A systematic review of structural and functional MRI studies on pain catastrophizing

Neuropathic pain, mood, and stress-related disorders: A literature review of comorbidity and co-pathogenesis

Neuropathic pain can be caused by multiple factors, and its prevalence can reach 10% of the global population. It is becoming increasingly evident that limited or short-lasting response to treatments for neuropathic pain is associated with psychological factors, which include psychiatric comorbidities known to affect quality of life. It is estimated that 60% of patients with neuropathic pain also experience depression, anxiety, and stress symptoms. Altered mood, including stress, can be a consequence of several painful conditions but can also favor pain chronicization when preexisting. Despite the apparent tight connection between clinical pain and mood/stress disorders, the exact physiological mechanisms remain unclear. This review aims to provide an overview of state-of-the-art research on the mechanisms of pain related to the pathophysiology of depression, anxiety, and stress disorders.

Multimodal covarying brain patterns mediate genetic and psychological contributions to individual differences in pain sensitivity

ABSTRACT

Individuals vary significantly in their pain sensitivity, with contributions from the brain, genes, and psychological factors. However, a multidimensional model integrating these factors is lacking due to their complex interactions. To address this, we measured pain sensitivity (ie, pain threshold and pain tolerance) using the cold pressor test, collected magnetic resonance imaging (MRI) data and genetic data, and evaluated psychological factors (ie, pain catastrophizing, pain-related fear, and pain-related anxiety) from 450 healthy participants with both sexes (160 male, 290 female). Using multimodal MRI fusion methods, we identified 2 pairs of covarying structural and functional brain patterns associated with pain threshold and tolerance, respectively. These patterns primarily involved regions related to self-awareness, sensory-discriminative, cognitive-evaluative, motion preparation and execution, and emotional aspects of pain. Notably, pain catastrophizing was negatively correlated with pain tolerance, and this relationship was mediated by the multimodal covarying brain patterns in male participants only. Furthermore, we identified an association between the single-nucleotide polymorphism rs4141964 within the fatty acid amide hydrolase gene and pain threshold, mediated by the identified multimodal covarying brain patterns across all participants. In summary, we suggested a model that integrates the brain, genes, and psychological factors to elucidate their role in shaping interindividual variations in pain sensitivity, highlighting the important contribution of the multimodal covarying brain patterns as important biological mediators in the associations between genes/psychological factors and pain sensitivity.

Pain Catastrophizing: How Far Have We Come

The perception of pain is strongly influenced by various social, emotional, and cognitive factors. A psychological variable which has consistently been shown to exert its influence on pain is a cognitive process referred to as pain catastrophizing. Numerous studies have found it to be a strong predictor of pain intensity and disability across different clinical populations. It signifies a maladaptive response to pain marked by an exaggerated negative assessment, magnification of symptoms related to pain, and, in general, a tendency to experience marked pain-related worry, as well as experiencing feelings of helplessness when it comes to dealing with pain. Pain catastrophizing has been correlated to many adverse pain-related outcomes, including poor treatment response, unsatisfactory quality of life, and high disability related to both acute and chronic pain. Furthermore, there has been consistent evidence in support of a correlation between pain catastrophizing and mental health disorders, such as anxiety and depression. In this review, we aim to provide a comprehensive overview of the current state of knowledge regarding pain catastrophizing, with special emphasis on its clinical significance, and emerging treatment modalities which target it.

Effects of chronic daily headache with subclinical depression on brain volume: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

The relationship between chronic daily headache (CDH), depression symptoms, and brain volume remains unclear.

METHODS

To investigate the effects of CDH on brain volume and the impact of depressive symptoms (DSs) as well as the effects of demography and medication overuse, PubMed, Embase, and Web of Science databases were systematically searched using appropriate keyword strings to retrieve observational studies from inception to May 2023.

RESULTS

Two distinct comparisons were made in CDH patients: (1) those with DSs versus their pain-free counterparts and (2) those without DSs versus pain-free controls. The first comprised nine studies enrolling 225 CDH patients with DSs and 234 controls. Beck depression inventory, Hamilton depression scale, and Hospital anxiety/depression scale were used to assess DSs, revealing significantly more DSs in CDH patients with DSs compared to their controls (all p < 0.05). Besides, the second analysed four studies involving 117 CDH patients without DSs and 155 comparators. Compared to CDH patients without DSs, those with DSs had a smaller brain volume than controls (p = 0.03). Furthermore, CDH patients with DSs who did not overuse medications showed a smaller right cerebral cortical volume than overusers (p = 0.003). A significant inverse correlation between female prevalence and brain volume (p = 0.02) was revealed using regression analysis.

CONCLUSIONS

Pain-induced persistent depressive symptoms not only incur structural alterations but also encompass affective-motivational changes, involving medication use and gender-specific health concerns.

SIGNIFICANCE

This study highlighted the importance of an integrated CDH treatment, emphasizing psychological interventions for the affective-motivational component alongside pain management.

Associations Between Brain-Gut Axis and Psychological Distress in Fibromyalgia: A Microbiota and Magnetic Resonance Imaging Study

An altered brain-gut axis is suspected to be one of the pathomechanisms in fibromyalgia (FM). This cross-sectional study investigated the associations among altered microbiota, psychological distress, and brain functional connectivity (FC) in FM. We recruited 25 FM patients and 25 healthy people in the present study. Psychological distress was measured using standardized questionnaires. Microbiota analysis was performed on the participants' stools. Functional magnetic resonance imaging data were acquired, and seed-based resting-state FC (rs-FC) analysis was conducted with the salience network nodes as seeds. Linear regression and mediation analyses evaluated microbiota, symptoms, and rs-FCs associations. We found altered microbiota diversity in FM, of which Phascolarctobacterium and Lachnoclostridium taxa increased the most and Faecalibacterium taxon decreased the most compared to controls. The Phascolarctobacterium abundance significantly predicted Beck depression inventory (BDI-II) scores in FM (β = 6.83; P = .033). Rs-FCs from salience network nodes were reduced in FM, of which rs-FCs from the right lateral rostral prefrontal cortex (RPFC) to the lateral occipital cortex, superior division right (RPFC-sLOC) could be predicted by BDI-II scores in patients (β = -.0064; P = .0054). In addition, the BDI-II score was a mediator in the association between Phascolarctobacterium abundance and rs-FCs of RPFC-sLOC (ab = -.06; 95% CI: -.16 to -9.10-3). In conclusion, microbial dysbiosis might be associated with altered neural networks mediated by psychological distress in FM, emphasizing the critical role of the brain-gut axis in FM's non-pain symptoms and supporting further analysis of mechanism-targeted therapies to reduce FM symptoms. PERSPECTIVE: Our study suggests microbial dysbiosis might be associated with psychological distress and the altered salience network, supporting the role of brain-gut axis dysfunction in fibromyalgia pathomechanisms. Further targeting therapies for microbial dysbiosis should be investigated to manage fibromyalgia patients in the future.

The moderating effect of resting heart rate variability on the relationship between pain catastrophizing and depressed mood: an empirical study

Previous research indicated that pain catastrophizing-a negative emotional and cognitive response toward actual or anticipated pain-could contribute to pain intensity and could be associated with depressive symptoms not just in chronic pain patients but in healthy population as well. Accumulated evidence suggests that resting heart rate variability (HRV) as a putative proxy of emotion regulation could moderate the association of self-reported pain catastrophizing and depressed mood. In the present cross-sectional study, we investigated these associations in a healthy young adult sample controlling for the effect of trait rumination. Seventy-two participants (58 females, mean age = 22.2 ± 1.79 years ranging from 19 to 28 years old) completed the Pain Catastrophizing Scale, the Zung Self-Rating Depression Scale and the Ruminative Response Scale. Resting HRV was measured by time domain metric of HRV, the root mean square of successive differences (RMSSD). The results showed that the relationship between pain catastrophizing and depressive symptoms is significantly moderated by resting HRV (indexed by lnRMSSD). Specifically, in participants with higher resting HRV there was no significant relationship between the two investigated variables, while in participants with relatively low or medium HRV pain catastrophizing and depressed mood showed significant positive association. The relationship remained significant after controlling for sex, age and trait rumination. These results might indicate that measuring pain catastrophizing and depressive symptoms is warranted in non-clinical samples as well and higher resting HRV could have a buffer or protective role against depressive symptoms.

