Central sensitization: a biopsychosocial explanation for chronic widespread pain in patients with fibromyalgia and chronic fatigue syndrome

Cross-Cultural Adaptation and Validation of the Central Sensitization Inventory Into Simplified Chinese

PURPOSE

To translate the Central Sensitization Inventory from English into simplified Chinese (CSI-sC) and test the psychometric properties of the CSI-sC in patients with chronic pain.

DESIGN

A cross-sectional design was used.

METHODS

Cross-cultural adaptation of the CSI-sC was performed following Beaton's guidelines. Using a convenient sampling method, 172 patients with chronic spinal pain and 74 healthy individuals were enrolled. The Visual Analog Scale (VAS), Insomnia Severity Index (ISI), EuroQol Five Dimensions Questionnaire (EQ-5D), and Neck Disability Index (NDI) or Oswestry Disability Index (ODI) were used to measure insomnia, pain, quality of life, and functional status. Associations between CSI-sC with these measures were examined for concurrent and convergent validity assessment. Discriminant validity was confirmed by comparing CSI-sC scores between different groups. Exploratory factor analysis was used for the structural validity assessment. Reliability was assessed by internal consistency and test-retest reliability.

RESULTS

The Cronbach's alpha of the CSI-sC was 0.886. The intra-class correlation coefficient was 0.757. The CSI-sC showed a five-factor structure (57.2% of variances). The CSI-sC was significantly correlated with the ISI (r = 0.625), EQ-5D index (r = -0.363), EQ-5D health score (r = -0.355), VAS (r = 0.290), NDI (r = 0.432) and ODI (r = 0.333). CSI-sC scores were statistically higher in females compared to males (p = .006) and in the patient population compared to healthy controls (p < .001).

CONCLUSIONS

The CSI-sC demonstrated good reliability and validity in chronic spinal pain patients.

CLINICAL IMPLICATIONS

This study offers a good tool for the assessment and identification of central sensitization symptomology in clinical nursing practice, which may help optimize the treatment for patients with chronic pain.

The efficiency of tactile discrimination training and oculomotor exercises in people with chronic neck pain: a randomized controlled trial

BACKGROUND

Tactile discrimination training (TDT) and oculomotor exercises (OEs) have been widely used somatosensory-based interventions for a wide range of chronic pain conditions. There is, however, little evidence for the effectiveness of these approaches in people with chronic neck pain. This study aimed to determine the superiority of one intervention over another on pain outcomes in people with chronic neck pain.

METHODS

Fifty seven participants were randomly divided into three groups: TDT, OEs, and a control group who received no intervention. TDT, OEs groups received either TDT or OEs, respectively, three times per week for four weeks. The control group received no intervention. Pain intensity, neck pain-related disability, pressure pain thresholds (PPTs), mechanical pain of temporal summation (mTSP), and conditioned pain modulation were assessed as pain outcomes. Depending on the normality, a repeated measures ANOVA or F1-LD-F1 design was used to analyse the data.

RESULTS

A significant group*time interaction and main effects for time were found for pain intensity (p: 0.001, p: 0.001, respectively) and pain-related disability (p < 0.019, p < 0.009; respectively). There was a significant main effect for time for mTSP at the painful side of the neck (p: 0.022). TDT and OEs resulted in a significantly higher improvement in pain intensity (p: 0.005, p < 0.001; respectively) and neck pain-related disability (p: 0.005, p: 0.007; respectively). There was a higher improvement in pain intensity in OEs group compared to TDT group (p: 0.010). A significantly higher improvement in PPT at the painful site after OEs was found (p: 0.038). The control group demonstrated a significantly higher improvement in mTSP in the painful area of the neck (p: 0.048). There were no other significant within- or between-group changes.

CONCLUSION

OEs and TDT are effective somatosensory-based interventions for improving pain intensity and pain-related disability.

IMPACT

This study demonstrated that sensory retraining interventions improves the subjective pain perception.

TRIAL REGISTRATION

Trial Registration Number: NCT05605132, Date of trial registration: 10/29/2022, Name of trial registry: Neck Pain.

Effectiveness of multicomponent treatment compared with other therapeutic interventions in patients with fibromyalgia: A systematic review with meta-analysis

BackgroundFibromyalgia (FM) is a chronic pain disease characterized by widespread musculoskeletal pain. The multicomponent treatment has showed improves symptom management in patients with FM. However, inconsistent results have been demonstrated in previous studies. Additionally, none of these studies have analyzed the effect on psychological outcomes.ObjectiveTo determine the effectiveness of multicomponent treatment compared with other therapeutic interventions for pain intensity and functional status, quality of life, depression and pain anxiety in patients with FM.MethodsAn electronic search was performed using MEDLINE, CENTRAL EMBASE, Web of Science, PEDro, CINAHL, SPORTDiscus, Scopus, and LILACS databases. The eligibility criteria included randomized clinical trials (RCTs) investigating the effects of multicomponent treatment compared with other therapeutic interventions (active and passive) in patients older than 18 years with FM. Effect sizes were calculated as a standard mean difference (SMD) with 95% CI using random-effects Hartung-Knapp-Sidik-Jonkman or the Mantel-Haenszel fixed method. The quality of intervention reporting was assessed with the Risk of Bias (RoB) 2, and certainty of evidence was assessed using GRADE approach. Two authors independently performed the search, study selection, data extraction, and risk-of-bias assessment.ResultsTwenty-five RCTs met the eligibility criteria, including 3476 patients. At 10-16 weeks, for multicomponent treatment versus all other interventions, the standardized mean difference in pain intensity was -0.51 (95% CI: -0.92 to -0.10, P = 0.021). For functional status, quality of life, depression, and anxiety, statistically significant differences were found in favor of multicomponent treatment (all P values <0.05). Additionally, there were no differences in the effects of multicomponent treatment and passive interventions on any clinical outcomes. Finally, our study has some limitations such as lack methodology of some clinical trials included and high heterogeneity could be over-or-under estimation the effects of the intervention's studied.ConclusionIn the medium term, multicomponent treatment, in comparison with all other interventions (active and passive), showed statistically and clinically significant differences with moderate effect size in pain intensity in patients with FM. The quality of evidence was low to high according to the GRADE approach. Additionally, there were no differences between multicomponent treatment and passive interventions in patients with FM.PROSPERO registration numberCRD42020142082.

The most effective therapeutic exercises for pain intensity in women with fibromyalgia: A systematic review and network meta-analysis

BACKGROUND

Therapeutic exercise (TE) is the only intervention with strong recommendation for fibromyalgia. However, there is controversy as to which type of exercise is the most beneficial.

OBJECTIVE

To determine which TE approach is the most effective in reducing pain intensity in women with fibromyalgia.

METHODS

A systematic review was performed with a network meta-analysis (NMA). Six databases were searched from inception until January 2024. Randomized controlled trials (RCTs) evaluating the effects of TE on pain intensity were included in women with fibromyalgia. Methodological quality was assessed using the Physiotherapy Evidence Database scale. The size of the effect and the clinically important difference were determined in the short-term (≤3 months) and long-term (>3 months).

RESULTS

Sixty-one studies were identified, of which 51 were included in the quantitative synthesis (n = 2873). Fifteen TE interventions and eight comparison interventions (comparators) were identified. Aquatic exercise (p-score: 0.8713) was found to provide best benefits in the short-term and resistance training in the long-term (p-score: 0.9749). Statistically significant differences were found in favor of aquatic exercise, Pilates, qigong, resistance training, virtual reality, mixed exercise, and aerobic exercise (in the short-term) and in favor of resistance training, dance, functional training, aquatic exercise, virtual reality, and aerobic exercise (in the long-term) compared to usual care.

CONCLUSION

With a moderate level of evidence, our NMA shows that, in the short-term, aquatic exercise is the most effective TE intervention to reduce pain intensity in women with fibromyalgia, while resistance training is the most effective in the long-term. More RCTs are needed to strengthen these findings.

Association Between Educational Attainment and Chronic Pain: A Mediation Mendelian Randomization Study

Background

The underlying association between educational attainment (EA) and chronic pain (CP) risk is not clear. This study aimed to investigate the causal relationship of EA with CP using Mendelian randomization (MR).

Methods

Single nucleotide polymorphisms (SNPs) for EA were selected from the Social Science Genetic Association Consortium (SSGAC). Inverse-variance weighted (IVW), weighted median, penalized weighted median, maximum likelihood (ML), and MR-Egger methods were used to estimate causal effects. Two sample MR analyses were undertaken to assess whether EA has a causal effect on CP. We also performed mediation analyses to estimate the mediation effects.

