Controllability and hippocampal activation during pain expectation in fibromyalgia syndrome

The autobiographical memory system and chronic pain: A neurocognitive framework for the initiation and maintenance of chronic pain

Chronic pain affects approximately 20% of the world's population, exerting a substantial burden on the affected individual, their families, and healthcare systems globally. Deficits in autobiographical memory have been identified among individuals living with chronic pain, and even found to pose a risk for the transition to chronicity. Recent neuroimaging studies have simultaneously implicated common brain regions central to autobiographical memory processing in the maintenance of and susceptibility to chronic pain. The present review proposes a novel neurocognitive framework for chronic pain explained by mechanisms underlying the autobiographical memory system. Here, we 1) summarize the current literature on autobiographical memory in pain, 2) discuss the role of the hippocampus and cortical brain regions including the ventromedial prefrontal cortex, anterior temporal lobe, and amygdala in relation to autobiographical memory, memory schemas, emotional processing, and pain, 3) synthesize these findings in a neurocognitive framework that explains these relationships and their implications for patients' pain outcomes, and 4) propose translational directions for the prevention, management, and treatment of chronic pain.

Brain stimulation targets for chronic pain: Insights from meta-analysis, functional connectivity and literature review

Noninvasive brain stimulation (NIBS) techniques have demonstrated their potential for chronic pain management, yet their efficacy exhibits variability across studies. Refining stimulation targets and exploring additional targets offer a possible solution to this challenge. This study aimed to identify potential brain surface targets for NIBS in treating chronic pain disorders by integrating literature review, neuroimaging meta-analysis, and functional connectivity analysis on 90 chronic low back pain patients. Our results showed that the primary motor cortex (M1) (C3/C4, 10-20 EEG system) and prefrontal cortex (F3/F4/Fz) were the most used brain stimulation targets for chronic pain treatment according to the literature review. The bilateral precentral gyrus (M1), supplementary motor area, Rolandic operculum, and temporoparietal junction, were all identified as common potential NIBS targets through both a meta-analysis sourced from Neurosynth and functional connectivity analysis. This study presents a comprehensive summary of the current literature and refines the existing NIBS targets through a combination of imaging meta-analysis and functional connectivity analysis for chronic pain conditions. The derived coordinates (with integration of the international electroencephalography (EEG) 10/20 electrode placement system) within the above brain regions may further facilitate the localization of these targets for NIBS application. Our findings may have the potential to expand NIBS target selection beyond current clinical trials and improve chronic pain treatment.

Diet and Lifestyle Modifications for Fibromyalgia

Fibromyalgia (FM) is a complex, widespread pain disorder characterized by symptoms such as fatigue, sleep deprivation, mental fog, mood swings, and headaches. Currently, there are only three FDA-approved medications for FM patients: duloxetine, milnacipran, and pregabalin, with outcomes frequently being inadequate. This research team aims to investigate the effects of diet and lifestyle modifications on FM, with emphasis on anti-inflammatory diet, antioxidants, and gluten-free diets, as well as supplementation with Magnesium, CQ10, and Vitamin D, microbiome, sleep, exercise, and cognitive behavioral therapy. We reviewed the pathophysiology of certain foods that can be proinflammatory with the release of cytokines leading to activation of pain, fatigue and aggravation of the majority of Fibromyalgia symptoms. A literature review was performed by identifying FM articles published between 1994 and 2022 via PubMed and EMBASE databases, with particular emphasis on randomized controlled trials, meta-analysis, and evidence-based treatment guidelines. This review article was completed by a comprehensive narrative review process, in which our team systematically examined relevant scientific literature to provide a comprehensive overview of the significant role that diet and other lifestyle modifications play in mediating symptoms of Fibromyalgia. We propose that diet modifications and lifestyle changes, such as sleep, exercise, and weight loss, can be important steps in managing FM.

