Dynamic functional brain connectivity underlying temporal summation of pain in fibromyalgia

Reevaluating fibromyalgia diagnosis: a proposal to integrate deep tendon reflex responses into current criteria

Fibromyalgia is a complex condition characterized by widespread pain, fatigue, and various other symptoms. The symptoms of fibromyalgia overlap with numerous other disorders (e.g., infections, chronic fatigue syndrome), which makes diagnosis challenging. Existing diagnostic criteria for fibromyalgia rely particularly on subjective patient reports. Such a limitation may lead to both missed diagnoses and potential overdiagnoses. Recent research has identified significantly increased deep tendon reflex (DTR) responses in patients with fibromyalgia. The results also demonstrated the potential for DTR examination to help with the diagnostic process, particularly with ruling out fibromyalgia. The potential underlying mechanisms behind the increased DTR responses in fibromyalgia are central nervous system dysregulation, altered muscular properties, autonomic nervous system dysfunction, and accompanying conditions such as hypomagnesemia and anxiety. By integrating DTR responses into current diagnostic criteria sets, physicians may more effectively differentiate fibromyalgia from other conditions and avoid the pitfalls of misdiagnosis, as well as overdiagnosis. The use of DTR testing in the diagnostic evaluation of fibromyalgia shows promise. Yet, it has both advantages and limitations. The potential benefits of this approach include improved diagnostic accuracy, but challenges remain in its low specificity. This means that hyperreflexia testing alone is not definitive in diagnosing fibromyalgia. Nonetheless, given the high sensitivity, a decreased DTR response could still contribute to ruling out fibromyalgia.

Childhood abuse and health outcomes in patients with fibromyalgia: a cross-sectional exploratory study of the moderating effects of pain catastrophizing and mindfulness

BACKGROUND

Childhood abuse has been linked to poorer health outcomes in individuals with fibromyalgia (FM), and this relationship may be affected by cognitive processes such as pain catastrophizing and mindfulness.

OBJECTIVE

This study investigated the impact of childhood abuse on pain-related symptoms and functioning in individuals with (FM) and examined how the critical psychosocial constructs of pain catastrophizing and mindfulness might moderate this relationship. We hypothesized that childhood abuse would be linked to greater physical symptoms and lower functioning, with pain catastrophizing and mindfulness influencing these associations.

METHODS

The study sample consisted of 113 women with FM. Correlational analyses were conducted to examine the relationship between childhood abuse and health outcomes (pain severity, pain interference, fibromyalgia impact, and physical functioning). Moderation analyses were conducted to examine the impact of pain catastrophizing and mindfulness on the relationship between childhood abuse and health outcomes.

RESULTS

As expected, catastrophizing was generally associated with elevated pain-related symptomatology and reduced functioning, and higher levels of mindfulness were associated with reduced pain impact. However, contrary to our hypothesis, childhood abuse was not directly associated with pain severity, pain interference, fibromyalgia impact, or physical functioning. Pain catastrophizing and mindfulness were significant moderators of the relationship between childhood abuse and health outcomes. Specifically, childhood abuse was related to higher pain interference only at low levels of catastrophizing and was associated with greater fibromyalgia impact and reduced physical functioning only at high levels of mindfulness.

CONCLUSION

Our findings suggest that while childhood abuse did not directly impact pain-related outcomes in this sample of fibromyalgia patients, cognitive factors like pain catastrophizing and mindfulness play significant roles in moderating these effects. These results underscore the importance of assessing for cognitive and psychological factors in the management of fibromyalgia, especially for patients with a history of childhood abuse. Further research is needed to explore these relationships in more diverse samples and to develop personalized and targeted interventions for this patient population.

Transcutaneous electrical nerve stimulation for fibromyalgia-like syndrome in patients with Long-COVID: a pilot randomized clinical trial