Results

A genetically predicted higher EA was associated with a decreased risk of multisite chronic pain (MCP) (odds ratio [OR] = 0.772, 95% confidence interval [CI] 0.732-0.816 per one standard deviation of longer education, P < 0.05), and the Genome-wide association studies (GWAS) data for chronic widespread pain (CWP) supported the result mentioned above. Potential mediators included body mass index (BMI) (OR = 1.176, 95% CI 1.091-1.267, P < 0.05), smoking (OR = 1.054, 95% CI 1.028-1.081, P < 0.05), and depression (OR = 1.201, 95% CI 1.147-1.258, P < 0.05) have all been proven to be causally associated with MCP. The proportions of the effects of genetically predicted EA mediated through genetically predicted BMI, smoking, and depression were 17.1%, 23.6%, and 9.2%, respectively.

Conclusion

Genetically predicted higher educational attainment reduces multisite chronic pain risk, partially mediated by body mass index (17.1%), smoking (23.6%), and depression (9.2%), highlighting education's protective role and its potential in chronic pain prevention strategies.

Pain distribution can be determined by classical conditioning

ABSTRACT

Chronic widespread pain (CWP)-as in many other clinical presentations-manifests in ongoing pain without identifiable structural cause, with pain that spreads over multiple body areas. The development and maintenance of symptoms may involve learning mechanisms. Ninety-four healthy volunteers participated in this study and were randomly distributed to 4 groups. In the classical conditioning combined with the verbal suggestion group, US- (small pain distribution) and US+ (large pain distribution) were paired with visual stimuli (CS+ and CS-), and participants were told about this association. In the verbal suggestion group, the conditioning was not performed, whereas in the classical conditioning-only group, learning was not combined with suggestion. In the control group, conditioning and suggestion did not take place. Ratings of perceived pain distribution were collected after each trial and ratings of pain intensity after each block of trials. During the testing phase, participants were exposed to electrocutaneous stimuli corresponding to only the small (US-) pain distribution. The results showed significant differences between CS+ and CS- pain distribution ratings across the experimental groups: conditioning + verbal suggestion (P < 0.01), conditioning-only group (P < 0.05), and verbal suggestion-only group (P < 0.05), but not in the control group (P > 0.05). Furthermore, significant differences in the perceived pain distribution were found between the control group and all experimental groups. This result supports our main hypothesis that the perceived pain distribution can be influenced by classical conditioning as well as verbal suggestion, although the effect is stronger when both are combined.

Metabotropic Glutamate Receptor 5: A Potential Target for Neuropathic Pain Treatment

Neuropathic pain, a multifaceted and incapacitating disorder, impacts a significant number of individuals globally. Despite thorough investigation, the development of efficacious remedies for neuropathic pain continues to be a formidable task. Recent research has revealed the potential of metabotropic glutamate receptor 5 (mGlu5) as a target for managing neuropathic pain. mGlu5 is a receptor present in the central nervous system that has a vital function in regulating synaptic transmission and the excitability of neurons. This article seeks to investigate the importance of mGlu5 in neuropathic pain pathways, analyze the pharmacological approach of targeting mGlu5 for neuropathic pain treatment, and review the negative allosteric mGlu5 modulators used to target mGlu5. By comprehending the role of mGlu5 in neuropathic pain, we can discover innovative treatment approaches to ease the distress endured by persons afflicted with this incapacitating ailment.

Efficacy of a pain neuroscience educational program in improving executive function and pain intensity in fibromyalgia patients (Fibrobrain project): Study protocol for a randomized controlled clinical trial

BACKGROUND

Fibromyalgia (FM) is a chronic musculoskeletal condition typically characterized by chronic pain, sleep disturbances, chronic fatigue, and cognitive problems. The present study aims to examine the efficacy of a pain neuroscience education program (PNE) in improving executive functions and pain intensity in patients with FM and compare them with those of standard treatment protocols.

METHODS

This blinded, controlled clinical trial will compare changes in executive function and pain intensity between two groups. The first group will receive standard treatment supplemented with PNE, consisting of ten sessions spread over five weeks, with each session lasting 40-45 min. The main objective of this method is to remodel cognitive and emotional reactions to pain, challenging the idea that pain is directly related to injury and highlighting the influence of emotions, sleep, and physical activity on pain perception. The second group will receive only standard pharmacological treatment. The study sample will include 62 adults diagnosed with FM, according to initial sample size estimates based on previous evidence. A baseline assessment of baseline characteristics will be performed, after which patients will be randomly assigned to the PNE group or the control group. The results of the intervention will be evaluated and statistically compared after 5 weeks. This protocol complies with all relevant ethical guidelines. It has been approved by two institutional committees (Reference: NR2006; Conbioethics:21-CEI-004-20,170,829).

CONCLUSION

It is anticipated that this intervention will be a cost-effective and superior alternative to standard treatments.

CLINICAL TRIAL REGISTRATION

NCT05084300.

Yoga, Physical Therapy and Home Exercise Effects on Chronic Low Back Pain: Pain Perception, Function, Stress, and Quality of Life in a Randomized Trial

Low back pain is a common health problem. In this study, we investigated the effects of yoga, physical therapy (PT), and home exercise (HE) on pain perception, function, stress, and quality of life in chronic low back pain (cLBP). We randomly assigned 54 participants to three distinct treatment groups: (a) a physical therapy group (PT) who received spinal stabilization exercises (SSE) combined with local heat and transcutaneous electrical stimulation; (b) a home exercise group (HE) who received SSE as part of the home program; and (c) a yoga group who received yoga exercises. The primary outcome measures were a Visual Analog Scale (VAS) for measuring pain, and the Oswestry Disability Index (ODI) to measure function. Secondary outcome measures were the Tampa Kinesiophobia Scale (TKS), Central Sensitization Inventory (CSI), pain sensitivity (L3 and deltoid R/L PPTs), Spielberger State-Trait Anxiety Inventory (STAI), plasma cortisol and DHEA-S levels, Transversus Abdominis (TrA) muscle activation, and the Nottingham Health Profile (NHP). Assessments were conducted before and after a six-week intervention period. All three groups demonstrated improvements in pain on the VAS, function on the ODI, pain sensitivity on the L3 and deltoid R/L PPTs, CSI, anxiety on the STAI, TrA muscle activation, and quality of life on the NHP (p < .05). The PT group exhibited a more pronounced improvement on the ODI score (p < .05) than the other groups. Cortisol levels only decreased in the PT group (p < .05). The exercises did not impact DHEA-S and NHP-S parameters. Thus, all interventions resulted in decreased stress, pain intensity, pain sensitivity, central sensitization, and improved function and quality of life; there was no singularly superior approach between interventions. These findings will aid in tailoring treatment programs for managing cLBP according to individual needs.

Effects of therapeutic exercise on pain processing in people with chronic non-specific neck pain - A systematic review and meta-analysis

BACKGROUND

Emerging evidence suggests that individuals with chronic non-specific neck pain may experience altered sensory processing, potentially contributing to the modest response to therapeutic exercise treatments.

OBJECTIVE

This systematic review aims to explore the effect of therapeutic exercise on pain processing among patients with chronic non-specific neck pain.

METHODS

A systematic search was conducted in multiple databases (PubMed, EMBASE, CINAHL, PEDro, SportDiscus, and Cochrane CENTRAL) from inception to June 2023. Inclusion criteria included randomized controlled trials (RCT) comparing therapeutic exercise to non-exercise treatments or no treatment. The screening and data extraction was conducted by two reviewers. The methodological quality was evaluated using the PEDro scale and the certainty of evidence using GRADE. The primary outcomes assessed were pressure pain threshold (PPT), temporal summation, and conditioned pain modulation.

RESULTS

Thirteen trials included a total of 948 participants, with 586 in the exercise therapy group and 362 in the non-exercise group. The therapeutic exercise was not superior to non-exercise treatments for both local and PPT in the immediate (MD = 0.13, 95%CI = -0.18 to 0.43), and short-term follow-up (MD = 0.17, 95%CI = -0.27 to 0.61). In the medium term, therapeutic exercise demonstrated a small effect size in increasing local PPT (Kg/cm2) (MD = 0.64, 95%CI = 0.08 to 1.19) compared to non-exercise interventions. The certainty of evidence for these outcomes was very low.

CONCLUSIONS

There is very low certainty of evidence that therapeutic exercise is not superior than non-exercise treatment on pain processing in patients with chronic non-specific neck pain.

Inflammatory injury induces pain sensitization that is expressed beyond the site of injury in male (and not in female) mice

Pain is a crucial protective mechanism for the body. It alerts us to potential tissue damage or injury and promotes the avoidance of harmful stimuli. Injury-induced inflammation and tissue damage lead to pain sensitization, which amplifies responses to subsequent noxious stimuli even after an initial primary injury has recovered. This phenomenon, commonly referred to as hyperalgesic priming, was investigated in male and female mice to determine whether it is specific to the site of previous injury. We used 10μl of 50 % Freund's complete adjuvant (CFA) administered to the left hind paw as a model of peripheral injury. Both male and female mice exhibited robust site-specific mechanical hypersensitivity after CFA, which resolved within one-week post-injection. After injury resolution, only male CFA-primed mice showed enhanced and prolonged mechanical sensitivity in response to a chemical challenge or a single 0.5 mA electric footshock. Among CFA-primed male mice, shock-induced mechanical hypersensitivity was expressed in both the left (previously injured) and the right (uninjured) hind paws, suggesting a pivotal role for altered centralized processes in the expression of pain sensitization. These findings indicate that pain history regulates sensory responses to subsequent mechanical and chemical pain stimuli in a sex-specific manner-foot-shock-induced hyperalgesic priming expression among male mice generalized beyond the initial injury site.

