Pain catastrophizing is associated with pain thresholds for heat, cold and pressure in women with chronic pelvic 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.

Cognitive-affective changes mediate the mindfulness-based intervention effect on endometriosis-related pain and mental health: A path analysis approach

BACKGROUND

There is poor knowledge about the therapeutic mechanisms of the conservative interventions for endometriosis. We hypothesized that the effects of a brief mindfulness-based intervention (bMBI) on pelvic pain intensity (PPI), pain unpleasantness (PU) and quality of life mental health (QoL-MH) are mediated by direct and indirect paths of changes in pain catastrophizing (PC), positive affect (PA) and negative affect (NA).

METHODS

A secondary analysis of a pilot randomized controlled trial of women with endometriosis, assigned to standard medical treatment (n = 32) and standard medical treatment plus bMBI (n = 31). We tested a series of parallel and serial mediators (PC, PA and NA) of the relationship between bMBI and outcomes (PPI, PU and QoL-MH).

RESULTS

The bMBI group demonstrated improvement in PA (Cohen's f2  = 0.12 [0.01, 0.36]), decreases in NA (Cohen's f2  = 0.06 [0.00, 0.24]) and PC (Cohen's f2  = 0.16 [0.02, 0.42]). The PC reduction mediated the effect of the bMBI on PPI and PU directly; however, the PC effect through PA increase mediated the PU marginally but not PPI changes. bMBI effect on Qol-MH was mediated directly by PA and NA. The PC improved Qol-MH through PA increase and Pain decrease but not via NA.

CONCLUSIONS

Our findings showed that bMBI impacts pain through changes in pain-related cognitive-affective factors. bMBI can improve QoL-MH by multiple pathways, including but not limited to pain reduction, highlighting the independent potential of improvement in affect to restore mental health in endometriosis.

SIGNIFICANCE

Brief mindfulness-based intervention improves endometriosis pain through pain-related cognitive-affective factors and quality of life mental health via pain and affect changes unrelated to pain.

Evaluation of a scoring system for the detection of central sensitization among women with chronic pelvic pain

BACKGROUND

Central sensitization is frequently associated with chronic pelvic pain and requires specific management. The pain is described as hypersensitivity to an innocuous stimulus that is both widespread and persistent. However, no study has evaluated if central sensitization can be measured objectively with neurophysiological tests in the pelvic and perineal area to prove this concept in women with chronic pelvic pain.

OBJECTIVE

This study aimed to evaluate nociceptive thresholds (primary objective) and spatial and temporal diffusion of pain among women with chronic pelvic pain and high or low scores of central sensitization.

STUDY DESIGN

This prospective, assessor-blinded, comparative study compared a cohort of women with chronic pelvic pain and a high (>5/10; n=29) vs low (<5/10; n=24) score of sensitization according to the Convergences PP criteria. Participants underwent a noninvasive bladder sensory test, a rectal barostat test, and a muscular (algometer) and a vulvar (vulvagesiometer) sensory test. Poststimulation pain (minutes), quality of life (Medical Outcomes Study 36-Item Short Form Survey), and psychological state, comprising anxiety (State-Trait Anxiety Inventory), depression (Beck Depression Inventory Short Form), and catastrophizing (Pain Catastrophizing Scale), were assessed.

