Pain Catastrophising Predicts Alcohol Hangover Severity and Symptoms

Alcohol hangover is a cause of considerable social and economic burden. Identification of predictors of alcohol hangover severity have the potential to contribute to reductions in costs associated with both absenteeism/presenteeism and health care. Pain catastrophising (PC) is the tendency to ruminate and describe a pain experience in more exaggerated terms. The current study examines the possibility that this cognitive coping strategy may influence experience of alcohol hangover. The aims of the current study were to (1) examine the relationship between hangover severity and PC, (2) explore and identify discreet factors within the Acute Hangover Scale (AHS) and (3) explore whether independent factors/dimensions of acute hangover are differentially predicted by PC. A retrospective survey (n = 86) was conducted in which participants completed the Acute Hangover Scale (AHS); the Pain Catastrophising Scale (PCS); a questionnaire pertaining to the amount of alcohol consumed; and a demographic information questionnaire. Regression analyses showed a significant relationship between PC and hangover severity scores and demonstrated that PC was, in fact, a stronger predictor of perceived hangover severity than estimated peak blood alcohol concentrations (eBACs). Factor analysis of the AHS scale, resulted in the identification of two distinct symptom dimensions; ‘Headache and thirst’, and ‘Gastric and cardiovascular’ symptoms. Regression analyses showed that both eBAC and PCS score were significantly associated with ‘Headache and thirst’. However, only PCS score was associated with ‘Gastric and cardiovascular’ symptoms. These novel findings implicate a role for cognitive coping strategies in self-reports of alcohol hangover severity, and may have implications for understanding behavioural response to hangover, as well as suggesting that hangover and PC may be important factors mediating the motivation to drink and/or abuse alcohol, with potential implications in addiction research. Furthermore, these findings suggest that distinct alcohol hangover symptoms may be associated with different mechanisms underlying the experience of alcohol hangover.

Pain catastrophizing: rumination is a discriminating factor among individuals with different pain characteristic

The objective of this study was to compare the scores of the Helplessness, Magnification, Rumination, and Catastrophizing factors of the Pain Catastrophizing Scale (PCS) between samples with different pain characteristics. The psychometric properties of the PCS were evaluated in 1,151 Brazilian adults (78.9% female; 38.6 (SD = 10.8) years): 335 had no pain, 390 had been in pain for less than 3 months, 250 had been in recurring pain for more than 3 months, and 176 had been in continuous pain for more than 3 months. Confirmatory factor analysis (CFA) was conducted to verify the fit of the PCS models. Convergent validity and reliability were evaluated. Multi-group analysis was used to estimate the invariance of the factorial model. The global score for the PCS factors was obtained using the regression weight matrix for estimating factor scores from CFA. Analysis of variance was used to compare scores between samples. After excluding three items, the tri-factorial model showed adequate fit. The model parameters were invariant (Δχ2(λ,i,β,Res); p≥0.05). Individuals experiencing pain showed higher scores for catastrophic thoughts. Individuals with pain for less than 3 months had the highest scores for Rumination (p < 0.001). The PCS showed valid, reliable, and invariant results for the sample of Brazilian adults in no pain or with different pain conditions. The PCS adequately discriminated individuals in pain from those without pain. Among those in pain, Rumination was the only discriminating factor.

Multiple diagnoses, increased kinesiophobia? - Patients with high kinesiophobia levels showed a greater number of temporomandibular disorder diagnoses

OBJECTIVES

The aim of this study was to empirically derive subgroups according to pain-related fear of movement beliefs using cluster analysis within a sample of TMD patients and asymptomatic volunteers.

METHODS

129 volunteers participated in this cross-sectional study (34.78, standard deviation [SD]: 12.49 years; 92 TMD patients and 37 symptom-free volunteers). Mechanical pain sensitivity through pressure pain threshold (PPT) on orofacial and remote sites, kinesiophobia, pain catastrophizing, anxiety and depression were assessed. A cluster analysis was used to derive subgroups according to kinesiophobia scores (TSK/TMD).

RESULTS

Three subgroups were derived: cluster 1 (high kinesiophobia [n = 53], TSK score: 33, SD[standard deviation] = 2.9), cluster 2 (moderate kinesiophobia [n = 50], TSK score: 26.2, SD = 2.14) and cluster 3 (no/low kinesiophobia [n = 26], TSK score 12.12, SD = 2.08) which included patients with higher overall PPT and lower scores on psychosocial variables. The group with high kinesiophobia showed high levels of pain catastrophizing, anxiety, and orofacial pain-related disability compared to the other subgroups and mechanical pain hyperalgesia in remote site compared to the low-kinesiophobia group. Also, we found a greater prevalence of triple diagnosis for the high-kinesiophobia subgroup compared to the moderate kinesiophobia group - odds ratio: 12.6 (95% confidence interval [CI]: 3.31-43.52, p < 0.01).

