Identifying and Managing Nociplastic Pain in Individuals With Rheumatic Diseases: A Narrative Review

How to Distinguish Non-Inflammatory from Inflammatory Pain in RA?

PURPOSE OF THE REVIEW

Managing non-inflammatory pain in rheumatoid arthritis (RA) can be a huge burden for the rheumatologist. Pain that persists despite optimal RA treatment is extremely challenging for patient and physician alike. Here, we outline the latest research relevant to distinguishing non-inflammatory from inflammatory RA pain and review the current understanding of its neurobiology and management.

RECENT FINDINGS

Nociplastic pain is a recently introduced term by the international pain community. Its definition encompasses the non-inflammatory pain of RA and describes pain that is not driven by inflamed joints or compromised nerves, but that is instead driven by a functional reorganisation of the central nervous system (CNS). Insights from all areas of nociplastic pain research, including fibromyalgia, support a personalised pain management approach for non-inflammatory pain of RA, with evidence-based guidelines favouring use of non-pharmacological interventions. Future developments include novel CNS targeting pharmacotherapeutic approaches to treat nociplastic pain.

An interdisciplinary perspective on peripheral drivers of pain in rheumatoid arthritis

Pain is one of the most debilitating symptoms of rheumatoid arthritis (RA), and yet remains poorly understood, especially when pain occurs in the absence of synovitis. Without active inflammation, experts most often attribute joint pain to central nervous system dysfunction. However, advances in the past 5 years in both immunology and neuroscience research suggest that chronic pain in RA is also driven by a variety of abnormal interactions between peripheral neurons and mediators produced by resident cells in the local joint environment. In this Review, we discuss these novel insights from an interdisciplinary neuro-immune perspective. We outline a potential working model for the peripheral drivers of pain in RA, which includes autoantibodies, resident immune and mesenchymal cells and their interactions with different subtypes of peripheral sensory neurons. We also offer suggestions for how future collaborative research could be designed to accelerate analgesic drug development.

Temporal Summation but Not Expectations of Pain Relief Predict Response to Acupuncture Treatment in Fibromyalgia

Fibromyalgia (FM) is a common chronic pain condition for which acupuncture treatment is increasingly utilized. However, there is no universally accepted measure to predict whether a specific patient will benefit from acupuncture. This is a single-center, single-blind, sham-controlled, randomized, noncrossover, longitudinal trial of 76 subjects with FM, assigned to either electroacupuncture (EA) or a placebo control, mock laser (ML) acupuncture. Outcome measures included clinical pain severity (Brief Pain Inventory [BPI]), degree of nociplastic pain (Fibromyalgia Survey Questionnaire), and pressure pain tolerance (PPtol). Baseline measures of temporal summation of pain and expectations for treatment relief were used as predictors. Individuals in both treatment groups experienced significant reductions in BPI (EA: P < .001, ML: P = .018) and Fibromyalgia Survey Questionnaire (EA: P = .032, ML: P = .002) after treatment; however, neither group showed a significant increase in PPtol. Lower temporal summation at baseline was correlated with greater post-treatment improvement in BPI in the EA group (rho = .389, P = .025) but not in the ML group (rho = -.272, P = .109). Lower-baseline temporal summation was correlated with greater decreases in PPtol following EA (rho = .400, P = .040), whereas the opposite was seen for ML (rho = -.562, P = .001). Treatment expectancy at baseline was not correlated with any outcome after EA or ML treatments. Our results support using a quantitative sensory testing metric, temporal summation of pain, but not expectations, to predict analgesia following acupuncture treatment for pain. PERSPECTIVE: A randomized study of acupuncture in FM found baseline temporal summation, but not expectations of pain relief, to be predictive of treatment response. CLINICAL TRIAL REGISTRATION: Registered under ClinicalTrials.gov identifier NCT02064296.

Nociplastic pain in axial spondyloarthritis and psoriatic arthritis: role of JAK kinases in immunopathology and therapeutic impact of JAK inhibitors

INTRODUCTION

Pain in both peripheral and axial joints is a major symptom in patients with psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). Emerging evidence demonstrates pain mechanisms, beyond those related to inflammation or joint damage, based on aberrant processing of nociceptive stimuli peripherally as well as centrally. The Janus kinase/signal transducers and activators of transcription (JAK-STAT) signaling pathway has been implicated in the processing of pain beyond its role in mediating inflammation and inhibitors of this pathway approved for the treatment of axSpA and PsA have been shown to alleviate a broad array of pain outcomes in both axial and peripheral joints.

