Hyperexcitability of the Central Nervous System in Children with Chronic Pain: A Systematic Review

Navigating through 65 years of insights: lessons learned on functional abdominal pain in children

In 1958, Apley and Naish authored a groundbreaking paper in Archives of Disease in Childhood, elucidating the epidemiology and risk factors of recurrent abdominal pain in children-a subject that had confounded clinicians of their time. Surprisingly, even after 65 years, there are several unanswered questions regarding the etiology, pathophysiology, and management of pediatric abdominal pain. Contrary to the prevailing notion that children naturally outgrow functional abdominal pain, compelling evidence suggests it's possible these children develop a number of clinically significant psychological issues that could profoundly impact their quality of life and, consequently, future health and educational outcomes. In this light, we aimed to comprehensively review the current literature to update the knowledge of practicing clinicians on functional abdominal pain, summarizing the evidence from the last 65 years.Conclusion: The enduring unanswered questions surrounding childhood abdominal pain continue to challenge clinicians, resulting in unnecessary investigations, thereby contributing to substantial healthcare expenditures. It is also evident that children with long-standing symptoms would progress to adulthood with the potential to develop irritable bowel syndrome and many psychological disturbances. Several key interventions using pharmacological agents, such as amitriptyline, showed that some of these drugs are no more effective than the placebo in clinical trials. Several research during the recent past suggest that psychological interventions such as gut-directed hypnotherapy alleviate symptoms and ensure better prognosis in the long run. Therefore, clinicians and researchers must join hands to explore the pathophysiological mechanisms underpinning functional abdominal pain and novel therapeutic strategies to ensure the well-being of these children. What is Known: • Functional abdominal pain disorders are common among children, with a worldwide prevalence of 13.5% of children suffering from at least one of these disorders • These disorders contribute to a significant reduction in the quality of life of affected children and their families and lead to an array of psychological problems What is New: • The biological basis of functional abdominal pain is becoming more explicit, including complex interactions between altered microbiome, deranged motility, and psychological dysfunction with gut-brain interactions • Novel approaches giving minimal emphasis on pharmacological interventions and exploring psychological interventions are showing promising results.

Chronic pain as an emergent property of a complex system and the potential roles of psychedelic therapies

Despite research advances and urgent calls by national and global health organizations, clinical outcomes for millions of people suffering with chronic pain remain poor. We suggest bringing the lens of complexity science to this problem, conceptualizing chronic pain as an emergent property of a complex biopsychosocial system. We frame pain-related physiology, neuroscience, developmental psychology, learning, and epigenetics as components and mini-systems that interact together and with changing socioenvironmental conditions, as an overarching complex system that gives rise to the emergent phenomenon of chronic pain. We postulate that the behavior of complex systems may help to explain persistence of chronic pain despite current treatments. From this perspective, chronic pain may benefit from therapies that can be both disruptive and adaptive at higher orders within the complex system. We explore psychedelic-assisted therapies and how these may overlap with and complement mindfulness-based approaches to this end. Both mindfulness and psychedelic therapies have been shown to have transdiagnostic value, due in part to disruptive effects on rigid cognitive, emotional, and behavioral patterns as well their ability to promote neuroplasticity. Psychedelic therapies may hold unique promise for the management of chronic pain.

Different Analgesia Techniques for Postoperative Pain in Children Undergoing Abdominal Surgery for Intractable Constipation: A Retrospective Cohort Study in a Single Tertiary Children's Hospital