CONCLUSION

These results suggested that patients with TMD and higher levels of kinesiophobia beliefs may show a more complex clinical feature, with high psychosocial distress, widespread mechanical pain sensitivity, and a more complex TMD disorder. In this way, we suggest a relationship between the number of TMD diagnoses and kinesiophobia severity.

The Pain Catastrophizing Scale-short form: psychometric properties and threshold for identifying high-risk individuals

OBJECTIVE

The Pain Catastrophizing Scale (PCS) measures three aspects of catastrophic cognitions about pain-rumination, magnification, and helplessness. To facilitate assessment and clinical application, we aimed to (a) develop a short version on the basis of its factorial structure and the items' correlations with key pain-related outcomes, and (b) identify the threshold on the short form indicative of risk for depression.

DESIGN

Cross-sectional survey.

SETTING

Social centers for older people.

PARTICIPANTS

664 Chinese older adults with chronic pain.

MEASUREMENTS

Besides the PCS, pain intensity, pain disability, and depressive symptoms were assessed.

RESULTS

For the full scale, confirmatory factor analysis showed that the hypothesized 3-factor model fit the data moderately well. On the basis of the factor loadings, two items were selected from each of the three dimensions. An additional item significantly associated with pain disability and depressive symptoms, over and above these six items, was identified through regression analyses. A short-PCS composed of seven items was formed, which correlated at r=0.97 with the full scale. Subsequently, receiver operating characteristic (ROC) curves were plotted against clinically significant depressive symptoms, defined as a score of ≥12 on a 10-item version of the Center for Epidemiologic Studies-Depression Scale. This analysis showed a score of ≥7 to be the optimal cutoff for the short-PCS, with sensitivity = 81.6% and specificity = 78.3% when predicting clinically significant depressive symptoms.

CONCLUSIONS

The short-PCS may be used in lieu of the full scale and as a brief screen to identify individuals with serious catastrophizing.

Higher Cortical Facilitation and Serum BDNF Are Associated with Increased Sensitivity to Heat Pain and Reduced Endogenous Pain Inhibition in Healthy Males

Background

Although the brain-derived neurotrophic factor (BDNF) has been intensively investigated in animal models of chronic pain, its role in human pain processing is less understood.

Objective

To study the neurophysiology of BDNF modulation on acute experimental pain, we performed a cross-sectional study.

Methods

We recruited 20 healthy male volunteers (19-40 years old) and assessed their serum BDNF levels, quantitative sensory testing, and cortical excitability parameters using transcranial magnetic stimulation.

Results

Linear regression models demonstrated that the BDNF (β = -5.245, P = 0.034) and intracortical facilitation (β = -3.311, P = 0.034) were inversely correlated with heat pain threshold (adjusted R2 = 44.26). The BDNF (β = -3.719, P ≤ 0.001) was also inversely correlated with conditioned pain modulation (adjusted R2 = 56.8).

Conclusions

Our findings indicate that higher serum BDNF and intracortical facilitation of the primary motor cortex are associated with increased sensitivity to heat pain and high serum BDNF with reduced pain inhibition during noxious heterotopic stimulation.

Large Treatment Effect With Extended Home-Based Transcranial Direct Current Stimulation Over Dorsolateral Prefrontal Cortex in Fibromyalgia: A Proof of Concept Sham-Randomized Clinical Study

This randomized, double-blind controlled trial tested the hypothesis that 60 sessions of home-based anodal (a)-transcranial direct current stimulation (tDCS) over dorsolateral prefrontal cortex (DLPFC) would be better than home-based sham-tDCS to improve the widespread pain and the disability-related to pain. The anodal-tDCS (2 mA for 30 minutes) over the left DLPFC was self-administered with a specially developed device following in-person training. Twenty women, 18 to 65 years old were randomized into 2 groups [active-(a)-tDCS (n = 10) or sham-(s)-tDCS (n = 10)]. Post hoc analysis revealed that after the first 20 sessions of a-tDCS, the cumulative pain scores reduced by 45.65% [7.25 (1.43) vs 3.94 (1.14), active vs sham tDCS, respectively]. After 60 sessions, during the 12-week assessment, pain scores reduced by 62.06% in the actively group [visual analogue scale reduction, 7.25 (1.43) to 2.75 (.85)] compared to 24.92% in the s-tDCS group, [mean (SD) 7.10 (1.81) vs 5.33 (.90)], respectively. It reduced the risk for analgesic use in 55%. Higher serum levels of the brain-derived neurotrophic factor predicted higher decreases on the pain scores across of treatment. PERSPECTIVE: These findings bring 3 important insights: 1) show that an extended period of treatment (60 sessions, to date the largest number of tDCS sessions tested) for fibromyalgia induces large pain decreases (a large effect size of 1.59) and 2) support the feasibility of home-based tDCS as a method of intervention; 3) provide additional data on DLPFC target for the treatment of fibromyalgia. Finally, our findings also highlight that brain-derived neurotrophic factor to index neuroplasticity may be a valuable predictor of the tDCS effect on pain scores decreases across the treatment.