AREAS COVERED

We review recent definitions and standardization of the nomenclature for categorizing chronic pain according to causality, assessment tools to evaluate nociplastic pain, the pathophysiologic role of JAK-STAT signaling in nociplastic pain, evidence for the presence of nociplastic pain in axSpA and PsA, and the impact of JAK inhibitors (JAKi) on pain outcomes in clinical trials (PubMed: 01/01/2019-04/01-2024).

EXPERT OPINION

Nociplastic pain assessment has been confined almost entirely to the use of a limited number of questionnaires in cross-sectional studies of these diseases. Though effective for alleviating pain, it is unclear if JAKi specifically impact nociplastic pain.

The problem of residual pain in the assessment of rheumatoid arthritis activity

Residual pain is a major unmet medical need observed in patients suffering from rheumatoid arthritis (RA), which decreases their quality of life, even after achieving remission or low disease activity. The article has two aims: 1) to present mechanisms involved in the pathophysiology of residual pain, both inflammatory and non-inflammatory, i.e. neuropathic and nociplastic pain, as well as secondary pain syndromes, i.e. osteoarthritis and fibromyalgia, which can contribute to residual pain; 2) to show the limitations of current disease activity measures recommended by European Alliance of Associations for Rheumatology (EULAR) and American College of Rheumatology (ACR), which raise the need for a separate assessment of pain, and examples of methods that could be used by medical professionals to assess the pain and make a differential diagnosis. In conclusion, establishing a valid method to assess pain is essential to identify the pathomechanism of residual pain and to create treatments tailored specifically to individual RA patients.

Repetitive Transcranial Magnetic Stimulation in Fibromyalgia: Exploring the Necessity of Neuronavigation for Targeting New Brain Regions

Fibromyalgia and osteoarthritis are among the most prevalent rheumatic conditions worldwide. Nonpharmacological interventions have gained scientific endorsements as the preferred initial treatments before resorting to pharmacological modalities. Repetitive transcranial magnetic stimulation (rTMS) is among the most widely researched neuromodulation techniques, though it has not yet been officially recommended for fibromyalgia. This review aims to summarize the current evidence supporting rTMS for treating various fibromyalgia symptoms. Recent findings: High-frequency rTMS directed at the primary motor cortex (M1) has the strongest support in the literature for reducing pain intensity, with new research examining its long-term effectiveness. Nonetheless, some individuals may not respond to M1-targeted rTMS, and symptoms beyond pain can be prominent. Ongoing research aims to improve the efficacy of rTMS by exploring new brain targets, using innovative stimulation parameters, incorporating neuronavigation, and better identifying patients likely to benefit from this treatment. Summary: Noninvasive brain stimulation with rTMS over M1 is a well-tolerated treatment that can improve chronic pain and overall quality of life in fibromyalgia patients. However, the data are highly heterogeneous, with a limited level of evidence, posing a significant challenge to the inclusion of rTMS in official treatment guidelines. Research is ongoing to enhance its effectiveness, with future perspectives exploring its impact by targeting additional areas of the brain such as the medial prefrontal cortex, anterior cingulate cortex, and inferior parietal lobe, as well as selecting the right patients who could benefit from this treatment.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Clinical and Serologic Phenotyping and Damage Indices in Patients With Systemic Lupus Erythematosus With and Without Fibromyalgia

OBJECTIVE

Given fibromyalgia (FM) frequently co-occurs with autoimmune disease, this study was initiated to objectively evaluate FM in a multiracial/ethnic cohort of patients with systemic lupus erythematosus (SLE).

METHODS

Patients with SLE were screened for FM using the 2016 FM classification criteria during an in-person rheumatologist visit. We evaluated hybrid Safety of Estrogens in Lupus National Assessment (SELENA)-SLE Disease Activity Index (SLEDAI) scores, SLE classification criteria, and Systemic Lupus International Collaborating Clinics damage index. We compared patients with and without FM and if differences were present, compared patients with FM with patients with non-FM related chronic pain.