Serotonin Transporter (5-Hydroxytryptamine Transporter, SERT, SLC6A4) and Sodium-dependent Reuptake Inhibitors as Modulators of Pain Behaviors and Analgesic Responses

The serotonin transporter (5-hydroxytryptamine transporter [5-HTT], Serotonin Transporter (SERT), SLC6A4) modulates the activity of serotonin via sodium-dependent reuptake. Given the established importance of serotonin in the control of pain, 5-HTT has received much interest in studies of pain states and as a pharmacological target for serotonin reuptake inhibitors (SRIs). Animal models expressing varying levels of 5-HTT activity show marked differences in pain behaviors and analgesic responses, as well as many serotonin-related physiological effects. In humans, functional nucleotide variations in the SLC6A4 gene, which encodes the serotonin transporter 5-HTT, are associated with certain pathologic pain conditions and differences in responses to pharmacological therapy. These findings collectively reflect the importance of 5-HTT in the intricate physiology and management of pain, as well as the scientific and clinical challenges that need to be considered for the optimization of 5-HTT-related analgesic therapies. PERSPECTIVE: The serotonin transporter 5-HTT/SCL6A4 is sensitive to pharmacological SRIs. Experimental studies on the physiological functions of serotonin, as well as genetic mouse models and clinical phenotype/genotype correlations of nucleotide variation in the human 5-HTT/SCL6A4 gene, provide new insights for the use of SRIs in chronic pain management.

Oxytocin Modulation in Mindfulness-Based Pain Management for Chronic Pain

In the context of chronic pain management, opioid-based treatments have been heavily relied upon, raising concerns related to addiction and misuse. Non-pharmacological approaches, such as Mindfulness-Based Pain Management, offer alternative strategies. We conducted a mechanistic clinical study to investigate the impact of an 8-week Mindfulness-Based Pain Management intervention on chronic pain, the modulation of inflammatory markers, stress physiology, and oxytocin, and their interplay with clinical pain symptoms and perception, in comparison to a patient wait-list active control. A total of 65 participants, including 50 chronic pain patients and 15 healthy controls, underwent salivary assays to assess endocrine markers, oxytocin, interleukin (IL)-1b, IL-6, IL-8, tumor necrosis factor (TNF)-a, and dehydroepiandrosterone sulphate (DHEA-S). Psychological assessments were also conducted to evaluate aspects of pain perception, mindfulness, mood, and well-being. Findings revealed significant differences between chronic pain patients and healthy controls in various clinical metrics, highlighting the psychological distress experienced by patients. Following Mindfulness-Based Pain Management, oxytocin levels significantly increased in chronic pain patients, that was not observed in the patient wait-list control group. In contrast, cytokine and DHEA-S levels decreased (not to statistically significant margins) supporting anti-inflammatory effects of Mindfulness-Based Pain Management. The fact DHEA-S levels, a marker of stress, did attenuate but not to statistically meaningful levels, suggests that pain reduction was not solely related to stress reduction, and that oxytocin pathways may be more salient than previously considered. Psychological assessments demonstrated substantial improvements in pain perception and mood in the intervention group. These results contribute to the growing body of evidence regarding the effectiveness of mindfulness-based interventions in chronic pain management and underscore oxytocin's potential role as a therapeutic target.

Postoperative Psychological Predictors for Chronic Postsurgical Pain After a Knee Arthroplasty: A Prospective Observational Study

OBJECTIVE

Chronic postsurgical pain (CPSP) is a significant adverse effect shown in around 20% of people who had undergone a knee arthroplasty (KA). Psychological risk factors have emerged as significant and potentially modifiable risk factors for its development. However, there is still little evidence when assessing these factors during the acute postoperative period. This study aimed to assess the predictive value of postoperative pain catastrophizing, pain-related fear of movement, anxiety, depression, and pain attitudes in developing CPSP after KA.

METHODS

A 6-month follow-up prospective observational study design was used. The study sample comprised 115 people who underwent a KA due to painful primary osteoarthritis. Measures of pain catastrophizing, pain-related fear of movement, anxiety, depression, and pain attitudes were obtained 1 week after surgery. CPSP was set at an intensity of ≥30 using a 100-mm visual analog scale at 3 and 6 months after surgery.

RESULTS

Analysis revealed that baseline pain intensity, pain catastrophizing, pain-related fear of movement, anxiety, depression, and maladaptive pain attitudes were significant predictors of chronic pain at 3 and 6 months after surgery in a univariate analysis. However, at 3 months after surgery, only pain intensity and pain catastrophizing were predictors in the final multivariate model forecasting disturbing pain. Moreover, 6 months after surgery, pain intensity and distrust in medical procedures remained independent predictors. Most of the psychological factors can be grouped into a single dimension defined as pain-related psychological distress.

CONCLUSION

The results suggest that postoperative pain intensity, pain catastrophizing, and pain attitudes are independent predictors for CPSP after KA.

IMPACT

Postoperative cognitive and emotional factors should be considered alongside pain intensity during postoperative rehabilitation after KA because they could influence the development of CPSP.

A Randomized Controlled Neuroimaging Trial of Cognitive Behavioral Therapy for Fibromyalgia Pain

OBJECTIVE

Fibromyalgia (FM) is characterized by pervasive pain-related symptomatology and high levels of negative affect. Mind-body treatments such as cognitive behavioral therapy (CBT) appear to foster improvement in FM via reductions in pain-related catastrophizing, a set of negative, pain-amplifying cognitive and emotional processes. However, the neural underpinnings of CBT's catastrophizing-reducing effects remain uncertain. This randomized controlled mechanistic trial was designed to assess CBT's effects on pain catastrophizing and its underlying brain circuitry.

METHODS

Of 114 enrolled participants, 98 underwent a baseline neuroimaging assessment and were randomized to 8 weeks of individual CBT or a matched FM education control (EDU) condition.

RESULTS

Compared with EDU, CBT produced larger decreases in pain catastrophizing post treatment (P < 0.05) and larger reductions in pain interference and symptom impact. Decreases in pain catastrophizing played a significant role in mediating those functional improvements in the CBT group. At baseline, brain functional connectivity between the ventral posterior cingulate cortex (vPCC), a key node of the default mode network (DMN), and somatomotor and salience network regions was increased during catastrophizing thoughts. Following CBT, vPCC connectivity to somatomotor and salience network areas was reduced.

CONCLUSION

Our results suggest clinically important and CBT-specific associations between somatosensory/motor- and salience-processing brain regions and the DMN in chronic pain. These patterns of connectivity may contribute to individual differences (and treatment-related changes) in somatic self-awareness. CBT appears to provide clinical benefits at least partially by reducing pain-related catastrophizing and producing adaptive alterations in DMN functional connectivity.

A systematic review of the added value of perioperative pain neuroscience education

OBJECTIVE

To identify and summarize evidence about the benefits of perioperative pain neuroscience education (PNE) on pain-related and psychosocial outcomes.

METHODS

Included were reports written in English that carried out PNE or its synonyms; perioperative period; aged ≥ 18 years; interventional studies and observational studies. Secondary studies, conference abstracts, and editorials were excluded. There was no time limitation.

INFORMATION SOURCES

PubMed, Virtual Health Library, Cochrane Library, and Science Direct. Search: June 20th 2023. The risk of bias was assessed using the Joanna Briggs Institute checklists, and synthesis followed the recommendations of the Synthesis Without Meta-analysis (SWiM) guideline. Register: Center for Open Science website (10.17605/OSF.IO/ZTNEJ).

RESULTS

The sample consisted of 18 reports. For pain outcomes, it was not possible to attribute PNE benefits because ten reports found improvements in both intervention and control groups. For psychosocial outcomes, fourteen reports found benefits for PNE groups. All the analyzed reports showed low risk of bias.

CONCLUSION

PNE had additional benefits beyond those obtained with conventional treatment for psychosocial outcomes.

PRACTICAL IMPLICATIONS

Due to the lack of evidence, it was not possible to indicate the clinical use of PNE. It is suggested that further studies are needed aimed at clarifying the possible benefits.

Effect of Catastrophic Thinking on the Analgesic Effect of Electroacupuncture

Introduction

Patients with chronic pain and high-level catastrophic thoughts often do not respond to acupuncture. This may be related to hypofunctioning of the dorsolateral prefrontal cortex and the descending pain inhibitory system. Therefore, we examined the relationship between the level of catastrophic thinking and the analgesic effect of electroacupuncture using the pain catastrophizing scale (PCS). We also evaluated the descending pain inhibitory system using conditioned pain modulation (CPM) and offset analgesia (OA). The relationship between catastrophic thinking and the descending pain inhibitory system was also examined.

Materials and Methods

After testing the hospital anxiety and depression scale and the PCS in 14 healthy adults, the current pain threshold (CPT), CPM, and OA were measured, in order, before the intervention. Thereafter, electroacupuncture was applied to 3 limbs (the dominant hand and both lower extremities) at 4 Hz, and to the scalp at 100 Hz, for 30 minutes, and the CPT was measured again immediately after the intervention. The difference in the CPT before and after the intervention was taken as the analgesic effect.

