The IASP classification of chronic pain for ICD-11: chronic primary pain

Associations between sickness behavior, but not inflammatory cytokines, and psychiatric comorbidity in chronic pain

OBJECTIVES

Approximately one in five adults experiences chronic pain, often in co-occurrence with depression, insomnia, anxiety, and lower self-rated health. Elevated levels of cytokines, e.g. tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8), and interleukin 10 (IL-10), have been identified in patients with chronic pain. Depression, insufficient sleep, poor self-rated health, and pain intensity have also been associated with inflammatory biomarkers. This study aimed to investigate the interrelationships between inflammatory biomarkers and depression, insomnia, anxiety, self-rated health, sickness behavior, and pain intensity in patients with chronic pain.

METHODS

Self-report questionnaires and blood samples analyzed for plasma levels of inflammatory biomarkers were collected from 80 adult patients with chronic pain. Associations between inflammatory biomarkers (TNF-α, IL-6, IL-8, IL-10, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)) and depression, insomnia, anxiety, self-rated health, sickness behavior, and pain intensity, were analyzed using bivariate Spearman rank correlation coefficients and regression analyses.

RESULTS

Participants were mainly women (72.5 %), with a mean age of 50.8 years, and a reported mean pain duration of 16.7 years. There were significant correlations between insomnia and CRP (rs =.26, p <.05); sex and ESR (rs =.29, p <.05); age and IL-6 (rs =.29, p <.05) and IL-8 (rs =.30, p <.05); BMI and IL-6 (rs =.50, p <.001), CRP (rs =.63, p <.001) and ESR (rs =.42, p <.001). Ratings of depression were positively and significantly related to ratings of sickness behavior and anxiety (β =.32 and β =.40, respectively), explaining 49 % of the total variance in depression ratings. Insomnia was positively and significantly related to sickness behavior (β =.37) explaining 31 % of the total variance in insomnia ratings. Inflammatory biomarkers, however, did not contribute significantly to the models.

CONCLUSIONS

Participants reported high levels of symptoms, yet the associations between these ratings and the inflammatory biomarkers were either absent or weak. Also, despite high levels of self-reported sickness behavior, overall the inflammatory status remained within the normal range. Ratings of sickness behavior contributed more than inflammatory markers in explaining ratings of depression and insomnia. The present results point to the complexity of chronic pain, and the challenges of identifying biomarkers that explain symptomatology.

Downregulation of lysine-specific histone demethylase 1A (KDM1A/LSD1) in medial prefrontal cortex facilitates chronic stress-induced pain and emotional dysfunction in female mice

Chronic primary pain, characterized by overlapping symptoms of chronic pain, anxiety, and depression, is strongly associated with stress and is particularly prevalent among females. Recent research has convincingly linked epigenetic modifications in the medial prefrontal cortex (mPFC) to chronic pain and chronic stress. However, our understanding of the role of histone demethylation in the mPFC in chronic stress-induced pain remains limited. In this study, we investigated the function of lysine-specific histone demethylase 1A (KDM1A/LSD1) in the context of chronic overlapping pain comorbid with anxiety and depression in female mice. We employed a chronic variable stress model to induce pain hypersensitivity in the face and hindpaws, as well as anxiety-like and depression-like behaviors, in female mice. Our findings revealed that chronic stress led to a downregulation of KDM1A mRNA and protein expression in the mPFC. Notably, overexpressing KDM1A in the mPFC alleviated the pain hypersensitivity, anxiety-like behaviors, and depression-like behaviors in female mice, without affecting basal pain responses or inducing emotional distress. Conversely, conditional knockout of KDM1A in the mPFC exacerbated pain sensitivity and emotional distress specifically in females. In summary, this study highlights the crucial role of KDM1A in the mPFC in modulating chronic stress-induced overlapping pain, anxiety, and depression in females. Our findings suggest that KDM1A may serve as a potential therapeutic target for treating chronic stress-related overlap pain and associated negative emotional disorders.

Genetic influence on treatment outcomes in patients with pain-related temporomandibular disorders

BACKGROUND

Single nucleotide polymorphisms (SNPs) may influence pain susceptibility and impact treatment response in pain-related temporomandibular disorders (TMDp).

OBJECTIVE

Explore the role of COMT (rs4646310, rs6269, rs4818, rs4680) and OPRM1 (rs1799971) genotypes in regulating treatment response.

METHODS

Sixty TMDp patients (55 females and 5 males), diagnosed with the Diagnostic Criteria for TMD (DC/TMD), underwent standardised treatment (information and education, home physical therapy, occlusal splint) for 6 months. Treatment outcomes included: pain intensity, pain-free mouth opening, jaw functional limitation, depression, and anxiety. Genotyping for COMT and OPRM1 SNPs was performed using DNA from buccal mucosa swabs and TaqMan assays. Statistical analysis was carried out to compare the changes in treatment outcomes and the influence of genotypes on treatment response.

RESULTS

Significantly less pain reduction was observed in minor allele carriers of rs4646310, and rs4680 compared to dominant homozygous (p < .025). Minor allele carriers of rs1799971 and rs4646310 demonstrated worsening in pain-free mouth opening while dominant homozygous exhibited improvement (p < .025). Significantly less anxiety reduction was observed in minor allele carriers of rs4646310 compared to dominant homozygous (p = .003). Of the all variables assessed in the regression model, carrying a minor allele of rs1799971 predicted a poorer treatment response considering pain-free mouth opening while carrying a minor allele of rs4646310 predicted less pain and less anxiety reduction.

CONCLUSION

Our findings indicate that certain SNP variants of the COMT and OPRM1 genes were associated with poorer treatment response and may therefore play a significant role in the classification of TMDp patients. Also, assessment of patient genotype could potentially aid in predicting treatment response.

A systematic review of the prevalence of chronic postsurgical pain in children

Two prior reviews highlight the scarcity and conflicting nature of available data on chronic postsurgical pain in children, reporting a wide prevalence range of 3.2% to 64% (at ≥3 months). This updated systematic review aimed to consolidate information on the prevalence of pediatric chronic postsurgical pain. A thorough literature search of full English-text publications from April 2014 to August 2021 was conducted using Ovid MEDLINE, PubMed, and Cochrane Database of Systematic Reviews, with search terms: postoperative pain, child, preschool, pediatrics, adolescent, chronic pain. Seventeen relevant studies were identified. Most assessed chronicity once greater than 3 months duration postoperatively (82%), were predominantly prospective (71%) and conducted in inpatient settings (88%). The surgeries examined included orthopedic (scoliosis and limb), urological, laparotomy, inguinal, and cardiothoracic procedures, involving numbers ranging from 36 to 750, totaling 3137 participants/2792 completers. The studies had wide variations in median age at surgery (6 days to 16 years), the percentage of female participants (unspecified or 12.5% to 90%), and follow-up duration (2.5 months to 9 years). Various pain, functional, psychosocial, and health-related quality of life outcomes were documented. Chronic postsurgical pain prevalence varied widely from 2% to 100%. Despite increased data, challenges persist due to heterogeneity in definitions, patient demographics, mixed versus single surgical populations, diverse perioperative analgesic interventions, follow-up durations and reported outcomes. Interpretation is further complicated by limited information on impact, long-term analgesia and healthcare utilization, and relatively small sample sizes, hindering the assessment of reported associations. In some cases, preoperative pain and deformity may not have been addressed by surgery and persisting pain postoperatively may then be inappropriately termed chronic postsurgical pain. Larger-scale, procedure-specific data to better assess current prevalence, impact, and whether modifiable factors link to negative long-term outcomes, would be more useful and allow targeted perioperative interventions for at-risk pediatric surgical patients.

Pains Revisited

OBJECTIVES

The management of pain patients has not evolved as rapidly as envisioned when IASP was founded almost 50 years ago. We sought to identify factors that could contribute to this situation, with a focus on concepts of pain and the education of pain physicians.

METHODS

Relevant literature describing new strategies for diagnosing and managing patients with high-impact chronic pain was reviewed.

RESULTS

It appears that the acute-chronic dichotomy has outlived its usefulness and pains should be identified as of peripheral origin or due to central processing errors. Pains of peripheral origin and those of central processing errors require different diagnostic and therapeutic strategies.

DISCUSSION

Peripheral treatments and opioids are not effective for central pains. When the cause of the pain lies in the central nervous system, a more centrally focused approach is needed to minimize wasteful pursuit of peripheral causes. The education and training of pain physicians should reflect the skills needed to address these 2 very different clinical problems.

Living well with chronic pain: a 12-month randomized controlled trial revealing impact from the digital pain self-management program EPIO

Introduction

Chronic pain affects a wide range of physical and psychological aspects of life for those impacted. Psychosocial treatment approaches may be of support, but outreach is still limited.