Exercise-based interventions on sleep quality in patients with fibromyalgia syndrome: An umbrella and mapping review with meta-analysis

The main aim of this umbrella review was to assess the impact of exercise-based interventions (EBIs) on sleep quality in patients with fibromyalgia syndrome (FMS). We searched systematically in PubMed, PEDro, EMBASE, CINAHL, SPORTDiscus and Google Scholar. Methodological quality was analyzed using AMSTAR and ROBIS scale, and the strength of evidence was established according to GRADE. Nine systematic reviews were included. Meta-analysis (MA) of primary studies (n = 42) were performed with a random-effects model. The MA revealed a moderate statistically significant effect of EBIs (SMD=-0.46 [-0.69 to -0.23]). Subgroup analyses by type of exercise showed significant effect of body-mind exercises (SMD=-0.55 [-0.86 to -0.23]) and combined exercises (SMD=-1.11 [-2.12 to -0.11]) but not for aerobic (SMD=-0.04 [-0.15 to 0.07]) or strength (SMD=-0.52 [-1.14 to 0.1]) exercises in isolation. The results obtained showed that EBIs were effective in improving sleep quality compared to minimal intervention, no intervention or usual care, with a low certainty of evidence. Subgroup analyses showed that mind-body and combined exercises elicited the strongest effect, while aerobic and strength exercise in isolation did not show significant effects.

Electrophysiological indices of pain expectation abnormalities in fibromyalgia patients

Fibromyalgia is a chronic pain syndrome characterized by dysfunctional processing of nociceptive stimulation. Neuroimaging studies have pointed out that pain-related network functioning seems to be altered in these patients. It is thought that this clinical symptomatology may be maintained or even strengthened because of an enhanced expectancy for painful stimuli or its forthcoming appearance. However, neural electrophysiological correlates associated with such attentional mechanisms have been scarcely explored. In the current study, expectancy processes of upcoming laser stimulation (painful and non-painful) and its further processing were explored by event-related potentials (ERPs). Nineteen fibromyalgia patients and twenty healthy control volunteers took part in the experiment. Behavioral measures (reaction times and subjective pain perception) were also collected. We manipulated the pain/no pain expectancy through an S1–S2 paradigm (cue-target). S1 (image: triangle or square) predicted the S2 appearance (laser stimulation: warmth or pinprick sensation). Laser stimuli were delivered using a CO₂ laser device. Temporal and spatial principal component analyses were employed to define and quantify the ERP component reliability. Statistical analyses revealed the existence of an abnormal pattern of pain expectancy in patients with fibromyalgia. Specifically, our results showed attenuated amplitudes at posterior lCNV component in anticipation of painful stimulation that was not found in healthy participants. In contrast, although larger P2 amplitudes to painful compared to innocuous events were shown, patients did not show any amplitude change in this laser-evoked response as a function of pain predictive cues (as occurred in the healthy control group). Additionally, analyses of the subjective perception of pain and reaction time indicated that laser stimuli preceded by pain cues were rated as more painful than those signaling non-pain expectancy and were associated with faster responses. Differences between groups were not found. The present findings suggest the presence of dysfunction in pain expectation mechanisms in fibromyalgia that eventually may make it difficult for patients to correctly interpret signs that prevent pain symptoms. Furthermore, the abnormal pattern in pain expectancy displayed by fibromyalgia patients could result in ineffective pain coping strategies. Understanding the neural correlates of pain processing and its modulatory factors is crucial to identify treatments for chronic pain syndromes.

Digital pain extent is associated with pain intensity but not with pain-related cognitions and disability in people with chronic musculoskeletal pain: a cross-sectional study

Background

To evaluate whether digital pain extent is associated with an array of psychological factors such as optimism, pessimism, expectations of recovery, pain acceptance, and pain self-efficacy beliefs as well as to analyse the association between digital pain extent and pain intensity and pain-related disability in people with chronic musculoskeletal pain.

Methods

A descriptive cross-sectional study conducted in a primary health care setting was carried out including 186 individuals with chronic musculoskeletal pain. Patient-reported outcomes were used to assess psychological factors, pain intensity, and pain-related disability. Digital pain extent was obtained from pain drawings shaded using a tablet and analysed using novel customized software. Multiple linear regression models were conducted to evaluate the association between digital pain extent and the aforementioned variables.

Results

Digital pain extent was statistically significantly associated with pain intensity. However, digital pain extent was not associated with any psychological measure nor with pain-related disability.

Discussion

The results did not support an association between digital pain extent and psychological measures.

Intact pain modulation through manipulation of controllability and expectations in aging

BACKGROUND

Pain expectation and controllability can modulate pain processing. However, little is known about age-related effects on these cognitive factors involved in pain control. This study assessed age-related brain changes associated with pain expectation and controllability.

METHODS

17 healthy older adults (9 men; 65.65 ± 4.34 years) and 18 healthy younger adults (8 men; 20.56 ± 5.56 years) participated in the study. Pain evoked potentials and pain ratings were recorded while participants received painful electrical stimuli under two different conditions of pain controllability over the intensity of the stimulation (self-controlled vs. computer controlled) and two conditions of pain expectations (high vs. low pain).