This study investigated the effect of Transcutaneous Electrical Nerve Stimulation (TENS) for fibromyalgia-like symptoms including chronic widespread musculoskeletal pain, fatigue, and/or gait impairment in twenty-five individuals with long-COVID. Participants were randomized to a high dose (intervention group, IG) or low dose (placebo group, PG) TENS device. Both groups received daily 3-5 h of TENS therapy for 4-weeks. The Brief Pain Inventory assessed functional interference from pain (BPI-I), and pain severity (BPI-S). The global fatigue index (GFI) assessed functional interference from fatigue. Wearable technology measured gait parameters during three 30-feet consecutive walking tasks. At 4-weeks, the IG exhibited a greater decrease in BPI-I compared to the PG (mean difference = 2.61, p = 0.008), and improved in gait parameters including stride time (4-8%, test condition dependent), cadence (4-10%, depending on condition), and double-support phase (12% in dual-task) when compared to baseline. A sub-group meeting the 2010 American College of Rheumatology Fibromyalgia diagnostic criteria undergoing high-dose TENS showed GFI improvement at 4-weeks from baseline (mean change = 6.08, p = 0.005). Daily TENS therapy showed potential in reducing functional interference from pain, fatigue, and gait alterations in long-COVID individuals. The study's limited power could affect the confirmation of certain observations. Extending the intervention period may improve treatment effectiveness.

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.

How to understand the overlap of long COVID, chronic fatigue syndrome/myalgic encephalomyelitis, fibromyalgia and irritable bowel syndromes

Long COVID should be limited to patients with multiple, persistent symptoms not related to well-defined organ damage. Once redefined, a focused review of long COVID demonstrates striking similarity to chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), fibromyalgia (FM) and irritable bowel syndrome (IBS). Research in long COVID has revealed similar findings to those noted in CFS/ME and FM, characterized by central nervous system organ dysfunction. Long COVID, like CFS/ME, FM and IBS, is best understood as a bidirectional mind-body, neuroimmune illness.

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.

Broadening the Scope of Resilience in Chronic Pain: Methods, Social Context, and Development

PURPOSE OF REVIEW

A wellspring of new research has offered varying models of resilience in chronic pain populations; however, resilience is a multifaceted and occasionally nebulous construct. The current review explores definitional and methodological issues in existing observational and clinical studies and offers new directions for future studies of pain resilience.

RECENT FINDINGS

Definitions of pain resilience have historically relied heavily upon self-report and from relatively narrow scientific domains (e.g., positive psychology) and in narrow demographic groups (i.e., Caucasian, affluent, or highly educated adults). Meta-analytic and systematic reviews have noted moderate overall quality of resilience-focused assessment and treatment in chronic pain, which may be attributable to these narrow definitions. Integration of research from affiliated fields (developmental models, neuroimaging, research on historically underrepresented groups, trauma psychology) has the potential to enrich current models of pain resilience and ultimately improve the empirical and clinical utility of resilience models in chronic pain.

Efficacy and safety of transcranial direct current stimulation in the treatment of fibromyalgia: A systematic review and meta-analysis

OBJECTIVES

To update a systematic review of the efficacy and safety of transcranial direct current stimulation (tDCS) for analgesia, for antidepressant effects, and to reduce the impact of fibromyalgia (FM), looking for optimal areas of stimulation.

METHODS

We searched five databases to identify randomized controlled trials comparing active and sham tDCS for FM. The primary outcome was pain intensity, and secondary outcome measures included FM Impact Questionnaire (FIQ) and depression score. Meta-analysis was conducted using standardized mean difference (SMD). Subgroup analysis was performed to determine the effects of different regional stimulation, over the primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), opercular-insular cortex (OIC), and occipital nerve (ON) regions. We analyzed the minimal clinically important difference (MCID) by the value of the mean difference (MD) for an 11-point scale for pain, the Beck Depressive Inventory-II (BDI-II), and the Fibromyalgia Impact Questionnaire (FIQ) score. We described the certainty of the evidence (COE) using the tool GRADE profile.

RESULTS

Twenty studies were included in the analysis. Active tDCS had a positive effect on pain (SMD= -1.04; 95 % CI -1.38 to -0.69), depression (SMD= -0.46; 95 % CI -0.64 to -0.29), FIQ (SMD= -0.73; 95 % CI -1.09 to -0.36), COE is moderate. Only group M1 (SD=-1.57) and DLPFC (SD=-1.44) could achieve MCID for analgesia; For BDI-II, only group DLPFC (SD=-5.36) could achieve an MCID change. Adverse events were mild.

CONCLUSION

tDCS is a safe intervention that relieves pain intensity, reduces depression, and reduces the impact of FM on life. Achieving an MCID is related to the stimulation site and the target symptom.