Effectiveness of a novel multicomponent treatment in women with fibromyalgia: A randomized clinical trial

Background

Multicomponent treatment is commonly used. However, there are no studies that included graded motor imagery and therapeutic neuroscience education to multicomponent treatment for patients with fibromyalgia This study aims to compare the short-term effects (at 12 weeks) of a multicomponent treatment combined with graded motor imagery and therapeutic neuroscience education versus standard treatment in patients with FM.

Methods

The study was a single-blinded randomized controlled trial. Sixty-five women with a clinical diagnosis of FM were randomly allocated (1:1) into two groups. The experimental group (n = 33) received a novel multicomponent treatment combined with graded motor imagery and neuroscience education. The control group (n = 32) received a standard treatment including pharmacotherapy and standard physician education. The primary outcome was pain intensity assessed with the Numeric Pain Rating Scale (NPRS). The secondary outcomes were changes in the Fibromyalgia Impact Questionnaire (FIQ), the Pain Catastrophizing Scale (PCS), the Tampa Scale of Kinesiophobia (TSK-17), and the Pittsburgh Sleep Quality Index (PSQI) scores. All outcomes were assessed at baseline and 12 weeks.

Results

All of the participants completed the trial. The between-group mean differences at 12 weeks were: NPRS-1.18 points (95% confidence interval [CI] -0.4 to -1.8; η2 = 0.47; p < .001); FIQ-16.21 points (95% CI -10.9 to -22.1; η2 = 0.58; p < .001); PCS total domain -12.5 points (95% CI -7.2 to -17.8; η2 = 0.61; p < .001); TSK-17-6.15 points (95% CI -3.5 to -8.7; η2 = 0.52; p < .001); and PSQI-2.74 points (95% CI -1.4 to 4.0; η2 = 0.54; p < .001). All differences were statistically significant in favor of the novel multicomponent treatment group and had a large effect size.

Conclusions

In the short term, a novel multicomponent treatment, including graded motor imagery and neuroscience education, was an effective therapeutic intervention for improving clinical outcomes compared with standard treatment in women with FM. Additional studies are needed to support long-term clinical effectiveness in these patients.

Laryngeal and Global Somatosensation in Primary Muscle Tension Dysphonia

INTRODUCTION

Primary muscle tension dysphonia (pMTD) is a functional voice disorder that reduces communicative abilities and adversely impacts occupational productivity and quality of life. Patients with pMTD report increased vocal effort, fatigue, discomfort, and odynophonia. Although laryngeal and paralaryngeal muscle tension and hyperfunction are the most commonly proposed mechanisms underlying these symptoms, recent studies suggest pMTD may have more to do with the somatosensory system. However, relationships between voice symptoms and somatosensory mechanisms are poorly understood, creating challenges for mechanistic-based pMTD management. The first objective was to compare laryngeal, paralaryngeal, and global somatosensation between subjects with and without pMTD. The second was to determine relationships between pMTD symptoms and somatosensation.

METHODS

Fifty-two (20 pMTD and 32 control) subjects underwent laryngeal sensory testing with aesthesiometers, as well as peripheral mechanosensory and dynamic temporal summation testing to paralaryngeal and limb regions. Voice symptom severities (vocal effort, fatigue, discomfort, and odynophonia) were collected on 100-mm visual analog scales before and after laryngeal sensory testing. Participants also completed the Central Sensitization Inventory.

RESULTS

Patients with pMTD reported significantly higher laryngeal sensations (P = 0.0072) and voice symptom severities (P < 0.001) compared with the control group, and had significantly more vocal tract discomfort postlaryngeal sensory testing compared with the prelaryngeal sensory testing timepoint (P = 0.0023). However, there were no significant group differences in laryngeal airway protection responses suggestive of peripheral laryngeal hypersensitivities (P = 0.444). There were also no significant group differences on paralaryngeal or global sensitivities (P > 0.05), and no correlations between severity of voice symptoms and perceptual laryngeal sensations or hypersensitivities (P > 0.05).

CONCLUSION

Patients with pMTD perceive more sensitivities in the larynx and feel more sensations related to the voice (vocal effort, fatigue, discomfort, and pain). However, in general, patients with pMTD do not have abnormal peripheral laryngeal hypersensitivities, increased global somatosensation, or heightened central sensitivity. The lack of significant correlations between peripheral laryngeal hypersensitivities and voice symptom severity ratings suggests these outcome variables target distinct mechanistic constructs.

The role of fatigue in patients with complex regional pain syndrome

BACKGROUND AND PURPOSE

Fatigue affects patients across a variety of neurological diseases, including chronic pain syndromes such as complex regional pain syndrome (CRPS). In CRPS, fatigue is often underestimated, as the focus lies in the assessment and managing of pain and sensorimotor deficits. This study aimed to investigate the prevalence, characteristics, and influence of fatigue on CRPS severity and quality of life in these patients. Such insights could enhance the clinical management of this challenging condition.

METHODS

In this prospective study, 181 CRPS patients and 141 age and gender-matched individuals with injury but without chronic pain were interviewed using the Fatigue Scale for Motor and Cognitive Function to assess fatigue. Depressive symptoms and quality of life (QoL) were also evaluated as additional outcome measures. Statistical analysis was performed to examine differences in fatigue prevalence between the groups, as well as associations with CRPS severity, pain levels, and clinical phenotype. In addition, best subsets regression was used to identify the primary factors influencing QoL. Fatigue was tested in a mediation analysis as a mediator between pain and depression.

RESULTS

CRPS patients showed significantly higher fatigue levels compared to controls (CRPS: 75 [IQR: 57-85] vs. controls: 39 [IQR: 25-57]). Based on the FSMC, 44.2% in the control group experienced fatigue, while 85% of patients with CRPS experienced fatigue (p < 0.001), of which 6% were mild, 15% moderate, and 67% severe. In CRPS severe fatigue was associated with higher pain intensities compared to no fatigue (pain at rest: p = 0.003; pain during movement: p = 0.007) or moderate fatigue (pain during movement: p = 0.03). QoL in our cohort was mainly influenced by pain (pain during movement: adj.R2 = 0.38; p < 0.001, pain at rest: Δadj.R2 = 0.02, p = 0.007) and depressive symptoms (Δadj.R2 = 0.12, p < 0.001). Subsequent analyses indicated that pain and depressive symptoms primarily impact QoL in CPRS whereas fatigue may exert an indirect influence by mediating the connection between pain and depression (p < 0.001).

CONCLUSIONS

This pioneering study investigates the prevalence of fatigue in CRPS patients and its relation to disease characteristics. Our results indicate a high prevalence of severe fatigue, strongly correlated with pain intensity, and its importance in the interaction between pain and depression in CRPS. These findings underscore the significant role of fatigue as a disease factor in CRPS. Therefore, the evaluation of CRPS-related disability should include a standardized assessment of fatigue for comprehensive clinical management.

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.

Central Sensitization: The Missing Link Between Psychological Distress and Poor Outcome Following Primary Total Knee Arthroplasty

BACKGROUND

While preoperative psychological distress is known to predict risk for worse total knee arthroplasty (TKA) outcomes, distress may be too broad and nonspecific a predictor in isolation. We tested whether there are distinct preoperative TKA patient types based jointly on psychological status and measures of altered pain processing that predict adverse clinical outcomes.

METHODS

In 112 TKA patients, we preoperatively assessed psychological status (depression, anxiety, and catastrophizing) and altered pain processing via a simple quantitative sensory testing protocol capturing peripheral and central pain sensitization. Outcomes (pain, function, opioid use) were prospectively evaluated at 6 weeks and 6 months after TKA. Cluster analyses were used to empirically identify TKA patient subgroups.

RESULTS

There were 3 distinct preoperative TKA patient subgroups identified from the cluster analysis. A low-risk (LR) group was characterized by low psychological distress and low peripheral and central sensitization. In addition, 2 subgroups with similarly elevated preoperative psychological distress were identified, differing by pain processing alterations observed: high-risk centralized pain and high-risk peripheral pain. Relative to LR patients, high-risk centralized pain patients displayed significantly worse function and greater opioid use at 6 months after TKA (P values <.05). The LR and high-risk peripheral pain patient subgroups had similar 6-month outcomes (P values >.05).

CONCLUSIONS

Among patients who have psychological comorbidity, only patients who have central sensitization were at elevated risk for poor functional outcomes and increased opioid use. Central sensitization may be the missing link between psychological comorbidity and poor TKA clinical outcomes. Preoperative testing for central sensitization may have clinical utility for improving risk stratification in TKA patients who have psychosocial risk factors.