RESULTS

316 patients with SLE completed the FM questionnaire. 55 (17.4%) met criteria for FM. The racial composition of patients with FM differed from those without FM (P = 0.023), driven by fewer Asian patients having FM. There was no difference in SLE disease duration, SELENA-SLEDAI score, or active serologies. There was more active arthritis in the FM group (16.4%) versus the non-FM group (1.9%) (P < 0.001). The Widespread Pain Index and Symptom Severity Score did not correlate with degree of SLE activity (r = -0.016; 0.107) among patients with FM or non-FM chronic pain (r = 0.009; -0.024). Regarding criteria, patients with FM had less nephritis and more malar rash. Systemic Lupus International Collaborating Clinics damage index did not differ between groups.

CONCLUSION

Except for arthritis, patients with SLE with FM are not otherwise clinically or serologically distinguishable from those without FM, and Widespread Pain Index and Symptom Severity Score indices do not correlate with SLEDAI. These observations support the importance of further understanding the underlying biology of FM in SLE.

Motor Dysfunctions in Fibromyalgia Patients: The Importance of Breathing

The classification of fibromyalgia (FM) is not always immediate and simple, with the time from the first diagnosis, compared to the onset of symptoms, of a few years. Currently, we do not have instrumental or biochemical tests considered as gold standards; the clinician will make a diagnosis of FM based on the patient's medical history and subjective assessment. The symptoms can involve physical, cognitive and psychological disorders, with the presence of pain of different origins and classifications: nociplastic, nociceptive and neuropathic pain. Among the symptoms highlighted, postural disorders and neuromotor uncoordination emerge, whose functional dysfunctions can increase the mortality and morbidity rate. An alteration of the diaphragm muscle could generate such functional motor problems. Considering that the current literature underestimates the importance of breathing in FM, the article aims to highlight the relationship between motor and diaphragmatic difficulties in the patient, soliciting new points of view for the clinical and therapeutic framework.

Pain in axial spondyloarthritis: role of the JAK/STAT pathway

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that is characterized by new bone formation in the axial musculoskeletal system, with X-ray discriminating between radiographic and non-radiographic forms. Current therapeutic options include non-steroidal anti-inflammatory drugs in addition to biological disease-modifying anti-rheumatic drugs that specifically target tumor necrosis factor-alpha (TNFα) or interleukin (IL)-17. Pain is the most critical symptom for axSpA patients, significantly contributing to the burden of disease and impacting daily life. While the inflammatory process exerts a major role in determining pain in the early phases of the disease, the symptom may also result from mechanical and neuromuscular causes that require complex, multi-faceted pharmacologic and non-pharmacologic treatment, especially in the later phases. In clinical practice, pain often persists and does not respond further despite the absence of inflammatory disease activity. Cytokines involved in axSpA pathogenesis interact directly/indirectly with the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling cascade, a fundamental component in the origin and development of spondyloarthropathies. The JAK/STAT pathway also plays an important role in nociception, and new-generation JAK inhibitors have demonstrated rapid pain relief. We provide a comprehensive review of the different pain types observed in axSpA and the potential role of JAK/STAT signaling in this context, with specific focus on data from preclinical studies and data from clinical trials with JAK inhibitors.

A Review of Difficult-to-Treat Rheumatoid Arthritis: Definition, Clinical Presentation, and Management

PURPOSE OF REVIEW

A subset of patients with rheumatoid arthritis (RA) who fail multiple biologic therapies are deemed to have "difficult-to-treat" (D2T) RA. In 2021, a European Alliance of Associations for Rheumatology (EULAR) task force proposed a clinical definition of D2T RA. Here we review RA phenotypes and clinical assessment of RA, propose a different definition of D2T RA, discuss possible D2T RA risk factors, and summarize existing literature on the management of D2T RA.