Objectives

To evaluate the efficacy of EPIO, an evidence-informed, user-centered digital self-management intervention for people with chronic pain, in a 12-month randomized controlled trial.

Methods

People living with chronic pain (N = 266) were randomized to the EPIO intervention (n = 132) or a usual-care control group (n = 134). The intervention was delivered in a simple blended care model, and outcome measures collected at baseline, 6 months, and 12 months. Generalized linear models for repeated measures were fitted to compare groups over time.

Results

Participants were primarily female (81%), median age 49 years (range 22-78), with heterogeneous pain conditions, and had lived with pain >5 years (77.6%). A mixed linear model with all timepoints included revealed no statistically significant group differences for the primary outcome of pain interference. Significant psychological benefits in favor of the intervention group were however detected for depression (P = 0.022), self-regulatory fatigue (P = 0.024), vitality (P = 0.016), and mental health (P = 0.047). Baseline to 12-month changes showed additional favorable effects for anxiety (between-group mean differences [MDs] = 0.79, P = 0.047), depression (MD = 1.08, P = 0.004), self-regulatory fatigue (MD = 2.42, P = 0.021), pain catastrophizing (MD = 2.62, P = 0.009), and health-related quality of life.

Conclusions

The EPIO program aims to improve outreach of evidence-based pain self-management interventions. Findings demonstrate how using EPIO can lead to sustainable psychological change, enhancing mental health and health-related quality of life for people suffering from pain, providing a chance to live well with the pain.

The Effectiveness of Auricular Acupressure on Chronic Musculoskeletal Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: To assess the effectiveness of auricular acupressure (AA) in managing pain and disability in individuals with chronic musculoskeletal pain. Materials and Methods: A systematic search on six electronic databases was performed from their inception to May 7, 2023, to identified relevant randomized controlled trials (RCTs). Two independent reviewers screened the abstracts and full texts, extracted data, and assessed risk of bias using RoB 2. The primary outcomes were pain intensity and disability. The secondary outcomes were pain pressure thresholds, pain catastrophizing level, and fear avoidance beliefs. A random-effects model was used for meta-analyses. The certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation. Sensitivity analyses were conducted after removing low-quality papers. Results: Of 633 identified records, six studies involving 496 participants were included. All included studies compared the effectiveness of AA with sham controls in treating various chronic musculoskeletal pain. Four meta-analyses were conducted to compare the effectiveness of AA with sham controls. Low-quality evidence supported that AA had a large effect size on postintervention subjective pain reduction (standardized mean difference [SMD] = -0.95; 95% confidence interval [CI]: -1.36 to -0.54; p = 0.00; I2 = 52.61%); moderate-quality evidence substantiated that AA had a large effect size on enhancing postintervention pressure pain threshold (SMD = -0.55; 95% CI: -0.88 to -0.23; p = 0.00; I2 = 0%). There was low-quality evidence that AA had a large effect on reducing postintervention disability (SMD = -0.68; 95% CI: -1.24 to -0.12; p = 0.02; I2 = 51.33%). Our sensitivity analysis reaffirmed the same conclusion regarding pain reduction immediately after the intervention. Fourteen participants reported minimal adverse events, including soreness, tenderness, irritation, and redness, which disappeared within 1-7 days. Discussion: Our systematic review revealed that AA significantly improved pain, pressure pain thresholds, and disability in individuals with various chronic musculoskeletal pain conditions immediately post-treatment compared with sham treatment. Given the paucity of studies and inconsistent protocols, future RCTs are warranted to evaluate the effectiveness of AA in people with chronic musculoskeletal pain at a longer follow-up with detailed protocols, which allows researchers and clinicians to optimize AA intervention. Conclusion: AA has immediate post-treatment benefits for chronic musculoskeletal pain, whereas its effects at the 1- or 6-month follow-up remain uncertain.

Beyond the chronic pain stage: default mode network perturbation depends on years lived with back pain

ABSTRACT

Research has indicated that the default mode network (DMN) is perturbated in patients with chronic pain when compared with healthy controls, and this perturbation is correlated with the duration of pain during the chronic pain stage. It remains unclear whether DMN adaptations manifest during the subacute pain stage and progress over time because of the duration of pain experience, rather than being a specific correlate of the chronic pain stage. Furthermore, information regarding whether these adaptations are related to cognitive processes of adaptation is lacking. To this end, we examined the DMN in 31 patients with chronic back pain (CBP), 77 patients with subacute back pain (SBP), as well as 39 healthy pain-free controls (HC) applying a graph-theoretic network approach on functional resting-state magnetic resonance imaging. Beyond the comparison between groups, we used a linear analysis considering the years lived with pain (YLP) across all patients with back pain and additionally performed a mediation analysis of the role of cognitive pain coping. In line with previous studies, we found significant DMN perturbation in CBP compared with HC. However, this did not apply to the comparison of CBP with SBP. Instead, we observed a positive correlation between DMN perturbation and YLP. This was significantly mediated by coping attitudes towards pain. Default mode network perturbation may thus reflect neural adaptation processes to pain experience rather than a single correlate of the chronic pain stage and be modulated by cognitive adaption. This points to potentially underinvestigated significant adaptation processes that could enable more fine-grained patient stratification.

Pain, Return to Community Status, and 90-Day Mortality Among Hospitalized Patients With Heart Failure

BACKGROUND

Pain is common among patients with heart failure but has not been examined with short-term discharge outcomes. The purpose was to examine whether pain at discharge predicts return to community status and 90-day mortality among hospitalized patients with heart failure.

METHODS

Data from medical records of 2169 patients hospitalized with heart failure were analyzed in this retrospective cohort study. The independent variable was a diagnosis of pain at discharge. Outcomes were return to community status (yes/no) and 90-day mortality. Logistic regression was used to address aims. Covariates included age, gender, race, vital signs, comorbid symptoms, comorbid conditions, cardiac devices, and length of stay.

RESULTS

The sample had a mean age of 66.53 years, and was 57.4% women and 55.9% Black. Of 2169 patients, 1601 (73.8%) returned to community, and 117 (5.4%) died at or before 90 days. Patients with pain returned to community less frequently (69.6%) compared with patients without pain (75.2%), which was a statistically significant relationship (odds ratio, 0.74; 95% confidence interval, 0.57-0.97; P = .028). Other variables that predicted return to community status included age, comorbid conditions, dyspnea, fatigue, systolic blood pressure, and length of stay. Pain did not predict increased 90-day mortality. Variables that predicted mortality included age, liver disease, and systolic blood pressure.

CONCLUSION

Patients with pain were less likely to return to community but did not have higher 90-day mortality. Pain in combination with other symptoms and comorbid conditions may play a role in mortality if acute pain versus chronic pain can be stratified in a future study.

Chronic stress induces wide-spread hyperalgesia: The involvement of spinal CCK1 receptors

Chronic primary pain (CPP) occurs in the absence of tissue injury and includes temporomandibular disorders (TMD), fibromyalgia syndrome (FMS) and irritable bowel syndrome (IBS). CPP is commonly considered a stress-related chronic pain and often presents as wide-spread pain or comorbid pain conditions in different regions of the body. However, whether prolonged stress can directly result in the development of CPP comorbidity remains unclear. In the present study, we adapted a 21 day heterotypic stress paradigm in mice and examined whether chronic stress induced wide-spread hyperalgesia, modeling comorbid CPP in the clinic. We found that chronic stress induced anxiety- and depression-like behaviors, and resulted in long-lasting wide-spread hyperalgesia over several body regions such as the orofacial area, hindpaw, thigh, upper back and abdomen in female mice. We further found that the expression of cholecystokinin (CCK)1 receptors was significantly increased in the L4-L5 spinal dorsal horn of the female mice after 14 and 21 day heterotypic stress compared with the control animals. Intrathecal injection of the CCK1 receptor antagonist CR-1505 blocked pain hypersensitivity in the subcervical body including the upper back, thigh, hindpaw and abdomen. These findings suggest that the upregulation of spinal CCK1 receptors after chronic stress contributes to the central mechanisms underlying the development of wide-spread hyperalgesia, and may provide a potential and novel central target for clinical treatment of CPP.