Attenuation of Streptozotocin-Induced Diabetic Neuropathic Allodynia by Flavone Derivative Through Modulation of GABA-ergic Mechanisms and Endogenous Biomarkers

Diabetic neuropathic pain is one of the most devasting disorders of peripheral nervous system. The loss of GABAergic inhibition is associated with the development of painful diabetic neuropathy. The current study evaluated the potential of 3-Hydroxy-2-methoxy-6-methyl flavone (3-OH-2'MeO6MF), to ameliorate peripheral neuropathic pain using an STZ-induced hyperglycemia rat model. The pain threshold was assessed by tail flick, cold, mechanical allodynia, and formalin test on days 0, 14, 21, and 28 after STZ administration accompanied by evaluation of several biochemical parameters. Administration of 3-OH-2'-MeO6MF (1,10, 30, and 100 mg/kg, i.p) significantly enhanced the tail withdrawal threshold in tail-flick and tail cold allodynia tests. 3-OH-2'-MeO6MF also increased the paw withdrawal threshold in mechanical allodynia and decreased paw licking time in the formalin test. Additionally, 3-OH-2'-MeO6MF also attenuated the increase in concentrations of myeloperoxidase (MPO), thiobarbituric acid reactive substances (TBARS), nitrite, TNF-α, and IL 6 along with increases in glutathione (GSH). Pretreatment of pentylenetetrazole (PTZ) (40 mg/kg, i.p.) abolished the antinociceptive effect of 3-OH-2'-MeO6MF in mechanical allodynia. Besides, the STZ-induced alterations in the GABA concentration and GABA transaminase activity attenuated by 3-OH-2'-MeO6MF treatment suggest GABAergic mechanisms. Molecular docking also authenticates the involvement of α2β2γ2L GABA-A receptors and GABA-T enzyme in the antinociceptive activities of 3-OH-2'-MeO6MF.

Development of an interdisciplinary training program about chronic pain management with a cognitive behavioural approach for healthcare professionals: part of a hybrid effectiveness-implementation study

BACKGROUND

Many applied postgraduate pain training programs are monodisciplinary, whereas interdisciplinary training programs potentially improve interdisciplinary collaboration, which is favourable for managing patients with chronic pain. However, limited research exists on the development and impact of interdisciplinary training programs, particularly in the context of chronic pain.

METHODS

This study aimed to describe the development and implementation of an interdisciplinary training program regarding the management of patients with chronic pain, which is part of a type 1 hybrid effectiveness-implementation study. The targeted groups included medical doctors, nurses, psychologists, physiotherapists, occupational therapists, dentists and pharmacists. An interdisciplinary expert panel was organised to provide its perception of the importance of formulated competencies for integrating biopsychosocial pain management with a cognitive behavioural approach into clinical practice. They were also asked to provide their perception of the extent to which healthcare professionals already possess the competencies in their clinical practice. Additionally, the expert panel was asked to formulate the barriers and needs relating to training content and the implementation of biopsychosocial chronic pain management with a cognitive behavioural approach in clinical practice, which was complemented with a literature search. This was used to develop and adapt the training program to the barriers and needs of stakeholders.

RESULTS

The interdisciplinary expert panel considered the competencies as very important. Additionally, they perceived a relatively low level of healthcare professionals' possession of the competencies in their clinical practice. A wide variety of barriers and needs for stakeholders were formulated and organized within the Theoretical Domain Framework linked to the COM-B domains; 'capability', 'opportunity', and 'motivation'. The developed interdisciplinary training program, including two workshops of seven hours each and two e-learning modules, aimed to improve HCP's competencies for integrating biopsychosocial chronic pain management with a cognitive behavioural approach into clinical practice.

CONCLUSION

We designed an interdisciplinary training program, based on formulated barriers regarding the management of patients with chronic pain that can be used as a foundation for developing and enhancing the quality of future training programs.

Muscle Pressure Correlates With Pain Levels in Fibromyalgia Patients

BACKGROUND/OBJECTIVE

We evaluated patients with fibromyalgia syndrome (FMS) to determine whether there is a correlation between pain scores based on a 0- to 10-point visual analog scale (VAS) and muscle pressure.

METHODS

One hundred forty-two patients who satisfied the American College of Rheumatology classification criteria for FMS and 38 non-FMS controls comprised the study groups. Muscle pressure was measured in mm Hg using a pressure gauge attached to a no. 22 needle inserted into the midportion of the trapezius muscle. The muscle pressure was then correlated with the VAS pain score of 0 to 10, some with an increment of 0.5. A second muscle pressure was obtained from 19 patients at a subsequent visit, which was compared with their pain scores.

RESULTS

The mean (SD) pain score for 142 patients with FMS was 6.6 (SD, 1.84) on a 0- to 10-point VAS. The mean pain score in the non-FMS subjects was 0.7 (SD, 1.26). The mean muscle pressure in the FMS group was 32.9 (SD, 6.57) mm Hg. The mean muscle pressure in the non-FMS subjects was 10.6 (SD, 3.85) mm Hg. The calculated Pearson correlation coefficient for muscle pressure versus pain score was 0.8312 ( p < 0.0001). This indicates a highly significant association between subjects' muscle pressure and pain scores. For the repeat muscle pressures, the change in muscle pressure was correlated with the change in pain score, and the resulting Pearson correlation coefficient was 0.9255 ( p < 0.0001). These results again indicate a highly significant association between subjects' muscle pressure and pain scores.

CONCLUSION

The results show that increased muscle pressure may be a significant cause of pain in FMS, and the etiology of the pain may have a large peripheral component in addition to a centralized origin of the pain.

Efficacy of neuromodulation on the treatment of fibromyalgia: A network meta-analysis

OBJECTIVE

Several types of neuromodulation have been investigated for the treatment of fibromyalgia, but they show varied efficacy on pain, functioning, comorbid depression and comorbid anxiety. Whether some types of neuromodulation or some factors are associated with a better response also awaits clarification.

METHODS

We conducted a systematic review and network meta-analysis of randomized controlled trials to evaluate the efficacy of neuromodulation in patients with fibromyalgia. We searched PubMed, EMBASE, the Cochrane Central Register of Controlled Trials and PsycINFO before March 2022. We employed a frequentist random-effects network meta-analysis.

RESULTS

Forty trials involving 1541 participants were included. Compared with sham control interventions, several types of transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), and high-frequency repetitive transcranial magnetic stimulation (rTMS) were associated with significant reduction of pain, depression, anxiety, and improvement in functioning. Many significantly effective treatment options involve stimulation of the primary motor cortex or dorsolateral prefrontal cortex.

CONCLUSION

We concluded that several types of rTMS, tDCS and tRNS may have the potential to be applied for clinical purposes.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Expanding the notion of mechanism to further understanding of biopsychosocial disorders? Depression and medically-unexplained pain as cases in point

Evidence-Based Medicine has little consideration for mechanisms and philosophers of science and medicine have recently made pleas to increase the place of mechanisms in the medical evidence hierarchy. However, in this debate the notions of mechanisms seem to be limited to 'mechanistic processes' and 'complex-systems mechanisms,' understood as 'componential causal systems'. I believe that this will not do full justice to how mechanisms are used in biological, psychological and social sciences and, consequently, in a more biopsychosocial approach to medicine. Here, I propose, following (Kuorikoski, 2009), to pay more attention to 'abstract forms of interaction' mechanisms. The present work scrutinized review articles on depression and medically unexplained pain, which are considered to be of multifactorial pathogenesis, for their use of mechanisms. In review articles on these disorders there seemed to be a range of uses between more 'abstract forms of interaction' and 'componential causal system' mechanisms. I therefore propose to expand the notions of mechanisms considered in medicine to include that of more 'abstract forms of interaction' to better explain and manage biopsychosocial disorders.

Clinical relevance of resistance training in women with fibromyalgia: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

There has been an increase in the number of papers assessing the effects of resistance training (RT) in patients with fibromyalgia. Therefore, the objective of our study was to evaluate the clinical relevance and effectiveness of RT for pain intensity, functionality and severity of the disease specifically in women with fibromyalgia through a systematic review with meta-analysis.

DATABASES AND DATA TREATMENT

Seven databases were searched. Randomized controlled trials conducted in women over 18 years of age with fibromyalgia were included. Fifteen trials were included in the systematic review and 14 of these studies were included in the three meta-analyses performed. Study quality assessment was performed using the PEDro scale. In addition, the GRADE recommendations were used.

RESULTS

The global meta-analysis revealed statistically significant differences in the RT group versus the control group on pain intensity (SMD = -0.49; 95% CI [-0.74, -0.24], p = 0.0001), functionality (SMD = -0.23; 95% CI [0.01, 0.45], p = 0.04) and on severity of the disease (SMD = -0.58; 95% CI [-0.90, -0.26], p = 0.0005). Clinically relevant improvements in the overall outcome of the three variables studied in favour of RT were obtained.