A preliminary validation of the Swedish version of the Pain Catastrophizing Scale for Children (PCS-C) for children and adolescents with cancer

Objectives: Pain is reported as one of the most common and difficult symptoms for children and adolescents with cancer to cope with. Pain catastrophizing has been identified as a process clearly related to pain intensity and disability. The Pain Catastrophizing Scale for Children (PCS-C) has been validated in several languages and populations but remains to be validated in pediatric oncology. The aim of the study was to validate a Swedish version of the PCS-C for children and adolescents with cancer.

Methods: All children, 7–18 years of age, being treated for cancer in Sweden at the time of the study were invited to participate. Study material was sent out to the registered address. Internal consistency, test–retest reliability and convergent validity were calculated. Factor structure was examined using principal component analysis (PCA). Descriptive statistics were used to investigate background data and norm values.

Results: 61 children/adolescents were included in the analyses. The results did not support the original three-factor structure of the PCS-C, but rather suggested that a two-factor structure excluding item 8 best represented the data. The internal consistency of that solution was good (α=0.87), the test–rest reliability was excellent (ICC=0.75) and convergent validity was demonstrated (r=0.46). The mean (SD) for the PCS-C in the sample was 19.1 (9.2), without item 8. A statistically significant difference was shown between genders, where girls reported a higher level of pain catastrophizing than boys. No difference was found with regard to age.

Discussion: The Swedish version of the PCS-C is now preliminarily validated for children and adolescents with cancer, for whom gender- and age-specific norm values are now available. Questions remain regarding the optimal factor structure of the PCS-C.

Differential Neuroplastic Changes in Fibromyalgia and Depression Indexed by Up-Regulation of Motor Cortex Inhibition and Disinhibition of the Descending Pain System: An Exploratory Study

Background: Major depressive disorder (MDD) and fibromyalgia (FM) present overlapped symptoms. Although the connection between these two disorders has not been elucidated yet, the disruption of neuroplastic processes that mediate the equilibrium in the inhibitory systems stands out as a possible mechanism. Thus, the purpose of this cross-sectional exploratory study was: (i) to compare the motor cortex inhibition indexed by transcranial magnetic stimulation (TMS) measures [short intracortical inhibition (SICI) and intracortical facilitation (ICF)], as well as the function of descending pain modulatory systems (DPMS) among FM, MDD, and healthy subjects (HS); (ii) to compare SICI, ICF, and the role of DPMS evaluated by the change on Numerical Pain Scale (NPS) during the conditioned pain modulation test (CPM-test) between FM and MDD considering the BDNF-adjusted index; (iii) to assess the relationship between the role of DPMS and the BDNF-adjusted index, despite clinical diagnosis. Patients and Methods: A cohort of 63 women, aged 18 to 75 years [FM (n = 18), MDD (n = 19), and HC (n = 29)]. Results: The MANCOVA analysis revealed that the mean of SICI was 53.40% larger in FM compared to MDD [1.03 (0.50) vs. 0.55 (0.43)] and 66.99% larger compared to HC [1.03 (0.50) vs. 0.34 (0.19)], respectively. The inhibitory potency of the DPMS assessed by the change on the NPS during CPM-test was 112.29 % lower in the FM compared to MDD [0.22 (1.37) vs. -0.87 (1.49)]. The mean of BDNF from FM compared to MDD was 35.70% higher [49.82 (16.31) vs. 14.12 (8.86)]. In FM, the Spearman's coefficient between the change in the NPS during CPM-test with the SICI was Rho = -0.49, [confidence interval (CI) 95%; -0.78 to -0.03]. The BDNF-adjusted index was positively correlated with the disinhibition of the DPMS. Conclusion: These findings support the hypothesis that in FM a deteriorated function of cortical inhibition, indexed by a higher SICI parameter, a lower function of the DPMS, together with a higher level of BDNF indicate that FM has different pathological substrates from depression. They suggest that an up-regulation phenomenon of intracortical inhibitory networks associated with a disruption of the DPMS function occurs in FM.