RESULTS

The participants mostly suffered from endometriosis (35.8%), irritable bowel syndrome (35.8%), bladder pain syndrome (32.1%), and vestibulodynia (28.3%). Baseline characteristics were similar. Women with a high sensitization score had more painful diseases diagnosed (2.7±1.3 vs 1.6±0.8; P=.002) and suffered for longer (11±8 vs 6±5 years; P=.028) than participants with a low score. The bladder maximum capacity was equivalent between participants (399±168 vs 465±164 mL; P=.18). However, the pain felt at each cystometric threshold was significantly increased in women with a high sensitization score. No difference was identified for the rectal pain pressure step (29.3±5.5 vs 30.7±6.5 mm Hg; P=.38). Rectal compliance was decreased in women with a high sensitization score with a considerable increase in pain felt. The average of pain pressure thresholds at the 5 vulvar sites tested was decreased in these participants (162.5±90.5 vs 358.7±196.5 g; P=.0003). Similar results were found for the average of the pain pressure thresholds at 6 muscles tested (1.34±0.41 vs 2.63±1.52 kg/m2; P=.0002). A longer period was needed for patients with high sensitization score to obtain a VAS <3 out of 10 after the stimulation of the bladder (4.52±5.26 vs 1.27±2.96 minutes; P=.01), the rectum (3.75±3.81 vs 1.19±1.23 minutes; P=.009), and the muscles (1.46±1.69 vs 0.64±0.40 minutes; P=.002). The psychological state was equivalent between groups. No association was found between the sensory thresholds and the psychological state results. The physical component of the quality of life score was reduced in women with high sensitization score (P=.0005), with no difference in the mental component.

CONCLUSION

Using neurophysiological tests, this study showed that there are objective elements to assess for the presence of central sensitization, independently of psychological factors.

Quantitative sensory testing in a magnetic resonance environment: considerations for thermal sensitivity and patient safety

Introduction

Quantitative sensory testing (QST) is often used to understand the perceptual basis of acute and chronic conditions, including pain. As the need grows for developing a mechanistic understanding of neurological pathways underlying perception in the basic and clinical sciences, there is a greater need to adapt techniques such as QST to the magnetic resonance (MR) environment. No studies have yet evaluated the impact of the MR environment on the perception of thermal stimuli. This study aimed to evaluate the differences in temperature sensitivity outside an MR environment and during an MRI scanning session. We hypothesized that there would be a difference in how participants reported their pain sensitivity between the two environments.

Methods

Healthy participants underwent thermal QST outside the MR scanning environment, where they were asked to rate the temperature of a noxious stimulus at which they perceived their pain to be 7/10, using a Likert scale ranging from 0 to 10. Participants repeated this procedure inside a 3.0 T MRI approximately 30 min later. We repeated our investigation in a clinical cohort of participants with a chronic pain condition.

Results

There were statistically significant changes of 1.1°C in thermal sensitivity between environments. This increase in pain threshold was found in healthy participants and replicated in the clinical cohort.

Discussion

Findings can be applied toward improving MR safety, the resolution of brain pathways underlying pain mechanisms, and to more broadly comment on the impact of the MR environment on investigations that integrate perception-influenced processes.

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.

The Effect of Spinal Muscle Fatigue and Psychosocial Factors on Pressure-Pain Threshold in Healthy Adults

Objective

Pain sensitivity decreases following isometric exercise. It is not clear whether this exercise-induced hypoalgesia (EIH) occurs to the same extent in men and women. It is also unclear if the effect is systemic or local to the exercised musculature. The aim of our study was to investigate whether fatiguing isometric exercise of the spinal and hip extensors would result in increased pressure pain threshold (PPT) at sites local to and remote from the exercised muscles in healthy men and women and whether there is a relationship between central sensitization, psychosocial factors, and PPT.

Subjects

35 healthy adults (age 27.1 ± 4.5 years, 22 women).

Methods

This was a within-subjects cohort study. Participants completed questionnaires quantifying central sensitization, pain catastrophizing, sleepiness/insomnia, anxiety, and depression. PPT was assessed at the lumbar and thoracic paraspinals, hamstrings, gastrocnemius, wrist, and third digit before and immediately after participants performed the Biering-Sorensen test to failure.

Results

PPT increased postexercise in the thoracic paraspinals, hamstrings, and gastrocnemius in men and women and in the lumbar paraspinals in men only but did not change at the wrist and digit sites. A lower average PPT at baseline was associated with a higher central sensitization scores. A greater increase in average PPT postfatigue was significantly associated with higher average PPT at baseline.

