA.

METHODS

In this double-blinded randomized controlled trial, a total of 40 adult patients with knee OA were randomly allocated to either the TENS or the tDCS group. Patients in either group received 6 sessions of the TENS or tDCS for 2 weeks. Knee strengthening exercises were performed twice daily for the entire treatment period. Patients were evaluated using the visual analogue scale (VAS) and Western Ontario and McMaster Universities (WOMAC).

RESULTS

Significant improvement was observed in all outcomes in both TENS and tDCS groups at each follow up compared to baseline although the early improvement (first follow-up) in the WOMAC index was not significant in the TENS group. Based on the within-subject analysis, the behavior of two treatment groups did not differ regarding the changes in the course of the VAS, WOMAC score and its subscales, i.e. stiffness, pain and function (p = 0.263, 0.051, 0.198, 0.075, and 0.146, respectively).

CONCLUSIONS

Based on the results of this study, the effect of tDCS and TENS was not significantly different on pain and function of patients with knee OA.

Functional Near-Infrared Spectroscopy to Assess Central Pain Responses in a Nonpharmacologic Treatment Trial of Osteoarthritis

BACKGROUND AND PURPOSE

Knee osteoarthritis (OA) is a common source of pain in older adults. Although OA-induced pain can be relieved with analgesics and anti-inflammatory drugs, the current opioid epidemic is fostering the exploration of nonpharmacologic strategies for pain mitigation. Amongs these, transcranial direct current stimulation (tDCS) and mindfulness-based meditation (MBM) hold potential for pain-relief efficacy due to their neuromodulatory effects of the central nervous system, which is known to play a fundamental role in pain perception and processing.

METHODS

In this double-blind study, we used functional near-infrared spectroscopy (fNIRS) to investigate the effects of tDCS combined with MBM on underlying pain processing mechanisms at the central nervous level in older adults with knee OA. Nineteen subjects were randomly assigned to two groups undergoing a 10-day active tDCS and MBM regimen and a sham tDCS and MBM regimen, respectively.

RESULTS

Our results showed that the neuromodulatory intervention significantly relieved pain only in the group receiving active treatment. We also found that only the active treatment group showed a significant increase in oxyhemoglobin activation of the superior motor and somatosensory cortices colocated to the placement of the tDCS anodal electrode. To our knowledge, this is the first study in which the combined effect of tDCS and MBM is investigated using fNIRS.

CONCLUSION

In conclusion, fNIRS can be effectively used to investigate neural mechanisms of pain at the cortical level in association with nonpharmacological, self-administered treatments.

Understanding the Role of Interleukin-6 (IL-6) in the Joint and Beyond: A Comprehensive Review of IL-6 Inhibition for the Management of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, debilitating autoimmune disorder involving inflammation and progressive destruction of the joints, affecting up to 1% of the population. The majority of patients with RA have one or more comorbid conditions, the most common being cardiovascular disease, osteoporosis, and depression, the presence of which are associated with poorer clinical outcomes and lower health-related quality of life. RA pathogenesis is driven by a complex network of proinflammatory cells and cytokines, and of these, interleukin-6 (IL-6) plays a key role in the chronic inflammation associated with RA. Through cell signaling that can be initiated by both membrane-bound and soluble forms of its receptor, IL-6 acts both locally to promote joint inflammation and destruction, and in the circulation to mediate extra-articular manifestations of RA, including pain, fatigue, morning stiffness, anemia, and weight loss. This narrative review describes the role of IL-6 in the pathogenesis of RA, its comorbidities, and extra-articular systemic manifestations, and examines the effects of the IL-6 receptor inhibitors sarilumab and tocilizumab on clinical endpoints of RA, patient-reported outcomes, and common comorbidities and extra-articular manifestations.

Two sides on the fibromyalgia coin: physical pain and social pain (invalidation)

Although fibromyalgia (FM) has been traditionally defined by the extent of physical pain sites alongside other non-pain symptoms, recent evidence has highlighted the importance of social dimension in definition of pain perception. Social pain or invalidation, which denotes painful feeling following social conflicts or misunderstanding about illness legitimacy, is an important but ignored issue in the FM lexicon. While physical and social pain seem to be different and separate entities, we hypothesize that they are completely intertwined with indistinct borders in FM. Accumulating emergent neuroscience and behavioral evidence highlights the overlapping of physical and social pain in different painful conditions. However, this overlapping seems to reach its maximum in FM. This review sheds more light on the tight interconnectivity between physical and social pain in FM from the perspective of intuitional commonalities, clinical aspects, and shared neural pathways. The conceptualization of FM as an integrative physical-social pain paradigm will move us closer to necessitating the incorporation of social pain in future models of FM diagnosis and management. Key Points • Considering of social pain as one key concept is relatively mute in FM literature. • Overlapping of physical and social pain seems to be unique in FM due to its nature. • Acknowledging social pain in the FM lexicon could shift the paradigm of diagnosis and management of FM patients.

