Pain-related cognitions and emotional distress are not associated with conditioned pain modulation: an explorative analysis of 1142 participants with acute, subacute, and chronic pain

The effect of expectancy on conditioned pain modulation: evidence from functional near-infrared spectroscopy

Background and objective

The psychological mechanisms that make Conditioned Pain Modulation (CPM) an effective non-pharmacological intervention are still not fully understood. Expectancy is believed to be a critical psychological factor affecting CPM effects, but its specific role has yet to be fully clarified. This study aims to explore the relationship between expectancy and CPM while providing physiological evidence using functional near-infrared spectroscopy (fNIRS).

Method

A standardized CPM induction paradigm was implemented, with verbal guidance used to induce expectancy. The Numeric Rating Scale (NRS) assessed the intensity of the test stimulus (TS), while an 11-point scale evaluated participants' attentional focus on the TS and the effect of expectancy. fNIRS was employed to monitor changes in prefrontal cortex (PFC) activity.

Results

Expectancy significantly amplified the CPM effect (p = 0.036) while markedly reducing attention to the experimental stimulus (p = 0.004). fNIRS findings indicated significant reductions in activity within the left frontal eye field, left dorsolateral prefrontal cortex, and left frontal pole regions. In the post-test, the control group demonstrated significantly higher cortical activity in the right frontal pole region compared to the expectancy group (p < 0.05). Within the expectancy group, bilateral frontal pole cortical activity was significantly lower in the post-test compared to the pre-test (p < 0.05).

Conclusion

Expectancy represents a key psychological mechanism underlying the CPM effect, potentially modulating its magnitude through attention regulation and accompanied by a reduction in oxygenated hemoglobin activity in the frontal pole region and introduced the Expectancy-Attention-CPM Modulation Model (ECAM).

Exploring the value of a well-established conditioned pain modulation paradigm in women: a Translational Research in Pelvic Pain (TRiPP) study

Background

Conditioned pain modulation (CPM) is considered a human proxy for descending inhibitory pain pathways. However, there is wide variation in the CPM response described in the literature and ongoing debate about its utility.

Methods

Here we explored CPM in women with (n = 59) and without (n = 26) chronic pelvic pain (CPP), aiming to determine the magnitude of effect and factors influencing variability in the CPM response.

Results

Using a pressure pain threshold test stimulus and ischaemic pressure cuff conditioning stimulus (CS), we found no significant difference in the mean CPM effect between CPP and control participants. Using a robust statistical method (+/-2 standard error of measurement) to further investigate CPM, there was no significant difference in the proportion exhibiting inhibition between controls and CPP participants (X2  = 0.003, p = 0.96). Notably, only 23.1% of our healthy controls demonstrated a "true" CPM effect (n = 4 inhibitory, n = 2 facilitatory). Despite a rich data set, we were unable to identify any single questionnaire, clinical or psychophysical covariate correlating with the CPM effect.

Conclusions

Despite using one of the recommended CPM paradigms we were only able to demonstrate "true" CPM in 23.1% of control participants. Thus, the absence of differences between women with and without chronic pelvic pain must be interpreted with caution. Future studies using different CPM paradigms or larger sample sizes may find different results. Although CPM in chronic pain populations is of major theoretical mechanistic interest, the lack of an established assessment standard led us to question its added value in current clinical research.

The Association between Pressure Pain Thresholds, Conditioned Pain Modulation, Clinical Status, and Sleep Quality in Fibromyalgia Patients: A Clinical Trial Secondary Analysis

Background: Fibromyalgia (FM) is a complex multidimensional disorder primarily characterized by chronic widespread pain, significantly affecting patients' quality of life. FM is associated with some clinical signs found with quantitative sensory testing (QST), sleep disturbance, or psychological problems. This study aims to explore the associations between pressure pain thresholds (PPTs), conditioned pain modulation (CPM), clinical status, and sleep quality in FM patients, offering insights for better clinical management and assessment tools. Methods: This secondary analysis utilized data from a clinical trial involving 129 FM patients. Various assessments, including the Fibromyalgia Impact Questionnaire (FIQ), Pain Catastrophizing Scale (PCS), State-Trait Anxiety Inventory (STAI), and Jenkins Sleep Scale (JSS), were employed to evaluate the clinical and psychological status and sleep quality. PPTs and CPM were measured to understand their relationship with clinical parameters. Results: Our findings revealed that PPTs and CPM are not significantly associated with the clinical status or sleep quality of FM patients. Instead, pain catastrophizing and anxiety state showed a stronger correlation with the impact of fibromyalgia and sleep disturbances. These results highlight the importance of psychological and cognitive factors in managing FM. Conclusions: The study suggests that while PPTs and CPM may not be reliable biomarkers for clinical status in FM, the use of comprehensive assessments including FIQ, PCS, STAI, and JSS can provide a more accurate evaluation of patients' condition. These tools are cost-effective, can be self-administered, and facilitate a holistic approach to FM management, emphasizing the need for personalized treatment plans.