Conclusions

Exercise-induced hypoalgesia occurs at sites overlying the muscles involved in fatiguing exercise, but not at remote sites, and is more evident in males than females. The magnitude of EIH depends upon baseline PPT. Even in healthy individuals, greater central sensitization is associated with lower baseline PPT.

An Exploration of the Influence of Non-Biomechanical Factors on Lifting-Related LBP

Objective: The primary objective was to compare non-biomechanical factors between manual workers with and without a history of LBP related to lifting. A secondary objective was to investigate associations between the change in pain intensity during repeated lifting (termed pain ramp) and non-biomechanical factors tested in the LBP group. Methods: Manual workers currently in lifting occupations with and without a history of lifting-related LBP were recruited (21 LBP and 20 noLBP) and took part in a repeated (100) lift task. A series of non-biomechanical factors, including psychological, work-related, lifestyle, whole health and psychophysical factors, were collected. Psychophysical factors (pressure pain thresholds (PPTs) and fatigue) were also measured at different time points. Associations between pain ramp during lifting and non-biomechanical factors were investigated with linear regression. Results: The LBP group reported worse perceived sleep quality, more musculoskeletal pain sites other than LBP and greater symptoms related to gastrointestinal complaints and pseudo-neurology compared to the group with no history of LBP. The group with LBP were also slightly more worried about the lifting task and felt more fatigued at the end of the lifting task. The feeling of fatigue during lifting was positively associated with pain ramp in the LBP group. Anxiety and gastrointestinal complaints were weakly negatively associated with pain ramp during lifting. Conclusions: The group differences of poorer perceived sleep, greater non-specific health complaints, slightly more worry about the lifting task and more perceived fatigue in the LBP group highlight the complex and multi-factorial nature of LBP related to lifting. The feeling of fatigue was positively associated with pain ramp in the LBP group, suggesting a close relationship with pain and fatigue during lifting that requires further exploration.

The role of catastrophizing in chronic cyclical pelvic pain: A systematic review and meta-analysis

BACKGROUND

Dysmenorrhea (painful menstrual cramps) is one of the most common gynecological complaints in women and girls. Dysmenorrhea may be a condition itself or a result of another medical condition, including endometriosis and chronic pelvic pain. Research examining the relationship between menstrual pain ratings and catastrophizing has produced mixed results.

OBJECTIVE

To review and meta-analyze the relationship between catastrophizing and pain ratings of chronic cyclical pelvic pain.

DESIGN

Cross-sectional, longitudinal, and intervention studies that reported the relationship between menstrual/pelvic pain and catastrophizing were included. Study populations had to include healthy menstruating persons or persons with a condition associated with cyclical pelvic pain including primary dysmenorrhea, endometriosis, and/or chronic pelvic pain.

DATA SOURCES AND METHODS

A systematic search of articles published since 2012 on PubMed, PsychInfo, CINHAL, and Medline was conducted in January and rerun in November of 2022. Search terms included cyclical pelvic pain, dysmenorrhea, endometriosis, pelvic pain, and catastrophizing. Data extraction was completed independently by two extractors and cross-checked for errors. A random-effects meta-regression was used to synthesize the data using restricted maximum likelihood.

RESULTS

Twenty-five studies examining 4,540 participants were included. A random effects model found a meta-correlation between catastrophizing and pain of r = .31 (95% confidence interval: .23-.40) p < .001. Heterogeneity was large and significant (I2 = 84.5%, Q(24) = 155.16, p < .001). Studies that measured general pelvic pain rather than cyclical pelvic pain specifically and those that used multi-item rather than single-item measures of pain had significantly higher correlations. Age and depression did not moderate the relationship between catastrophizing and pain.

CONCLUSION

A systematic review and meta-analysis found that catastrophizing had a small but significant positive association with pain ratings. Patients experiencing cyclical pelvic pain may benefit from interventions targeting the psychological management of pain.

REGISTRATION

This meta-analysis was registered in PROSPERO on 14 January 2022. Registration number: CRD42022295328.