Validation of the Swedish version of the Pain Catastrophizing Scale for Parents (PCS-P) for parents of children with cancer

OBJECTIVES

Pain is reported as one of the most common and burdensome symptoms for children with cancer. Pain catastrophizing is clearly related to pain intensity and disability. Catastrophizing in parents is associated with both child functioning and parent distress. The Pain Catastrophizing Scale for Parents (PCS-P) remains to be validated for parents of children with cancer. The aim of the study was to validate the Swedish version of the PCS-P for parents of children with cancer experiencing pain.

METHODS

Parents of all children who were being treated for cancer in Sweden at the time of the study were invited to participate. Study material was sent out to the registered address. Internal consistency, test-retest reliability, and convergent validity were calculated, and factor analysis was conducted. Descriptive statistics was used to investigate the background data and norm values.

RESULTS

A total of 243 parents participated in the study. The results did not support the original three-factor structure of the PCS-P, but rather suggested that a two-factor structure best represented the data. The results showed excellent internal consistency (a=0.93), excellent temporal stability (intraclass correlation coefficient =0.86) and moderate convergent validity (r=0.57). The mean (SD) for the PCS-P in the sample was 28.3 (10.7). A statistically significant difference was found between mothers and fathers, where mothers reported a higher level of pain catastrophizing than fathers.

CONCLUSION

The psychometric properties of the PCS-P has now been supported in a sample of parents of children with cancer, and norm values are now available. The factor structure does, however, deserve more investigation.

Factor structure and internal consistency of a Swedish version of the Pain Catastrophizing Scale

BACKGROUND

Pain catastrophizing is highly relevant to assess in the context of long-standing pain. The Pain Catastrophizing Scale (PCS) is a well-established questionnaire used to measure catastrophizing in individuals with long-standing pain. So far, no Swedish translation has been evaluated in regard to validity and reliability. The aims of this study were to translate the PCS questionnaire from English to Swedish, and to investigate its construct validity (face, content, and structural validity) and reliability (internal consistency).

METHODS

We translated the original English version of the PCS to Swedish and collected item responses from 194 persons suffering from primarily long-standing musculoskeletal pain. We used confirmatory factor analysis to evaluate structural validity, and tested the model fit of a one-factor model, an oblique two-factor model, and an oblique three-factor model. We evaluated the measure's reliability in regard to internal consistency calculated with Cronbach's alpha.

RESULTS

A three-factor model comprising a four-item rumination factor, a three-item magnification factor, and a six-item helplessness factor provided the best fit to the data. Internal consistency was adequate and Cronbach's α was 0.92 for the entire scale, 0.84 for the rumination subscale; 0.69 for the magnification subscale, and 0.89 for the helplessness subscale.

CONCLUSIONS

The results indicated adequacy of a three-factor solution and the questionnaire's internal consistency, and provide initial support for the structural validity and internal consistency of a Swedish version of the PCS. Future studies should replicate the study in larger samples and extend the current evaluation in regard to validity and reliability.

Intramuscular electrical stimulus potentiates motor cortex modulation effects on pain and descending inhibitory systems in knee osteoarthritis: a randomized, factorial, sham-controlled study

Background

Neuroplastic changes in nociceptive pathways contribute to severity of symptoms in knee osteoarthritis (KOA). A new look at neuroplastic changes management includes modulation of the primary motor cortex by transcranial direct current stimulation (tDCS).

Objectives

We investigated whether tDCS combined with intramuscular electrical stimulation (EIMS) would be more efficacious than a sham (s) intervention (s-tDCS/s-EIMS) or a single active(a)-tDCS/s-EIMS intervention and/or s-tDCS/a-EIMS in the following domains: pain measures (visual analog scale [VAS] score and descending pain modulatory system [DPMS], and outcomes, and analgesic use, disability, and pain pressure threshold (PPT) for secondary outcomes.

Registration

The trial is registered in Clinicaltrials.gov: NCT01747070.

Methods

Sixty women with KOA, aged 50–75 years old, randomly received five sessions of one of the four interventions (a-tDCS/a-EIMS, s-tDCS/s-EIMS, a-tDCS/s-EIMS, and s-tDCS/a-EIMS). tDCS was applied over the primary motor cortex (M1), for 30 minutes at 2 mA and the EIMS paraspinal of L1–S2.

Results

A generalized estimating equation model revealed the main effect of the a-tDCS/a-EIMS in the VAS pain scores at end treatment compared with the other three groups (P<0.0001). There existed a significant effect of time and a significant interaction between group and time (P<0.01 for both). The delta-(Δ) pain score on VAS in the a-tDCS/a-EIMS group was −3.59, 95% CI: −4.10 to −2.63. The (Δ) pain scores on VAS in the other three groups were: a-tDCS/s-EIMS=−2.13, 95% CI: −2.48 to −1.64; s-tDCS/a-EIMS=−2.25, 95% CI: −2.59 to −1.68; s-tDCS/s-EIMS MR =–1.77, 95% CI: −2.08 to −1.38. The a-tDCS/a-EIMS led to better effect in DPMS, PPT, analgesic use, and disability related to pain.