Functional constipation in the pediatric population is a prevalent issue that is usually well managed. However, in rare cases, conservative treatment fails, and surgical intervention is necessary. This retrospective cohort study aimed to describe and compare different perioperative analgesic techniques in children undergoing major abdominal surgery for intractable constipation. Conducted between 2011 and 2021, this study enrolled patients under 18 years old who underwent initial major abdominal surgery for intractable constipation (i.e., creation of ostomy or subtotal colectomy). Patients were categorized according to the perioperative analgesic technique (i.e., systemic, neuraxial, or truncal block). Of 65 patients, 46 (70.8%) were female, and the median age was 13.5 [8.8-16.1] years during initial major abdominal surgery. Systemic analgesia was used in 43 (66.2%), neuraxial in 17 (26.2%), and truncal blocks in 5 (7.7%) of the surgeries. Patients with neuraxial analgesia reported less postoperative pain (median [interquartile range] numeric rating scale (NRS) 2.0 [0-4.0]), compared to systemic analgesia (5.0 [2.0-7.0], p < 0.001) and to truncal blocks (5.0 [3.0-6.5], p < 0.001). In this preliminary investigation, neuraxial analgesia appears to be the most effective approach to reducing acute postoperative pain in pediatric patients undergoing major abdominal surgery for intractable functional constipation. However, well-designed studies are warranted.

The Influence of Children's Pain-Related Attention Shifting Ability and Pain Catastrophizing Upon Negatively Biased Pain Memories in Healthy School Children

The current study investigated the influence of children's ability to flexibly shift attention toward and away from pain information on the development of negatively biased pain memories, thereby employing a direct measure of attention control reliant on behavioral responses in the context of pain (ie, an attention switching task). The direct influence of children's attention-shifting ability and pain catastrophizing as well as the moderating role of this shifting ability in the relationship between pain catastrophizing and the development of negatively biased pain memories was examined. Healthy school children (N = 41; 9-15 years old) received painful heat stimuli and completed measures of state and trait pain catastrophizing. They then performed an attention-switching task wherein they had to shift attention between personally relevant pain-related and neutral cues. Two weeks after the painful task, children's pain-related memories were elicited via telephone. Findings indicated that children's reduced ability to disengage attention away from pain information predicted more fear memory bias 2 weeks later. Children's pain-related attention-shifting ability did not moderate the relationship between children's pain catastrophizing and negatively biased pain memories. Findings highlight the contribution of children's attention control skills in the development of negatively biased pain memories. PERSPECTIVE: Results of the current study indicate that children with a reduced ability to shift attention away from pain information are at risk for developing negatively biased pain memories. Findings can inform interventions to minimize the development of these maladaptive negatively biased pain memories by targeting pain-relevant attention control skills in children.

Significant pain decrease in children with non-systemic Juvenile Idiopathic Arthritis treated to target: results over 24 months of follow up

BACKGROUND

The aim of this study was to compare pain-scores in three targeted treatment-strategies in JIA-patients and to identify characteristics predicting persistent pain.

METHODS

In the BeSt-for-Kids-study 92 DMARD-naïve JIA-patients were randomized in 3 treatment-strategies: 1) initial sequential DMARD-monotherapy 2) initial methotrexate (MTX)/prednisolone-bridging or 3) initial MTX/etanercept. Potential differences in VAS pain scores (0-100 mm) over time between treatment-strategies were compared using linear mixed models with visits clustered within patients. A multivariable model was used to assess the ability of baseline characteristics to predict the chance of high pain-scores during follow-up.

RESULTS

Pain-scores over time reduced from mean 55.3 (SD 21.7) to 19.5 (SD 25.3) mm after 24 months. On average, pain-scores decreased significantly with β -1.37 mm (95% CI -1.726; -1.022) per month. No significant difference was found between treatment-strategies (interaction term treatment arm*time (months) β (95% CI) arm 1: 0.13 (-0.36; 0.62) and arm 2: 0.37 (-0.12; 0.86) compared to arm 3). Correction for sex and symptom duration yielded similar results. Several baseline characteristics were predictive for pain over time. Higher VAS pain [β 0.44 (95% CI 0.25; 0.65)] and higher active joint count [0.77 (0.19; 1.34)] were predictive of higher pain over time, whereas, low VAS physician [ -0.34 (-0.55; -0.06)], CHQ Physical [ -0.42 (-0.72; -0.11)] and Psychosocial summary Score [ -0.42 (-0.77; -0.06)] were predictive of lower pain.