Large-scale momentary brain co-activation patterns are associated with hyperalgesia and mediate focal neurochemistry and cross-network functional connectivity in fibromyalgia

ABSTRACT

Fibromyalgia has been characterized by augmented cross-network functional communication between the brain's sensorimotor, default mode, and attentional (salience/ventral and dorsal) networks. However, the underlying mechanisms of these aberrant communication patterns are unknown. In this study, we sought to understand large-scale topographic patterns at instantaneous timepoints, known as co-activation patterns (CAPs). We found that a sustained pressure pain challenge temporally modulated the occurrence of CAPs. Using proton magnetic resonance spectroscopy, we found that greater basal excitatory over inhibitory neurotransmitter levels within the anterior insula orchestrated higher cross-network connectivity between the anterior insula and the default mode network through lower occurrence of a CAP encompassing the attentional networks during sustained pain. Moreover, we found that hyperalgesia in fibromyalgia was mediated through increased occurrence of a CAP encompassing the sensorimotor network during sustained pain. In conclusion, this study elucidates the role of momentary large-scale topographic brain patterns in shaping noxious information in patients with fibromyalgia, while laying the groundwork for using precise spatiotemporal dynamics of the brain for the potential development of therapeutics.

Painful Cutaneous Laser Stimulation for Temporal Summation of Pain Assessment

Variability in pain sensitivity arises not only from the differences in peripheral sensory receptors but also from the differences in central nervous system (CNS) pain inhibition and facilitation mechanisms. Temporal summation of pain (TSP) is an experimental protocol commonly used in human studies of pain facilitation but is susceptible to confounding when elicited with the skin-contact thermode, which adds the responses of touch-related Aβ low-threshold mechanoreceptors to nociceptive receptors. In the present study, we evaluate an alternative method involving the use of a contactless cutaneous laser for TSP assessment. We show that repetitive laser stimulations with a one second inter-stimulus interval evoked reliable TSP responses in a significant proportion of healthy subjects (N = 36). Female subjects (N = 18) reported greater TSP responses than male subjects confirming earlier studies of sex differences in central nociceptive excitability. Furthermore, repetitive laser stimulations during TSP induction elicited increased time-frequency electroencephalography (EEG) responses. The present study demonstrates that repetitive laser stimulation may be an alternative to skin-contact methods for TSP assessment in patients and healthy controls. PERSPECTIVE: Temporal summation of pain (TSP) is an experimental protocol commonly used in human studies of pain facilitation. We show that contactless cutaneous laser stimulation is a reliable alternative to the skin contact approaches during TSP assessment.

Resting-state functional connectivity changes in older adults with sleep disturbance and the role of amyloid burden

Sleep and related disorders could lead to changes in various brain networks, but little is known about the role of amyloid β (Aβ) burden-a key Alzheimer's disease (AD) biomarker-in the relationship between sleep disturbance and altered resting state functional connectivity (rsFC) in older adults. This cross-sectional study examined the association between sleep disturbance, Aβ burden, and rsFC using a large-scale dataset from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Sample included 489 individuals (53.6% cognitively normal, 32.5% mild cognitive impairment, and 13.9% AD) who had completed sleep measures (Neuropsychiatric Inventory), PET Aβ data, and resting-state fMRI scans at baseline. Within and between rsFC of the Salience (SN), the Default Mode (DMN) and the Frontal Parietal network (FPN) were compared between participants with sleep disturbance versus without sleep disturbance. The interaction between Aβ positivity and sleep disturbance was evaluated using the linear regressions, controlling for age, diagnosis status, gender, sedatives and hypnotics use, and hypertension. Although no significant main effect of sleep disturbance was found on rsFC, a significant interaction term emerged between sleep disturbance and Aβ burden on rsFC of SN (β = 0.11, P = 0.006). Specifically, sleep disturbance was associated with SN hyperconnectivity, only with the presence of Aβ burden. Sleep disturbance may lead to altered connectivity in the SN when Aβ is accumulated in the brain. Individuals with AD pathology may be at increased risk for sleep-related aberrant rsFC; therefore, identifying and treating sleep problems in these individuals may help prevent further disease progression.

Abnormal temporal variability of rich-club organization in three major psychiatric conditions

Introduction

Convergent evidence has demonstrated a shared rich-club reorganization across multiple major psychiatric conditions. However, previous studies assessing altered functional couplings between rich-club regions have typically focused on the mean time series from entire functional magnetic resonance imaging (fMRI) scanning session, neglecting their time-varying properties.

Methods

In this study, we aim to explore the common and/or unique alterations in the temporal variability of rich-club organization among schizophrenia (SZ), bipolar disorder (BD), and attention deficit/hyperactivity disorder (ADHD). We employed a temporal rich-club (TRC) approach to quantitatively assess the propensity of well-connected nodes to form simultaneous and stable structures in a temporal network derived from resting-state fMRI data of 156 patients with major psychiatric disorders (SZ/BD/ADHD = 71/45/40) and 172 healthy controls. We executed the TRC workflow at both whole-brain and subnetwork scales across varying network sparsity, sliding window strategies, lengths and steps of sliding windows, and durations of TRC coefficients.