Conclusion

This study provides additional evidence regarding additive clinical effects to improve pain measures and descending pain inhibitory controls when the neuromodulation of the primary motor cortex with tDCS is combined with a bottom-up modulation with EIMS in KOA. Also, it improved the ability to walk due to reduced pain and reduced analgesic use.

Potency of descending pain modulatory system is linked with peripheral sensory dysfunction in fibromyalgia: An exploratory study

Fibromyalgia (FM) is characterized by chronic widespread pain whose pathophysiological mechanism is related to central and peripheral nervous system dysfunction. Neuropathy of small nerve fibers has been implicated due to related pain descriptors, psychophysical pain, and neurophysiological testing, as well as skin biopsy studies. Nevertheless, this alteration alone has not been previously associated to the dysfunction in the descending pain modulatory system (DPMS) that is observed in FM. We hypothesize that they associated, thus, we conducted a cross-sectional exploratory study.To explore small fiber dysfunction using quantitative sensory testing (QST) is associated with the DPMS and other surrogates of nociceptive pathways alterations in FM.We run a cross-sectional study and recruited 41 women with FM, and 28 healthy female volunteers. We used the QST to measure the thermal heat threshold (HTT), heat pain threshold (HPT), heat pain tolerance (HPT), heat pain tolerance (HPTo), and conditional pain modulation task (CPM-task). Algometry was used to determine the pain pressure threshold (PPT). Scales to assess catastrophizing, anxiety, depression, and sleep disturbances were also applied. Serum brain-derived neurotrophic factor (BDNF) was measured as a marker of neuroplasticity. We run multivariate linear regression models by group to study their relationships.Samples differed in their psychophysical profile, where FM presented lower sensitivity and pain thresholds. In FM but not in the healthy subjects, regression models revealed that serum BDNF was related to HTT and CPM-Task (Hotelling Trace = 1.80, P < .001, power = 0.94, R = 0.64). HTT was directly related to CPM-Task (B = 0.98, P = .004, partial-η = 0.25), and to HPT (B = 1.61, P = .008, partial η = 0.21), but not to PPT. Meanwhile, BDNF relationship to CPM-Task was inverse (B = -0.04, P = .043, partial-η = 0.12), and to HPT was direct (B = -0.08, P = .03, partial-η = 0.14).These findings high spot that in FM the disinhibition of the DPMS is positively correlated with the dysfunction in peripheral sensory neurons assessed by QST and conversely with serum BDNF.

TRANSLATION, CROSS-CULTURAL ADAPTATION AND PRELIMINARY EVALUATION OF THE BRAZILIAN VERSIONOF THE PAIN CATASTROPHIZING SCALE-PARENTS

OBJECTIVE

In Brazil, there is no scale to assess parental catastrophizing about their child's pain. This study aimed to translate and cross-culturally adapt the Pain Catastrophizing Scale-Parents to the Brazilian Portuguese language, as well as to preliminarily evaluate its psychometric properties among parents/guardians of children with and without a toothache.

METHODS

A cross-sectional study was conducted with 237 parents/other relatives of 237 children. Across-cultural adaptation of the scale into Brazilian Portuguese was carried out according to the universalistic approach. To assess the reliability and validity of the scale, parents/other relatives reported on the child's toothache and filled out the Brazilian versions of the Pain Catastrophizing Scale-Parents and the Dental Discomfort Questionnaire.

RESULTS

There was semantic equivalence with the original version after minor modifications. TheCronbach's alpha for the 13 items of the scale was 0.83, and the respective test-retest intraclass correlation coefficients ranged from 0.63 to 0.97. The scores obtained from the Pain Catastrophizing Scale-Parents and the Dental Discomfort Questionnaire had a low correlation (rho=0.25; p<0.001). Thetotal score of the Pain Catastrophizing Scale-Parents differed significantly (p<0.001) in children with a toothache at night (median: 3.0, 25-75 percentile: 25.0-35.5) compared to those who did not have a toothache at night (25.5; 20.0-31.0).

CONCLUSIONS

The Brazilian version of the Pain Catastrophizing Scale-Parents was acceptable in this preliminary evaluation and can be used in Brazilian clinical and research practice.