CONCLUSIONS

Treatment-to-target seems effective in pain-reduction in non-systemic JIA-patients irrespective of initial treatment-strategy. Several baseline-predictors for pain over time were found, which could help to identify patients with a high risk for development of chronic pain.

TRIAL REGISTRATION

Dutch Trial Registry number 1574.

Healthcare Professionals’ Knowledge about Pediatric Chronic Pain: A Systematic Review

Pediatric chronic pain is a common public health problem with a high prevalence among children and adolescents. The aim of this study was to review the current knowledge of health professionals on pediatric chronic pain between 15–30% among children and adolescents. However, since this is an underdiagnosed condition, it is inadequately treated by health professionals. To this aim, a systematic review was carried out based on a search of the electronic literature databases (PubMed and Web of Science), resulting in 14 articles that met the inclusion criteria. The analysis of these articles seems to show a certain degree of heterogeneity in the surveyed professionals about the awareness of this concept, especially regarding its etiology, assessment, and management. In addition, the extent of knowledge of the health professionals seems to be insufficient regarding these aspects of pediatric chronic pain. Hence, the knowledge of the health professionals is unrelated to recent research that identifies central hyperexcitability as the primary factor affecting the onset, persistence, and management of pediatric chronic pain.

Biofeedback assisted relaxation training and distraction therapy for pain in children undergoing botulinum neurotoxin A injections: A crossover randomized controlled trial

AIM

To compare biofeedback assisted relaxation training (BART) with distraction therapy for pain during botulinum neurotoxin A (BoNT-A) treatment.

METHOD

This was a crossover randomized controlled trial. Eligible participants were 7 years and older with neurological conditions. Participants were randomized to receive BART or distraction during their first BoNT-A treatment, followed by the alternative intervention in their subsequent BoNT-A treatment. BART was delivered via BrightHearts, an interactive heart-rate-responsive application. Outcomes were pain (Faces Pain Scale - Revised), fear (Children's Fear Scale), and anxiety (numerical rating scale, State-Trait Anxiety Inventory). Demographics, paired t-tests, and linear mixed models were used to compare outcomes.

RESULTS

Thirty-eight participants (mean [SD] age 13 years 5 months [3 years 4 months], 20 males, 34 with cerebral palsy) completed both interventions. There were non-significant differences in overall pain (mean difference - 0.05, 95% confidence interval [CI] -0.91 to 0.80, p = 0.902) and worst pain (mean difference 0.37, 95% CI -0.39 to 1.13, p = 0.334) when using BART and distraction therapy. There were non-significant differences in fear and anxiety between interventions. Younger age, heightened pre-procedural state anxiety, and Gross Motor Function Classification System levels III and IV were associated with poorer outcomes (p < 0.05). Participants who received BART before distraction therapy reported lower pain and anxiety scores during both BoNT-A treatments (p < 0.05).

INTERPRETATION

Children reported similar pain when using BART and distraction therapy. Those who used BART before distraction therapy reported lower pain and anxiety during both treatments.

WHAT THIS PAPER ADDS

Children reported similar pain (overall; worst) when using biofeedback assisted relaxation training (BART) and distraction therapy. Children who used BART before distraction therapy reported lower pain and anxiety over both botulinum neurotoxin A treatments. Younger age, pre-procedural state anxiety, and Gross Motor Function Classification System levels III and IV predicted a worse pain experience. Distraction therapy and BART were acceptable non-pharmacological interventions for procedural pain management.

The relationships of kinesiophobia and physical function and physical activity level in juvenile idiopathic arthritis

BACKGROUND

Kinesiophobia may hinder physical performance measures and functional quality of life in children with juvenile idiopathic arthritis (JIA). This study aims to quantify differences in physical function in patients with JIA compared to healthy controls, and determine the effects of kinesiophobia on physical function and physical activity.