Spinal neuronal activity and neuroinflammatory component in a mouse model of CFA-induced vestibulodynia

Vestibulodynia is a complex pain disorder characterized by chronic discomfort in the vulvar region, often accompanied by tactile allodynia and spontaneous pain. In patients a depressive behaviour is also observed. In this study, we have used a model of vestibulodynia induced by complete Freund's adjuvant (CFA) focusing our investigation on the spinal cord neurons and microglia. We investigated tactile allodynia, spontaneous pain, and depressive-like behavior as key behavioral markers of vestibulodynia. In addition, we conducted in vivo electrophysiological recordings to provide, for the first time to our knowledge, the characterization of the spinal sacral neuronal activity in the L6-S1 dorsal horn of the spinal cord. Furthermore, we examined microglia activation in the L6-S1 dorsal horn using immunofluorescence, unveiling hypertrophic phenotypes indicative of neuroinflammation in the spinal cord. This represents a novel insight into the role of microglia in vestibulodynia pathology. To address the therapeutic aspect, we employed pharmacological interventions using GABApentin, amitriptyline, and PeaPol. Remarkably, all three drugs, also used in clinic, showed efficacy in alleviating tactile allodynia and depressive-like behavior. Concurrently, we also observed a normalization of the altered neuronal firing and a reduction of microglia hypertrophic phenotypes. In conclusion, our study provides a comprehensive understanding of the CFA-induced model of vestibulodynia, encompassing behavioral, neurophysiological and neuroinflammatory aspects. These data pave the way to investigate spinal cord first pain plasticity in vestibulodynia.

Does One Measure Fit All? The Role of Experimentally Induced Pain Tests in the Assessment of Women with Provoked Vestibular Pain

Purpose

A diagnostic algorithm was recently suggested to address the underlying mechanisms of provoked-vestibulodynia (PVD). It delineates four subgroups (Hormonal-associated, Augmented-anterior, Hymenal-associated and Hypertonicity-associated), each manifesting a distinctive vulvar pain-hypersensitivity regarding location (circumferential vs posterior-only vestibulodynia) and pain characteristics. We aimed to explore the significance of various experimentally induced vulvar pain measures in the manifestation of pain hypersensitivity in each subgroup.

Methods

Women with PVD (n = 113) and 43 controls reported pain intensity provoked during vaginal penetration and tampon insertion. Vestibular tenderness (anterior and posterior) was assessed by Q-tip test, and pressure stimulation delivered to the puborectalis assessed muscle tenderness. Pain thresholds were measured using a vulvar-algesiometer. These measures were compared between patients and controls and among the PVD subgroups. Correlations between the clinical and experimentally induced-pain measures were assessed. Finally, to address whether the association between experimentally induced-pain measures and dyspareunia severity is mediated by hypertonicity, the conditional indirect effect was analyzed in each subgroup.

Results

Compared to controls, augmented vulvar pain-hypersensitivity and hypertonicity were observed among patients (p < 0.001). ANOVA revealed no subgroup differences in dyspareunia severity. Nevertheless, some experimentally induced-pain measures were differently correlated with dyspareunia intensity in each subgroup, allowing discrimination of subgroups according to the unique findings of vulvar pain-hypersensitivity. The degree of pelvic floor muscle-hypertonicity mediated the association between vulvar pain-hypersensitivity and dyspareunia severity, emphasizing the key role of hypertonicity in distinguishing between subgroups.

Conclusion

The findings offer more evidence of variations among PVD subtypes, demonstrating that insertional dyspareunia may originate from dissimilar alterations in the mucosal and muscular tissues. The results also emphasize the significance of utilizing a wide battery of tests to capture different experimentally induced-pain measures, revealing the unique patterns of vulvar pain-hypersensitivity in each subgroup.

Age and Sex Differences in Pediatric Neuropathic Pain and Complex Regional Pain Syndrome: A Scoping Review

BACKGROUND

Age and sex differences may exist in the frequency (incidence, prevalence) or symptoms of neuropathic pain (NP) and complex regional pain syndrome (CRPS) due to biopsychosocial factors (eg, neurodevelopment, physiological and hormonal changes, psychosocial differences) that evolve through childhood and adolescence. Age and sex differences may have implications for evaluating screening and diagnostic tools and treatment interventions.

OBJECTIVE

To map the existing literature on pediatric NP and CRPS with respect to age and sex distributions, and age and sex differences in symptomology and frequency.

METHODS

A scoping literature review was conducted. Databases were searched from inception to January 2023. Data were collected on study design, setting, demographics, and age and sex differences in frequency and symptoms.

RESULTS

Eighty-seven studies were included. Distribution of participants with CRPS (n=37 studies) was predominantly early adolescence (10 to 14 y) and female sex, while NP (n=42 studies) was most commonly reported throughout adolescence (10 to 19 y) in both sexes. Forty-one studies examined age and sex differences in frequency; 6 studies reported higher frequency in adolescence. Very few studies (n=11) examined differences in symptomology.

DISCUSSION

Large epidemiological studies are required to further understand age and sex differences in frequency of pediatric NP and CRPS. Age and sex differences must be considered when evaluating screening and diagnostic tools and treatment interventions to ensure relevance and validity to both sexes and across ages. Validated tools will improve understanding of age-dependent and sex-dependent differences in symptoms, pathophysiology, and psychosocial impact of pediatric NP and CRPS.

The effectiveness of peer support interventions for community-dwelling adults with chronic musculoskeletal pain: a systematic review and meta-analysis of randomised trials

ABSTRACT

This systematic review and meta-analysis critically examined the evidence for peer support interventions to reduce pain and improve health outcomes in community-dwelling adults with chronic musculoskeletal pain (PROSPERO CRD42022356850). A systematic search (inception-January 2023) of electronic databases and grey literature was undertaken to identify relevant randomised controlled trials, with risk of bias and GRADE assessments performed on included studies. Meta-analyses used a generic, inverse-variance, random-effects model, calculating mean difference (MD) or standardised mean difference (SMD). Of 16,445 records identified, 29 records reporting on 24 studies (n = 6202 participants) were included. All evidence had unclear/high risk of bias and low-very low certainty. Peer support interventions resulted in small improvements in pain (medium-term: MD -3.48, 95% CI -6.61, -0.35; long-term: MD -1.97, 95% CI -3.53, -0.42), self-efficacy (medium-term: SMD 0.26, 95% CI 0.16, 0.36; long-term: SMD 0.21, 95% CI 0.07, 0.36), and function (long-term: SMD -0.10, 95% CI -0.19, -0.00) relative to usual care and greater self-efficacy (medium-term: SMD 0.36, 95% CI 0.20, 0.51) relative to waitlist control. Peer support interventions resulted in similar improvement as active (health professional led) interventions bar long-term self-efficacy (MD -0.41, 95% CI -0.77, -0.05), which favoured active interventions. No point estimates reached minimal clinically important difference thresholds. Pooled health service utilisation outcomes showed unclear estimates. Self-management, quality of life, and social support outcomes had mixed evidence. Despite low-very low evidence certainty, peer support interventions demonstrated small improvements over usual care and waitlist controls for some clinical outcomes, suggesting that peer support may be useful as an adjunct to other treatments for musculoskeletal pain.

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

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

Acceptance and commitment therapy for patients with chronic pain: A systematic review and meta-analysis on psychological outcomes and quality of life

OBJECTIVES

To assess the efficacy of acceptance and commitment therapy (ACT) for patients with chronic pain.

MATERIALS AND METHODS

The research conducted a systematic search of the Cochrane Library, Web of Science, PubMed, EMBASE, PsycINFO, and Cumulative Index of Nursing and Allied Health Literature (CINAHL) databases following the PRISMA guidelines. The retrieval time limit was from the establishment of the database to October 2023. A meta-analysis was carried out for the randomized controlled trials (RCTs) that meet the inclusion and exclusion criteria by using RevMan 5.3.

RESULTS

Twenty-one RCTs were included. At post-treatment, a significant medium effect size (ES) was found in measuring pain interference, functional impairment, pain acceptance, psychological inflexibility, and depression; Pain intensity, anxiety, and quality of life (QOL) had a small ES. At three months post-treatment, a large ES was found in measuring functional impairment, and a medium ES was found in the other indicators.

CONCLUSION

The researchers provided evidence for the effectiveness of ACT as an intervention for patients with chronic pain, which can be applied by clinicians or nurses in practice. Future research should explore the applicability of ACT to different pain conditions and modalities.

IMPLICATIONS FOR NURSING

Post-treatment data highlight the efficacy of ACT in moderating pain-related outcomes. Clinical nurses are encouraged to incorporate ACT into routine patient education and interventions, including promoting pain acceptance, promoting mindfulness practices, and using cognitive stress reduction techniques. Standardized follow-up after an ACT intervention for patients with chronic pain is critical, including regular assessment, feedback, and realignment of treatment strategies. Overall, ACT became an important tool for nurses to improve the lives of patients with chronic pain.