RESULTS

Although the intensity of the painful stimulation was kept constant, all participants showed reduced pain perception in the controllable and low pain expectancy conditions. However, older participants showed reduced amplitudes of pain evoked potentials in the time window between 150 and 500 ms after stimulus onset as compared to younger participants. Moreover, younger participants showed greater negative amplitudes from 80 to 150 ms after stimulus onset for uncontrollable versus controllable pain.

CONCLUSIONS

These results suggest that although cognitive pain modulation is preserved during ageing, neural processing of pain is reduced in older adults.

SIGNIFICANCE

This research describes the impact of age on cognitive pain modulation evoked by the manipulation of pain controllability and pain expectations. Our findings constitute a first step in the understanding of the greater vulnerability of older individuals to chronic pain. Moreover, we show that older adults can benefit from cognitive pain control mechanisms to increase the efficacy of pain treatments.

Controllability over stressor decreases responses in key threat-related brain areas

Controllability over stressors has major impacts on brain and behavior. In humans, however, the effect of controllability on responses to stressors is poorly understood. Using functional magnetic resonance imaging (fMRI), we investigated how controllability altered responses to a shock-plus-sound stressor with a between-group yoked design, where participants in controllable and uncontrollable groups experienced matched stressor exposure. Employing Bayesian multilevel analysis at the level of regions of interest and voxels in the insula, and standard voxelwise analysis, we found that controllability decreased stressor-related responses across threat-related regions, notably in the bed nucleus of the stria terminalis and anterior insula. Posterior cingulate cortex, posterior insula, and possibly medial frontal gyrus showed increased responses during control over stressor. Our findings support the idea that the aversiveness of stressors is reduced when controllable, leading to decreased responses across key regions involved in anxiety-related processing, even at the level of the extended amygdala.

Different Electrophysiological Responses to Pain-Related Visual Stimuli Between Fibromyalgia and Chronic low Back Pain Women: A Pilot Case-Control Study

BACKGROUND

Fibromyalgia is a chronic pain syndrome which occurs in the absence of an organic damage, whom causes is still unclear. Aims of this pilot study were to investigate the neural correlates of fibromyalgia in response to pain-related visual stimuli and explore the psychological differences among fibromyalgia, chronic low back pain (CLBP) and healthy conditions.

METHODS

After a clinical assessment, electrophysiological responses to pain-related visual stimuli were recorded using a 256-Hydrocel Geodesic-Sensor-Net. Event-related potentials (ERPs), standardised low-resolution electromagnetic tomography (sLORETA), and psychological (Symptom Checklist-90-Revised) data were analysed for a total sample of 23 women (5 healthy volunteers, 12 fibromyalgia patients, 6 CLBP patients).

RESULTS

The main finding was that fibromyalgia women reported a different brain response to pain-related visual stimuli on the frontal montage compared to women with CLBP (p = .028). Moreover, fibromyalgia women showed an increased activity mainly on the hippocampus (p = .003) and the posterior cingulate cortex (p ≤ .001) in response to algic stimuli compared to not algic ones. Lastly, these women presented higher scores on the somatization (p = .002), obsession-compulsion (p = .045), depression (p = .043) and positive symptom distress (p = .023) dimensions compared to the healthy women.

CONCLUSIONS

These preliminary results suggest that although the painful symptoms are similar, the central elaboration of pain could be different between women with fibromyalgia and those with CLBP. Moreover, these findings provide preliminary evidences about the great alert and the central sensitivity to pain-related information regarding fibromyalgia patients.

Effectiveness of Exercise on Fatigue and Sleep Quality in Fibromyalgia: A Systematic Review and Meta-analysis of Randomized Trials

OBJECTIVES

To determine the effects of exercise on fatigue and sleep quality in fibromyalgia (primary aim) and to identify which type of exercise is the most effective in achieving these outcomes (secondary aim).

DATA SOURCES

PubMed and Web of Science were searched from inception until October 18, 2018.