Correlations of The Central Sensitization Inventory, conditioned pain modulation, cognitions and psychological factors in individuals with chronic neck pain: A cross-sectional study

INTRODUCTION

Chronic neck pain (CNP) is a global public health problem, with high prevalence and absenteeism rates. Central sensitization (CS) as a basis for chronic pain may play an essential role in its development and progression. It is often comorbid with low conditioned pain modulation (CPM) effects, cognitions, and psychological problems.

OBJECTIVES

The purposes of this study were to (1) explore the relationship between pain-related cognitions and psychological factors, CPM effects, and the central sensitization inventory (CSI) scores; and (2) determine whether cognitions and psychological factors can predict CSI scores and CPM effects in individuals with CNP.

METHODS

Fifty-four individuals with CNP were recruited for this cross-sectional study. The following outcome measures were evaluated: The CSI (screening tool) was compared with the cold pressor test (CPT), which was the psychophysical test used to assess the CPM; neck pain intensity using the visual analogue scale (VAS), as well as pain-related cognitions (including kinesiophobia and pain catastrophization) and psychological states (including anxiety and depression) using self-report questionnaires.

RESULTS

CSI score was not associated with the CPM effect (r = 0.257, p > 0.05), and no cognitions or psychological factors were associated with CPM (p > 0.05), but CSI score was moderately positively correlated with kinesiophobia (r = 0.554, p < 0.01), lowly positively correlated with pain catastrophization (r = 0.332, p = 0.017) and anxiety (r = 0.492, p < 0.01), but not depression (r = 0.207, p = 0.132). Multiple linear regression analysis showed that kinesiophobia (B = 1.308, p < 0.01) and anxiety (B = 1.806, p = 0.02) were significant positive predictors of CSI score.

CONCLUSIONS

The findings confirm some of our hypotheses. Accordingly, the findings inferred that the CSI does not seem to respond to CPM effect in patients with CNP effectively. In addition, CSI score was associated with cognitions and psychological factors, of which kinesiophobia and anxiety were effective predictors. In clinical practice, pain-related cognitions and psychological factors should be fully considered to manage neck pain efficiently.

Trim14-IκBα Signaling Regulates Chronic Inflammatory Pain in Rats and Osteoarthritis Patients

Chronic inflammatory pain is the highest priority for people with osteoarthritis when seeking medical attention. Despite the availability of NSAIDs and glucocorticoids, central sensitization and peripheral sensitization make pain increasingly difficult to control. Previous studies have identified the ubiquitination system as an important role in the chronic inflammatory pain. Our study displayed that the E3 ubiquitin ligase tripartite motif-containing 14 (Trim14) was abnormally elevated in the serum of patients with osteoarthritis and pain, and the degree of pain was positively correlated with the degree of Trim14 elevation. Furthermore, CFA-induced inflammatory pain rat model showed that Trim14 was significantly increased in the L3-5 spinal dorsal horn (SDH) and dorsal root ganglion (DRG), and in turn the inhibitor of nuclear factor Kappa-B isoform α (IκBα) was decreased after Trim14 elevation. After intrathecal injection of Trim14 siRNA to inhibit Trim14 expression, IκBα expression was reversed and increased, and the pain behaviors and anxiety behaviors of rats were significantly relieved. Overall, these findings suggested that Trim14 may contribute to chronic inflammatory pain by degrading IκBα, and that Trim14 may become a novel therapeutic target for chronic inflammatory pain.

Weak Relationships Between Psychological Factors and Experimental Pain Outcomes in Pain-Free Individuals: An Aggregate Analysis of 8 Studies

Although psychological factors such as anxiety, depression, and pain catastrophizing are known to influence pain outcomes in chronic pain populations, there are mixed results regarding whether they influence experimental pain outcomes in pain-free individuals. The objectives of this study were to determine the associations between psychological factors and experimental pain outcomes in pain-free adolescents and adults. Relationships between anxiety, depression, and pain catastrophizing and experimental pain outcomes across 8 different studies (total N = 595) were examined in different populations of pain-free adult and adolescent participants. Analyses were conducted with and without controlling for sex, age, and race. Studies were analyzed separately and as part of an aggregate analysis. Individual study analyses resulted in 136 regression models. Of these, only 8 models revealed a significant association between psychological factors and pain outcomes. The significant results were small and likely due to Type 1 error. Controlling for demographic factors had minimal effect on the results. The aggregate analyses revealed weak relationships between anxiety and pressure pain threshold (Fisher's z = -.10 [-.19, -.01]), anxiety and cold pain intensity ratings (Fisher's z = .18 [.04, .32]), and pain catastrophizing and pressure pain threshold (Fisher's z = -.14 [-.26, -.02]). Sample size calculations based on the aggregate analyses indicated that several hundred participants would be required to detect true relationships between these psychological factors and pain measures. The overall negative findings suggest that in pain-free individuals, anxiety, depression, and pain catastrophizing are not meaningfully related to experimental pain outcomes. PERSPECTIVE: Psychological variables have been shown to predict pain outcomes in chronic pain populations but these relationships may not generalize to pain-free populations. An analysis of 595 pain-free individuals across 8 studies in our lab revealed that anxiety, depression, and pain catastrophizing were not meaningfully related to experimental pain outcomes.