Results

The participants were divided into 2 groups, the H-PCS group (≥16 points) and the L-PCS group (≤15 points), according to the PCS score, and the analgesic effects of electroacupuncture were significantly different (P = 0.04). However, no relationship was found between the PCS score and the CPM (r = -0.02, P = 0.94) and OA effects (r = -0.19, P = 0.49).

Conclusion

It was suggested that people with high-level catastrophic thinking may find it difficult to obtain the analgesic effects of electroacupuncture.

Within-Individual BOLD Signal Variability and its Implications for Task-Based Cognition: A Systematic Review

Within-individual blood oxygen level-dependent (BOLD) signal variability, intrinsic moment-to-moment signal fluctuations within a single individual in specific voxels across a given time course, is a relatively new metric recognized in the neuroimaging literature. Within-individual BOLD signal variability has been postulated to provide information beyond that provided by mean-based analysis. Synthesis of the literature using within-individual BOLD signal variability methodology to examine various cognitive domains is needed to understand how intrinsic signal fluctuations contribute to optimal performance. This systematic review summarizes and integrates this literature to assess task-based cognitive performance in healthy groups and few clinical groups. Included papers were published through October 17, 2022. Searches were conducted on PubMed and APA PsycInfo. Studies eligible for inclusion used within-individual BOLD signal variability methodology to examine BOLD signal fluctuations during task-based functional magnetic resonance imaging (fMRI) and/or examined relationships between task-based BOLD signal variability and out-of-scanner behavioral measure performance, were in English, and were empirical research studies. Data from each of the included 19 studies were extracted and study quality was systematically assessed. Results suggest that variability patterns for different cognitive domains across the lifespan (ages 7-85) may depend on task demands, measures, variability quantification method used, and age. As neuroimaging methods explore individual-level contributions to cognition, within-individual BOLD signal variability may be a meaningful metric that can inform understanding of neurocognitive performance. Further research in understudied domains/populations, and with consistent quantification methods/cognitive measures, will help conceptualize how intrinsic BOLD variability impacts cognitive abilities in healthy and clinical groups.

Brain network functional connectivity changes in patients with anterior knee pain: a resting-state fMRI exploratory study

BACKGROUND

This study investigates the functional brain connectivity in patients with anterior knee pain (AKP). While biomechanical models are frequently employed to investigate AKP, it is important to recognize that pain can manifest even in the absence of structural abnormalities. Leveraging the capabilities of functional magnetic resonance imaging (fMRI), this research aims to investigate the brain mechanisms present in AKP patients.

METHODS

Forty-five female subjects (24 AKP patients, 21 controls) underwent resting-state fMRI and T1-weighted structural MRI. Functional brain connectivity patterns were analyzed, focusing on pain network areas, and the influence of catastrophizing thoughts was evaluated.

RESULTS

Comparing patients and controls, several findings emerged. First, patients with AKP exhibited increased correlation between the right supplementary motor area and cerebellum I, as well as decreased correlation between the right insula and the left rostral prefrontal cortex and superior frontal gyrus. Second, in AKP patients with catastrophizing thoughts, there was increased correlation of the left lateral parietal cortex with two regions of the right cerebellum (II and VII) and the right pallidum, and decreased correlation between the left medial frontal gyrus and the right thalamus. Furthermore, the correlation between these regions showed promising results for discriminating AKP patients from controls, achieving a cross-validation accuracy of 80.5%.

CONCLUSIONS

Resting-state fMRI revealed correlation differences in AKP patients compared to controls and based on catastrophizing thoughts levels. These findings shed light on neural correlates of chronic pain in AKP, suggesting that functional brain connectivity alterations may be linked to pain experience in this population.

RELEVANCE STATEMENT

Etiopathogenesis of pain in anterior knee pain patients might not be limited to the knee, but also to underlying alterations in the central nervous system: cortical changes might lead a perpetuation of pain.

KEY POINTS

• Anterior knee pain patients exhibit distinct functional brain connectivity compared to controls, and among catastrophizing subgroups. • Resting-state fMRI reveals potential for discriminating anterior knee pain patients with 80.5% accuracy. • Functional brain connectivity differences improve understanding of pain pathogenesis and objective anterior knee pain identification.

The Contribution of Cancer-Specific Psychosocial Factors to the Pain Experience in Cancer Survivors

Palliative care teams are increasingly called up to manage chronic pain in cancer survivors. Chronic pain is common in cancer survivors and is heavily influenced by biopsychosocial factors. This study aimed to determine the relative contribution of unique cancer-specific psychosocial factors, pain catastrophizing, and multisite pain to the pain experience in 41 cancer survivors who completed curative cancer treatment. To test the research hypotheses, a series of nested linear regression models were used with likelihood ratio testing to test the individual and collective contribution of cancer-specific psychosocial factors (fear of cancer recurrence, cancer distress, cancer-related trauma), pain catastrophizing, and the number of pain sites on the pain experience. The results indicate pain catastrophizing and multisite pain explained a significant degree of variance in pain interference scores ( P < .001) and pain severity ( P = .005). Cancer-specific psychosocial factors did not significantly predict variability in pain interference ( P = .313) or pain severity ( P = .668) over and above pain catastrophizing and the number of sites of pain. In summary, pain catastrophizing and multisite pain contribute to the chronic cancer-related pain experienced by cancer survivors. Palliative care nurses are well positioned to improve chronic pain among cancer survivors by assessing and treating pain catastrophizing and multisite pain.

Dysfunctional Activation of the Dorsolateral Prefrontal Cortex During Pain Anticipation Is Associated With Altered Subsequent Pain Experience in Fibromyalgia Patients

The ability to accurately predict pain is an adaptive feature in healthy individuals. However, in chronic pain, this mechanism may be selectively impaired and can lead to increased anxiety and excessive avoidance behavior. Recently, we reported the first data demonstrating brain activation in fibromyalgia (FM) patients during conditioned pain responses, in which FM patients revealed a tendency to form new pain-related associations rather than extinguishing irrelevant ones. The aim of the present study was to extend our previous analysis, to elucidate potential neural divergences between subjects with FM (n = 65) and healthy controls (HCs) (n = 33) during anticipatory information (ie, prior to painful stimulus onset). Using functional magnetic resonance imaging (fMRI), the current analyses include 1) a congruently cued paradigm of low and high pain predictive cues, followed by 2) an incongruently cued paradigm where low and high pain predictive cues were followed by an identical mid-intensity painful pressure. During incongruently cued high-pain associations, FM exhibited reduced left dorsolateral prefrontal cortex (dlPFC) activation compared to HCs, which was followed by an altered subsequent pain experience in FM, as patients continued to rate the following painful stimuli as high, even though the pressure had been lowered. During congruently cued low pain anticipation, FM exhibited decreased right dlPFC activation compared to HCs, as well as decreased brain connectivity between brain regions implicated in cognitive modulation of pain (dlPFC) and nociceptive processing (primary somatosensory cortex/postcentral gyrus [S1] and supplementary motor area [SMA]/midcingulate cortex [MCC]). These results may reflect an important feature of validating low pain expectations in HCs and help elucidate behavioral reports of impaired safety processing in FM patients. PERSPECTIVE: FM exhibited a stronger conditioned pain response for high-pain associations, which was associated with reduced dlPFC activation during the incongruent trial. During (congruent and incongruent) low pain associations, FM dlPFC brain activation remained indifferent. Imbalances in threat and safety pain perception may be an important target for psychotherapeutic interventions.

Levels of preoperative cerebrospinal fluid pro-inflammatory mediators and chronic pain after total knee arthroplasty surgery

BACKGROUND

Patients undergoing total knee arthroplasty (TKA) surgery are at high risk of chronic postsurgical pain (CPSP). Accumulating evidence suggests an active role of neuroinflammation in chronic pain. However, its role in the progression to CPSP following TKA surgery remains unanswered. Here, we examined the associations between preoperative neuroinflammatory states and pre- and postsurgical chronic pain in TKA surgery.

METHODS

The data of 42 patients undergoing elective TKA surgery for chronic knee arthralgia at our hospital were analyzed in this prospective study. Patients completed the following questionnaires: brief pain inventory (BPI), hospital anxiety and depression scale, painDETECT, and pain catastrophizing scale (PCS). Cerebrospinal fluid (CSF) samples were collected preoperatively and concentrations of IL-6, IL-8, TNF, fractalkine, and CSF-1 were measured by electrochemiluminescence multiplex immunoassay. CPSP severity was ascertained, using the BPI, 6 months postsurgery.