Emotional dysregulation in women with endometriosis with cyclical and non-cyclical chronic pelvic pain

BACKGROUND

Endometriosis is a pathophysiological condition characterized by glands and stroma outside the uterus in regions such as the bladder, ureter, fallopian tubes, peritoneum, ovaries, and even in extra pelvic sites. One of the main clinical problems of endometriosis is chronic pelvic pain (CPP), which considerably affects the patients' quality of life. Patients with endometriosis may, cyclically or non-cyclically (80% of cases) experience CPP. High levels of anxiety and depression have been described in patients with endometriosis related to CPP; however, this has not been evaluated in endometriosis women with different types of CPP. Therefore, the research question of this study was whether there is a difference in the emotional dysregulation due to the type of pain experienced by women with endometriosis?

METHODS

This work was performed in the National Institute of Perinatology (INPer) in Mexico City from January 2019 to March 2020 and aimed to determine if there are differences in emotional dysregulation in patients with cyclical and non-cyclical CPP. 49 women from 18 to 52 years-old diagnosed with endometriosis presenting cyclical and non-cyclical CPP answered several batteries made up of Mini-Mental State Examination, Visual Analog Scale, Beck's Depression Inventory, State Trait-Anxiety Inventory, and Generalized Anxiety Inventory. Mann-Whitney U and Student's t-test for independent samples to compare the difference between groups was used. Relative risk estimation was performed to determine the association between non-cyclical and cyclical CPP with probability of presenting emotional dysregulation.

RESULTS

We observed that patients with non-cyclical CPP exhibited higher levels of depression and anxiety (trait-state and generalized anxiety) than patients with cyclical pain, p < 0.05 was considered significant. No differences were observed in pain intensity, but there was a higher probability of developing emotional dysregulation (anxiety or depression) in patients with non-cyclical CPP. No differences were observed in cognitive impairment.

CONCLUSIONS

Our data suggest that patients with non-cyclical (persistent) CPP present a higher emotional dysregulation than those with cyclical pain.

Persistent Pelvic Pain in Patients With Endometriosis

As our understanding of chronic pain conditions, including endometriosis-related pain and chronic pelvic pain evolves, the evaluation and management of patients should reflect our increasing appreciation of the role of central sensitization, comorbid conditions and biopsychosocial factors on the pain experience and treatment outcomes. This review provides a systematic approach to persistent pain in patients with endometriosis. Expanding the evaluation and treatment of endometriosis-related pain by all health care providers could limit unnecessary surgical interventions and best meet our patient's needs.

Parenting Styles, Mental Health, and Catastrophizing in Women with Chronic Pelvic Pain: A Case-Control Study

Chronic pelvic pain (CPP) in women is a highly prevalent condition worldwide and requires multimodal treatment. Adverse childhood experiences have been associated with CPP in women, while allodynia and poor outcomes have been linked to pain catastrophizing in these patients. Pain perception has been associated with parenting style during childhood. The objective of this study was to investigate the association between parenting style, pain catastrophizing, anxiety, depression and CPP in women. A case-control study was conducted between May 2018 and August 2021 with 123 women with CPP and 123 pain-free controls. Questionnaires were used to collect participants' data. The association between parenting style and CPP was assessed using multiple logistic regression, with odds ratios (OR) and 95% confidence intervals (CI) being calculated. The correlation between catastrophizing, pain intensity, pain duration, anxiety, depression, and parenting style in women with CPP was assessed using Spearman's rank correlation coefficient (r). A higher frequency of low maternal care (60.7% versus 45.2%; p = 0.026), anxiety (79.7% versus 56.9%; p < 0.001), depression (73.2% versus 56.1%; p = 0.008) and physical violence (31.7% versus 14.6%; p = 0.003) was found in the CPP group compared to the controls. There was no association between parenting style and CPP in the adjusted analysis. A positive correlation was found between catastrophizing and pain intensity (r = 0.342; p < 0.001), anxiety (r = 0.271; p = 0.002), depression (r = 0.272; p = 0.002), and maternal overprotection (r = 0.185; p = 0.046). A negative correlation was found between anxiety and maternal (r = -0.184; p = 0.047) and paternal (r = -0.286; p = 0.006) care and between depression and maternal (r = -0.219; p = 0.018) and paternal (r = -0.234; p = 0.026) care. The present results suggest a significant but weak association of parenting style with pain catastrophizing, the mental health of women with CPP, and the way in which they experience pain.