Establishing central sensitization inventory cut-off values in Dutch-speaking patients with chronic low back pain by unsupervised machine learning

BACKGROUND

Human Assumed Central Sensitization (HACS) is involved in the development and maintenance of chronic low back pain (CLBP). The Central Sensitization Inventory (CSI) was developed to evaluate the presence of HACS, with a cut-off value of 40/100. However, various factors including pain conditions (e.g., CLBP), contexts, and gender may influence this cut-off value. Unsupervised clustering approaches can address these complexities by considering diverse factors and exploring possible HACS-related subgroups. Therefore, this study aimed to determine the cut-off values for a Dutch-speaking population with CLBP based on unsupervised machine learning.

METHODS

Questionnaire data covering pain, physical, and psychological aspects were collected from patients with CLBP and aged-matched healthy controls (HC). Four clustering approaches were applied to identify HACS-related subgroups based on the questionnaire data and gender. The clustering performance was assessed using internal and external indicators. Subsequently, receiver operating characteristic (ROC) analysis was conducted on the best clustering results to determine the optimal cut-off values.

RESULTS

The study included 63 HCs and 88 patients with CLBP. Hierarchical clustering yielded the best results, identifying three clusters: healthy group, CLBP with low HACS level, and CLBP with high HACS level groups. The cut-off value for the overall groups were 35 (sensitivity 0.76, specificity 0.76).

CONCLUSION

This study found distinct patient subgroups. An overall CSI cut-off value of 35 was suggested. This study may provide new insights into identifying HACS-related patterns and contributes to establishing accurate cut-off values.

Prevalence of functional disorders across Europe: a systematic review and meta-analysis

Functional Disorders (FD) refer to persistent somatic symptoms caused by changes in the functioning of bodily processes. Previous findings suggest that FD are highly prevalent, but overall prevalence rates for FD in European countries are scarce. Therefore, the aim of the present work was to estimate the point prevalence of FD in adult general populations. PubMed and Web of Science were searched from inception to June 2022. A generalized linear mixed-effects model for statistical aggregation was used for statistical analyses. A standardized quality assessment was performed, and PRISMA guidelines were followed. A total of 136 studies were included and systematically synthesized resulting in 8 FD diagnoses. The large majority of studies was conducted in the Northern Europe, Spain, and Italy. The overall point prevalence for FD was 8.78% (95% CI from 7.61 to 10.10%) across Europe, with the highest overall point prevalence in Norway (17.68%, 95% CI from 9.56 to 30.38%) and the lowest in Denmark (3.68%, 95% CI from 2.08 to 6.43%). Overall point prevalence rates for specific FD diagnoses resulted in 20.27% (95% CI from 16.51 to 24.63%) for chronic pain, 9.08% (95% CI from 7.31 to 11.22%) for irritable bowel syndrome, and 8.45% (95% CI from 5.40 to 12.97%) for chronic widespread pain. FD are highly prevalent across Europe, which is in line with data worldwide. Rates implicate the need to set priorities to ensure adequate diagnosis and care paths to FD patients by care givers and policy makers.

Chronic pain in pediatric patients: epidemiology, pathophysiology, and mitigation strategies

PURPOSE OF REVIEW

To provide an updated summary on the epidemiology, pathophysiology, and treatment strategies of chronic pain in pediatric patients and its differences with chronic pain in adults.

RECENT FINDINGS

Chronic pain in children is common, can be debilitating and can progress into adulthood, thus it requires an interdisciplinary evaluation and management. Targeting interdisciplinary care, including psychology, physical, and/or occupational therapy, has been shown to improve pain and function. Recent decline in mental health post pandemic has correlated with increase in pediatric chronic pain thus the need to identify patients at risk and offer early interdisciplinary treatment.

SUMMARY

Chronic pediatric pain should be addressed under the biopsychosocial model, where the biological, psychological, and social factors are evaluated on how they influence the pain perception, pain experience, functional ability, and treatment focus. Pain education to patients and their families is the crucial initial step towards a functional rehabilitation of pain.

Perceived Injustice and Anger in Fibromyalgia With and Without Comorbid Mental Health Conditions: A Hebrew Validation of the Injustice Experience Questionnaire

OBJECTIVES

Perceived injustice (PI), assessed by the Injustice Experience Questionnaire (IEQ), is an important trigger of anger. Both PI and anger are associated with adverse chronic pain outcomes, and with comorbid mental health severity. We aimed examined the roles of PI and anger in mediating pain across Fibromyalgia patients, with and without comorbid anxiety/depression (FM+A/D, FM-A/D, respectively), as well as rheumatoid arthritis (RA), and pain-free controls (PFC). We hypothesized the highest levels of PI, anger, and pain in FM+A/D patients, followed by FM-A/D, RA, and PFC, thus also validating a Hebrew version of the IEQ.

METHODS

We translated the IEQ using the forward-backward method and collected data online. Based on self-reported anxiety/depression, the sample comprised 66 FM+A/D patients, 64 FM-A/D, 34 RA, and 32 PFCs. Assessments included the IEQ, state and trait anger, pain intensity, anxiety, depression, and pain catastrophizing. The structure and reliability of the Hebrew IEQ were examined using factor analysis and Cronbach alpha. Bootstrapped-based modeling was used to test the roles of state and trait anger in mediating and moderating the relationship between PI and pain intensity.

RESULTS

We confirmed a one-factor structure of the IEQ, with excellent reliability. FM+A/D patients demonstrated the highest scores in all measures. Within this group, trait anger moderated the mediating effect of state anger in the relationship between PI and pain intensity.

DISCUSSION

Our findings validate a Hebrew IEQ and highlight the importance of PI and state and trait anger in the differential manifestation of mental health comorbidity in FM.

Pain characterization in patients with Parkinson's disease

BACKGROUND

Patients with Parkinson's disease (PD) often report chronic pain, which is one of the most complex non-motor symptoms. Therefore, this study aims to review the literature on the characteristics of pain in patients with PD.

METHODS

A systematic literature review was conducted following MOOSE recommendations. Observational studies reporting pain in patients with PD were included. No time restrictions were applied, but studies in Portuguese, Spanish, and English were considered. The search was performed in PubMed®, LILACS, and SciELO databases.

RESULTS

Twenty-six articles of observational studies were identified, reporting an average pain prevalence of 67.36%, emphasizing the significance of this symptom in the PD population. Pain was reported in various body regions, including lower limbs, upper limbs, lumbar spine, cervical spine, and other joints. Pain classification varied, encompassing musculoskeletal pain, PD-related pain, neuropathic pain, and dystonic pain, among others.

DISCUSSION

Pain in patients with PD is a prevalent and multifactorial condition, significantly impacting patients' quality of life.

CONCLUSION

Heterogeneity in data across included studies was observed, highlighting the need for additional research to elucidate the underlying mechanisms of pain in patients with PD and develop effective therapeutic strategies to address this symptom and improve the quality of life for individuals living with the disease.

Evaluating the feasibility of delivering a pain management programme for adults living with sickle cell disease

Background

Pain is the prominent feature of sickle cell disease (SCD) and negatively affects quality of life. Delivery of pain management programmes (PMPs) has been suggested in clinical guidelines for pain management in SCD; however, further evidence of the feasibility and effectiveness of PMPs in this population is needed. This study explored the feasibility of delivering a sickle cell pain management programme (SCPMP) for adults within a haemoglobinopathies service.

Methods

A single arm, repeated-measures observational design was used to determine feasibility of delivering the SCPMP at one study site. Primary feasibility outcomes were recruitment, completion of treatment and outcome measures, satisfaction, credibility and acceptability to participants. Secondary feasibility outcomes were treatment outcomes and processes, frequency of vaso-occlusive crisis (VOC) and healthcare utilisation.

Results

Four of five feasibility criteria were met. Annual recruitment of eight participants to a SCPMP was not achieved. Twenty-nine people began a SCPMP during the study period. Twenty-five (86.2%) participants attended ≥5/8 sessions and 21(84%) programme completers provided all end of programme questionnaires. Mean scores of >7 on ten-point scales were seen across satisfaction and credibility questions. At least moderate (Hedges g >0.5) effect sizes were seen in pre-post SCPMP measures of pain interference, anxiety, depression, self-efficacy, pain-related worry and acceptance. A small (Hedges g 0.4) effect size was seen in HRQoL. Following SCPMP attendance, mean frequency of self-reported VOC and hospital admissions reduced.

Conclusions

This study suggests that, given an adequate source of referrals, a SCPMP is feasible to deliver and appears acceptable and credible to participants. Exploration of influences on recruitment, such as barriers to group interventions, would be illuminating, prior to investigating feasibility of an adequately powered randomised-controlled trial.