METHODS

This was a comparative study of participants with JIA and healthy controls (JIA n = 26, control n = 17). All children with JIA had lower extremity joint involvement. Performance-based measures included gait speed, chair and stair navigation performance. Self-reported measures included Patient Reported Outcome Measurement Information System (PROMIS®) Physical Function Mobility, and Pain Interference and the Pediatric Functional Activity Brief Scale (Pedi-FABS). The Tampa Scale of Kinesiophobia (TSK-11) assessed patient fear of movement due to pain. Linear regression models were used to determine the contribution of TSK-11 scores on performance test and Pedi-FABS scores.

RESULTS

Gait speeds were 11-15% slower, chair rise repetitions were 28% fewer, and stair ascent and descent times were 26-31% slower in JIA than controls (p < .05). PROMIS® Physical Function Mobility scores were 10% lower and Pain Interference scores were 2.6 times higher in JIA than healthy controls (p = .003). TSK-11 scores were higher in JIA than controls (p < .0001). After controlling for covariates, TSK-11 scores explained 11.7-26.5% of the variance of regression models for stair climb time, chair rise performance and Pedi-FABS scores (p < .05).

CONCLUSIONS

Children with JIA experience difficulty with tasks related to body transfers. Kinesiophobia is a significant contributor to the functional task performance and may impact clinical outcomes.

In the Shoulder or in the Brain? Behavioral, Psychosocial and Cognitive Characteristics of Unilateral Chronic Shoulder Pain with Symptoms of Central Sensitization

The recognition of central sensitization (CS) is crucial, as it determines the results of rehabilitation. The aim of this study was to examine associations between CS and catastrophizing, functionality, disability, illness perceptions, kinesiophobia, anxiety, and depression in people with chronic shoulder pain (SP). In this cross-sectional study, 64 patients with unilateral chronic SP completed a few questionnaires including the Central Sensitization Inventory, the Oxford Shoulder Score, the Tampa Scale for Kinesiophobia, the Hospital Anxiety and Depression Scale, the Pain Catastrophizing Scale, the Brief Illness Perception Questionnaire and the “arm endurance” test. On the basis of three constructed linear regression models, it was found that pain catastrophizing and depression (model 1: p < 0.001, R = 0.57, R2 = 0.33), functionality (model 2: p < 0.001, R = 0.50, R2 = 0.25), and helplessness (model 3: p < 0.001, R = 0.53, R2 = 0.28) were significant predictors for CS symptoms in chronic SP. Two additional logistic regression models also showed that depression (model 4: p < 0.001, Nagelkerke R2 = 0.43, overall correct prediction 87.5%) and functionality (model 5: p < 0.001, Nagelkerke R2 = 0.26, overall correct prediction 84.4%) can significantly predict the classification of chronic SP as centrally sensitized. Patients who were classified as centrally sensitized (n = 10) were found to have significantly worse functionality, psychological factors (anxiety, depression, kinesiophobia, catastrophizing), and pain intensity (p < 0.05). Catastrophizing, depression, and functionality are predictive factors of CS symptoms in patients with chronic shoulder pain. Health care providers should adopt a precision medicine approach during assessment and a holistic rehabilitation of patients with unilateral chronic SP.

Psychosocial and psychophysical assessment in pediatric patients and young adults with chronic back pain: a cluster analysis

Background

Identifying subgroups with different clinical profiles may inform tailored management and improve outcomes. The objective of this study was to identify psychosocial and psychophysical profiles of children and adolescents with chronic back pain.

Methods

One hundred and ninety‐eight patients with chronic back pain were recruited for the study. Pain assessment was mainly conducted in the form of an interview and with the use of validated pain‐related questionnaires assessing their psychosocial factors and disability. All patients underwent mechanical and thermal quantitative sensory tests assessing detection and pain thresholds, and conditioned pain modulation efficacy.