Cannabinoids for fibromyalgia pain: a critical review of recent studies (2015-2019)

INTRODUCTION

Fibromyalgia is a chronic health condition characterized by widespread, severe musculoskeletal pain that affects an estimated 5-7% of the global population. Due to the highly comorbid nature of fibromyalgia, patients with the disorder often respond poorly to traditional pain treatments. Recent studies suggest that patient response may be more favorable to alternative analgesics, such as cannabis. However, the therapeutic potential of cannabis-based pain treatment for fibromyalgia remains unclear. The present study examined the most recent cannabis literature (2015-2019) and provides a critical review of current research on the safety and efficacy of medical cannabis treatments for fibromyalgia.

METHODS

We followed Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in searching the PubMed and Medline databases using the search terms "cannabis + fibromyalgia" and then "cannabinoids + fibromyalgia." Inclusion criteria were a) English language, b) published in peer review journals, c) published from 2015 to 2019, d) all study designs except for systematic reviews and meta-analyses, and e) all cannabis preparations.

RESULTS

The search identified five applicable studies involving 827 participants that used six different treatments. Review suggested several methodological problems pertaining to generalizability and validity.

CONCLUSION

Although the critically reviewed studies superficially suggest that medical cannabis is a safe and effective treatment for fibromyalgia pain, serious methodological limitations prevent a definitive conclusion regarding the use of cannabinoids for pain management in fibromyalgia patients at this time.

Understanding differences between men and women with axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory immune-mediated disease resulting in inflammatory low back pain and other inflammatory manifestations in peripheral joints and entheses. AxSpA encompasses both ankylosing spondylitis (AS), in which patients present with definitive sacroiliitis visible on radiographic imaging, as well as nonradiographic axSpA (nr-axSpA), in which such changes may not be discernable. Emerging evidence suggests that women and men experience axSpA differently. Although the prevalence of AS is approximately 2- to 3- fold higher in men than in women, nr-axSpA occurs with roughly equal frequency in women and men. The goal of this review is to increase awareness of sex differences in axSpA by exploring the distinct manifestations of disease and disease characteristics in women, the overall clinical burden, recommendations for diagnosis, and potential treatment options. We summarize and contextualize the results of recent studies that illuminate sex differences in nr-axSpA and AS, including differences in disease manifestation and progression. It is important that sex differences in axSpA are understood and considered when diagnosing and treating the spectrum of axSpA, including AS and nr-axSpA.

Prevalence and predictors of chronic pain intensity and disability among adults with sickle cell disease

Among 170 adults with sickle cell disease, we evaluated chronic pain impact and disability prevalence, assessed age and gender differences, and identified psychosocial predictors of chronic pain intensity and disability. Most participants had a high level of disability. Chronic pain intensity and disability were significantly associated with pain catastrophizing and chronic pain self-efficacy, and worsened with age. Further research is needed to confirm study findings and develop interventions, including palliative care approaches that address catastrophizing and disability, particularly for young women and middle-aged adults with sickle cell disease. Moreover, consistent clinical assessment of chronic pain and psychosocial health should be implemented.

Longitudinal effect of transcranial direct current stimulation on knee osteoarthritis patients measured by functional infrared spectroscopy: a pilot study

Significance: Knee osteoarthritis (OA) is a common joint disease causing chronic pain and functional alterations (stiffness and swelling) in the elderly population. OA is currently treated pharmacologically with analgesics, although neuromodulation via transcranial direct current stimulation (tDCS) has recently generated a growing interest as a safe side-effect free treatment alternative or a complement to medications for chronic pain conditions. Although a number of studies have shown that tDCS has a beneficial effect on behavioral measures of pain, the mechanistic action of neuromodulation on pain sensitivity and coping at the central nervous system is not well understood. Aim: We aimed at observing longitudinal changes of cortical hemodynamics in older adults with knee OA associated with a two-week-long tDCS self-treatment protocol. Approach: Hemodynamics was measured bilaterally in the motor and somatosensory cortices with functional near-infrared spectroscopy (fNIRS) in response to thermal pain induced ipsilaterally to the knee primarily affected by OA. Results: We found that both oxyhemoglobin- and deoxyhemoglobin-related functional activations significantly increased during the course of the tDCS treatment, supporting the notion that tDCS yields an increased cortical excitability. Concurrently, clinical measures of pain decreased with tDCS treatment, hinting at a potential spatial dissociation between cortically mediated pain perception and suppression and the prevalence of neuromodulatory effects over cortical pain processing. Conclusions: fNIRS is a valid method for objectively tracking pain in an ambulatory setting and it could potentially be used to inform strategies for optimized tDCS treatment and to develop innovative tDCS protocols.