CONCLUSIONS

RT is effective to improve pain intensity, functionality and severity of the disease in women with fibromyalgia. These improvements are clinically relevant. More clinical trials of RT are needed in women with fibromyalgia to support our results due to the low strength of evidence.

SIGNIFICANCE

This systematic review with meta-analysis provides evidence that RT produces clinically relevant improvements in women with fibromyalgia. The absence of immediate benefit is often a major barrier to adherence to treatment. Our findings will help clinicians to empower patients that if they continue treatment, they will achieve improvement in their disease.

Paradox pain sensitivity using cuff pressure or algometer testing in patients with hemophilia

INTRODUCTION

Pain is a common comorbidity in patients with hemophilia (PwH) due to hemophilic arthropathy. This study aims to explore pain sensitivity in PwH methodologically investigating in cuff pressure testing compared to algometer testing.

METHODS

37 PwH and 35 healthy control subjects (Con) enrolled in this study. Joint health status was assessed. Subjective pain was evaluated using numeric rating scales. Pain sensitivity was measured with pressure algometry and cuff pressure algometry. Pressure pain thresholds of the algometer (PPTa) were measured at knee, ankle joints, and forehead. Subsequently, thresholds of cuff pressure were measured at the left and right lower legs (PPTcuff). In both, lower values represent higher pain sensitivity.

RESULTS

PwH exerted a worse joint health status than Con. Pain sensitivity was higher in PwH compared to Con as PPTa of the knee and ankle joints were lower in PwH. No difference was observed in PPTa at the forehead. Contrastingly, lower pain sensitivity was detected in PwH by higher PPTcuff values compared to Con in both legs.

CONCLUSION

While PPTa of the knee and ankle joints are lower in PwH, PPTcuff are higher in PwH compared to Con. This reveals a paradox situation, highlighting that PwH experience local, joint- and hemophilic arthropathy-related pain, whereas pain sensitivity of non-affected soft tissue structures is lower. The reasons explaining the PPTcuff results remain elusive but might be explained by coping strategies counteracting chronic joint pain, resulting in lower sensitivity at non-affected structures.

Fast improvements in functional status after osteopathic manipulative treatment based on myofascial release in patients with moderate or severe fibromyalgia: a retrospective study

OBJECTIVES

Fibromyalgia (FM) is a chronic pain syndrome characterized by a large variety of symptoms. Evidence suggests that an alteration of central nervous system processing of pain could be involved. The purpose of this study is to analyze clinical records of patients affected by FM who underwent osteopathic manipulative treatment (OMT), predominantly based on a myofascial release approach (MFR).

METHODS

This retrospective study considered records of 21 FM patients with moderate or severe functional impact, who consented to OMT in addition to their usual care. The assessment considered the following measures: FIQ (functional status), SF36 (quality of life), VAS (pain), TSK (kinesiophobia) and PSQI (quality of sleeping). Patients were preliminarily assessed over a 1 month run-in phase, then after 1, 2 and 4 months; a 1 month follow-up was also considered.

RESULTS

After one month, 71% of patients reported a decrease in functional impact and scores remained stable until follow-up (from 69.8 to 52.37, p≤0.001). Overall, after four months, patients improved their quality of life, with a score ranging from 33.47 to 42.6 (p≤0.05). We also observed a reduction of pain (p≤0.05).

CONCLUSIONS

A series of OMT sessions based on MFR could play a therapeutic role in improving functional status, pain and quality of life over a period of 4 months.

Affordance-based practice: An ecological-enactive approach to chronic musculoskeletal pain management

BACKGROUND

The biomedical understanding of chronic musculoskeletal pain endorses a linear relationship between noxious stimuli and pain, and is often dualist or reductionist. Although the biopsychosocial approach is an important advancement, it has a limited theoretical foundation. As such, it tends to be misinterpreted in manners that lead to artificial boundaries between the biological, psychological, and social, with fragmented and polarized clinical applications.

OBJECTIVE

We present an ecological-enactive approach to complement the biopsychosocial model. In this approach, the disabling aspect of chronic pain is characterized as an embodied, embedded, and enactive process of experiencing a closed-off field of affordances (i.e., shutting down of action possibilities). Pain is considered as a multi-dimensional, multicausal, and dynamic process, not locatable in any of the biopsychosocial component domains. Based on a person-centered reasoning approach and a dispositional view of causation, we present tools to reason about complex clinical problems in face of uncertainty and the absence of 'root causes' for pain. Interventions to open up the field of affordances include building ability and confidence, encouraging movement variability, carefully controlling contextual factors, and changing perceptions through action according to each patient's self-identified goals. A clinical case illustrates how reasoning based on an ecological-enactive approach leads to an expanded, multi-pronged, affordance-based intervention.

CONCLUSIONS

The ecological-enactive perspective can provide an overarching conceptual and practical framework for clinical practice, guiding and constraining clinicians to choose, combine, and integrate tools that are consistent with each other and with a true biopsychosocial approach.

Fibromyalgia: Could hyperbaric oxygen therapy make the difference? Our experience

Fibromyalgia is a rare disease, difficult to diagnose and to treat. We think that hyperbaric oxygen therapy could improve its signs and symptoms although more evidences have to be accumulated.

Suffering from chronic tinnitus, chronic neck pain, or both: Does it impact the presence of signs and symptoms of central sensitization?

Chronic subjective tinnitus is a prevalent symptom, which has many similarities with chronic pain. Central sensitization is considered as a possible underlying mechanism of both symptoms. Central sensitization has already been investigated in chronic pain populations but not in patients with chronic subjective tinnitus. Therefore, the main objective of this cross-sectional study was to compare signs and symptoms, indicative for central sensitization, in tinnitus patients with and without chronic idiopathic neck pain, patients with chronic idiopathic neck pain only, and healthy controls. Also, differences in psychological and lifestyle factors, possibly influencing the association between central sensitization and tinnitus, were examined as well as correlations between signs and symptoms of central sensitization, and tinnitus, pain, psychological and lifestyle factors. Differences in signs and symptoms of central sensitization were examined using the self-report Central Sensitization Inventory and QST protocol (local and distant mechanical and heat hyperalgesia, conditioned pain modulation). Tinnitus, pain, psychological and lifestyle factors were evaluated using self-report questionnaires. Symptoms of central sensitization and local mechanical hyperalgesia were significantly more present in both tinnitus groups, compared to healthy controls, but were most extensive in the group with chronic tinnitus+chronic idiopathic neck pain. Distant mechanical hyperalgesia, indicative for central sensitization, was only observed in the group with both chronic tinnitus+chronic idiopathic neck pain. This group also displayed a significantly higher psychological burden and poorer sleep than patients with chronic tinnitus only and healthy controls. Signs and symptoms of central sensitization were also shown to be associated with tinnitus impact, pain-related disability, psychological burden and sleep disturbances. This study shows preliminary evidence for the presence of central sensitization in patients with chronic tinnitus+chronic idiopathic neck pain. This could be explained by the higher perceived tinnitus impact, psychological burden and sleep problems in this group. Trial registration: This study is registered as NCT05186259 (www.clinicaltrials.gov).

Neural indices of multimodal sensory and autonomic hyperexcitability in fibromyalgia

Fibromyalgia (FM) is characterized by chronic widespread musculoskeletal pain and psychological distress. Research suggests people with FM experience increased somatosensory sensitization which generalizes to other sensory modalities and may indicate neural hyperexcitability. However, the available evidence is limited, and studies including measures of neural responsivity across sensory domains and both central and peripheral aspects of the neuraxis are lacking. Thirty-nine participants (51.5 ± 13.6 years of age) with no history of neurological disorders, psychosis, visual, auditory, or learning deficits, were recruited for this study. People with FM (N = 19) and control participants (CNT, N = 20) did not differ on demographic variables and cognitive capacity. Participants completed a task that combined innocuous auditory stimuli with electrocutaneous stimulation (ECS), delivered at individually-selected levels that were uncomfortable but not painful. Event-related potentials (ERPs) and electrodermal activity were analyzed to examine the central and sympathetic indices of neural responsivity. FM participants reported greater sensitivity to ECS and auditory stimulation, as well as higher levels of depression, anxiety, ADHD, and an array of pain-related experiences than CNT. In response to ECS, the P50 deflection was greater in FM than CNT participants, reflecting early somatosensory hyperexcitability. The P50 amplitude was positively correlated with the FM profile factor obtained with a principal component analysis. The N100 to innocuous tones and sympathetic reactivity to ECS were greater in FM participants, except in the subgroup treated with gabapentinoids, which aligns with previous evidence of symptomatic improvement with GABA-mimetic medications. These results support the principal tenet of generalized neural hyperexcitability in FM and provide preliminary mechanistic insight into the impact of GABA-mimetic pharmacological therapy on ameliorating the neural excitation dominance.