Results

Hierarchal clustering partitioned our patients into three clusters accounting for 34.73% of the total variation of the data. The adaptive cluster represented 45.5% of the patients and was characterized to display high thermal and pressure pain thresholds. The high somatic symptoms cluster, representing 19.2% of patients, was characterized to use more sensory, affective, evaluative and temporal descriptors of pain, more likely to report their pain as neuropathic of nature, report a more functional disability, report symptoms of anxiety and depression and report poor sleep quality. The pain‐sensitive cluster, representing 35.4% of the cohort, displayed deep tissue sensitivity and thermal hyperalgesia.

Conclusions

This study identified clinical profiles of children and adolescents experiencing chronic back pain based on specific psychophysical and psychosocial characteristics highlighting that chronic pain treatment should address underlying nociceptive and non‐nociceptive mechanisms.

Significance

To our current knowledge, this study is the first to conduct cluster analysis with youth experiencing chronic back pain and displays clinical profiles based on specific physical and psychosocial characteristics. This study highlights that in a clinical context, chronic pain assessment should include multiple elements contributing to pain which can be assessed in a clinical context and addressed when pathoanatomical symptoms are unidentifiable.

Brain Structural Changes during Juvenile Fibromyalgia: Relationships with Pain, Fatigue and Functional Disability

Objective

Juvenile fibromyalgia (FM) is a prevalent chronic pain condition affecting children and adolescents worldwide during a critical period of brain development. To date, no published studies have addressed the pathophysiology of juvenile FM. This study was undertaken to characterize gray matter volume (GMV) alterations in juvenile FM patients for the first time, and to investigate their functional and clinical relevance.

Methods

Thirty‐four female adolescents with juvenile FM and 38 healthy adolescents underwent a structural magnetic resonance imaging examination and completed questionnaires assessing core juvenile FM symptoms. Using voxel‐based morphometry, we assessed between‐group GMV differences and associations between GMV and functional disability, fatigue, and pain interference in juvenile FM. We also studied whether validated brain patterns predicting pain, cognitive control, or negative emotion were amplified/attenuated in juvenile FM patients and whether structural alterations reported in adult FM were replicated in adolescents with juvenile FM.

Results

Compared to controls, juvenile FM patients showed GMV reductions in the anterior midcingulate cortex (aMCC) region (family‐wise error corrected P [P_FWE‐corr] = 0.04; estimated with threshold‐free cluster enhancement [TFCE]; n = 72) associated with pain. Within the juvenile FM group, patients reporting higher functional disability had larger GMV in inferior frontal regions (P_FWE‐corr = 0.006; TFCE estimated; n = 34) linked to affective, self‐referential, and language‐related processes. Last, GMV reductions in juvenile FM showed partial overlap with findings in adult FM, specifically for the anterior/posterior cingulate cortices (P = 0.02 and P = 0.03, respectively; n = 72).

Conclusion

Pain‐related aMCC reductions may be a structural hallmark of juvenile FM, whereas alterations in regions involved in emotional, self‐referential, and language‐related processes may predict disease impact on patients’ well‐being. The partial overlap between juvenile and adult FM findings strengthens the importance of early symptom identification and intervention to prevent the transition to adult forms of the disease.

The Impact of Parental Presence on their Children during Painful Medical Procedures:A Systematic Review

OBJECTIVE

Whether parental presence during their children's painful medical procedures is advantageous with regard to child's pain-related outcomes is questionable. Research regarding this topic is equivocal and additional questions, such as whether levels of parental involvement may play a role as well, remain to be assessed. The purpose of this systematic review is to summarize and critically appraise the literature regarding the impact of parental presence versus absence during their children's painful medical procedures on the child's pain-related outcomes.

METHODS

The review protocol was registered on Prospero (ID CRD42018116614). A systematic search in PubMed, Web of Science, and PsycArticles resulted in 22 eligible studies incorporating 2157 participants. Studies were considered eligible if they included children (≤ 18 years old) undergoing a painful medical procedure and compared parental presence and/or involvement with parental absence during the procedure.