Novel Insights of Effects of Pregabalin on Neural Mechanisms of Intracortical Disinhibition in Physiopathology of Fibromyalgia: An Explanatory, Randomized, Double-Blind Crossover Study

Background: The fibromyalgia (FM) physiopathology involves an intracortical excitability/inhibition imbalance as measured by transcranial magnetic stimulation measures (TMS). TMS measures provide an index that can help to understand how the basal neuronal plasticity state (i.e., levels of the serum neurotrophins brain-derived neurotrophic factor (BDNF) and S100-B protein) could predict the effect of therapeutic approaches on the cortical circuitries. We used an experimental paradigm to evaluate if pregabalin could be more effective than a placebo, to improve the disinhibition in the cortical circuitries in FM patients, than in healthy subjects (HS). We compared the acute intragroup effect of pregabalin with the placebo in FM patients and healthy subjects (HS) on the current silent period (CSP) and short intracortical inhibition (SICI), which were the primary outcomes. Pain scores and the pain pressure threshold (PPT) were secondary outcomes.

Methods: This study included 27 women (17 FM and 10 HS), with ages ranging from 19 to 65 years. In a blinded, placebo-controlled clinical trial, participants were randomized to receive, in a cross-over manner, oral pregabalin of 150 mg or a placebo. The cortical excitability pain measures were assessed before and 90 min after receiving the medication.

Results: A generalized estimating equation (GEE) model revealed that in FM, pregabalin increased the CSP by 14.34% [confidence interval (CI) 95%; 4.02 to 21.63] and the placebo reduced the CSP by 1.58% (CI 95%; −57 to 25.9) (P = 0.00). Pregabalin reduced the SICI by 8.82% (CI 95%, −26 to 46.00) and the placebo increased it by 19.56% (CI 95%; 8.10 to 59.45; P = 0.02). Pregabalin also improved the pain measures. In the treatment group, the BDNF-adjusted index was positively correlated and the serum S100-B negatively correlated with the CSP, respectively. However, in the HS, pregabalin and the placebo did not induce a statistically significant effect in either intracortical excitability or pain measures.

Conclusion: These results suggest that pregabalin’s effect on cortical neural networks occurs, particularly under basal neuronal hyperexcitability, because its impact on the cortical excitability and the pain measures was observed only in the FM group. This indicates that pregabalin increased the CSP to induce inhibition in specific neural networks, while it increased the SICI to improve the excitability in other neurobiological systems. Trial registration in clinicaltrials.gov Identifier: NCT02639533.

Insights About the Neuroplasticity State on the Effect of Intramuscular Electrical Stimulation in Pain and Disability Associated With Chronic Myofascial Pain Syndrome (MPS): A Double-Blind, Randomized, Sham-Controlled Trial

Background: There is limited evidence concerning the effect of intramuscular electrical stimulation (EIMS) on the neural mechanisms of pain and disability associated with chronic Myofascial Pain Syndrome (MPS). Objectives: To provide new insights into the EIMS long-term effect on pain and disability related to chronic MPS (primary outcomes). To assess if the neuroplasticity state at baseline could predict the long-term impact of EIMS on disability due to MPS we examined the relationship between the serum brain-derived-neurotrophic-factor (BDNF) and by motor evoked potential (MEP). Also, we evaluated if the EIMS could improve the descending pain modulatory system (DPMS) and the cortical excitability measured by transcranial magnetic stimulation (TMS) parameters. Methods: We included 24 right-handed female with chronic MPS, 19-65 years old. They were randomically allocated to receive ten sessions of EIMS, 2 Hz at the cervical paraspinal region or a sham intervention (n = 12). Results: A mixed model analysis of variance revealed that EIMS decreased daily pain scores by -73.02% [95% confidence interval (CI) = -95.28 to -52.30] and disability due to pain -43.19 (95%CI, -57.23 to -29.39) at 3 months of follow up. The relative risk for using analgesics was 2.95 (95% CI, 1.36 to 6.30) in the sham group. In the EIMS and sham, the change on the Numerical Pain Scale (NPS0-10) throughout CPM-task was -2.04 (0.79) vs. -0.94 (1.18), respectively, (P = 0.01). EIMS reduced the MEP -28.79 (-53.44 to -4.15), while improved DPMS and intracortical inhibition. The MEP amplitude before treatment [(Beta = -0.61, (-0.58 to -0.26)] and a more significant change from pre- to post-treatment on serum BDNF) (Beta = 0.67; CI95% = 0.07 to 1.26) were predictors to EIMS effect on pain and disability due to pain. Conclusion: These findings suggest that a bottom-up effect induced by the EIMS reduced the analgesic use, improved pain, and disability due to chronic MPS. This effect might be mediated by an enhancing of corticospinal inhibition as seen by an increase in IC and a decrease in MEP amplitude. Likewise, the MEP amplitude before treatment and the changes induced by the EIMS in the serum BDNF predicted it's long-term clinical impact on pain and disability due MPS. The trial is recorded in ClinicalTrials.gov: NCT02381171.