RESULTS

While no significant correlation was observed between the preoperative CSF mediator levels and preoperative pain profiles, the preoperative fractalkine level in the CSF showed a significant correlation with CPSP severity (Spearman's rho = -0.525; p = .002). Furthermore, multivariate linear regression analysis revealed that the preoperative PCS score (standardized β coefficient [β]: .11; 95% confidence interval [CI]: 0.06-0.16; p < .001) and CSF fractalkine level (β: -.62; 95% CI: -1.10 to -0.15; p = .012) were independent predictors of CPSP severity 6 months after TKA surgery.

CONCLUSIONS

We identified the CSF fractalkine level as a potential predictor for CPSP severity following TKA surgery. In addition, our study provided novel insights into the potential role of neuroinflammatory mediators in the pathogenesis of CPSP.

Physical symptoms and brain morphology: a population neuroimaging study in 12,286 pre-adolescents

Physical symptoms, also known as somatic symptoms, are those for which medical examinations do not reveal a sufficient underlying root cause (e.g., pain and fatigue). The extant literature of the neurobiological underpinnings of physical symptoms is largely inconsistent and primarily comprises of (clinical) case-control studies with small sample sizes. In this cross-sectional study, we studied the association between dimensionally measured physical symptoms and brain morphology in pre-adolescents from two population-based cohorts; the Generation R Study (n = 2649, 10.1 ± 0.6 years old) and ABCD Study (n = 9637, 9.9 ± 0.6 years old). Physical symptoms were evaluated using continuous scores from the somatic complaints syndrome scale from the parent-reported Child Behavior Checklist (CBCL). High-resolution structural magnetic resonance imaging (MRI) was collected using 3-Tesla MRI systems. Linear regression models were fitted for global brain metrics (cortical and subcortical grey matter and total white matter volume) and surface-based vertex-wise measures (surface area and cortical thickness). Results were meta-analysed. Symptoms of anxiety/depression were studied as a contrasting comorbidity. In the meta-analyses across cohorts, we found negative associations between physical symptoms and surface area in the (i) left hemisphere; in the lateral orbitofrontal cortex and pars triangularis and (ii) right hemisphere; in the pars triangularis, the pars orbitalis, insula, middle temporal gyrus and caudal anterior cingulate cortex. However, only a subset of regions (left lateral orbitofrontal cortex and right pars triangularis) were specifically associated with physical symptoms, while others were also related to symptoms of anxiety/depression. No significant associations were observed for cortical thickness. This study in preadolescents, the most representative and well-powered to date, showed that more physical symptoms are modestly related to less surface area of the prefrontal cortex mostly. While these effects are subtle, future prospective research is warranted to understand the longitudinal relationship of physical symptoms and brain changes over time. Particularly, to elucidate whether physical symptoms are a potential cause or consequence of distinct neurodevelopmental trajectories.

Differences in dynamic balance control based on pain catastrophizing level in individuals with nonspecific chronic low back pain

BACKGROUND

Pain catastrophization (PC) is related to motor control changes in individuals with nonspecific chronic low back pain (NSCLBP). However, differences in dynamic balance control based on the level of PC still remain unclear in these individuals.

OBJECTIVE

The aim of this study was to compare the dynamic balance control between healthy controls and individuals with NSCLBP with high and low PC.

METHODS

Forty individuals with NSCLBP and 20 healthy participants were enrolled in this cross-sectional study. Individuals with NSCLBP were classified into two groups of high and low PC. Dynamic balance control was assessed using the Modified Star Excursion Balance Test (MSEBT), Five-Time Sit-to-Stand Test (FTSST), and Timed Up and Go Test (TUGT).

RESULTS

Statistical analyses showed that mean values of reach distances in the anterior, posteromedial, and posterolateral directions of the MSEBT were significantly lower in individuals with NSCLBP with high PC compared to low PC (p = .04, p = .01, and p = .04, respectively) and healthy controls (p < .001, p = .001, and p = .006, respectively). In addition, for both the FTSS and TUG tests, the mean time was significantly greater in individuals with NSCLBP with high PC compared to low PC (p < .001 and p = .004, respectively) and healthy controls (p < .001).

CONCLUSIONS

Our results showed poor dynamic balance control in individuals with NSCLBP with high PC. This suggests that PC could contribute to the impaired dynamic balance control in individuals with NSCLBP. Combining balance exercises and cognitive-behavioral treatments targeting PC may be useful for the improvement of dynamic balance control in individuals with NSCLBP with high PC.

Associations Between Adolescent Pain and Psychopathology in the Adolescent Brain Cognitive Development (ABCD) Study

Pain and psychopathology co-occur in adolescence, but the directionality and etiology of these associations are unclear. Using the pain questionnaire and the Child Behavior Checklist from the Adolescent Brain Cognitive Development study (n = 10,414 children [770 twin pairs] aged 12-13), we estimated longitudinal, co-twin control, and twin models to evaluate the nature of these associations. In two-wave cross-lag panel models, there were small cross-lag effects that suggested bidirectional associations. However, the co-twin control models suggested that most associations were familial. Pain at age 12 and 13 was mostly environmental (A = 0-12%, C = 15-30%, E = 70-73%) and the twin models suggested that associations with psychopathology were primarily due to shared environmental correlations. The exception was externalizing, which had a phenotypic prospective effect on pain, a significant within-family component, and a non-shared environmental correlation at age 12. Environmental risk factors may play a role in pain-psychopathology co-occurrence. Future studies can examine risk factors such as stressful life events.

Individual Differences in Pain Catastrophizing and Regional Gray Matter Volume Among Community-dwelling Adults With Chronic Pain: A Voxel-based Morphology Study

OBJECTIVES

Elevations in pain catastrophizing (PC) are associated with more severe pain, emotional distress, and impairment within samples with chronic pain. However, brain structure correlates underlying individual differences in PC are not well understood and predict more severe pain and impairment within samples with chronic pain. This study assessed links between regional gray matter volume (GMV) and individual differences in PC within a large mixed chronic pain sample.

MATERIALS AND METHODS

Chinese adult community dwellers with chronic pain of at least 3 months duration (101 women and 59 men) completed self-report measures of background characteristics, pain severity, depression, and a widely validated PC questionnaire as well as a structural magnetic resonance imagining scan featuring voxel-based morphology to assess regional GMV correlates of PC.

RESULTS

After controlling for demographic correlates of PC, pain severity, and depression, higher PC scores had a significant, unique association with lower GMV levels in the inferior temporal area of the right fusiform gyrus, a region previously implicated in emotion regulation.

DISCUSSION

GMV deficits, particularly in right temporal-occipital emotion regulation regions, correspond to high levels of PC among individuals with chronic pain.

Patient Responses to the Term Pain Catastrophizing: Thematic Analysis of Cross-sectional International Data

Pain catastrophizing is understood as a negative cognitive and emotional response to pain. Researchers, advocates and patients have reported stigmatizing effects of the term in clinical settings and the media. We conducted an international study to investigate patient perspectives on the term pain catastrophizing. Open-ended electronic patient and caregiver proxy surveys were promoted internationally by collaborator stakeholders and through social media. 3,521 surveys were received from 47 countries (77.3% from the U.S.). The sample was mainly female (82.1%), with a mean age of 41.62 (SD 12.03) years; 95% reported ongoing pain and pain duration > 10 years (68.4%). Forty-five percent (n = 1,295) had heard of the term pain catastrophizing; 12% (n = 349) reported being described as a 'pain catastrophizer' by a clinician with associated high levels of feeling blamed, judged, and dismissed. We present qualitative thematic data analytics for responses to open-ended questions, with 32% of responses highlighting the problematic nature of the term. We present the patients' perspective on the term pain catastrophizing, its material effect on clinical experiences, and associations with negative gender stereotypes. Use of patient-centered terminology may be important for favorably shaping the social context of patients' experience of pain and pain care. PERSPECTIVE: Our international patient survey found that 45% had heard of the term pain catastrophizing, about one-third spontaneously rated the term as problematic, and 12% reported the term was applied to them with most stating this was a negative experience. Clinician education on patient-centered terminology may improve care and reduce stigma.

Sedentary Behavior and Pain after Physical Activity in Women with Fibromyalgia-The Influence of Pain-Avoidance Goals and Catastrophizing

BACKGROUND

Fibromyalgia is characterized by chronic pain and fatigue that triggers a functional disability caused by the lack of activity. Pain catastrophizing may contribute to avoiding activity with the intention of managing pain levels. Based on the sedentary behavior with fibromyalgia, the present study assessed the preference of pain-avoidance goals and pain catastrophizing as mediator and moderator variables, respectively, that influence pain perception after a 6-min-walking test.

METHODS

The sample was composed of 76 women with fibromyalgia (mean age = 55.05, SD = 7.70). Previous sedentary behavior, preference for pain-avoidance goals, and pain catastrophizing were evaluated before starting the walking-test. Subsequently, pain perception was evaluated.