Effectiveness of motor imagery in complex regional pain syndrome: A systematic review with meta-analysis

OBJECTIVE

The purpose of this study was to determine the effects of motor imagery (MI) on pain intensity and disability in individuals with complex regional pain syndrome (CRPS).

METHODS

A systematic search was conducted in various electronic databases to identify all relevant studies: PubMed, CINAHL, WOS, PEDro, CENTRAL, and Scopus. Randomized controlled trials assessing the effects of MI in individuals with CRPS were included. The risk of bias was assessed with the Cochrane Risk of Bias tool, the methodological quality was evaluated using PEDro scale, and the level of evidence was reported according to the GRADE. Between-groups standardized mean differences (SMD) were calculated.

RESULTS

Six studies were included. The meta-analysis found moderate-quality evidence that MI improves pain intensity and related disability as immediate (pain: SMD -1.07, 95% CI: -1.53 to -0.60; disability: SMD 1.05, 95% CI: 0.59 to 1.51), short-term (pain: SMD -1.28, 95% CI: -2.14 to -0.42; disability: SMD 1.37; 95% CI: 0.16 to 2.58), and long-term effects (pain: SMD -1.18; 95% CI: -1.89 to -0.46; disability: SMD 1.18; 95% CI: 0.46 to 1.89), as compared with a comparison group. The risk of bias of the trials was relatively low, but the imprecision of the results downgraded the level of evidence.

CONCLUSIONS

Moderate-quality evidence suggests a positive effect of MI for improving pain intensity and disability immediately after and at short-term in individuals with CRPS.

A Critical Examination of Ligamentous Pathogenesis of Bladder Pain/Lower Urinary Tract Symptoms Using the UEDA Criteria

To critically analyse the relationship of bladder pain syndrome (BPS/IC), as defined, to the posterior fornix syndrome, "PFS" predictably co-occurring bladder urgency, frequency, nocturia, chronic pelvic pain, emptying symptoms/retention, caused by uterosacral ligament (USL) laxity and cured by USL repair. The starting and end points of this paper are the questions, "Are there arguments that BPS/IC can, in some cases, be linked to PFS?" And if so, "To what extent?" We used the criteria required by Ueda for proper diagnosis: "understanding symptoms, detecting abnormal findings and verifying them as a cause of the symptoms." Literature, diagnostic and surgical, indicate that chronic pelvic pain "of unknown origin" can be caused by unsupported visceral pelvic plexuses because of weak USLs; these cause fire of afferent impulses, which the brain mistakenly interprets as coming from the end-organ itself (i.e., genitourinary pain, lower urinary tract symptoms). The same lax USLs can also weaken the pelvic muscles which contract to stretch the vagina to support the urothelial stretch receptors from below: these may prematurely fire off afferent impulses to activate micturition at lower bladder volumes, interpreted as urgency. A speculum placed in the vagina can relieve pain and urgency by mechanically supporting the vaginal wall and USLs, thus predicting an eventual cure by USL repair. There is need to evaluate what percentage of women with known BPS/IC also pass the criteria for PFS. Identifying a significant percentage of BPS/IC women with the causative relation between PFS pathogenesis and BPS/ IC may open a new way of diagnosing and treating BPS/IC in some women.

Chronic Postsurgical Pain in Children and Adolescents: A Call for Action

Chronic postsurgical pain (CPSP) affects a significant proportion of children and adolescents after major surgery and is a detriment to both short- and long-term recovery outcomes. While clinical characteristics and psychosocial risk factors for developing CPSP in children and adults are well established in the literature, there has been little progress on the prevention and management of CPSP after pediatric surgery. Limited evidence to support current pharmacologic approaches suggests a fundamentally new paradigm must be considered by clinicians to both conceptualize and address this adverse complication. This narrative review provides a comprehensive evaluation of both the known and emerging mechanisms that support our current understanding of CPSP. Additionally, we discuss the importance of optimizing perioperative analgesic strategies to mitigate CPSP based on individual patient risks. We highlight the importance of postoperative pain trajectories to identify those most at risk for developing CPSP, the early referral to multi-disciplinary pain clinics for comprehensive evaluation and treatment of CPSP, and additional work needed to differentiate CPSP characteristics from other chronic pain syndromes in children. Finally, we recognize ongoing challenges associated with the universal implementation of available knowledge about pediatric CPSP into practically useful care plans for clinicians.

The challenge of pharmacotherapy for musculoskeletal pain: an overview of unmet needs

Musculoskeletal disorders are characterized by several impairments, including pain, affecting muscles, bones, joints and adjacent connective tissue, resulting in temporary or permanent functional limitations and disability. Musculoskeletal pain is particularly prevalent worldwide and greatly impacts the quality of life, social participation and economic burden. To date, several issues persist about the classification of musculoskeletal pain and its management strategies and resources. The treatment of musculoskeletal pain conditions is complex and often requires a multimodal approach, including pharmacological and non-pharmacological therapy that might be ineffective in many cases, resulting in poor patient satisfaction and controversial expectations about the potential benefits of available interventions. This manuscript provides an overview of unmet needs in managing musculoskeletal pain, particularly focusing on pharmacotherapeutic pitfalls in this context.

The usage of a modified straight-leg raise neurodynamic test and hamstring flexibility for diagnosis of non-specific low back pain: A cross-sectional study

OBJECTIVES

The main purpose of this research study was to compare mean modified straight-leg raise test (mSLR) and hamstring muscle length (HL) between chronic non-specific low back pain (LBP) and healthy subjects to understand the possibility of neuropathic causes in LBP population as it may impact the diagnosis and treatment of LBP. Another purpose was to compare mean mSLR between those with lumbar nerve root impingement and those without as determine by magnetic resonance imaging (MRI).

METHODS

The design of the study is cross sectional and included 32 subjects with ages ranging from 18-50 years old. Clinical exam objective measures were collected such as patient questionnaires, somatosensory tests, HL range of motion, and a mSLR test, and were compared to the findings from a structural lumbar spine MRI.

RESULTS

There were no significant differences in mean HL angulation and mSLR angulation between LBP and healthy subjects (p>0.05). There was no significant difference in mean HL by impingement by versus no impingement (38.3±15.6 versus 44.8±9.4, p = 0.08, Cohen's d = 0.50). On the other hand, there was a significant difference in mean mSLR angulation by impingement (57.6.3±8.7 versus 63.8±11.6, p = 0.05, Cohen's d = 0.60).

CONCLUSIONS

The mSLR test was found to be associated with lumbar nerve root compression, regardless of the existence of radiating leg symptoms, and showed no association solely with the report of LBP. The findings highlight the diagnostic dilemma facing clinicians in patients with chronic nonspecific LBP with uncorrelated neuroanatomical image findings. Clinically, it may be necessary to reevaluate the common practice of exclusively using the mSLR test for patients with leg symptoms. This study may impact the way chronic LBP and neuropathic symptoms are diagnosed, potentially improving treatment methods, reducing persistent symptoms, and ultimately improving disabling effects.

Factors associated with depression in patients undergoing rehabilitation for chronic pain: a cross-sectional analytical study at a referral hospital in Peru

Despite the well-known impact of depression on patients with chronic pain and its association, few studies have evaluated its related factors in Physical Medicine and Rehabilitation settings. The objective of the present study was to assess the factors associated with depression in adult patients undergoing rehabilitation for chronic pain at Hospital Rebagliati (HNERM) in Peru. A cross-sectional analytical study was conducted between June and August 2023, involving 212 adult patients with chronic pain undergoing rehabilitation at HNERM. Data were collected through a survey, including sociodemographic information, pain characteristics, and depression assessment using the Patient Health Questionnaire-9 (PHQ-9). Statistical analysis included descriptive statistics and generalized linear models to identify factors associated with depression. Among 212 participants, 17.9% had a depression diagnosis based on the PHQ-9 (cutoff score: 10 points). Factors associated with a higher frequency of depression included a time since pain diagnosis of 3-6 months [adjusted prevalence ratios (aPR): 1.15, 95% confidence interval (CI): 1.04-1.27], severe pain (aPR: 1.17, 95% CI: 1.04-1.32), comorbidities (for 1: aPR: 1.21, 95% CI: 1.08-1.35; for 2: aPR: 1.17, 95% CI: 1.06-1.29; for ≥3: aPR: 1.27, 95% CI: 1.10-1.47), use of ≥2 medications for pain management (aPR: 1.27, 95% CI: 1.13-1.42), and receipt of psychological therapy (aPR: 1.26, 95% CI: 1.09-1.46). Nonpharmacological interventions did not show an association with an increased prevalence of depression. These findings underscore the significance of adopting a comprehensive approach to chronic pain management, including the screening, assessment, and treatment of associated depression.