Cognitive effects of transcranial direct current stimulation combined with working memory training in fibromyalgia: a randomized clinical trial

Cognitive dysfunction in fibromyalgia has been reported, especially memory. Anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in enhancing this function. We tested the effects of eight sessions of tDCS and cognitive training on immediate and delayed memory, verbal fluency and working memory and its association with brain-derived neurotrophic factor (BDNF) levels. Forty females with fibromyalgia were randomized to receive eight sessions of active or sham tDCS. Anodal stimulation (2 mA) was applied over the DLPFC and online combined with a working memory training (WMT) for 20 minutes. Pre and post-treatment neurocognitive tests were administered. Data analysis on deltas considering years of education and BDNF as covariates, indicated active-tDCS + WMT significantly increased immediate memory indexed by Rey Auditory Verbal Learning Test score when compared to sham. This effect was dependent on basal BDNF levels. In addition, the model showed active stimulation increased orthographic and semantic verbal fluency scores (Controlled Oral Word Association Test) and short-term memory (Forward Digit Span). The combination of both techniques seemed to produce effects on specific cognitive functions related to short-term and long-term episodic memory and executive functions, which has clinical relevance for top-down treatment approaches in FM.

Development, psychometric evaluation and validation of a brief measure of emotional preoperative stress (B-MEPS) to predict moderate to intense postoperative acute pain

BACKGROUND

Preoperative stress might influence postoperative pain, thereby, it is desirable to assess it more precisely. Thus, we developed and evaluated the psychometric properties of a brief measure of emotional preoperative stress (B-MEPS) index using Item Response Category Characteristic Curves. We validated and assessed whether the B-MEPS can predict moderate to intense acute postoperative pain (MIAPP).

METHODS

We included 863 adult patients who underwent elective surgeries (ASA I-III physical status). The B-MEPS was constructed based on items selected from instruments to assess anxiety, depression, future self-perception and minor psychiatric disorders. We identified 24 items with greatest discriminant power to identify patients who should undergo surgery to treat cancer with MIAPP. The reliability was maximized using the Cronbach's alpha indices. Fifteen items remained, which were adjusted by the Generalized Partial Credit Model. The convergent validity was assessed correlating the B-MEPS index with the pain catastrophizing (n = 100). Finally, the B-MEPS was applied in a prospective cohort of patients who underwent an abdominal hysterectomy (n = 150).

RESULTS

The Cronbach's alpha for selected items was 0.83. The correlation coefficient between B-MEPS index and catastrophizing was r = 0.37 (P < 0.01). A hierarchical regression model evidenced that the B-MEPS index was a factor independent to predict MIAPP after an abdominal hysterectomy [odds ratio (OR)=1.20, confidence interval (CI) 95% 1.05-1.43).

CONCLUSIONS

The B-MEPS index presents satisfactory psychometric evaluations based on its internal consistency, convergent, and discriminant validity. The B-MEPS is a propensity index to MIAPP, which might help the clinician to decide on the best therapeutic approaches for acute postoperative pain.

Comparison of pain burden and psychological factors in Brazilian women living with HIV and chronic neuropathic or nociceptive pain: An exploratory study

Psychological factors including pain catastrophizing and resilience associate with adjustment and quality of life in people living with chronic pain. Nevertheless, their presentation among females living with HIV and chronic pain has been poorly studied. Given that chronic pain in those living with HIV might occur due to different mechanisms (nociceptive or neuropathic), we hypothesize that the associated psychological states could also differ between these groups. We aimed to compare pain frequency and interference, psychological factors and sleep quality between females living with chronic nociceptive or neuropathic pain. Also, we explored correlations between psychological factors, pain severity and interference in females living with HIV and chronic pain. We performed a cross sectional study assessing females living with HIV and chronic pain, and compared it with a female HIV-positive, pain-free control sample in Brazil. To discriminate the most likely underlying mechanism for the chronic pain, we applied the Leeds Assessment for Neuropathic Signs and Symptoms (LANSS). Forty-nine females living with HIV and chronic pain were assessed, and divided in control (n = 12), nociceptive (n = 10) and neuropathic pain (n = 27) groups. Using validated scales, their pain catastrophizing, resilience, depression, anxiety and sleep disorders were assessed between May 2014 and August 2015. Compared to controls, females living with HIV and neuropathic chronic pain had higher pain frequency (p<0.001), interference on activities (p = 0.002), interference with emotions (p<0.001), catastrophizing (p<0.001), depression (p = 0.015), and lower resilience (p = 0.011). Catastrophizing was also significantly correlated to the burden of chronic pain. The type of chronic pain in females living with HIV should raise concerns regarding significant burden in psychological states in this population (particularly neuropathic pain). Using scales such as the LANSS to identify the type of choric pain, could be of use to address relevant issues for the patients, and to propose tailored therapies.