RESULTS

A significant moderated-mediation model was found in which pain-avoidance goals mediated the relationship between sedentarism and pain after a walking-test, and pain catastrophizing moderated the relationship between the preference for pain-avoidance goals and pain perception. Specifically, high levels of pain catastrophizing contributed to increased pain perceptions after completing the test (B = 0.570, p = 0.03, CI 95% (0.09, 0.11)].

CONCLUSIONS

The results suggest that motivational interventions can improve the symptoms because their objectives are focused on managing conflict goals. These interventions should focus on catastrophic cognitions considering that pain catastrophizing is deemed to be one of the major inhibitors of physical activity in fibromyalgia.

Primary somatosensory cortex and periaqueductal gray functional connectivity as a marker of the dysfunction of the descending pain modulatory system in fibromyalgia

Background

Resting-state functional connectivity (rs-FC) may aid in understanding the link between pain-modulating brain regions and the descending pain modulatory system (DPMS) in fibromyalgia (FM). This study investigated whether the differences in rs-FC of the primary somatosensory cortex in responders and non-responders to the conditioned pain modulation test (CPM-test) are related to pain, sleep quality, central sensitization, and the impact of FM on quality of life.

Methods

This cross-sectional study included 33 females with FM. rs-FC was assessed by functional magnetic resonance imaging. Change in the numerical pain scale during the CPM-test assessed the DPMS function. Subjects were classified either as non-responders (i.e., DPMS dysfunction, n = 13) or responders (n = 20) to CPM-test. A generalized linear model (GLM) and a receiver operating characteristic (ROC) curve analysis were performed to check the accuracy of the rs-FC to differentiate each group.

Results

Non-responders showed a decreased rs-FC between the left somatosensory cortex (S1) and the periaqueductal gray (PAG) (P < 0.001). The GLM analysis revealed that the S1-PAG rs-FC in the left-brain hemisphere was positively correlated with a central sensitization symptom and negatively correlated with sleep quality and pain scores. ROC curve analysis showed that left S1-PAG rs-FC offers a sensitivity and specificity of 85% or higher (area under the curve, 0.78, 95% confidence interval, 0.63-0.94) to discriminate who does/does not respond to the CPM-test.

Conclusions

These results support using the rs-FC patterns in the left S1-PAG as a marker for predicting CPM-test response, which may aid in treatment individualization in FM patients.

Neurosurgical Treatment of Pain

The aim of this review is to draw attention to neurosurgical approaches for treating chronic and opioid-resistant pain. In a first chapter, an up-to-date overview of the main pathophysiological mechanisms of pain has been carried out, with special emphasis on the details in which the surgical treatment is based. In a second part, the principal indications and results of different surgical approaches are reviewed. Cordotomy, Myelotomy, DREZ lesions, Trigeminal Nucleotomy, Mesencephalotomy, and Cingulotomy are revisited. Ablative procedures have a limited role in the management of chronic non-cancer pain, but they continues to help patients with refractory cancer-related pain. Another ablation lesion has been named and excluded, due to lack of current relevance. Peripheral Nerve, Spine Cord, and the principal possibilities of Deep Brain and Motor Cortex Stimulation are also revisited. Regarding electrical neuromodulation, patient selection remains a challenge.

Early Life Pain Experience Changes Adult Functional Pain Connectivity in the Rat Somatosensory and the Medial Prefrontal Cortex

Early life pain (ELP) experience alters adult pain behavior and increases injury-induced pain hypersensitivity, but the effect of ELP on adult functional brain connectivity is not known. We have performed continuous local field potential (LFP) recording in the awake adult male rats to test the effect of ELP on functional cortical connectivity related to pain behavior. Primary somatosensory cortex (S1) and medial prefrontal cortex (mPFC) LFPs evoked by mechanical hindpaw stimulation were recorded simultaneously with pain reflex behavior for 10 d after adult incision injury. We show that, after adult injury, sensory evoked S1 LFP δ and γ energy and S1 LFP δ/γ frequency coupling are significantly increased in ELP rats compared with controls. Adult injury also induces increases in S1-mPFC functional connectivity, but this is significantly prolonged in ELP rats, lasting 4 d compared with 1 d in controls. Importantly, the increases in LFP energy and connectivity in ELP rats were directly correlated with increased behavioral pain hypersensitivity. Thus, ELP alters adult brain functional connectivity, both within and between cortical areas involved in sensory and affective dimensions of pain. The results reveal altered brain connectivity as a mechanism underlying the effects of ELP on adult pain perception.SIGNIFICANCE STATEMENT Pain and stress in early life has a lasting impact on pain behavior and may increase vulnerability to chronic pain in adults. Here, we record pain-related cortical activity and simultaneous pain behavior in awake adult male rats previously exposed to pain in early life. We show that functional connectivity within and between the somatosensory cortex and the medial prefrontal cortex (mPFC) is increased in these rats and that these increases are correlated with their behavioral pain hypersensitivity. The results reveal that early life pain (ELP) alters adult brain connectivity, which may explain the impact of childhood pain on adult chronic pain vulnerability.

Brain activity changes associated with pain perception variability

Pain perception can be modulated by several factors. Phenomena like temporal summation leads to increased perceived pain, whereas behavioral conditioning can result in analgesic responses. Furthermore, during repeated, identical noxious stimuli, pain intensity can vary greatly in some individuals. Understanding these variations is important, given the increase in investigations that assume stable baseline pain for accurate response profiles, such as studies of analgesic mechanisms. We utilized functional magnetic resonance imaging to examine the differences in neural circuitry between individuals displaying consistent pain ratings and those who experienced variable pain during a series of identical noxious stimuli. We investigated 63 healthy participants: 31 were assigned to a "consistent" group, and 32 were assigned to a "variable" group dependent on pain rating variability. Variable pain ratings were associated with reduced signal intensity in the dorsolateral prefrontal cortex (dlPFC). Furthermore, the dlPFC connectivity with the primary somatosensory cortex and temperoparietal junction was significantly reduced in variable participants. Our results suggest that investigators should consider variability of baseline pain when investigating pain modulatory paradigms. Additionally, individuals with consistent and variable pain ratings differ in their dlPFC activity and connectivity with pain-sensitive regions during noxious stimulation, possibly reflecting the differences in attentional processing and catastrophizing during pain.

The hypertrophic amygdala shape associated with anxiety in patients with primary dysmenorrhea during pain-free phase: insight from surface-based shape analysis

Background

Primary dysmenorrhea (PDM) is highly associated with mood symptoms. However, the neuropathology of these comorbidities is unclear. In the present study, we aimed to investigate the structural changes in the amygdala of patients with PDM during the pain-free phase using a surface-based shape analysis.

Methods

Forty-three PDM patients and forty healthy controls were recruited in the study, and all participants underwent structural magnetic resonance imaging scans during their periovulatory phase. FMRIB’s Integrated Registration and Segmentation Tool (FIRST) was employed to assess the subcortical volumetric and surface alterations in patients with PDM. Moreover, correlation and mediation analyses were used to detect the clinical significance of the subcortical morphometry alteration.

Results

PDM patients showed hypertrophic alteration of the amygdala in the left superficial nuclei and right basolateral and superficial nuclei but not for the whole amygdala volume. The hypertrophic amygdala was associated with disease duration, pain severity and anxiety symptoms during the menstrual period. Furthermore, the hypertrophic left amygdala could mediate the association between disease duration and anxiety severity.

Conclusions

The results of the current study demonstrated that the localized amygdala shape hypertrophy was present in PDM patients even in the pain-free phase. In addition, the mediator role of the hypertrophic amygdala indicates the potential target of amygdala for anxiety treatment in PDM treatment in the pain-free phase.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11682-022-00664-3.

fMRI Findings in Cortical Brain Networks Interactions in Migraine Following Repetitive Transcranial Magnetic Stimulation

Background

Repetitive transcranial magnetic stimulation (rTMS) is one of the high-potential non-pharmacological methods for migraine treatment. The purpose of this study is to define the neuroimaging markers associated with rTMS therapy in patients with migraine based on data from functional MRI (fMRI).

Materials and Methods

A total of 19 patients with episodic migraine without aura underwent a 5-day course of rTMS of the fronto-temporo-parietal junction bilaterally, at 10 Hz frequency and 60% of motor threshold response of 900 pulses. Resting-state functional MRI (1.5 T) and a battery of tests were carried out for each patient to clarify their diagnosis, qualitative and quantitative characteristics of pain, and associated affective symptoms. Changes in functional connectivity (FC) in the brain's neural networks before and after the treatment were identified through independent components analysis.