Mediators of change in depressed mood following pain rehabilitation among participants with mild, moderate, or severe depressive symptoms

BACKGROUND

Prior research indicates that depression and chronic pain commonly co-exist and impact each other. Interdisciplinary pain rehabilitation programs (IPRPs) have been shown to lead to statistically and clinically significant improvements for patients who report both depressed mood and chronic pain, however there is a gap in the literature regarding the mechanisms by which these improvements occur.

METHODS

This two-site, distinct sample study (Study 1: N = 303, 10-week, individual format, ACT-based program; Study 2: N = 406, 3-week, group format, CBT-based program) evaluated mediators of treatment improvement in depressive symptoms among adult IPRP participants who reported elevated depressive symptoms at program admission and examined treatment mechanisms for depressive symptoms.

RESULTS

Self-reported pain self-efficacy and pain catastrophizing - particularly the helplessness domain - mediated the treatment-related change in depression among IPRP participants with elevated depressive symptoms across the two sites and samples. In one sample, full mediation was achieved while in the other sample, partial mediation was achieved. Participants in both samples showed improvement on all measures.

LIMITATIONS

This study relied on self-report measures of depressive severity and not clinical diagnosis. Results may not generalize to other populations of patients with chronic pain. There was no control condition in either study.

CONCLUSION

Increasing pain self-efficacy and decreasing a sense of helplessness are important treatment targets among IPRP participants who endorse symptoms of depression.

A Single-blind, randomized, pilot study of a brief Mindfulness-Based Intervention for the endometriosis-related pain management

BACKGROUND

Women with endometriosis suffer from frequent symptoms despite multiple treatments in tertiary care. Although there is a need for a biopsychosocial perspective on endometriosis treatment, few conservative treatments have been investigated. We aimed to investigate the effects of a brief Mindfulness-Based Intervention (bMBI) in women with deep endometriosis who remain symptomatic despite undergoing conventional medical treatment.

METHODS

A randomized controlled trial was performed with 2 groups: a standard medical treatment plus bMBI program and only standard medical treatment as a control. A total of 63 eligible participants were randomized to bMBI and control group. The primary outcome was endometriosis-related pain, and secondary outcomes were quality of life and stress perception posttreatment. Analyses were carried out using multiple regression models.

RESULTS

The results show that bMBI significantly improved pain unpleasantness (Cohen's f2 = 0.67, NNT = 3.2), pelvic pain (Cohen's f2 = 0.16, NNT = 5.3), and dyschezia (Cohen's f2 = 0.23, NNT = 2.9) immediately posttreatment and decreased all endometriosis-related pain (Cohen's f2 ranging from 0.20 to 0.60 and NNT ranging from 5 to -9) after the follow-up. We found an extensive positive effect of bMBI on the mental health dimension in the two time-point measures (Cohen's f2 = 0.34 and 0.25, NNT = 3.5 and 2.3) and vitality (Cohen's f2 = 0.22, NNT = 2.1) after the follow-up.

CONCLUSIONS

Our study suggests that bMBI is useful for managing endometriosis-related pain and restoring women's psychological well-being.

Association Between Experimental Pain Thresholds and Trajectories of Postoperative Recovery Measures After Benign Hysterectomy

Purpose

Quantitative sensory testing (QST) can be applied to quantify the sensitivity to different painful stimuli. This study aims to evaluate the association between preoperative pressure and thermal pain thresholds and trajectories of measurements of postoperative recovery (patient-reported daily maximum and average pain intensity, sum score of symptoms, and analgesic consumption) after benign hysterectomy.