RECENT FINDINGS

High disease activity at the time of diagnosis or prior to treatment with a biologic is associated with the development of D2T RA. Prolonged time from diagnosis to beginning treatment has been consistently associated with the development of D2T RA. Other clinical factors such as burden of disease, extraarticular disease, obesity, smoking, pain, fatigue, and psychological conditions have inconsistent associations with D2T RA according to current literature. D2T RA is a relatively new concept that represents an area of great need for research regarding the characterization of those with the disease as well as how best to treat the disease. With this gained knowledge, rheumatologists will be able to better identify patients at the time of diagnosis that are likely to develop D2T RA to help guide management.

A Latent Change Score Approach to Understanding Chronic Bodily Pain Outcomes Following Knee Arthroplasty: A Secondary Analysis of Longitudinal Data

BACKGROUND

The extent to which chronic bodily pain changes following total knee arthroplasty (TKA) is unknown. We determined the extent of chronic bodily pain changes at 1 year following TKA.

METHODS

Data from our randomized trial of pain coping skills, which revealed no effect of the studied interventions, were used. The presence and severity of chronic pain in 16 body regions, excluding the surgically treated knee, were determined prior to and 1 year following surgery. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale was used to quantify the extent of surgical knee pain. Latent change score (LCS) models were used to determine the extent to which true chronic bodily pain scores change after TKA.

RESULTS

The mean age of the sample of 367 participants was 63.4 ± 8.0 years, and 247 (67%) were female. LCS analyses showed significant 20% to 54% reductions in pain in the surgically treated lower limb (not including the surgically treated knee), pain in the non-surgically treated lower limb, and whole body pain. In bivariate LCS analyses, greater improvement in the WOMAC pain score, indicating surgical benefit of TKA, led to greater improvement in all 4 bodily pain areas beyond the surgically treated knee, even after controlling for the latent change in pain catastrophizing.

CONCLUSIONS

Clinically important chronic bodily pain reductions occurred following TKA and may be causally linked to the surgical procedure. Reduction in chronic bodily pain in sites other than the surgically treated knee is an additional benefit of TKA.

LEVEL OF EVIDENCE

Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Narrative Review of the Complex Interaction between Pain and Trauma in Children: A Focus on Biological Memory, Preclinical Data, and Epigenetic Processes

The incidence and collective impact of early adverse experiences, trauma, and pain continue to increase. This underscores the urgent need for translational efforts between clinical and preclinical research to better understand the underlying mechanisms and develop effective therapeutic approaches. As our understanding of these issues improves from studies in children and adolescents, we can create more precise preclinical models and ultimately translate our findings back to clinical practice. A multidisciplinary approach is essential for addressing the complex and wide-ranging effects of these experiences on individuals and society. This narrative review aims to (1) define pain and trauma experiences in childhood and adolescents, (2) discuss the relationship between pain and trauma, (3) consider the role of biological memory, (4) decipher the relationship between pain and trauma using preclinical data, and (5) examine the role of the environment by introducing the importance of epigenetic processes. The ultimate scope is to better understand the wide-ranging effects of trauma, abuse, and chronic pain on children and adolescents, how they occur, and how to prevent or mitigate their effects and develop effective treatment strategies that address both the underlying causes and the associated physiological and psychological effects.

What Do We Know about Nociplastic Pain?

Nociplastic pain is a recently distinguished type of pain, distinct from neuropathic and nociceptive pain, and is well described in the literature. It is often mistaken for central sensitization. Pathophysiology has not been clearly established with regard to alteration of the concentration of spinal fluid elements, the structure of the white and gray matter of the brain, and psychological aspects. Many different diagnostic tools, i.e., the painDETECT and Douleur Neuropathique 4 questionnaires, have been developed to diagnose neuropathic pain, but they can also be applied for nociplastic pain; however, more standardized instruments are still needed in order to assess its occurrence and clinical presentation. Numerous studies have shown that nociplastic pain is present in many different diseases such as fibromyalgia, complex regional pain syndrome type 1, and irritable bowel syndrome. Current pharmacological and nonpharmacological treatments for nociceptive and neuropathic pain are not entirely suitable for treating nociplastic pain. There is an ongoing effort to establish the most efficient way to manage it. The significance of this field has led to several clinical trials being carried out in a short time. The aim of this narrative review was to discuss the currently available evidence on pathophysiology, associated diseases, treatment possibilities, and clinical trials. It is important that physicians widely discuss and acknowledge this relatively new concept in order to provide optimized pain control for patients.