STUDY SELECTION

Eligible studies contained information on population (fibromyalgia), intervention (exercise), and outcomes (fatigue or sleep). Randomized controlled trials (RCT) testing the effectiveness of exercise compared with usual care and randomized trials (RT) comparing the effectiveness of 2 different exercise interventions were included for the primary and secondary aims of the present review, respectively. Two independent researchers performed the search, screening, and final eligibility of the articles. Of 696 studies identified, 17 RCTs (n=1003) were included for fatigue and 12 RCTs (n=731) for sleep. Furthermore, 21 RTs compared the effectiveness of different exercise interventions (n=1254).

DATA EXTRACTION

Two independent researchers extracted the key information from each eligible study.

DATA SYNTHESIS

Separate random-effect meta-analyses were performed to examine the effects from RCTs and from RTs (primary and secondary aims). Standardized mean differences (SMD) effect sizes were calculated using Hedges' adjusted g. Effect sizes of 0.2, 0.4, and 0.8 were considered small, moderate, and large. Compared with usual care, exercise had moderate effects on fatigue and a small effect on sleep quality (SMD, -0.47; 95% confidence interval [CI], -0.67 to -0.27; P<.001 and SMD, -0.17; 95% CI, -0.32 to -0.01; P=.04). RTs in which fatigue was the primary outcome were the most beneficial for lowering fatigue. Additionally, meditative exercise programs were the most effective for improving sleep quality.

CONCLUSIONS

Exercise is moderately effective for lowering fatigue and has small effects on enhancing sleep quality in fibromyalgia. Meditative exercise programs may be considered for improving sleep quality in fibromyalgia.

Ceftriaxone inhibits stress-induced bladder hyperalgesia and alters cerebral micturition and nociceptive circuits in the rat: A multidisciplinary approach to the study of urologic chronic pelvic pain syndrome research network study

AIMS

Emotional stress plays a role in the exacerbation and development of interstitial cystitis/bladder pain syndrome (IC/BPS). Given the significant overlap of brain circuits involved in stress, anxiety, and micturition, and the documented role of glutamate in their regulation, we examined the effects of an increase in glutamate transport on central amplification of stress-induced bladder hyperalgesia, a core feature of IC/BPS.

METHODS

Wistar-Kyoto rats were exposed to water avoidance stress (WAS, 1 hour/day x 10 days) or sham stress, with subgroups receiving daily administration of ceftriaxone (CTX), an activator of glutamate transport. Thereafter, cystometrograms were obtained during bladder infusion with visceromotor responses (VMR) recorded simultaneously. Cerebral blood flow (CBF) mapping was performed by intravenous injection of [¹⁴ C]-iodoantipyrine during passive bladder distension. Regional CBF was quantified in autoradiographs of brain slices and analyzed in three dimensional reconstructed brains with statistical parametric mapping.

RESULTS

WAS elicited visceral hypersensitivity during bladder filling as demonstrated by a decreased pressure threshold and VMR threshold triggering the voiding phase. Brain maps revealed stress effects in regions noted to be responsive to bladder filling. CTX diminished visceral hypersensitivity and attenuated many stress-related cerebral activations within the supraspinal micturition circuit and in overlapping limbic and nociceptive regions, including the posterior midline cortex (posterior cingulate/anterior retrosplenium), somatosensory cortex, and anterior thalamus.

CONCLUSIONS

CTX diminished bladder hyspersensitivity and attenuated regions of the brain that contribute to nociceptive and micturition circuits, show stress effects, and have been reported to demonstrated altered functionality in patients with IC/BPS. Glutamatergic pharmacologic strategies modulating stress-related bladder dysfunction may be a novel approach to the treatment of IC/BPS.

The medial temporal lobe in nociception: a meta-analytic and functional connectivity study

Recent neuroimaging studies implicate the medial temporal lobe (MTL) in nociception and pain modulation. Here, we aim to identify which subregions of the MTL are involved in human pain and to test its connectivity in a cohort of chronic low-back pain patients (CBP). We conducted 2 coordinate-based meta-analyses to determine which regions within the MTL showed consistent spatial patterns of functional activation (1) in response to experimental pain in healthy participants and (2) in chronic pain compared with healthy participants. We followed PRISMA guidelines and performed activation likelihood estimate (ALE) meta-analyses. The first meta-analysis revealed consistent activation in the right anterior hippocampus (right antHC), parahippocampal gyrus, and amygdala. The second meta-analysis revealed consistently less activation in patients' right antHC, compared with healthy participants. We then conducted a seed-to-voxel resting state functional connectivity of the right antHC seed with the rest of the brain in 77 CBP and 79 age-matched healthy participants. We found that CBP had significantly weaker antHC functional connectivity to the medial prefrontal cortex compared with healthy participants. Taken together, these data indicate that the antHC has abnormally lower activity in chronic pain and reduced connectivity to the medial prefrontal cortex in CBP. Future studies should investigate the specific role of the antHC in the development and management of chronic pain.