Self-reported Fatigue was Associated with Increased White-matter Alterations in Long-term Traumatic Brain Injury and Posttraumatic Stress Disorder Patients

Fatigue is a long-lasting problem in traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD), with limited research that investigated the fatigue-related white-matter changes within TBI and/or PTSD cohorts. This exploratory cross-sectional study used diffusion tensor imaging (DTI) and neuropsychological data collected from 153 male Vietnam War veterans, as part of the Alzheimer's Disease Neuroimaging Initiative - Department of Defense, and were divided clinically into control veterans, PTSD, TBI, and with both TBI and PTSD (TBI + PTSD). The existence of fatigue was defined by the question "Do you often feel tired, fatigued, or sleepy during the daytime?". DTI data were compared between fatigue and non-fatigue subgroups in each clinical group using tract-based spatial statistics voxel-based differences. Fatigue was reported in controls (29.55%), slightly higher in TBI (52.17%, PBenf = 0.06), and significantly higher in both TBI + PTSD (66.67%, PBenf = 0.001) and PTSD groups (79.25%, PBenf < 0.001). Compared to non-fatigued subgroups, no white-matter differences were observed in the fatigued subgroups of control or TBI, while the fatigued PTSD subgroup only showed increased diffusivity measures (i.e., radial and axial), and the fatigued TBI + PTSD subgroup showed decreased fractional anisotropy and increased diffusivity measures (PFWE ≤ 0.05). The results act as preliminary findings suggesting fatigue to be significantly reported in TBI + PTSD and PTSD decades post-trauma with a possible link to white-matter microstructural differences in both PTSD and TBI + PTSD. Future studies with larger cohorts and detailed fatigue assessments would be required to identify the white-matter changes associated with fatigue in these cohorts.

Do "central sensitization" questionnaires reflect measures of nociceptive sensitization or psychological constructs? A systematic review and meta-analyses

ABSTRACT

Central sensitization (CS) is defined as an increased nociceptive responsiveness due to sensitization of neurons in the central nervous system, usually the result of prolonged nociceptive input or a disease state associated with noxious inputs (eg, polyarthritis). The concept of CS has recently been adopted in clinical assessments of chronic pain, but its diagnosis in humans may now include a wide range of hypervigilant responses. The purpose of this review is to ascertain whether self-report questionnaires linked with CS are associated with enhanced nociceptive responses or whether they measure sensitivity in a broader sense (ie, emotional responses). According to our published, PROSPERO-registered review protocol (CRD42021208731), a predefined search of studies that involve the Central Sensitization Inventory (CSI) or Pain Sensitivity Questionnaire (PSQ), correlated with either nociceptive sensory tests or emotional hypervigilance was conducted on MEDLINE, PsycINFO, and Web of Science. Correlations between the CSI or PSQ with our primary outcomes were extracted and meta-analysed. A review of 66 studies totalling 13,284 participants found that the CSI (but not the PSQ) strongly correlated with psychological constructs: depression, anxiety, stress, pain catastrophising, sleep, and kinesiophobia. The CSI and PSQ showed weak or no correlations with experimental measures of nociceptive sensitivity: pain thresholds, temporal summation, or conditioned pain modulation. The PSQ did, however, correlate strongly with phasic heat and tonic cold pain tests. The studies reviewed did not provide sufficient evidence that self-report measures reflect a canonical understanding of CS. The CSI more closely reflects psychological hypervigilance than increased responsiveness of nociceptive neurons.

Emotional arousal and valence in patients with fibromyalgia: a pilot study

The pathogenesis of pain in fibromyalgia is still not completely understood. A disrupted emotional modulation could affect the physiology of nociception and contributes to an altered perception of pain. The aim of this study was to test the role of emotional arousal and valence in pain susceptibility in fibromyalgia using the International Affective Picture System (IAPS) paradigm and the Fibromyalgia Severity Scale (FSS). The study focused on comparing emotional arousal and valence between patients with fibromyalgia and the control group. The secondary objective was to examine the correlation between emotional indices and scores on the FSS and the duration of the disease. The 20 patients with fibromyalgia enrolled showed a higher mean arousal score for all the stimuli, including a higher score for unpleasant and socially unpleasant stimuli. The valence scores for social-relevant stimuli were also higher. Increased arousal to unpleasant and socially unpleasant images and increased valence of them correlated with the duration of the disease and the severity of symptoms and could reflect impairment in social cognition and marked sensitivity to pain in interaction with central nociceptive dysregulation.

Efficiency of pain inhibition and facilitation of fibromyalgia patients is not different from healthy controls: Relevance of sensitivity-adjusted test stimuli

Background

Pain is a dynamic phenomenon dependent on the balance of endogenous excitatory and inhibitory systems, which can be characterized by quantitative sensory testing. Many previous studies of pain modulatory capacity of patients with fibromyalgia syndrome (FM) have reported decreased pain inhibition or increased pain facilitation. This is the first study to assess pain modulation, including conditioned pain modulation (CPM) and temporal pain summation, in the same healthy control (HC) and FM participants.

Methods

Only sensitivity-adjusted stimuli were utilized for testing of conditioned pain modulation (CPM) and temporal pain summation in 23 FM patients and 28 HC. All subjects received sensitivity-adjusted ramp-hold (sRH) during testing of pain facilitation (temporal summation) and pain inhibition (CPM). CPM efficacy was evaluated with test stimuli applied either concurrently or after application of the conditioning stimulus. Finally, the effects of CPM on pressure pain thresholds were tested.

Results

FM subjects required significantly less intense test and conditioning stimuli than HC participants to achieve standardized pain ratings of 50 ± 10 numerical rating scale (NRS) (p = 0.03). Using such stimuli, FM subjects' temporal pain summation and CPM efficacy was not significantly different from HC (all p > 0.05), suggesting similar pain facilitation and inhibition. Furthermore, the CPM efficacy of FM and HC participants was similar regardless of whether the test stimuli were applied during or after the conditioning stimulus (p > 0.05).

Conclusion

Similar to previous studies, FM participants demonstrated hyperalgesia to heat, cold, and mechanical stimuli. However, using only sensitivity-adjusted stimuli during CPM and temporal summation testing, FM patients demonstrated similarly effective pain inhibition and facilitation than HC, suggesting that their pain modulation is not abnormal.

Pressure Pain Thresholds and Central Sensitization in Relation to Psychosocial Predictors of Chronicity in Low Back Pain

(1) Background: Peripheral, as well as central, sensitization have been described in chronic low back pain (cLBP). The purpose of this study is to investigate the influence of psychosocial factors on the development of central sensitization. (2) Methods: This prospective study investigated local and peripheral pressure pain thresholds and their dependence on psychosocial risk factors in patients with cLBP receiving inpatient multimodal pain therapy. Psychosocial factors were assessed using the Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ). (3) Results: A total of 90 patients were included in the study, 61 (75.4% women, 24.6% men) of whom had significant psychosocial risk factors. The control group consisted of 29 patients (62.1% women, 37.9% men). At baseline, patients with psychosocial risk factors showed significantly lower local and peripheral pressure pain thresholds, suggesting central sensitization, compared to the control group. Sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI), was also correlated with altered PPTs. After multimodal therapy, all participants reported increased local pain thresholds compared to at admission, independent of psychosocial chronification factors. (4) Conclusions: Psychosocial chronicity factors measured using the ÖMPSQ have a significant influence on pain sensitization in cLBP. A 14-day multimodal pain therapy increased local, but not peripheral, pressure pain thresholds.

Effectiveness of a Primary Care Multidisciplinary Treatment for Patients with Chronic Pain Compared with Treatment as Usual

To manage chronic pain, multidisciplinary interventions have been increasingly deployed, mostly in secondary or tertiary care settings. Evidence on the effectiveness of multidisciplinary intervention within primary care is scarce. This study examined the effectiveness of a primary care multidisciplinary treatment for chronic pain compared with treatment as usual (TAU). The intervention consisted of pain neuroscience education and treatment by a GP, psychologist, and physiotherapist. Both groups filled out patient-reported outcome measures at baseline, 6 months, and 12 months. The results indicated there were no statistically significant differences for the primary outcomes of pain intensity, number of pain sites, and health-related quality of life (HR-QoL). There was a statistically significant difference in the secondary outcome perceived health change in favor of the intervention group. None of the other differences were statistically significant. A post-hoc analysis showed that there were statistically significant effects on patients' illness perceptions in favor of the intervention group. Based on the results, the findings do not support effectiveness of a low intensity outpatient multidisciplinary primary care treatment to treat chronic pain compared with TAU. However, as a result of several study limitations, it is considered unwarranted to conclude that multidisciplinary treatment in primary care is not valuable at all.