RESULTS

The children's pain-related outcomes included self-reported pain intensity, self-reported fear, anxiety and distress, observed pain-related behavior, and physiological parameters. Overall, evidence points in the direction of beneficial effects of parental presence versus absence with regard to children's self-reported pain intensity and physiological parameters, whereas mixed findings were recorded for children's self-reported fears, anxiety and distress, and observed pain-related behaviors.

CONCLUSIONS

: In order to provide clear recommendations on how to involve the parent during the procedure, as well as for which type of children and parents parental presence has the best effects, further research is needed, as indicated in this review.

Nociplastic Pain Criteria or Recognition of Central Sensitization? Pain Phenotyping in the Past, Present and Future

Recently, the International Association for the Study of Pain (IASP) released clinical criteria and a grading system for nociplastic pain affecting the musculoskeletal system. These criteria replaced the 2014 clinical criteria for predominant central sensitization (CS) pain and accounted for clinicians' need to identify (early) and correctly classify patients having chronic pain according to the pain phenotype. Still, clinicians and researchers can become confused by the multitude of terms and the variety of clinical criteria available. Therefore, this paper aims at (1) providing an overview of what preceded the IASP criteria for nociplastic pain ('the past'); (2) explaining the new IASP criteria for nociplastic pain in comparison with the 2014 clinical criteria for predominant CS pain ('the present'); and (3) highlighting key areas for future implementation and research work in this area ('the future'). It is explained that the 2021 IASP clinical criteria for nociplastic pain are in line with the 2014 clinical criteria for predominant CS pain but are more robust, comprehensive, better developed and hold more potential. Therefore, the 2021 IASP clinical criteria for nociplastic pain are important steps towards precision pain medicine, yet studies examining the clinimetric and psychometric properties of the criteria are urgently needed.

Somatosensory Testing in Pediatric Patients with Chronic Pain: An Exploration of Clinical Utility

We aimed to evaluate the utility of clinical somatosensory testing (SST), an office adaptation of laboratory quantitative sensory testing, in a biopsychosocial assessment of a pediatric chronic somatic pain sample (N = 98, 65 females, 7–18 years). Stimulus–response tests were applied at pain regions and intra-subject control sites to cutaneous stimuli (simple and dynamic touch, punctate pressure and cool) and deep pressure stimuli (using a handheld pressure algometer, and, in a subset, manually inflated cuff). Validated psychological, pain-related and functional measures were administered. Cutaneous allodynia, usually regional, was elicited by at least one stimulus in 81% of cases, most frequently by punctate pressure. Central sensitization, using a composite measure of deep pressure pain threshold and temporal summation of pain, was implied in the majority (59.2%) and associated with worse sleep impairment and psychological functioning. In regression analyses, depressive symptoms were the only significant predictor of pain intensity. Functional interference was statistically predicted by deep pressure pain threshold and depressive symptoms. Manually inflated cuff algometry had comparable sensitivity to handheld pressure algometry for deep pressure pain threshold but not temporal summation of pain. SST complemented standard biopsychosocial assessment of pediatric chronic pain; use of SST may facilitate the understanding of disordered neurobiology.

Paediatric functional abdominal pain disorders

Paediatric functional abdominal pain disorders, currently referred to as disorders of gut-brain interaction, comprise irritable bowel syndrome, functional dyspepsia, abdominal migraine and functional abdominal pain not otherwise specified, as defined by the Rome IV diagnostic criteria. Functional abdominal pain disorders are common disorders with a prevalence of 3-16% depending on country, age and sex. A greater understanding of aetiopathogenesis and pathophysiology is emerging and includes intestinal components (inflammation, motility and the microbiota), central factors (psychological aspects, sensitization and/or differences in connectivity or activity of certain brain regions) as well as extrinsic factors (infections). In particular, the timing of disruption of the microbiota-gut-brain axis seems to be important. Diagnosis is challenging but is primarily based on clinical symptoms and exclusion of other organic causes, with an emphasis on avoiding unnecessary invasive diagnostic procedures. The available pharmacological interventions are limited in children and, therefore, management has focused on combined approaches, including mind-targeted interventions (hypnotherapy and cognitive behavioural therapy), diet (probiotics) and percutaneous electrical nerve field stimulation. The evidence for their clinical efficacy, although limited, is favourable, with positive impacts on symptoms and overall quality of life. The coming decades hold promise for improved understanding and management of these enigmatic disorders.