Results

Over the course of therapy, we observed an increase in FC of the default mode network within it, with pain system components and with structures of the visual network. We also noted a decrease in FC of the salience network with sensorimotor and visual networks, as well as an increase in FC of the visual network. Besides, we identified 5 patients who did not have a positive response to one rTMS course after the first week of treatment according to the clinical scales results, presumably because of an increasing trend of depressive symptoms and neuroimaging criteria for depressive disorder.

Conclusions

Our results show that a 5-day course of rTMS significantly alters the connectivity of brain networks associated with pain and antinociceptive brain systems in about 70% of cases, which may shed light on the neural mechanisms underlying migraine treatment with rTMS.

Top-down threat bias in pain perception is predicted by intrinsic structural and functional connections of the brain

Top-down processes such as expectations play a key role in pain perception. In specific contexts, inferred threat of impending pain can affect perceived pain more than the noxious intensity. This biasing effect of top-down threats can affect some individuals more strongly than others due to differences in fear of pain. The specific characteristics of intrinsic brain characteristics that mediate the effects of top-down threat bias are mainly unknown. In this study, we examined whether threat bias is associated with structural and functional brain connectivity. The variability in the top-down bias was mapped to the microstructure of white matter in diffusion weighted images (DWI) using MRTrix3. Mean functional connectivity of five canonical resting state networks was tested for association with bias scores and with the identified DWI metrics. We found that the fiber density of the splenium of the corpus callosum was significantly low in individuals with high top-down threat bias (FWE corrected with 5000 permutations, p < 0.05). The mean functional connectivity within the language/memory and between language/memory and default mode networks predicted the bias scores. Functional connectivity within language memory networks predicted the splenium fiber density, higher pain catastrophizing and lower mindful awareness. Probabilistic tractography showed that the identified region in the splenium connected several sensory regions and high-order parietal regions between the two hemispheres, indicating the splenium's role in sensory integration. These findings demonstrate that individuals who show more change in pain with changes in the threat of receiving a stronger noxious stimulus have lower structural connectivity in the pathway necessary for integrating top-down cue information with bottom-up sensory information. Conversely, systems involved in memory recall, semantic and self-referential processing are more strongly connected in people with top-down threat bias.

Negative time perspective predicts the self-perceived affective and physical components of pain independently from depression, anxiety, and early life circumstances

People's attitudes toward time, the time perspectives (TPs) rooted in past experiences, might be crucial for the emotional evaluation of life events, such as painful situations. In a survey-based study (N = 353), we investigated the relationship of TPs with the self-perceived affective and physical aspects of pain. Specifically, we hypothesised that past-negative TP would be associated with a negative emotional appraisal of pain characterised by higher pain-related catastrophizing, fear, and physical sensitivity to pain. We tested this hypothesis with hierarchical regression models, adding depression, anxiety, and variables of early life circumstances to the model stepwise. Early life circumstances (i.e., socioeconomic status, household unpredictability, and family resources) were measured retrospectively using questionnaires. In addition, based on the results of the regression analyses, we built a structural equation model (SEM) and tested whether past-negative mediates the effect of household unpredictability toward emotional and physical appraisal of pain. We found that individuals scoring high on past-negative TP had greater pain catastrophizing, pain-related fear, and sensitivity to pain. Further, there was evidence that these associations are independent from depression, anxiety, and early life circumstances. Finally, SEM analysis suggested that unpredictable early life circumstances were directed toward intense, negatively emotionalised pain perception via the mediation of the past-negative TP. The findings generally support the view that pain behaviour is formed by emotional states and attitudes that are linked to past experiences that are not necessarily specific to the context of pain.

Associations between pain catastrophizing and resting-state functional brain connectivity: Ethnic/race group differences in persons with chronic knee pain

Chronic pain is a significant public health problem, and the prevalence and societal impact continues to worsen annually. Multiple cognitive and emotional factors are known to modulate pain, including pain catastrophizing, which contributes to pain facilitation and is associated with altered resting-state functional connectivity in pain-related cortical and subcortical circuitry. Pain and catastrophizing levels are reported to be higher in non-Hispanic black (NHB) compared with non-Hispanic White (NHW) individuals. The current study, a substudy of a larger ongoing observational cohort investigation, investigated the pathways by which ethnicity/race influences the relationship between pain catastrophizing, clinical pain, and resting-state functional connectivity between anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (dlPFC), insula, and primary somatosensory cortex (S1). Participants included 136 (66 NHBs and 70 NHWs) community-dwelling adults with knee osteoarthritis. Participants completed the Coping Strategies Questionnaire-Revised Pain Catastrophizing subscale and Western Ontario and McMaster Universities Osteoarthritis Index. Magnetic resonance imaging data were obtained, and resting-state functional connectivity was analyzed. Relative to NHW, the NHB participants were younger, reported lower income, were less likely to be married, and self-reported greater clinical pain and pain catastrophizing (ps < 0.05). Ethnicity/race moderated the mediation effects of catastrophizing on the relationship between clinical pain and resting-state functional connectivity between the ACC, dlPFC, insula, and S1. These results indicate the NHB and NHW groups demonstrated different relationships between pain, catastrophizing, and functional connectivity. These results provide evidence for a potentially important role of ethnicity/race in the interrelationships among pain, catastrophizing, and resting-state functional connectivity.

Pain catastrophizing: A patient-centered approach to assessment

ABSTRACT

Pain is a subjective experience and its perception and expression vary widely. Pain catastrophizing, which refers to patients' thoughts or feelings about their pain, may impact their communication of pain and nurses' subsequent response. This article discusses how nurses can more readily recognize, assess, and manage pain catastrophizing.

Pain and the Triple Network Model

Acute pain is a physiological response that causes an unpleasant sensory and emotional experience in the presence of actual or potential tissue injury. Anatomically and symptomatically, chronic pathological pain can be divided into three distinct but interconnected pathways, a lateral “painfulness” pathway, a medial “suffering” pathway and a descending pain inhibitory circuit. Pain (fullness) can exist without suffering and suffering can exist without pain (fullness). The triple network model is offering a generic unifying framework that may be used to understand a variety of neuropsychiatric illnesses. It claims that brain disorders are caused by aberrant interactions within and between three cardinal brain networks: the self-representational default mode network, the behavioral relevance encoding salience network and the goal oriented central executive network. A painful stimulus usually leads to a negative cognitive, emotional, and autonomic response, phenomenologically expressed as pain related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, which encodes behavioral relevance of the painful stimuli and the central sympathetic control network. When pain lasts longer than the healing time and becomes chronic, the pain- associated somatosensory cortex activity may become functionally connected to the self-representational default mode network, i.e., it becomes an intrinsic part of the self-percept. This is most likely an evolutionary adaptation to save energy, by separating pain from sympathetic energy-consuming action. By interacting with the frontoparietal central executive network, this can eventually lead to functional impairment. In conclusion, the three well-known pain pathways can be combined into the triple network model explaining the whole range of pain related co-morbidities. This paves the path for the creation of new customized and personalized treatment methods.

Differential Rearrangement of Excitatory Inputs to the Medial Prefrontal Cortex in Chronic Pain Models

Chronic pain patients suffer a disrupted quality of life not only from the experience of pain itself, but also from comorbid symptoms such as depression, anxiety, cognitive impairment, and sleep disturbances. The heterogeneity of these symptoms support the idea of a major involvement of the cerebral cortex in the chronic pain condition. Accordingly, abundant evidence shows that in chronic pain the activity of the medial prefrontal cortex (mPFC), a brain region that is critical for executive function and working memory, is severely impaired. Excitability of the mPFC depends on the integrated effects of intrinsic excitability and excitatory and inhibitory inputs. The main extracortical sources of excitatory input to the mPFC originate in the thalamus, hippocampus, and amygdala, which allow the mPFC to integrate multiple information streams necessary for cognitive control of pain including sensory information, context, and emotional salience. Recent techniques, such as optogenetic methods of circuit dissection, have made it possible to tease apart the contributions of individual circuit components. Here we review the synaptic properties of these main glutamatergic inputs to the rodent mPFC, how each is altered in animal models of chronic pain, and how these alterations contribute to pain-associated mPFC deactivation. By understanding the contributions of these individual circuit components, we strive to understand the broad spectrum of chronic pain and comorbid pathologies, how they are generated, and how they might be alleviated.