Current and future advances in practice: tendinopathies of the hip

Tendinopathy describes persistent tendon pain and loss of function related to mechanical loading. Two common hip tendinopathies seen in practice are gluteal tendinopathy and proximal hamstring tendinopathy. Both conditions can be frustrating for patients and clinicians due to the delay in diagnosis, significant disability caused and lack of response to common treatments. Tendinopathy is a clinical diagnosis and can most often be made using findings from the patient interview and pain provocation tests, without the need for imaging. Specific education and progressive exercise offer a low-risk and effective option for gluteal tendinopathy and result in greater rates of treatment success than corticosteroid injection, both in the short term (8 weeks) and at 1 year. Proximal hamstring tendinopathy is a common, but less researched, and under-recognized cause of persistent ischial pain. As research on proximal hamstring tendinopathy is limited, this review summarizes the available evidence on diagnosis and treatment following similar principles to other well-researched tendinopathies.

Conditioned Pain Modulation Does Not Differ Between People With Lower-Limb Tendinopathy and Nontendinopathy Controls: A Systematic Review With Individual Participant Data Meta-analysis

OBJECTIVE: To explore whether people with lower-limb tendinopathy have reduced relative conditioned pain modulation (CPM) when compared to nontendinopathy controls. DESIGN: Systematic review with individual participant data (IPD) meta-analysis. LITERATURE SEARCH: Eight databases were searched until August 29, 2022. STUDY SELECTION CRITERIA: Cross-sectional studies comparing the magnitude of the CPM effect in people with lower-limb tendinopathy to nontendinopathy controls in a case-control design. DATA SYNTHESIS: Included studies provided IPD, which was reported using descriptive statistics. Generalized estimating equations (GEEs) determined between-group differences in the relative CPM effect, when adjusting for co-variables. Study quality was assessed using a Joanna Briggs Institute checklist, and certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluations. RESULTS: Five records were included, IPD were provided for 4 studies (n = 219 with tendinopathy, n = 226 controls). The principal GEE (model 1) found no significant relative CPM effects for tendinopathy versus controls (B = -1.73, P = .481). Sex (B = 4.11, P = .160), age (B = -0.20, P = .109), and body mass index (B = 0.28, P = .442) did not influence relative CPM effect. The Achilles region had a reduced CPM effect (B = -22.01, P = .009). In model 2 (adjusting for temperature), temperature (B = -2.86, P = .035) and female sex (B = 21.01, P = .047) were associated with the size of the relative CPM effect. All studies were low-quality, and the certainty of the evidence was moderate. CONCLUSION: There were no between-group differences in the magnitude of the CPM effect, suggesting clinicians should manage lower-limb tendinopathy using interventions appropriate for peripherally dominant pain (eg, tendon loading exercises such as heavy slow resistance). Based on the "moderate"-certainty evidence, future studies are unlikely to substantially change these findings. J Orthop Sports Phys Ther 2023;54(1):1-10. Epub 19 October 2023. doi:10.2519/jospt.2023.11940.

Lifestyle factors and psychological factors are associated with central pain processing in service members with persistent low-back pain: A cross-sectional exploratory study

Persistent low-back pain (LBP) is highly prevalent in the military. Altered central pain processing is one of the mechanisms found to underlie persistent LBP. Our aim was to explore which factors are associated with altered pain processing in Dutch service members with persistent LBP. This knowledge may guide clinicians in what factors to address in the treatment of dysfunctional pain processing in service members with persistent LBP. Twenty-one service members with persistent LBP (mean age 34.0 years, 18 males) were included in this cross-sectional exploratory study. Participants completed questionnaires regarding lifestyle and psychological factors. Altered central pain processing was measured by temporal summation of pain to examine the function of the pain facilitatory system and by conditioned pain modulation to examine the pain inhibitory function. Univariable and multivariable linear regression analyses were performed. A higher local temporal summation of pain was associated with a longer sitting time, a higher level of physical activity and a higher level of pain catastrophizing. A higher local conditioned pain modulation was associated with a higher level of pain catastrophizing, anxiety and depression symptoms, and with a lower sleep quality. A higher remote conditioned pain modulation effect was associated with a higher level of physical activity, a higher body mass index and a shorter sitting time. This study succeeded in identifying lifestyle and psychological factors associated with altered pain processing in service members with persistent LBP. Prospective studies are needed to examine causality in these relationships.