A Narrative Review of the Reciprocal Relationship Between Sleep Deprivation and Chronic Pain: The Role of Oxidative Stress

Sleep is crucial for human health, insufficient sleep or poor sleep quality may negatively affect sleep function and lead to a state of sleep deprivation. Sleep deprivation can result in various health problems, including chronic pain. The intricate relationship between sleep and pain is complex and intertwined, with daytime pain affecting sleep quality and poor sleep increasing pain intensity. The article first describes the influence of sleep on the onset and development of pain, and then explores the impact of daytime pain intensity on nighttime sleep quality and subsequent pain thresholds. However, the primary emphasis is placed on the pivotal role of oxidative stress in this bidirectional relationship. Although the exact mechanisms underlying sleep and chronic pain are unclear, this review focuses on the role of oxidative stress. Numerous studies on sleep deprivation have demonstrated that it can lead to varying degrees of increased pain sensitivity, while chronic pain leads to sleep deprivation and further exacerbates pain. Further research on the role of oxidative stress in the mechanism of sleep deprivation-induced pain sensitization seems reasonable. This article comprehensively reviews the current research on the interrelationship between sleep deprivation, pain and the crucial role of oxidative stress.

Emotion Processing in Peripheral Neuropathic Pain: An Observational Study

BACKGROUND

In clinical practice, the implementation of tailored treatment is crucial for assessing the patient's emotional processing profile. Here, we investigate all three levels of analysis characterizing emotion processing, i.e., recognition, representation, and regulation, in patients with peripheral neuropathic pain (PNP).

METHODS

Sixty-two patients and forty-eight healthy controls underwent quantitative sensory testing, i.e., psychophysical tests to assess somatosensory functions such as perception of cold (CDT), heat-induced pain (HPT), and vibration (VDT), as well as three standardized tasks to assess emotional processing: (1) the Ekman 60-Faces Test (EK-60F) to assess recognition of basic facial emotions, (2) the Reading the Mind in the Eyes Test (RME) to assess the ability to represent the feelings of another person by observing their eyes, and (3) the 20-item Toronto Alexithymia Scale (TAS-20) to assess emotional dysregulation, i.e., alexithymia.

RESULTS

General Linear Model analysis revealed a significant relationship between left index finger VDT z-scores in PNP patients with alexithymia. The RME correlated with VDT z-scores of the left little finger and overall score for the EK-60F.

CONCLUSIONS

In patients with PNP, emotion processing is impaired, which emphasizes the importance of assessing these abilities appropriately in these patients. In this way, clinicians can tailor treatment to the needs of individual patients.

The prevalence of chronic pain in children and adolescents: a systematic review update and meta-analysis

ABSTRACT

Chronic pain, defined as persistent or recurring pain or pain lasting longer than 3 months, is a common childhood problem. The objective of this study was to conduct an updated systematic review and meta-analysis on the prevalence of chronic pain (ie, overall, headache, abdominal pain, back pain, musculoskeletal pain, multisite/general pain, and other) in children and adolescents. EMBASE, PubMed, CINAHL, and PsycINFO were searched for publications between January 1, 2009, and June 30, 2023. Studies reporting population-based estimates of chronic nondisease related pain prevalence in children or adolescents (age ≤ 19 years) were included. Two independent reviewers screened articles based on a priori protocol. One hundred nineteen studies with a total of 1,043,878 children (52.0% female, mean age 13.4 years [SD 2.4]) were included. Seventy different countries were represented, with the highest number of data points of prevalence estimates coming from Finland and Germany (n = 19 each, 4.3%). The overall prevalence of chronic pain in children and adolescents was 20.8%, with the highest prevalence for headache and musculoskeletal pain (25.7%). Overall, and for all types of pain except for back pain and musculoskeletal pain, there were significant differences in the prevalence between boys and girls, with girls having a higher prevalence of pain. There was high heterogeneity (I 2 99.9%). Overall risk of bias was low to moderate. In summary, approximately 1 in 5 children and adolescents experience chronic pain and prevalence varies by pain type; for most types, there is higher pain prevalence among girls than among boys. Findings echo and expand upon the systematic review conducted in 2011.

Validation of the Danish Version of the Fibromyalgia Impact Questionnaire Revised

Purpose

Increasing recognition of chronic pain diseases, including Fibromyalgia, warrants the need for tools to monitor the impact of the disease as well as the efficacy of interventions. The Revised Fibromyalgia Impact Questionnaire (FIQR) has previously proved to be a valuable tool in both clinical and research settings. The study objective was to translate and validate the FIQR in Danish.

Patients and Methods

A forward/backward translation, following the WHO-guidelines, was used to develop the Danish version of FIQR. The Danish translation of FIQR was answered by 101 patients suffering from fibromyalgia. The patients simultaneously answered the Hospital Anxiety and Depression Scale (HADS) and the 36-Item Short-Form Health Survey (SF-36) for validation.

Results

The Danish FIQR showed excellent internal consistency, and reliability with Interclass Correlation Coefficients above 0.9. The correlations to HADS and SF-36 ranged from fair to very good. All results were found to have a p-value <0.05.

Conclusion

The present version of the Danish FIQR presents a valid and reliable tool for monitoring the impact of fibromyalgia.

A Conceptual Analysis of Opioid Use Disorder in Chronic Noncancer Pain Using Rodger's Evolutionary Approach

OBJECTIVE

This study aims to examine the complex nature of opioid use disorder (OUD) in chronic noncancer pain (CNCP) by exploring its antecedents, attributes, consequences, and interrelated concepts.

DESIGN

A systematic literature review was conducted to gather relevant studies published between 2015 and 2022, utilizing the CINAHL, MEDLINE, PsycINFO, and PubMed databases.

DATA SOURCES

The selected databases provided a comprehensive range of articles related to OUD in CNCP, ensuring a comprehensive topic analysis.

METHODS

Twenty-two articles meeting the inclusion criteria were included in the analysis. These articles were critically reviewed and analyzed to identify key themes and concepts related to OUD in CNCP.

RESULTS

The findings of this study shed light on the multifaceted aspects of OUD in CNCP, including its antecedents, such as goals of physical function improvement, prescription of opioids for CNCP, social influences, and mental health dynamics. The attributes of OUD in CNCP were identified as chronic pain, noncancer pain, opioid use, misuse, and abuse. OUD's consequences in CNCP include impaired functioning, increased health risks, psychological distress, social challenges, and economic burden.

CONCLUSION

Understanding the complexity of OUD in CNCP is crucial for improving patient outcomes. Collaborative efforts among healthcare systems, regulatory bodies, and professional organizations are needed to develop policies promoting safe and effective pain management while mitigating risks associated with opioid use in CNCP.

IMPLICATIONS FOR PRACTICE

Implementing policy recommendations derived from this study enhances care and outcomes for individuals with CNCP. By addressing complex issues of OUD in CNCP and adopting evidence-based practices, healthcare providers can optimize pain management and promote well-being in CNCP patients.

Interstitial cystitis-an imbalance of risk and protective factors?

Interstitial cystitis (IC) presents as a chronic pain condition with variable combinations of symptoms depending on the species and individual patient. It is diagnosed by the presence of lower urinary tract signs and symptoms in combination with a variety of comorbid health problems, a history of life adversities, and the absence of other conditions that could cause the lower urinary tract signs. IC occurs naturally in humans and cats as a dimensional condition, with patients presenting with mild, moderate, and severe symptoms. Most patients appear to recover without specific treatment. A number of rodent models of IC have been used to study its causes and treatments. Unfortunately, current therapies generally fail to ameliorate IC symptoms long-term. The recent classification of IC as a chronic primary pain disorder calls for a rethinking of current clinical and research approaches to it. Beginning when a patient encounters a clinician, precipitating, perpetuating, and palliating risk factors can be addressed until a cause or reliably effective therapy is identified, and identifying predisposing and preventive factors can inform epidemiological studies and health promotion interventions. Predisposing, precipitating, and perpetuating risk factors, including environmental, psychological, and biological, increase the activity of the central threat response system (CTRS), which plays a clinically important role in IC symptoms. Studies in cats and rodent models have revealed that environmental enrichment (EE), in the absence of bladder-directed therapies, leads to amelioration of IC symptoms, implying a central role for the CTRS in symptom precipitation and perpetuation. Conceptually moving the source of IC pain to the brain as a motivational state rather than one resulting from peripheral nociceptive input offers both clinicians and researchers novel opportunities to improve care for patients with IC and for researchers to use more ecologically valid rodent models. It may even be that IC results from an excess of risk to protective factors, making this imbalance a targetable cause rather than a consequence of IC.