Activity-related pain predicts pain and functional outcomes in people with knee osteoarthritis: A longitudinal study

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition, commonly resulting in pain and disability. However, pain and disability in this population are poorly related with the degree of structural joint damage. Underlying pain mechanisms, including activity-related pain and sensitization assessed via Quantitative Sensory Testing (QST), may better predict pain and functional outcomes of those with knee OA. Therefore, the aim of this study was to explore whether activity-related pain and sensitization assessed via QST predict future pain, function, fatigue, physical performance and quality of life outcomes in those living in the community with knee OA. Eighty-six participants with knee OA were recruited in Dunedin, New Zealand. Those eligible to participate underwent baseline testing including QST as well as measures of activity-related pain including Movement-evoked Pain (MEP) and Sensitivity to Physical Activity (SPA). Outcome measures exploring pain, function, fatigue and quality of life outcomes were collected at baseline, and two follow-up periods (two and nine weeks). Univariable linear regression models were developed followed by multivariable linear regression models for each prognostic marker adjusting for age, gender, BMI, OA duration, baseline pain intensity and socioeconomic status. Activity-related measures of pain, including MEP and SPA, demonstrated predictive associations with pain and functional outcomes prospectively in those with knee OA. Therefore, those demonstrating activity-related pain are at future risk of greater pain, disability and reduced quality of life. Larger, externally validated longitudinal studies are required which include individuals with more severe knee OA.

Mediation Effect of Pain on the Relationship between Kinesiophobia and Postural Control: Comparison and Correlations in Individuals with Fibromyalgia Syndrome and Asymptomatic Individuals-A Cross-Sectional Study

Background: Individuals with fibromyalgia syndrome (FM) usually present with a fear of movement (kinesiophobia), which causes their symptoms to be maintained and exacerbated. Kinesiophobia can significantly impact postural control; ascertaining their association is crucial in evaluating and managing individuals with FM. This study aims to (1) compare postural control between individuals with FM and asymptomatic individuals, (2) estimate the relationship between kinesiophobia and postural control in individuals with FM, and (3) evaluate whether pain intensity mediates the association between kinesiophobia and postural control in individuals with FM. Methods: This study enrolled 92 individuals (mean age: 51.52 ± 7.7 years) diagnosed with FM and 106 asymptomatic individuals (mean age: 50.47 ± 6.6 years). The examiners estimated the fear of movement and the intensity of pain utilizing the Tampa scale of kinesiophobia (TSK) scores and the visual analogue scale (VAS), respectively. The postural control variables included anteroposterior (A-P) sway in mm, medio-lateral (M-L) sway in mm, and ellipse area in mm2. Results: The individuals with FM had impaired postural control compared to the asymptomatic individuals (p < 0.001). Kinesiophobia exhibited mild-to-moderate correlations with the postural control variables (nondominant side: A-P sway: r = 0.48, M-L sway: r = 0.49, ellipse area: r = 0.43. Dominant side: A-P sway: r = 0.41, M-L sway: r = 0.33, ellipse area: r = 0.44). The pain intensity significantly mediated the relationship between kinesiophobia and postural control (p < 0.001). Conclusion: Kinesiophobia showed a significant positive relationship with postural control. The individuals with FM with higher TSK scores had decreased postural control. Pain intensity mediated the relationship between kinesiophobia and postural control. These factors must be considered when evaluating and formulating treatment strategies for people with FM.

Relationship between dysphonia and anxiety in fibromyalgia syndrome

BACKGROUND

Our aim in conducting this study is to determine the relationship dysphonia and anxiety in patients with fibromyalgia syndrome (FS).

METHODS

Between April 2021 and June 2021, 25 FS diagnosed patients (22 females, 3 males; mean age: 45.36 ± 7.68 years; range 27-65 years), and, for the control group, 25 healthy volunteers (20 females, 5 males; mean age: 42.60 ± 9.98 years; range 29-62 years) with similar demographic features were included in the study. Visual Analog Scale (VAS), Beck Anxiety Questionary (BAQ), and voice analyses were evaluated for all the participants. Acoustic parameters (AP), such as F₀ (Hz), jitter (%), shimmer (%), and Maximum Phonation Time (MPT), were measured for dysphonia. The correlation between MPT and BAQ was evaluated.

RESULTS

The demographic characteristics of the groups did not differ statistically significantly (p > 0.05). VAS and BAQ scores were statistically significantly higher in the FS group than healthy individuals. In the assessment of sound, there was no significant difference between F0 and jitteriness between the two groups. While shimmer scores were significantly higher in the FS group, MPT scores were statistically significantly higher in healthy individuals.

CONCLUSIONS

In our study, we observed that FS patients had statistically significantly higher BAQ, VAS scores compared to the control group. The shimmer of voice was increased and MPT values were decreased statistically significantly in FS patients. This says that there may be weakness in the laryngeal muscles affecting the vocal cord and thus voice quality. In addition to this, increased anxiety in FS patients may be associated with dysphonia. There is need for more controlled studies with increased number of patients to investigate the dysphonia in FS patients.

Factors affecting the prevalence, severity, and characteristics of ocular surface pain

Introduction

Ocular surface pain has been traditionally lumped under the umbrella term "dry eye" (DE) but is now understood as its own entity and can occur in the absence or presence of tear dysfunction. Identifying patients at risk for the development of chronic ocular surface pain, and factors contributing to its severity are important in providing precision medicine to patients.

Areas covered

In this review, we discuss factors linked to the presence and severity of ocular surface pain, including eye related features, systemic characteristics, and environmental findings. We discuss corneal nerves, whose anatomic and functional integrity can be characterized through in vivo confocal microscopy images and testing of corneal sensitivity. We review systemic diseases that are co-morbid with ocular surface pain, including physical and mental health diagnoses. Finally, we identify environmental contributors, including air pollution, previous surgeries, and medications, associated with ocular surface pain.

Expert opinion

Intrinsic and extrinsic factors contribute to ocular surface pain and must be considered when evaluating an individual patient. These factors can inform the suspected etiology of the pain, and guide management decisions such as tear replacement or medications targeting nerve pain.

Algometry for the assessment of central sensitisation to pain in fibromyalgia patients: a systematic review

INTRODUCTION

The pathophysiology of fibromyalgia (FM) is related to central sensitisation (CS) to pain. Algometry allows assessing CS based on dynamic evoked pain. However, current algometrýs protocols require optimising, unifying and updating.

OBJECTIVES

1) identify the dynamic pain measures used most frequently to effectively assess CS processes in FM, and 2) consider the future of the algometry assessing CS in these patients.

METHODS

Cochrane Collaboration guidelines and PRISMA statements were followed. The protocol was registered in PROSPERO database (ID: CRD42021270135). The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched.

RESULTS

Thirty-four studies were selected, including measures such as temporal summation of pain (TSP), aftersensations (AS), spatial summation of pain (SSP), the noxious flexion reflex (NFR) threshold, conditioned pain modulation (CPM), cutaneous silent period (CuSP), and slowly repeated evoked pain (SREP); and evoked pain combined with neuroimaging. Each measure offered various advantages and limitations. According to ROB, 28 studies were of low quality, 3 of moderate quality, and 3 of high quality.

CONCLUSIONS

Several pain indicators have been demonstrated to successfully examine CS involvement in FM in the last years. Algometry, especially when it involves diverse body sites and tissues, might provide further insight into (1) the evaluation of psychological factors known to influence pain experience, (2) new dynamic pain indicators, and (3) the simultaneous use of certain neuroimaging techniques. Further research clarifying the mechanisms underlying some of these measures, and homogenisation and optimisation of the algometrýs protocols, are needed. KEY MESSAGESAlgometry allows for assessing Central Sensitisation by applying dynamic evoked pain.The future of algometry could relapse in its combination with neuroimaging.Recently-emerged pain indicators should be considered for algometrýs new protocols.

Fibromyalgia and Chronic Fatigue Syndromes: A systematic review and meta-analysis of cardiorespiratory fitness and neuromuscular function compared with healthy individuals

OBJECTIVE

To determine cardiorespiratory fitness and neuromuscular function of people with CFS and FMS compared to healthy individuals.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Medline, CINAHL, AMED, Cochrane Central Register of Controlled Trials (CENTRAL), and PEDro from inception to June 2022.

ELIGIBLE CRITERIA FOR SELECTING STUDIES

Studies were included if presenting baseline data on cardiorespiratory fitness and/or neuromuscular function from observational or interventional studies of patients diagnosed with FMS or CFS. Participants were aged 18 years or older, with results also provided for healthy controls. Risk of bias assessment was conducted using the Quality Assessment Tool for Quantitative Studies (EPHPP).

RESULTS

99 studies including 9853 participants (5808 patients; 4405 healthy controls) met our eligibility criteria. Random effects meta-analysis showed lower cardiorespiratory fitness (VO2max, anaerobic threshold, peak lactate) and neuromuscular function (MVC, fatigability, voluntary activation, muscle volume, muscle mass, rate of perceived exertion) in CFS and FMS compared to controls: all with moderate to high effect sizes.