Results

The SZ and BD groups displayed significantly decreased TRC coefficients compared to corresponding HC groups at the whole-brain scale and in most subnetworks. In contrast, the ADHD group exhibited reduced TRC coefficients in longer durations, as opposed to shorter durations, which markedly differs from the SZ and BD groups. These findings reveal both transdiagnostic and illness-specific patterns in temporal variability of rich-club organization across SZ, BD, and ADHD.

Discussion

TRC may serve as an effective metric for detecting brain network disruptions in particular states, offering novel insights and potential biomarkers into the neurobiological basis underpinning the behavioral and cognitive deficits observed in these disorders.

Acute exercise as active inference in chronic musculoskeletal pain, effects on gait kinematics and muscular activity in patients and healthy participants: a study protocol for a randomised controlled laboratory trial

INTRODUCTION

Chronic musculoskeletal pain is a highly prevalent, complex and distressing condition that may negatively affect all domains of life. In view of an active inference framework, and resting on the concept of allostasis, human movement per se becomes a prerequisite for health and well-being while chronic pain becomes a sign of a system unable to attenuate an allostatic load. Previous studies on different subgroups of chronic pain conditions have demonstrated alterations in gait kinematics and muscle activity, indicating shared disturbances in the motor system from long-term allostatic load. We hypothesise that such alterations exist in heterogenous populations with chronic musculoskeletal pain, and that exposure to acute and controlled exercise may attenuate these alterations. Therefore, the main aim of this study is to investigate the acute effects of exercise on gait kinematics and activity of the back and neck muscles during diverse walking conditions in patients with chronic musculoskeletal pain compared with a reference sample consisting of healthy participants.

METHODS AND ANALYSIS

This two-sample two-armed parallel randomised controlled laboratory trial will include 40 participants with chronic musculoskeletal pain (>3 months) and 40 healthy participants. Participants will be randomly allocated to either 30 min of aerobic exercise or rest. Primary outcomes are gait kinematics (walking speed, step frequency, stride length, lumbar rotation, gait stability) and muscular activity (spatial and temporal) of the back and neck during diverse walking conditions. Secondary outcomes are variability of gait kinematics and muscle activity and subjective pain ratings assessed regularly during the trial.

ETHICS AND DISSEMINATION

The study has been approved by the Regional Ethics Review Board in Uppsala, Sweden (#2018/307). Findings will be disseminated via conference presentations, publications in peer-reviewed journals and engagement with patient support groups and clinicians.

TRIAL REGISTRATION NUMBER

NCT03882333.

Resting-State Functional Connectivity Changes in Older Adults with Sleep Disturbance and the Role of Amyloid Burden

Sleep and related disorders could lead to changes in various brain networks, but little is known about the role of amyloid β (Aβ) burden-a key Alzheimer's disease (AD) biomarker-in the relationship between sleep disturbance and altered resting state functional connectivity (rsFC) in older adults. This cross-sectional study examined the association between sleep disturbance, Aβ burden, and rsFC using a large-scale dataset from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Sample included 489 individuals (53.6% cognitively normal, 32.5% mild cognitive impairment, and 13.9% AD) who had completed sleep measures (Neuropsychiatric Inventory), PET Aβ data, and resting-state fMRI scans at baseline. Within and between rsFC of the Salience (SN), the Default Mode (DMN) and the Frontal Parietal network (FPN) were compared between participants with sleep disturbance versus without sleep disturbance. The interaction between Aβ positivity and sleep disturbance was evaluated using linear regressions, controlling for age, diagnosis status, gender, sedatives and hypnotics use, and hypertension. Although no significant main effect of sleep disturbance was found on rsFC, a significant interaction term emerged between sleep disturbance and Aβ burden on rsFC of SN (β=0.11, P=0.006). Specifically, sleep disturbance was associated with SN hyperconnectivity, only with the presence of Aβ burden. Sleep disturbance may lead to altered connectivity in the SN when Aβ is accumulated in the brain. Individuals with AD pathology may be at increased risk for sleep-related aberrant rsFC; therefore, identifying and treating sleep problems in these individuals may help prevent further disease progression.