Chronic Overlapping Pain Conditions and Nociplastic Pain

Chronic Overlapping Pain Conditions (COPCs) are a subset of chronic pain conditions commonly comorbid with one another and more prevalent in women and assigned female at birth (AFAB) individuals. Pain experience in these conditions may better fit with a new mechanistic pain descriptor, nociplastic pain, and nociplastic type pain may represent a shared underlying factor among COPCs. We applied GenomicSEM common-factor genome wide association study (GWAS) and multivariate transcriptome-wide association (TWAS) analyses to existing GWAS output for six COPCs in order to find genetic variation associated with nociplastic type pain, followed by genetic correlation (linkage-disequilibrium score regression), gene-set and tissue enrichment analyses. We found 24 independent single nucleotide polymorphisms (SNPs), and 127 unique genes significantly associated with nociplastic type pain, and showed nociplastic type pain to be a polygenic trait with significant SNP-heritability. We found significant genetic overlap between multisite chronic pain and nociplastic type pain, and to a smaller extent with rheumatoid arthritis and a neuropathic pain phenotype. Tissue enrichment analyses highlighted cardiac and thyroid tissue, and gene set enrichment analyses emphasized potential shared mechanisms in cognitive, personality, and metabolic traits and nociplastic type pain along with distinct pathology in migraine and headache. We use a well-powered network approach to investigate nociplastic type pain using existing COPC GWAS output, and show nociplastic type pain to be a complex, heritable trait, in addition to contributing to understanding of potential mechanisms in development of nociplastic pain.

Psychologically based interventions for adults with chronic neuropathic pain: a scoping review

OBJECTIVE

As psychologically based interventions have been shown to have clinical utility for adults with chronic pain generally, a similar benefit might be expected in the management of chronic neuropathic pain (NeuP). However, to date, this has not been established, with existing systematic reviews on this topic being hampered by the scarcity of randomized controlled trials (RCTs). This review aimed to identify the type of psychologically based interventions studied for adults with chronic NeuP. It also aimed to assess whether there are enough RCTs to justify undertaking an updated systematic review.

METHODS

Seven databases and 2 clinical trial registries were searched for NeuP and psychologically based interventions from database inception to December 2021, and the search was updated in February 2023. The search was broadened by reviewing the reference list of included studies and contacting field experts. Predetermined study characteristics were extracted.

RESULTS

Of 4682 records screened, 33 articles (less than 1%) met the eligibility criteria. Four broad intervention approaches were observed, including cognitive-behavioral approaches (n = 16), mindfulness/meditation (n = 10), trauma-focused therapy (n = 4), and hypnosis (n = 3). Thirteen RCTs were identified, and of these, 9 retained 20 participants in each arm after treatment.

CONCLUSIONS

Cognitive-behavioral therapy was the most common therapeutic approach identified, whereas mindfulness/meditation was the most frequently used technique. Almost half to two-thirds of the studies reported significant improvements in pain, disability, or distress, which suggests that psychologically based interventions are potentially beneficial for adults with chronic NeuP. An updated systematic review seems warranted.

STUDY REGISTRATION

Open Science Framework (https://osf.io) (December 6, 2021; DOI: 10.17605/OSF.IO/WNSTM).

Patients' perspective on the chronic pain classification in the 11th revision of the International Classification of Diseases (ICD-11): results from an international web-based survey

ABSTRACT

The 11th revision of the International Classification of Diseases and Related Health Problems (ICD-11) aims at improving the lives of persons with the lived experience of chronic pain by providing clearly defined and clinically useful diagnoses that can reduce stigma, facilitate communication, and improve access to pain management, among others. The aim of this study was to assess the perspective of people with chronic pain on these diagnoses. An international web-based survey was distributed among persons with the lived experience of chronic pain. After having seen an information video, participants rated the diagnoses on 8 endorsement scales (eg, diagnostic fit, stigma) that ranged from -5 to +5 with 0 representing the neutral point of no expected change. Overall ratings and differences between participants with chronic primary pain (CPP) and chronic secondary pain (CSP) were analyzed. N = 690 participants were included in the data analysis. The ratings on all endorsement scales were significantly higher than the neutral point of 0. The highest ratings were obtained for "openness" (2.95 ± 1.93) and "overall opinion" (1.87 ± 1.98). Participants with CPP and CSP did not differ in their ratings; however, those with CSP indicated an improved diagnostic fit of the new diagnoses, whereas participants with CPP rated the diagnostic fit of the new diagnoses similar to the fit of their current diagnoses. These results show that persons with the lived experience of chronic pain accept and endorse the new diagnoses. This endorsement is an important indicator of the diagnoses' clinical utility and can contribute to implementation and advocacy.

Patients' experiences of treatment-relevant processes in multimodal pain rehabilitation for severe complex regional pain syndrome - a qualitative study

PURPOSE

Complex regional pain syndrome (CRPS) is a longstanding condition with spontaneous and evoked pain, that usually occurs in an upper or lower extremity. Although it often resolves within the first year, it may for a minority progress to a chronic and occasionally severely disabling condition. The aim of this study was to explore patients' experiences and perceived effects of a specific treatment, designed for patients with severe and highly disabling CRPS, in order to identify possible treatment-relevant processes.

METHODS

The method used was a qualitative design, using semi-structured interviews with open-ended questions to capture participants' experiences and perceptions. Ten interviews were analyzed using applied thematic analysis.

RESULTS

Despite the fact that participants had a severe conditions, including nerve damage and a long duration of illness, they reported having been helped to increase flexible persistence, reduce fear and avoidance, and improve connections. This helped participants to significant improvements in daily life functioning.

CONCLUSIONS

The participants described distinct possible treatment-relevant processes leading to a substantial improvement in everyday life. The results imply that there is hope for this group that has been severely disabled for many years. This may help guide future clinical treatment trials.

Medical knowledge graph completion via fusion of entity description and type information

Medical Knowledge Graphs (MKGs) are vital in propelling big data technologies in healthcare and facilitating the realization of medical intelligence. However, large-scale MKGs often exhibit characteristics of data sparsity and missing facts. Following the latest advances, knowledge embedding addresses these problems by performing knowledge graph completion. Most knowledge embedding algorithms rely solely on triplet structural information, overlooking the rich information hidden within entity property sets, leading to bottlenecks in performance enhancement when dealing with the intricate relations of MKGs. Inspired by the semantic sensitivity and explicit type constraints unique to the medical domain, we propose BioBERT-based graph embedding model. This model represents an evolvable framework that integrates graph embedding, language embedding, and type information, thereby optimizing the utility of MKGs. Our study utilizes not only WordNet as a benchmark dataset but also incorporates MedicalKG to compare and corroborate the specificity of medical knowledge. Experimental results on these datasets indicate that the proposed fusion framework achieves state-of-art (SOTA) performance compared to other baselines. We believe that this incremental improvement provides promising insights for future medical knowledge graph completion endeavors.

Complex regional pain syndrome: advances in epidemiology, pathophysiology, diagnosis, and treatment

Complex regional pain syndrome (CRPS) is a rare pain disorder that usually occurs in a limb after trauma. The features of this disorder include severe pain and sensory, autonomic, motor, and trophic abnormalities. Research from the past decade has offered new insights into CRPS epidemiology, pathophysiology, diagnosis, and treatment. Early identification of individuals at high risk of CRPS is improving, with several risk factors established and some others identified in prospective studies during the past 5 years. Better understanding of the pathophysiological mechanisms of CRPS has led to its classification as a chronic primary pain disorder, and subtypes of CRPS have been updated. Procedures for diagnosis have also been clarified. Although effective treatment of CRPS remains a challenge, evidence-based integrated management approaches provide new opportunities to improve patient care. Further advances in diagnosis and treatment of CRPS will require coordinated, international multicentre initiatives.

Targeting TRPV4 Channels for Cancer Pain Relief

Despite the unique and complex nature of cancer pain, the activation of different ion channels can be related to the initiation and maintenance of pain. The transient receptor potential vanilloid 4 (TRPV4) is a cation channel broadly expressed in sensory afferent neurons. This channel is activated by multiple stimuli to mediate pain perception associated with inflammatory and neuropathic pain. Here, we focused on summarizing the role of TRPV4 in cancer etiology and cancer-induced pain mechanisms. Many studies revealed that the administration of a TRPV4 antagonist and TRPV4 knockdown diminishes nociception in chemotherapy-induced peripheral neuropathy (CIPN). Although the evidence on TRPV4 channels' involvement in cancer pain is scarce, the expression of these receptors was reportedly enhanced in cancer-induced bone pain (CIBP), perineural, and orofacial cancer models following the inoculation of tumor cells to the bone marrow cavity, sciatic nerve, and tongue, respectively. Effective pain management is a continuous problem for patients diagnosed with cancer, and current guidelines fail to address a mechanism-based treatment. Therefore, examining new molecules with potential antinociceptive properties targeting TRPV4 modulation would be interesting. Identifying such agents could lead to the development of treatment strategies with improved pain-relieving effects and fewer adverse effects than the currently available analgesics.