DISCUSSION

Our results demonstrate lower cardiorespiratory fitness and muscle function in those living with FMS or CFS when compared to controls. There were indications of dysregulated neuro-muscular interactions including heightened perceptions of effort, reduced ability to activate the available musculature during exercise and reduced tolerance of exercise.

TRAIL REGISTRATION

PROSPERO registration number: (CRD42020184108).

Online Questionnaire with Fibromyalgia Patients Reveals Correlations among Type of Pain, Psychological Alterations, and Effectiveness of Non-Pharmacological Therapies

Fibromyalgia (FM) is a chronic pain syndrome with an unclear etiology. In addition to pain, FM patients suffer from a diverse array of symptoms and comorbidities, encompassing fatigue, cognitive dysfunction, mood disorders, sleep deprivation, and dizziness. Due to the complexity of FM, the diagnosis and treatment of it are highly challenging. The aim of the present work was to investigate some clinical and psychological characteristics of FM patients, and to uncover possible correlations with pharmacological and non-pharmacological therapies. We conducted a cross-sectional, questionnaire-based study aimed at evaluating pain, psychological traits, and the self-perceived effectiveness of pharmacological and non-pharmacological treatments in an Italian population of FM patients. Descriptive statistics, correlation, and inference analyses were performed. We found a prevalence of a neuropathic/nociplastic type of pain, which correlated with psychological traits such as anxiety, low mood, psychophysical discomfort, and the inability to relax. The pain type and psychological traits proved to play a role in determining the self-perceived effectiveness of therapeutic interventions. Patients revealed a better response to non-pharmacological therapies, particularly dietary interventions, relaxation techniques, and psychotherapy rather than pharmacological interventions. The sum of our data indicates that for better outcomes, the type of pain and psychological traits should be considered for tailor-made treatments considering non-pharmacological protocols as a complement to the use of drugs.

A behavioral and brain imaging dataset with focus on emotion regulation of women with fibromyalgia

Fibromyalgia is a chronic condition characterized by widespread pain, as well as numerous symptoms related to central sensitization such as: fatigue, cognitive disturbances, constipation/diarrhea and sensory hypersensitivity. Furthermore, depression and anxiety are prevalent comorbidities, accompanied by emotion processing and regulation difficulties. Although fibromyalgia physiopathology is still not fully understood, neuroimaging research methods have shown brain structural and functional alterations as well as neuroinflammation abnormalities. We believe that open access to data may help fibromyalgia research advance more. Here, we present an open dataset of 33 fibromyalgia female patients and 33 paired healthy controls recruited from a Mexican population. Dataset includes demographic, clinical, behavioural and magnetic resonance imaging (MRI) data. The MRI data consists of: structural (T1- and T2- weighted) and functional (task-based and resting state) sequences. The task was an emotion processing and regulation task based on visual stimuli. The MRI data contained in the repository are unprocessed, presented in Brain Imaging Data Structure (BIDS) format and available on the OpenNeuro platform for future analysis.

Associations between visceral fat chronic low back pain and central sensitization in patients with lumbar spinal stenosis

BACKGROUND

Pain sensitization may be one of the mechanisms contributing to chronic low back pain (CLBP).

OBJECTIVE

To evaluate the association between visceral fat, CLBP, and central sensitization (CS); describe the relationship between low back pain (LBP) intensity and CS; and identify possible correlation between visceral fat and LBP intensity.

METHODS

Patients with CLBP were divided using their CS inventory (CSI) scores into low- (CSI < 40) and high-CSI (CSI ⩾ 40) subgroups. We compared computed tomography (CT) measurements and scores for association with pain according to the visual analogue scale (VAS) between the two groups.

RESULTS

The low-CSI and the high-CSI groups had 47 patients (67.1%; 21 men, 26 women) and 23 patients (32.9%; 11 men and 12 women), respectively. The high-CSI group had a significantly higher mean VAS score (p< 0.01) and estimated mean visceral fat area (p< 0.05) than the low-CSI group. There was a moderate positive correlation between VAS score and visceral fat (standardised partial regression coefficient: 0.659, p< 0.01) in the high-CSI group according to multiple linear regression analysis adjusted for age and sex.

CONCLUSIONS

Visceral fat is associated with CLBP, regardless of sex or age, and may be a potential therapeutic target for CLBP with CS.

Central Sensitization in Migraine: A Narrative Review

Central sensitization (CS) is an increase in the responsiveness of nociceptive neurons in the central nervous system to their normal afferent input. As a result, even minor irritation can induce severe pain, leading to the chronicity and severity of various diseases, such as neurological disorders. CS is associated with migraine, which is a major neurological disorder that inflicts a high disability in daily life. Specifically, CS is thought to be involved in the pathogenesis of cutaneous allodynia as well as chronification of migraine. In this article, we reviewed the association between CS and migraine, including pathophysiological aspects and evidence from clinical studies. We suggest that appropriate screening and management of CS in migraine could further improve the quality of life of migraine patients.

Network Analysis for Better Understanding the Complex Psycho-Biological Mechanisms behind Fibromyalgia Syndrome

The aim of this study was to assess potential associations between sensory, cognitive, health-related, and physical variables in women with fibromyalgia syndrome (FMS) using a network analysis for better understanding the complexity of psycho-biological mechanisms. Demographic, clinical, pressure pain threshold (PPT), health-related, physical, and psychological/cognitive variables were collected in 126 women with FMS. A network analysis was conducted to quantify the adjusted correlations between the modeled variables and to assess the centrality indices (i.e., the degree of connection with other symptoms in the network and the importance in the system modeled as a network. This model showed several local associations between the variables. Multiple positive correlations between PPTs were observed, being the strongest weight between PPTs over the knee and tibialis anterior (ρ: 0.28). Catastrophism was associated with higher hypervigilance (ρ: 0.23) and lower health-related EuroQol-5D (ρ: −0.24). The most central variables were PPT over the tibialis anterior (the highest strength centrality), hand grip (the highest harmonic centrality) and Time Up and Go (the highest betweenness centrality). This study, applying network analysis to understand the complex mechanisms of women with FMS, supports a model where sensory-related, psychological/cognitive, health-related, and physical variables are connected. Implications of the current findings, e.g., developing treatments targeting these mechanisms, are discussed.

"Convergent validity of the central sensitization inventory and experimental testing of pain sensitivity"

OBJECTIVES

The aim of the current study was to examine the convergent validity of the Central Sensitization Inventory by quantifying the correlation with experimental measures of pain sensitivity and self-reported psycho-social questionnaires, in a low back pain population.

METHODS

All participants were recruited from an outpatient hospital spine care clinic (Spine Centre of Southern Denmark). Participants underwent a standardized experimental pain test protocol and completed the Central Sensitization Inventory (CSI) along with additional self-reported questionnaires to assess psycho-social constructs across different domains. The association between the CSI, experimental pain measures and other self-reported psycho-social questionnaires were analyzed using correlation and contingency tests. ROC-curve analysis was used to determine sensitivity and specificity for CSI.

RESULTS

One hundred sixty-eight (168) participants were included. The CSI was weakly correlated with nine out of 20 variables in the experimental pain test protocol (rho range -0.37 to 0.22). The CSI was more closely correlated with psycho-social factors such as work ability, disability, and symptoms of exhaustion disorder. ROC-analysis identified an optimal cut-point of 44 on CSI (Sn=39.1% Sp=87.4%). The CSI had an area under the ROC curve of 0.656. Fisher's exact test demonstrated a statistically significant association between participants scoring ≥40 on CSI and participants categorized as sensitized by experimental pain tests (p-value=0.03).

CONCLUSIONS

Our findings are consistent with previous studies, indicating that the CSI is related to psycho-social constructs. However, the convergent validity with experimental pain measures is small and probably not clinically meaningful.

Thalamocortical bistable switch as a theoretical model of fibromyalgia pathogenesis inferred from a literature survey

Fibromyalgia (FM) is an unsolved central pain processing disturbance. We aim to provide a unifying model for FM pathogenesis based on a loop network involving thalamocortical regions, i.e., the ventroposterior lateral thalamus (VPL), the somatosensory cortex (SC), and the thalamic reticular nucleus (TRN). The dynamics of the loop have been described by three differential equations having neuron mean firing rates as variables and containing Hill functions to model mutual interactions among the loop elements. A computational analysis conducted with MATLAB has shown a transition from monostability to bistability of the loop behavior for a weakening of GABAergic transmission between TRN and VPL. This involves the appearance of a high-firing-rate steady state, which becomes dominant and is assumed to represent pathogenic pain processing giving rise to chronic pain. Our model is consistent with a bulk of literature evidence, such as neuroimaging and pharmacological data collected on FM patients, and with correlations between FM and immunoendocrine conditions, such as stress, perimenopause, chronic inflammation, obesity, and chronic dizziness. The model suggests that critical targets for FM treatment are to be found among immunoendocrine pathways leading to GABA/glutamate imbalance having an impact on the thalamocortical system.