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.

Using the Systems Biology Approach and Molecular Method to Investigate the Role of the Dopaminergic Pathway in Osteoarthritis: A Case Control Study

OBJECTIVE

Osteoarthritis is the most common type of arthritis and one of the leading causes of job loss and motor disabilities. Recently, the involvement of dopaminergic pathways and dopamine receptor genes has been considered in this disease. Therefore, studying and comparing the expression pattern of these receptor genes can lead to a greater understanding of the pathogenesis of this disease.

METHODS

In this research, we used the systems biology approach to investigate the role of the dopaminergic pathway in osteoarthritis. Then the gene expression pattern of dopamine receptor genes was examined in an osteoarthritis patientgroup in comparison with healthy individuals by Real-time PCR method.

RESULTS

The analysis of the transcriptome dataset of osteoarthritis identified some genes in the dopaminergic pathway and the six most important genes in this disease are in the network with a significant relationship to dopamine receptors which differentially expressed compared to health groups. Statistical analysis of the case control study showed a significant difference (P-value<0.05) in DRD1 and DRD2 family in the patients in comparison to healthy individuals.

DISCUSSION

We attained the significant expression pattern of dopamine receptors in the blood of osteoarthritis patients which could be useful to identify new strategies for the diagnosis, management, or treatment of this disease.

The effect of treatment regimens on salivary cortisol levels in patients with chronic musculoskeletal disorders

BACKGROUND

Increased levels of circulating cortisol have been associated with pain severity in patients with chronic musculoskeletal disorders (CMD). Little is known about the potential association between pain management and salivary cortisol alterations in CPM patients treated with different regimens.

OBJECTIVES

This prospective feasibility study aimed to determine the effect of two treatment regimens in comparison with sham therapy on pain intensity and disability and salivary cortisol concentration (SCC) in patients with CMD.

METHODS

Thirty patients were randomly assigned to 3 groups of 10: two experimental groups (A and B) and a control group (C). The experimental groups followed physiotherapy treatment (A) or acupuncture (B), while the control group (C) followed a sham therapy for 10 sessions. Pain data were collected using the Chronic Pain Grade (CPG) questionnaire and SCC was measured by enzyme-linked immunosorbent assay at pre- and posttreatment.

RESULTS

Repeated-measures analysis of variance showed that patients treated with acupuncture experienced greater decreases in pain intensity/pain disability (P < 0.05) than the physiotherapy and sham therapy groups. No statistical differences were found between the three groups for the SCC outcome variable. Bonferroni adjustments showed that the mean values of SCC were significantly decreased at posttreatment (P < 0.05) across the three groups.

CONCLUSION

There was a significant decrease in both pain and cortisol outcomes at posttreatment in patients with CMD. Because of the limitations of this study, we cannot draw conclusions regarding whether the lower SCC could be an indication of pain reduction in patients with CMD.

Diclofenac attenuates inflammation through TLR4 pathway and improves exercise performance after exhaustive swimming

BACKGROUND

The use of NSAIDs has become a common practice to counteract the pro-inflammatory acute effects of exercise, in order to improve sports performance. The liver, due to its central role in energy metabolism, may be involved primarily in the process of ROS generation and consequently inflammation after exhaustive exercise.

OBJECTIVE

To analyze the influence of diclofenac on the liver TLR4 pathway and time to exhaustion in rats submitted to repeated exhaustive swimming.

METHODS

An exhaustive test was performed in order to mimic athletes' routine, and inflammatory status and oxidative stress markers were evaluated in the liver. Animals were divided into sedentary and exhaustion groups, with this last performing three exhaustive swimming bouts. At the same time, diclofenac or saline was pre-administered once a day for nine days.