Enhancing Chronic Non-Cancer Pain Management: A Systematic Review of Mindfulness Therapies and Guided Imagery Interventions

Background and Objectives: There has been an increasing interest in the use of non-pharmacological approaches for the multidimensional treatment of chronic pain. The aim of this systematic review was to assess the effectiveness of mindfulness-based therapies and Guided Imagery (GI) interventions in managing chronic non-cancer pain and related outcomes. Materials and Methods: Searching three electronic databases (Web of Science, PubMed, and Scopus) and following the PRISMA guidelines, a systematic review was performed on Randomized Controlled Trials (RCTs) and pilot RCTs investigating mindfulness or GI interventions in adult patients with chronic non-cancer pain. The Cochrane Risk of Bias Tool was utilized to assess the quality of the evidence, with outcomes encompassing pain intensity, opioid consumption, and non-sensorial dimensions of pain. Results: Twenty-six trials met the inclusion criteria, with most of them exhibiting a moderate to high risk of bias. A wide diversity of chronic pain types were under analysis. Amongst the mindfulness interventions, and besides the classical programs, Mindfulness-Oriented Recovery Enhancement (MORE) emerges as an approach that improves interoception. Six trials demonstrated that mindfulness techniques resulted in a significant reduction in pain intensity, and three trials also reported significant outcomes with GI. Evidence supports a significant improvement in non-sensory dimensions of pain in ten trials using mindfulness and in two trials involving GI. Significant effects on opioid consumption were reported in four mindfulness-based trials, whereas one study involving GI found a small effect with that variable. Conclusions: This study supports the evidence of benefits of both mindfulness techniques and GI interventions in the management of chronic non-cancer pain. Regarding the various mindfulness interventions, a specific emphasis on the positive results of MORE should be highlighted. Future studies should focus on specific pain types, explore different durations of the mindfulness and GI interventions, and evaluate emotion-related outcomes.

Exploring the association between dietary Inflammatory Index and chronic pain in US adults using NHANES 1999-2004

Chronic pain, a substantial public health issue, may be influenced by dietary patterns through systemic inflammation. This cross-sectional study explored the association between Dietary Inflammatory Index (DII) and chronic pain among 2581 American adults from NHANES data. The DII, ranging from - 4.98 to 4.69, reflects the inflammatory potential of the diet, with higher scores indicating greater pro-inflammatory capacity. Our findings showed no significant association between the continuous DII score and chronic pain prevalence. However, a nonlinear relationship emerged. When the DII was categorized, a significant association between higher DII scores (DII ≥ 2.5) and chronic pain prevalence was observed. The analysis uncovered a U-shaped pattern, with an inflection point at a DII score of - 0.9, indicating an association between both low and high levels of dietary inflammation are associated with higher pain prevalence. This nuanced interaction between dietary inflammation and chronic pain indicates the possibility of incorporating dietary modification into pain management strategies and underscores the need for further research into the long-term effects of diet on chronic pain.

Genetically Regulated Gene Expression in the Brain Associated With Chronic Pain: Relationships With Clinical Traits and Potential for Drug Repurposing

BACKGROUND

Chronic pain is a common, poorly understood condition. Genetic studies including genome-wide association studies have identified many relevant variants, which have yet to be translated into full understanding of chronic pain. Transcriptome-wide association studies using transcriptomic imputation methods such as S-PrediXcan can help bridge this genotype-phenotype gap.

METHODS

We carried out transcriptomic imputation using S-PrediXcan to identify genetically regulated gene expression associated with multisite chronic pain in 13 brain tissues and whole blood. Then, we imputed genetically regulated gene expression for over 31,000 Mount Sinai BioMe participants and performed a phenome-wide association study to investigate clinical relationships in chronic pain-associated gene expression changes.

RESULTS

We identified 95 experiment-wide significant gene-tissue associations (p < 7.97 × 10-7), including 36 unique genes and an additional 134 gene-tissue associations reaching within-tissue significance, including 53 additional unique genes. Of the 89 unique genes in total, 59 were novel for multisite chronic pain and 18 are established drug targets. Chronic pain genetically regulated gene expression for 10 unique genes was significantly associated with cardiac dysrhythmia, metabolic syndrome, disc disorders/dorsopathies, joint/ligament sprain, anemias, and neurologic disorder phecodes. Phenome-wide association study analyses adjusting for mean pain score showed that associations were not driven by mean pain score.

CONCLUSIONS

We carried out the largest transcriptomic imputation study of any chronic pain trait to date. Results highlight potential causal genes in chronic pain development and tissue and direction of effect. Several gene results were also drug targets. Phenome-wide association study results showed significant associations for phecodes including cardiac dysrhythmia and metabolic syndrome, thereby indicating potential shared mechanisms.

Discordance between pain specialists and patients on the perception of dependence on pain medication: A multi-centre cross-sectional study

AIM

Patients with chronic non-cancer pain are referred to pain centres to improve their pain treatment. The discontinuation of pain medications in case of poor efficacy can be difficult to accept for patients, particularly opioid analgesics. Previous research has described that from the patients' perspective, the psychological relief of a negative effect of chronic pain and withdrawal symptoms of prescription opioids represent drivers of persistent use and first stage of opioid use disorder, despite insufficient pain relief. There is no validated tool to investigate this psychological dependence. This study aimed to assess discordance between patients and pain specialists in their perception of dependence on pain medication and investigate associations with characteristics of patients, type of pain and iatrogenic pharmacodependence.

METHODS

Self-administered questionnaires (patients and physicians) were administered in six pain centres in France. A question on perceived dependence on pain medications was addressed to the patient and the physician in a matched pair. Discordance between them was evaluated by the Cohen kappa coefficient. Demographics, pain, anxiety and depression, pain medication withdrawal symptoms, diverted use, and craving represented variables studied in a multivariate model as potentially associated with patient-physician discordance.

RESULTS

According to the 212 pairs of completed questionnaires, a perceived dependence was reported by the majority of patients (65.6%) and physicians (68.4%). However, the concordance was fair (kappa=0.38; CI [95%]: 0.25-0.51). Almost all patients (89.3%) were treated with an opioid analgesic. A higher likelihood of discordance was observed when patients suffered from nociplastic pain (odds ratio [OR]: 2.72, 95% [CI]: 1.29-5.84).

CONCLUSION

Medical shared-decision for changing pain treatment could be improved by taking into account the perception of patient dependence on medications for pain relief and or psychoactive effects, particularly in nociplastic pain for which the treatment is challenging.

Examining the Role of Structural and Functional Social Network Characteristics in the Context of Chronic Pain: An Ego-centered Network Design

The well-being and functioning of individuals with chronic pain (CP) vary significantly. Social factors, such as social integration, may help explain this differential impact. Specifically, structural (network size, density) as well as functional (perceived social support, conflict) social network characteristics may play a role. However, it is not yet clear whether and how these variables are associated with each other. Objectives were to examine 1) both social network characteristics in individuals with primary and secondary CP, 2) the association between structural network characteristics and mental distress and functioning/participation in daily life, and 3) whether the network's functionality mediated the association between structural network characteristics and mental distress, respectively, functioning/participation in daily life. Using an online ego-centered social network tool, cross-sectional data were collected from 303 individuals with CP (81.85% women). No significant differences between individuals with fibromyalgia versus secondary CP were found regarding network size and density. In contrast, ANCOVA models showed lower levels of perceived social support and higher levels of conflict in primary (vs secondary) CP. Structural equation models showed that 1) larger network size indirectly predicted lower mental distress via lower levels of conflict; 2) higher network density increased mental distress via the increase of conflict levels. Network size or density did not (in)directly predict functioning/participation in daily life. The findings highlight that the role of conflict, in addition to support, should not be underestimated as a mediator for mental well-being. Research on explanatory mechanisms for associations between the network's structure, functionality, and well-being is warranted. PERSPECTIVE: This paper presents results on associations between structural (network size, density) and functional (social support, conflict) social network characteristics and well-being in the context of CP by making use of an ego-centered network design. Results suggest an indirect association between structural network characteristics and individuals with CP their mental well-being.