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

OBJECTIVE

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

SETTING

Cohort study.

PARTICIPANTS

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

RESULTS

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

CONCLUSIONS

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

Altered neural activity to monetary reward/loss processing in episodic migraine

The dysfunctions of the mesolimbic cortical reward circuit have been proposed to contribute to migraine pain. Although supporting empirical evidence was mainly found in connection with primary rewards or in chronic migraine where the pain experience is (almost) constant. Our goal however was to investigate the neural correlates of secondary reward/loss anticipation and consumption using the monetary incentive delay task in 29 episodic migraine patients and 41 headache-free controls. Migraine patients showed decreased activation in one cluster covering the right inferior frontal gyrus during reward consumption compared to controls. We also found significant negative correlation between the time of the last migraine attack before the scan and activation of the parahippocampal gyrus and the right hippocampus yielded to loss anticipation. During reward/loss consumption, a relative increase in the activity of the visual areas was observed the more time passed between the last attack and the scan session. Our results suggest intact reward/loss anticipation but altered reward consumption in migraine, indicating a decreased reactivity to monetary rewards. The findings also raise the possibility that neural responses to loss anticipation and reward/loss consumption could be altered by the proximity of the last migraine attack not just during pre-ictal periods, but interictally as well.

Cognitive deficits in fibromyalgia syndrome are associated with pain responses to low intensity pressure stimulation

Background

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread musculoskeletal pain and diffuse tenderness, accompanied by complaints including morning stiffness, fatigue, insomnia and affective symptoms. In addition, affected patients frequently experience cognitive impairments such as concentration difficulties, forgetfulness or problems in planning and decision-making. These deficits are commonly ascribed to interference between nociceptive and cognitive processing.

Method

The present study investigated the association of cognitive performance with (a) pain responses to low intensity pressure stimulation (0.45–2.25 kg/cm²), (b) responses to stronger (above-threshold) stimulation (2.70 kg/cm²), and (c) pain threshold and tolerance in 42 women with FMS. Tests of attention, memory, processing speed, and executive functions were applied.

Results

While no significant correlations were seen for pain threshold and pain tolerance, inverse associations arose between pain intensity ratings during pressure stimulation and performance in all evaluated cognitive domains. The magnitude of the correlations increased with decreasing stimulus intensity.

Conclusions

It may be concluded that pain experience during somatosensory stimulation of low intensity is more closely related to attention, memory and executive functions in FMS than the traditional measures of pain threshold and pain tolerance. Considering that pain responses to low intensity stimulation reflect the hyperalgesia and allodynia phenomena characterizing FMS, it may be hypothesized that central nervous pain sensitization is involved in cognitive impairments in the disorder.

Bidirectional association between fibromyalgia and gastroesophageal reflux disease: two population-based retrospective cohort analysis

Fibromyalgia (FM) tends to coexist with gastroesophageal reflux disease (GERD). This retrospective cohort study was conducted to determine the bidirectional association between FM and GERD, using a nationwide database, the National Health Insurance of Taiwan. We established 2 study arms, including 35,117 patients with FM in arm 1 and 34,630 patients with GERD in arm 2, newly diagnosed between 2000 and 2010. For each study arm, we randomly selected 4-fold subjects with neither FM nor GERD from the same database, frequency matched by sex, age, and diagnosis date, as the respective control cohorts. Incidence of GERD in arm 1 and incidence of FM in arm 2 were estimated by the end of 2011. The overall incidence of GERD was 1.6-fold greater in the FM cohort than in the non-FM cohort (12.0 and 7.61 per 1000 person-years, crude hazard ratio [HR] = 1.58, 95% confidence interval [CI] = 1.51-1.66), with an adjusted HR (aHR) of 1.27 (95% CI = 1.22-1.33) after controlling for sex, age, comorbidities, and medications. The GERD cohort ultimately had a 1.5-fold higher incidence of FM than the non-GERD cohort (5.76 vs 3.96 per 1000 person-years), with an aHR of 1.44 (95% CI = 1.29-1.60). The present study suggests a bidirectional relationship between FM and GERD. There is a greater risk of developing GERD for patients with FM than developing FM for patients with GERD.