Patients and Methods

A prospective, longitudinal single-blinded, observational multicenter study was conducted in five hospitals in the southeast of Sweden between 2011 and 2017. A total of 406 women scheduled for abdominal or vaginal hysterectomy for benign conditions were enrolled in the study. QST measuring pressure (PPT), heat (HPT), and cold pain thresholds (CPT) were performed preoperatively. The cut-off levels for dichotomizing the pain thresholds (low/high) were set at the 25-percentile for PPT and HPT and the 75-percentile for CPT. The Swedish Postoperative Symptom Questionnaire was used to measure postoperative pain and other symptoms of discomfort (symptom sum score) on 13 occasions for six weeks postoperatively. Daily analgesic consumption of opioids and non-opioids was registered.

Results

A CPT above the 75-percentile was associated with high postoperative maximum pain intensity (p = 0.04), high symptom sum score (p = 0.03) and greater consumption of non-opioids (p = 0.03). A HPT below the 25-percentile was only associated with greater consumption of non-opioids (p = 0.02). PPT was not associated with any of the outcome measures.

Conclusion

CPT seemed to be predictive for postoperative pain and symptoms of discomfort after benign hysterectomy. Preoperative QST may be used to individualize the management of postoperative recovery for low pain threshold individuals.

Thermal Pain Thresholds Are Significantly Associated with Plasma Proteins of the Immune System in Chronic Widespread Pain-An Exploratory Pilot Study Using Multivariate and Network Analyses

Chronic widespread pain (CWP), including fibromyalgia (FM), is characterized by generalized musculoskeletal pain. An important clinical feature is widespread increased pain sensitivity such as lowered pain thresholds for different stimuli such as heat (HPT) and cold (CPT). There is a growing interest in investigating the activated neurobiological mechanisms in CWP. This explorative proteomic study investigates the multivariate correlation pattern between plasma and muscle proteins and thermal pain thresholds in CWP and in healthy controls (CON). In addition, we analysed whether the important proteins and their networks for CPT and HPT differed between CWP and CON. We used a proteomic approach and analysed plasma and muscle proteins from women with CWP (n = 15) and CON (n = 23). The associations between the proteins and CPT/HPT were analysed using orthogonal partial least square (OPLS). The protein-protein association networks for the important proteins for the two thermal pain thresholds were analysed using STRING database. CWP had lowered pain thresholds for thermal stimulus. These levels were generally not related to the included clinical variables except in CWP for HPT. Highly interacting proteins mainly from plasma showed strong significant associations with CPT and HPT both in CWP and in CON. Marked differences in the important proteins for the two thermal pain thresholds were noted between CWP and CON; more complex patterns emerged in CWP. The important proteins were part of the immune system (acute phase proteins, complement factors, and immunoglobulin factors) or known to interact with the immune system. As expected, CWP had lowered pain thresholds for thermal stimulus. Although different proteins were important in the two groups, there were similarities. For example, proteins related to the host defence/immunity such as acute phase proteins, complement factors, immunoglobulin factors, and cytokines/chemokines (although not in CON for CPT) were important habitual/tonic factors for thermal pain thresholds. The fact that peripheral proteins contribute to thermal pain thresholds does not exclude that central factors also contribute and that complex interactions between peripheral and central factors determine the registered pain thresholds in CWP.

Transcranial direct current electrical stimulation for the treatment of interstitial cystitis: A study protocol

BACKGROUND

Interstitial cystitis or painful bladder syndrome is a chronic disorder that presents an unknown etiology, with no generally accepted treatment. Although there is no gold standard treatment, transcranial direct current stimulation (tDCS) has shown efficacy in several chronic pain syndromes with decrease in pain, and improved functionality and mood. tDCS could be a safe, ease to use, and low-cost complementary intervention for patients with interstitial cystitis.