Pain sensitivity in young adults with juvenile idiopathic arthritis: a quantitative sensory testing study

BACKGROUND

To study for the first-time, pain perception, pain sensitivity, and self-reported pain in young adults with long disease duration of juvenile idiopathic arthritis (JIA) compared with controls.

METHODS

Children from Central Norway diagnosed with JIA between 1997 and 2004 were included consecutively in a population-based prospective study. Children with onset 1997-2000 were part of the Nordic JIA cohort. Controls were age- and sex-matched. In 2015-2017, study visits with investigator-blinded quantitative sensory testing (QST) comprising cold and warm detection thresholds (CDT/WDT), cold and heat pain thresholds (CPT/HPT), pressure pain threshold (PPT), and a suprathreshold heat pain test were performed. We constructed separate multilevel models for each variable of detection and pain thresholds with interaction between groups and site adjusted for the effect of age and sex.

RESULTS

Among 96 young adults with JIA, 71% were female, median age was 22.7 years, disease duration was 16.1 years, and 47% had oligoarticular disease. Among 109 controls, 71% were female, and median age was 23.5 years. Participants with JIA had lower pressure pain thresholds (PPTs) (95% CI) compared to controls, upper limb 888 (846,930) versus 1029 (999,1059) kPa and lower limb 702 (670,734) versus 760 (726,794) kPa. Participants with inactive disease had the lowest PPTs and cold pain thresholds (CPTs), compared to those in remission off medication and those with active disease. Minor differences were found regarding CDT/WDT and CPT/HPT in JIA compared to controls. The median (IQR) temperature needed to evoke pain = 6 on a 0-10 numeric rating scale (NRS) in the suprathreshold heat pain tests were lower in JIA than in controls (46 °C (45-47 °C) versus 47 °C (46-48 °C)). We found no associations between self-reported pain and pain thresholds.

CONCLUSIONS

Our results indicate for the first time that young adults with long disease duration of JIA may have altered pain perception and sensitivity compared to controls. A clinical implication may be the importance of early treatment to quickly achieve pain-free remission and avoid long-term pain sensitization.

Nutritional intervention in chronic pain: an innovative way of targeting central nervous system sensitization?

INTRODUCTION

Few treatment programs for chronic pain nowadays take a dietary pattern or adipose status into account.

AREAS COVERED

An important role of neuroinflammation in chronic pain is now well established, at least in part due to increased central nervous system glial activation. Based on preclinical studies, it is postulated that the interaction between nutrition and central sensitization is mediated via bidirectional gut-brain interactions. This model of diet-induced neuroinflammation and consequent central sensitization generates a rationale for developing innovative treatments for patients with chronic pain. Methods: An umbrella approach to cover the authors' expert opinion within an evidence-based viewpoint.

EXPERT OPINION

A low-saturated fat and low-added sugar dietary pattern potentially decreases oxidative stress, preventing Toll-like receptor activation and subsequent glial activation. A low-saturated fat and low-added sugar diet might also prevent afferent vagal nerve fibers sensing the pro-inflammatory mediators that come along with a high-(saturated) fat or energy-dense dietary pattern, thereby preventing them to signal peripheral inflammatory status to the brain. In addition, the gut microbiota produces polyamines, which hold the capacity to excite N-methyl-D-aspartate receptors, an essential component of the central nervous system sensitization. Hence, a diet reducing polyamine production by the gut microbiota requires exploration as a therapeutic target for cancer-related and non-cancer chronic pain.