Impact of bifrontal home-based transcranial direct current stimulation in pain catastrophizing and disability due to pain in fibromyalgia: a randomized, double-blind sham-controlled study

This randomized, double-blind trial tested the hypothesis that twenty sessions of home-based anodal(a)-transcranial direct current stimulation (tDCS) (2mA for 20 min) bifrontal, with anodal on the left dorsolateral prefrontal cortex (l-DLPFC) would be better than sham-(s)-tDCS to reduce scores on Pain Catastrophizing Scale (PCS) and disability-related to pain (DRP) assessed by the Profile of Chronic Pain: Screen (PCP:S) (primary outcomes). Secondary outcomes were depressive symptoms, sleep quality, heat pain threshold (HPT), heat pain tolerance (HPTo), and serum brain-derived-neurotrophic-factor (BDNF). Forty-eight women with fibromyalgia, 30-65 years-old were randomized into 2:1 groups [a-tDCS (n=32) or s-tDCS (n=16)]. Post hoc analysis revealed that a-tDCS reduced the PCS total scores by 51.38% compared to 26.96% in s-tDCS, and a-tDCS reduced PCP:S total scores by 31.43% compared to 19.15% in s-tDCS. The a-tDCS improved depressive symptoms, sleep quality and increased the HPTo. The delta-value in the serum BDNF (mean post treatment end minus pre-treatment) was conversely correlated with the a-tDCS effect in pain catastrophizing. In contrast, the a-tDCS impact on reducing the DRP at the treatment end was positively associated with a reduction in the serum BDNF and improvement of depressive symptoms, sleep quality and pain catastrophizing symptoms. PERSPECTIVE: Home-based bifrontal tDCS with a-tDCS on the l-DLPFC are associated with a moderate effect size (ES) in the following outcomes: (i) Decreased rumination and magnification of pain catastrophizing. (ii) Improved the disability for daily activities due to fibromyalgia symptoms. Overall, these findings support the feasibility of self-applied home-based tDCS on DLPFC to improve fibromyalgia symptoms.

Brain circuits for pain and its treatment

[Figure: see text].

Self-Healing: A Concept for Musculoskeletal Body Pain Management - Scientific Evidence and Mode of Action

Traditionally, musculoskeletal pain management has focused on the use of conventional treatments to relieve pain. However, multi-modal integrative medicine including alternative/complementary treatments is becoming more widely used and integrated into treatment guidelines around the world. The uptake of this approach varies according to country, with generally a higher uptake in developed countries and in females aged more than 40 years. Integral to the concept described here, is that the body has an innate ability to self-heal, which can be optimized by the use of integrative medical strategies. Stress triggers for acute or recurring musculoskeletal pain are diverse and can range from physical to psychological. The mechanism by which the body responds to triggers and initiates the self-healing processes is complex, but five body networks or processes are thought to be integral: the nervous system, microcirculation/vasodilation, immune modulation, muscular relaxation/contraction and psychological balance. Multi-modal integrative medicine approaches include nutritional/dietary modification, postural/muscular training exercises, and cognitive behavioral mind/body techniques. This article will review the self-healing concept and provide plausible scientific evidence where available.

Peripheral, Central, and Cross Sensitization in Endometriosis-Associated Pain and Comorbid Pain Syndromes

Endometriosis-associated pain and the mechanisms responsible for its initiation and persistence are complex and difficult to treat. Endometriosis-associated pain is experienced as dysmenorrhea, cyclical pain related to organ function including dysuria, dyschezia and dyspareunia, and persistent pelvic pain. Pain symptomatology correlates poorly with the extent of macroscopic disease. In addition to the local effects of disease, endometriosis-associated pain develops as a product of peripheral sensitization, central sensitization and cross sensitization. Endometriosis-associated pain is further contributed to by comorbid pain conditions, such as bladder pain syndrome, irritable bowel syndrome, abdomino-pelvic myalgia and vulvodynia. This article will review endometriosis-associated pain, its mechanisms, and its comorbid pain syndromes with a view to aiding the clinician in navigating the literature and terminology of pain and pain syndromes. Limitations of our current understanding of endometriosis-associated pain will be acknowledged. Where possible, commonalities in pain mechanisms between endometriosis-associated pain and comorbid pain syndromes will be highlighted.

The anatomy of pain and suffering in the brain and its clinical implications

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Chronic pain, with a prevalence of 20-30 % is the major cause of human suffering worldwide, because effective, specific and safe therapies have yet to be developed. It is unevenly distributed among sexes, with women experiencing more pain and suffering. Chronic pain can be anatomically and phenomenologically dissected into three separable but interacting pathways, a lateral 'painfulness' pathway, a medial 'suffering' pathway and a descending pain inhibitory pathway. One may have pain(fullness) without suffering and suffering without pain(fullness). Pain sensation leads to suffering via a cognitive, emotional and autonomic processing, and is expressed as anger, fear, frustration, anxiety and depression. The medial pathway overlaps with the salience and stress networks, explaining that behavioural relevance or meaning determines the suffering associated with painfulness. Genetic and epigenetic influences trigger chronic neuroinflammatory changes which are involved in transitioning from acute to chronic pain. Based on the concept of the Bayesian brain, pain (and suffering) can be regarded as the consequence of an imbalance between the two ascending and the descending pain inhibitory pathways under control of the reward system. The therapeutic clinical implications of this simple pain model are obvious. After categorizing the working mechanisms of each of the available treatments (pain killers, psychopharmacology, psychotherapy, neuromodulation, psychosurgery, spinal cord stimulation) to 1 or more of the 3 pathways, a rational combination can be proposed of activating the descending pain inhibitory pathway in combination with inhibition of the medial and lateral pathway, so as to rebalance the pain (and suffering) pathways.

"If You Don't Keep Going, You're Gonna Die": Helplessness and Perseverance Among Older Adults Living With Chronic Low Back Pain

BACKGROUND AND OBJECTIVES

Chronic low back pain (CLBP) is the leading cause of disability worldwide and the most common pain complaint among the rapidly growing older adult population. As part of a larger qualitative study examining the lived experience of CLBP among older adults, the objective of the present study is to understand how older pain clinic patients experience helplessness and also how they foster perseverance amid treatment-resistant CLBP.

RESEARCH DESIGN AND METHODS

Using van Manen's phenomenological method, semistructured, in-depth, one-on-one interviews were conducted with 21 older pain clinic patients (aged 66-83) living with CLBP. Data were iteratively analyzed via line-by-line thematic coding.

RESULTS

Findings dually illustrate how participants were living a battle between helplessness and perseverance; the final thematic structure revealed 5 subthemes: (a) Feeling helpless because nothing works; (b) Feeling down and depressed; (c) Distantly wishing for an end; (d) Accepting the reality of my pain; and (e) The pain stays, I keep going.

DISCUSSION AND IMPLICATIONS

This study contributes a vivid illustration of older adults' CLBP illness experiences that are substantially underpinned by helplessness, depression, and a drive to continue thriving in old age. Practice implications include the need for clinic-based mood and suicide assessment.

The effect of a pain educational video intervention upon child pain-related outcomes: A randomized controlled study

BACKGROUND

Pain neuroscience education (PNE) has received increasing research attention demonstrating beneficial effects on pain-related outcomes in adults. Conversely, studies on the effectiveness of PNE in children are scarce.

METHODS

This study investigated the effect of a pain educational video intervention on child pain-related outcomes (i.e. experienced pain intensity, pain-related fear and catastrophic worry about pain, pain threshold and pain knowledge) in healthy children undergoing an experimental pain task. Furthermore, the moderating role of children's demographic (i.e. sex and age) and psychological (i.e. baseline pain knowledge and anticipated pain intensity, pain-related fear and catastrophic worry) characteristics was examined. Participants were 89 children (M_age  = 11.85, SD = 1.78), randomly assigned to either a condition whereby they were instructed to watch a brief pain educational video (i.e. experimental group) or to a control condition whereby they did not watch any video.

RESULTS

Study findings revealed that accurate pain knowledge and pain threshold were higher amongst children in the experimental group compared to the control group. In contrast with expectations, no main effects of the video intervention were observed for experienced pain intensity, pain-related fear and catastrophic worry. Moderation analyses indicated that the video intervention contributed, in comparison with the control condition, to higher levels of pain knowledge amongst younger children only and to higher pain thresholds amongst boys only.

CONCLUSIONS

Further investigation is needed to optimize pain educational video interventions and to determine whether more beneficial outcomes can be found in clinical (i.e. non-experimental) situations and in children with persistent or recurring pain problems.

SIGNIFICANCE

Examining the impact of pain educational interventions within a non-clinical setting is deemed particularly important given that adaptive pain coping strategies likely play an important role in preventing the development and maintenance of future maladaptive pain-related behaviour. Further, study findings provide preliminary evidence of baseline and demographic (i.e. age and sex) characteristics explaining differences in the effect of a pain educational video intervention in pain knowledge and pain-related experiences during experimental pain.

Neural correlates of conditioned pain responses in fibromyalgia subjects indicate preferential formation of new pain associations rather than extinction of irrelevant ones

Supplemental Digital Content is Available in the Text.