AIM

This study will investigate the effects of a tDCS protocol on pain, functionality, and mood in patients with interstitial cystitis.

METHODS

A randomized controlled clinical trial with two arms. Women will be randomized into two groups: active or sham. Anodal tDCS over the primary motor cortex will be performed for 5 consecutive days with an intensity of 2 mA for 20 min. Participants will be evaluated five times: 1 week before intervention; on the 5^th day of tDCS; and 1, 6, and 12 months after the last day of tDCS. The outcomes will be assessed using the numeric rating scale, McGill pain questionnaire, positive and negative affect scale, international consultation on incontinence questionnaire for female lower urinary tract symptoms, Hamilton anxiety scale, six-minute walk test, patient global impression of change, and voiding diary.

DISCUSSION

Only the active group will be expected to show decreased pain. The results of this trial will be the first step in the use of neuromodulation in interstitial cystitis and will provide additional data to support new studies with tDCS.

Activity Patterns and Functioning. A Contextual-Functional Approach to Pain Catastrophizing in Women with Fibromyalgia

Background: The psychological flexibility model states that activity patterns are not deemed to be intrinsically functional or dysfunctional; it is considered that underlying factors, such as personal goals and contextual factors, are what will determine their effects on disability. Pain catastrophizing has frequently been associated with several important pain-related outcomes. Despite its recent conceptualization within affective–motivational approaches, its moderating role between activity patterns and dysfunction has not been analyzed. Methods: This study analyzes the moderating role of pain catastrophizing and its dimensions (Pain Catastrophizing Scale) between activity patterns (Activity Patterns Scale) and disease impact (Fibromyalgia Impact Questionnaire—Revised) in 491 women with fibromyalgia. Results: Activity avoidance (p < 0.001), excessive persistence (p < 0.001) and pacing (p < 0.01) patterns were positively associated with fibromyalgia impact. Helplessness shows a moderating role between pain avoidance (B = 0.100, t =2.30, p = 0.021, [0.01, 0.18]), excessive persistence (B = −0.09, t = −2.24, p = 0.02, [−0.18, −0.01]), pain persistence (B = −0.10, t = −2.04, p = 0.04, [−0.19, −0.004]) and functioning. Conclusion: Helplessness (within pain catastrophizing) is a relevant variable within psychological flexibility models applied to activity patterns. Specifically, pain avoidance is especially dysfunctional in patients with high helplessness. To improve excessive persistence and pain persistence, it is necessary to reduce helplessness before regulating activity patterns.

Anhedonia to Gentle Touch in Fibromyalgia: Normal Sensory Processing but Abnormal Evaluation

Social touch is important for interpersonal interaction. Gentle touch and slow brushing are typically perceived as pleasant, the degree of pleasantness is linked to the activity of the C-tactile (CT) fibers, a class of unmyelinated nerves in the skin. The inability to experience pleasure in general is called anhedonia, a common phenomenon in the chronic pain condition fibromyalgia. Here, we studied the perception and cortical processing of gentle touch in a well-characterized cohort of fibromyalgia. Patients and controls participated in functional brain imaging while receiving tactile stimuli (brushing) on the forearm. They were asked to provide ratings of pleasantness of the tactile stimulus and ongoing pain. We found high distress, pain catastrophizing, and insomnia, and a low perceived state of health in fibromyalgia. Further, patients rated both slow (CT-optimal) and fast (CT-suboptimal) brushing as less pleasant than healthy participants. While there was no difference in brain activity during touch, patients showed deactivation in the right posterior insula (contralateral to the stimulated arm) during pleasantness rating and activation during pain rating. The opposite pattern was observed in healthy participants. Voxel-based morphometry analysis revealed reduced grey matter density in patients, in the bilateral hippocampus and anterior insula. Our results suggest anhedonia to gentle touch in fibromyalgia with intact early-stage sensory processing but dysfunctional evaluative processing. These findings contribute to our understanding of the mechanisms underlying anhedonia in fibromyalgia.