RESULTS

Data showed significantly increased COX-2, TLR4, and MyD88 protein content in the liver after exhaustive swimming bouts. The levels of pro-inflammatory cytokines also increased after exhaustive exercise, while these effects were attenuated in the group treated with diclofenac plus exhaustive swimming bouts. The anti-inflammatory modulation provoked by diclofenac treatment was associated with an increased time to exhaustion in the exercise bouts. The exhaustive exercise increased TBARS formation, but diclofenac treatment blunted this elevation, while GSH/GSSG ratios in both exhaustion-saline and exhaustion-diclofenac-treated groups were lower than in the sedentary-saline group.

CONCLUSIONS

Our findings suggest that diclofenac may improve exercise performance and represent an effective tool to ameliorate the pro-inflammatory status in liver when associated with exhaustive exercise, and the liver may be a possible therapeutic target.

Disease activity flares and pain flares in an early rheumatoid arthritis inception cohort; characteristics, antecedents and sequelae

Background

RA flares are common and disabling. They are described in terms of worsening inflammation but pain and inflammation are often discordant. To inform treatment decisions, we investigated whether inflammatory and pain flares are discrete entities.

Methods

People from the Early RA Network (ERAN) cohort were assessed annually up to 11 years after presentation (n = 719, 3703 person-years of follow up). Flare events were defined in 2 different ways that were analysed in parallel; DAS28 or Pain Flares. DAS28 Flares satisfied OMERACT flare criteria of increases in DAS28 since the previous assessment (≥1.2 points if active RA or ≥ 0.6 points if inactive RA). A ≥ 4.8-point worsening of SF36-Bodily Pain score defined Pain Flares. The first documented episode of each of DAS28 and Pain Flare in each person was analysed. Subgroups within DAS28 and Pain Flares were determined using Latent Class Analysis. Clinical course was compared between flare subgroups.

Results

DAS28 (45%) and Pain Flares (52%) were each common but usually discordant, with 60% of participants in DAS28 Flare not concurrently in Pain Flare, and 64% of those in Pain Flare not concurrently in DAS28 Flare. Three discrete DAS28 Flare subgroups were identified. One was characterised by increases in tender/swollen joint counts (14.4%), a second by increases in symptoms (13.1%), and a third displayed lower flare severity (72.5%). Two discrete Pain Flare subgroups were identified. One occurred following low disease activity and symptoms (88.6%), and the other occurred on the background of ongoing active disease and pain (11.4%). Despite the observed differences between DAS28 and Pain Flares, each was associated with increased disability which persisted beyond the flare episode.

Conclusion

Flares are both common and heterogeneous in people with RA. Furthermore our findings indicate that for some patients there is a discordance between inflammation and pain in flare events. This discrete flare subgroups might reflect different underlying inflammation and pain mechanisms. Treatments addressing different mechanisms might be required to reduce persistent disability after DAS28 and Pain Flares.

Is Virtual Reality Effective in Orthopedic Rehabilitation? A Systematic Review and Meta-Analysis

BACKGROUND

Virtual reality (VR) is an interactive technology that allows customized treatment and may help in delivering effective person-centered rehabilitation.

PURPOSE

The purpose of this review was to systematically review and critically appraise the controlled clinical trials that investigated VR effectiveness in orthopedic rehabilitation.

DATA SOURCES

Pubmed, CINAHL, Embase, PEDro, REHABDATA, and Sage publications were searched up to September 2018. In addition, manual searching and snowballing using Scopus and Web of Science were done.

STUDY SELECTION

Two reviewers screened studies for eligibility first by title and abstract and then full text.

DATA EXTRACTION

Articles were categorized into general or region-specific (upper limbs, lower limbs, and spine) orthopedic disorders. Study quality was assessed using the Evaluation Guidelines for Rating the Quality of an Intervention Study scoring. Meta-analysis quantified VR effectiveness, compared with no treatment, in back pain.

DATA SYNTHESIS

Nineteen studies were included in the quality assessment. The majority of the studies were of moderate quality. Fourteen studies showed that VR did not differ compared with exercises. Compared with the no-treatment control, 5 studies favored VR and 3 other studies showed no differences. For low back pain, the meta-analysis revealed no significant difference between VR and no-treatment control (n = 116; standardized mean difference = -0.21; 95% confidence interval = -0.58 to 0.15).

LIMITATIONS

Limitations included heterogeneity in interventions and the outcome measures of reviewed studies. Only articles in English were included.

CONCLUSION

The evidence of VR effectiveness is promising in chronic neck pain and shoulder impingement syndrome. VR and exercises have similar effects in rheumatoid arthritis, knee arthritis, ankle instability, and post-anterior cruciate reconstruction. For fibromyalgia and back pain, as well as after knee arthroplasty, the evidence of VR effectiveness compared with exercise is absent or inconclusive.