Functional brain reconfiguration during sustained pain

Pain is constructed through complex interactions among multiple brain systems, but it remains unclear how functional brain networks are reconfigured over time while experiencing pain. Here, we investigated the time-varying changes in the functional brain networks during 20 min capsaicin-induced sustained orofacial pain. In the early stage, the orofacial areas of the primary somatomotor cortex were separated from other areas of the somatosensory cortex and integrated with subcortical and frontoparietal regions, constituting an extended brain network of sustained pain. As pain decreased over time, the subcortical and frontoparietal regions were separated from this brain network and connected to multiple cerebellar regions. Machine-learning models based on these network features showed significant predictions of changes in pain experience across two independent datasets (n = 48 and 74). This study provides new insights into how multiple brain systems dynamically interact to construct and modulate pain experience, advancing our mechanistic understanding of sustained pain.

The relationship between COVID-19 and fibromyalgia syndrome: prevalence, pandemic effects, symptom mechanisms, and COVID-19 vaccines

On March 11, 2020, the World Health Organization, realizing the level of spread worldwide and the severity of the condition, accepted coronavirus disease 19 (COVID-19) as a pandemic. Subsequently, quarantine conditions were implemented around the world, and these triggered particular results. Like all other individuals, fibromyalgia syndrome (FMS) patients were affected by these conditions. The stress load in pandemic conditions, difficulties in accessing healthcare services, changes in exercise compliance, variations in physiotherapy programs, and remote work conditions all had an impact on FMS patients. Although general expectations were negative, some FMS patients were able to manage the pandemic conditions and even turn them in their favor. This is thought to be due to this patient group having established strategies to cope with stress in the pre-pandemic period, and they had sufficient ability to adapt to changing situations. FMS-related symptoms occur in a subset of individuals following COVID-19. One of the factors is the increased psychological burden after COVID-19. There is evidence that neuroinflammatory pathways affect neuroplasticity in the central nervous system and trigger the onset of FMS-related symptoms. Among the probable mechanisms are alterations in inflammatory and anti-inflammatory pathways. Changes in the autonomic nervous system with the effect of SARS-CoV-2 may induce the emergence of FMS-related symptoms. FMS and COVID-19 can coexist, and FMS may create a tendency to vaccine hesitancy. Future studies should focus on elucidating FMS-related symptoms occurring post-COVID-19. There is a need to determine distinctions between the FMS clinical status that emerged following COVID-19 and the regular patient group in terms of diagnosis, treatment, and follow-up.

Abnormal Dynamics of Functional Connectivity Density Associated With Chronic Neck Pain

Background: Chronic neck pain (CNP) is highly prevalent and complicated, associated with limited movement, and accompanied by shoulder pain and other clinical manifestations such as dizziness, anxiety, and insomnia. Brain structural and functional abnormalities often occur in patients with CNP. However, knowledge of the brain’s functional organization and temporal dynamics in CNP patients is limited. Dynamic functional connectivity density (dFCD) can reflect the ability of brain areas or voxels to integrate information, and could become neuroimaging markers for objectively reflecting pain to a certain extent. Therefore, this study compared the dFCD between CNP patients and healthy controls (HCs) and investigated potential associations of the abnormal density variability in dynamic functional connectivity with pain characteristics in CNP patients.

Methods: Resting functional magnetic resonance imaging was performed for 89 CNP patients and 57 HCs. After preprocessing resting-state fMRI images by the Data Processing and Analysis of Brain Imaging toolbox, the sliding window method was applied to investigate dFCD changes in CNP patients and HCs using the DynamicBC toolbox. Then we quantified dFCD variability using their standard deviation. Based on the pain-associated factors collected from the case report form of CNP patients, the mean dFCD variability values of each dFCD from region of interest were extracted to calculate Pearson’s correlation coefficient to study the potential correlation between dFCD abnormal variability and pain.

Results: Compared with HCs, the dFCD values of the anterior cingulate cortex, occipital lobe, temporal lobe, and cerebellum were statistically different in patients with CNP. Subsequent correlation analysis showed that the variable dFCD in the related brain region was correlative with the course of the disease and clinical symptoms, such as pain and depression, in patients with CNP.

Conclusion: Dynamic functional alterations were observed in the brain regions of CNP patients, and the dFCD of these brain regions could become neuroimaging markers for objectively reflecting pain to a certain extent. This suggests that chronic pain may cause changes in pain processing and emotional feedback and highlights the link between dynamic neural communication in brain regions and disease conditions, deepening our understanding of chronic pain diseases, and guiding clinical practice.