Functional magnetic resonance imaging pain conditioning data suggest that fibromyalgia prioritizes updating their cerebral representation to forming new potential pain-related associations while simultaneously maintaining no longer relevant ones.

Behavioral studies have demonstrated aberrant safety processing in fibromyalgia subjects (FMSs) and suggested that patients accumulate new potential pain-related threats more effectively than extinguishing no longer relevant ones. The aim of the current study was to investigate the neural correlates of conditioned pain responses and their relationship with emotional distress in FMS (n = 67) and healthy controls (HCs, n = 34). Using functional magnetic resonance imaging, we traced conditioned pain responses to an identical moderately painful pressure (P30) depending on whether it was following a green (P30green) or a red (P30red) cue. The cues were previously associated with individually calibrated painful pressure stimuli of low and high intensity, corresponding to visual analogue scale 10 and 50 mm, respectively. Fibromyalgia subjects displayed increased P30green ratings over time, while P30red ratings remained elevated. Healthy controls adapted all pain ratings to resemble moderate pain. Fibromyalgia subjects exhibited increased activation for [P30green>P30red] in M1/anterior insula, whereas HC showed increased S2/mid-insula response to [P30red>P30green]. High pain catastrophizing scale (PCS) ratings in fibromyalgia (FM) covaried with heightened brain activation for [P30green] × PCS in left dorsolateral prefrontal cortex and medial prefrontal cortex/orbitofrontal cortex; and [P30green>P30red] × PCS in dorsal anterior cingulate cortex/mid-cingulate cortex; superior temporal pole, extending to anterior insula; bilateral thalamus; and posterior insula. Psychophysiological interaction analysis for FM [P30green>P30red] × PCS revealed a dissociation in functional connectivity between thalamus and bilateral inferior parietal lobe. In alignment with behavioral data, FMS displayed a cerebral response suggesting preferential formation of new pain-related associations while simultaneously maintaining no longer relevant ones. The opposite was observed in HC. Increased responses to pain-related threats in FM may contribute to dysfunctional pain-protective behaviors and disability.

A picture is worth a thousand words: linking fibromyalgia pain widespreadness from digital pain drawings with pain catastrophizing and brain cross-network connectivity

ABSTRACT

Pain catastrophizing is prominent in chronic pain conditions such as fibromyalgia and has been proposed to contribute to the development of pain widespreadness. However, the brain mechanisms responsible for this association are unknown. We hypothesized that increased resting salience network (SLN) connectivity to nodes of the default mode network (DMN), representing previously reported pain-linked cross-network enmeshment, would be associated with increased pain catastrophizing and widespreadness across body sites. We applied functional magnetic resonance imaging (fMRI) and digital pain drawings (free-hand drawing over a body outline, analyzed using conventional software for multivoxel fMRI analysis) to investigate precisely quantified measures of pain widespreadness and the associations between pain catastrophizing (Pain Catastrophizing Scale), resting brain network connectivity (Dual-regression Independent Component Analysis, 6-minute multiband accelerated fMRI), and pain widespreadness in fibromyalgia patients (N = 79). Fibromyalgia patients reported pain in multiple body areas (most frequently the spinal region, from the lower back to the neck), with moderately high pain widespreadness (mean ± SD: 26.1 ± 24.1% of total body area), and high pain catastrophizing scale scores (27.0 ± 21.9, scale range: 0-52), which were positively correlated (r = 0.26, P = 0.02). A whole-brain regression analysis focused on SLN connectivity indicated that pain widespreadness was also positively associated with SLN connectivity to the posterior cingulate cortex, a key node of the DMN. Moreover, we found that SLN-posterior cingulate cortex connectivity statistically mediated the association between pain catastrophizing and pain widespreadness (P = 0.01). In conclusion, we identified a putative brain mechanism underpinning the association between greater pain catastrophizing and a larger spatial extent of body pain in fibromyalgia, implicating a role for brain SLN-DMN cross-network enmeshment in mediating this association.

The catastrophization effects of an MRI report on the patient and surgeon and the benefits of 'clinical reporting': results from an RCT and blinded trials

PURPOSE

Inappropriate use of MRI leads to increasing interventions and surgeries for low back pain (LBP). We probed the potential effects of a routine MRI report on the patient's perception of his spine and functional outcome of treatment. An alternate 'clinical reporting' was developed and tested for benefits on LBP perception.

METHODS

In Phase-I, 44 LBP patients were randomized to Group A who had a factual explanation of their MRI report or Group B, who were reassured that the MRI findings showed normal changes. The outcome was compared at 6 weeks by VAS, PSEQ-2, and SF-12. In Phase-II, clinical reporting was developed, avoiding potential catastrophizing terminologies. In Phase-III, 20 MRIs were reported by both routine and clinical methods. The effects of the two methods were tested on four categories of health care professionals (HCP) who read them blinded on their assessment of severity of disease, possible treatment required, and the probability of surgery.

RESULTS

Both groups were comparable initial by demographics and pain. After 6 weeks of treatment, Group A had a more negative perception of their spinal condition, increased catastrophization, decreased pain improvement, and poorer functional status(p = significant for all). The alternate method of clinical reporting had significant benefits in assessment of lesser severity of the disease, shift to lesser severity of intervention and surgery in three groups of HCPs.

CONCLUSION

Routine MRI reports produce a negative perception and poor functional outcomes in LBP. Focussed clinical reporting had significant benefits, which calls for the need for 'clinical reporting' rather than 'Image reporting'.

An exploratory investigation into the effects of mental defeat on pain threshold, pain rating, pain anticipation, and mood

In chronic pain, mental defeat is considered as a disabling type of self-evaluation triggered by repeated episodes of debilitating pain. This exploratory study experimentally tested the effect of an activated sense of defeat, as well as its interaction with pain catastrophizing, on pain and mood. Participants (N = 71) were allocated to either high or low pain catastrophizing groups and then randomly assigned to receive either defeat or neutral manipulations. A cold pressor task administered before and after the thought manipulation measured pain threshold, alongside visual analogue scales for mental defeat, attention, pain intensity, pain anticipation as well as mood. Thought manipulation checks supported successful defeat activation. Defeat activation was associated with increased negative mood and attentional disengagement from the nociceptive stimuli, irrespective of pain catastrophizing tendency. There were no changes in pain threshold, pain or pain anticipation ratings. The results suggest that mental defeat can be experimentally activated using an autobiographical memory task and that an activated sense of defeat appears to operate independently from pain catastrophizing in influencing mood and attentional disengagement from the nociceptive stimuli. Future research can utilize our experimental approach to evaluate the effect of an activated sense of mental defeat in people with chronic pain, for whom the magnitude of pain, mood and attentional responses may be stronger and broader.

Challenges and opportunities in translational pain research - An opinion paper of the working group on translational pain research of the European pain federation (EFIC)

For decades, basic research on the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need. In this opinion paper bringing together pain researchers from very different disciplines, the opportunities and challenges of translational pain research are discussed. The many factors that may prevent the successful translation of bench observations into useful and effective clinical applications are reviewed, including interspecies differences, limited validity of currently available preclinical disease models of pain, and limitations of currently used methods to assess nociception and pain in non-human and human models of pain. Many paths are explored to address these issues, including the backward translation of observations made in patients and human volunteers into new disease models that are more clinically relevant, improved generalization by taking into account age and sex differences, and the integration of psychobiology into translational pain research. Finally, it is argued that preclinical and clinical stages of developing new treatments for pain can be improved by better preclinical models of pathological pain conditions alongside revised methods to assess treatment-induced effects on nociception in human and non-human animals. Significance: For decades, basic research of the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need.

Cortical Mechanisms of Visual Hypersensitivity in Women at Risk for Chronic Pelvic Pain

Multisensory hypersensitivity (MSH), which refers to persistent discomfort across sensory modalities, is a risk factor for chronic pain. Developing a better understanding of the neural contributions of disparate sensory systems to MSH may clarify its role in the development of chronic pain. We recruited a cohort of women (n=147) enriched with participants with menstrual pain at risk for developing chronic pain. Visual sensitivity was measured using a periodic pattern-reversal stimulus during EEG. Self-reported visual unpleasantness ratings were also recorded. Bladder pain sensitivity was evaluated with an experimental bladder-filling task associated with early clinical symptoms of chronic pelvic pain. Visual stimulation induced unpleasantness was associated with bladder pain and evoked primary visual cortex excitation; however, the relationship between unpleasantness and cortical excitation was moderated by bladder pain. Thus, future studies aimed at reversing the progression of MSH into chronic pain should prioritize targeting of cortical mechanisms responsible for maladaptive sensory input integration.