Hypnosis Enhances the Effects of Pain Education in Patients With Chronic Nonspecific Low Back Pain: A Randomized Controlled Trial

The potential benefits of combining pain education (PE) with clinical hypnosis (CH) has not yet been investigated in individuals with chronic pain. A total of 100 patients with chronic nonspecific low back pain were randomized to receive either: 1) PE alone, or 2) PE with CH. Outcomes were collected by a blinded assessor at 2 weeks and 3 months after randomization. The primary outcomes were average pain intensity, worst pain intensity (both assessed with 11-point numeric rating scales), and disability (24-item Roland Morris Disability Questionnaire) at 2 weeks. At 2 weeks, participants who received PE with CH reported lower worst pain intensity (mean difference = 1.35 points, 95% confidence interval [CI] = .32-2.37) and disability (mean difference = 2.34 points, 95% CI = .06-4.61), but not average pain intensity (mean difference = .67 point, 95% CI = -.27 to 1.62), relative to participants who received PE alone. PE with CH participants also reported more global perceived benefits at 2 weeks (mean difference = -1.98 points, 95% CI = -3.21 to -.75). At 3 months, participants who received PE with CH reported lower worst pain intensity (mean difference = 1.32 points, 95% CI = .29-2.34) and catastrophizing (mean difference = 5.30 points, 95% CI = 1.20-9.41). No adverse effects in either treatment condition were reported. To our knowledge, this is the first trial showing that additional use of hypnosis with PE results in improved outcomes over PE alone in patients with chronic nonspecific low back pain.

PERSPECTIVE

This study provides evidence supporting the efficacy of another treatment option for teaching patients to self-manage chronic low back pain that has a relatively low cost and that can be offered in groups.

Different doses of Pilates-based exercise therapy for chronic low back pain: a randomised controlled trial with economic evaluation

Objectives

To evaluate the effectiveness and cost-utility of the addition of different doses of Pilates to an advice for non-specific chronic low back pain (NSCLBP) from a societal perspective.

Design

Randomised controlled trial with economic evaluation.

Setting

Physiotherapy clinic in São Paulo, Brazil.

Participants

296 patients with NSCLBP.

Interventions

All patients received advice and were randomly allocated to four groups (n=74 per group): booklet group (BG), Pilates once a week (Pilates group 1, PG1), Pilates twice a week (Pilates group 2, PG2) and Pilates three times a week (Pilates group 3, PG3).

Main outcome measures

Primary outcomes were pain and disability at 6-week follow-up.

Results

Compared with the BG, all Pilates groups showed significant improvements in pain (PG1, mean difference (MD)=−1.2, 95% CI −2.2 to −0.3; PG2, MD=−2.3, 95% CI −3.2 to −1.4; PG3, MD=−2.1, 95% CI −3.0 to −1.1) and disability (PG1, MD=−1.9, 95% CI −3.6 to −0.1; PG2, MD=−4.7, 95% CI −6.4 to −3.0; PG3, MD=−3.3, 95% CI −5.0 to −1.6). Among the different doses, PG2 showed significant improvements in comparison with PG1 for pain (MD=−1.1, 95% CI −2.0 to −0.1) and disability (MD=−2.8, 95% CI −4.5 to −1.1). The cost-utility analysis showed that PG3 had a 0.78 probability of being cost-effective at a willingness-to-pay of £20 000 per quality-adjusted life-year gained.

Conclusions

Adding two sessions of Pilates exercises to advice provided better outcomes in pain and disability than advice alone for patients with NSCLBP; non-specific elements such as greater attention or expectation might be part of this effect. The cost-utility analysis showed that Pilates three times a week was the preferred option.

Trial registration number

NCT02241538, Completed.

Effects of Transcranial Direct Current Stimulation Block Remifentanil-Induced Hyperalgesia: A Randomized, Double-Blind Clinical Trial

Background: Remifentanil-induced hyperalgesia (r-IH) involves an imbalance in the inhibitory and excitatory systems. As the transcranial Direct Current Stimulation (tDCS) modulates the thalamocortical synapses in a top-down manner, we hypothesized that the active (a)-t-DCS would be more effective than sham(s)-tDCS to prevent r-IH. We used an experimental paradigm to induce temporal summation of pain utilizing a repetitive cold test (rCOLDT) assessed by the Numerical Pain Score (NPS 0-10) and we evaluated the function of the descending pain modulatory system (DPMS) by the change on the NPS (0–10) during the conditioned pain modulation (CPM)-task (primary outcomes). We tested whether a-tDCS would be more effective than s-tDCS to improve pain perception assessed by the heat pain threshold (HPT) and the reaction time during the ice-water pain test (IPT) (secondary outcomes).

Methods: This double-blinded, factorial randomized trial included 48 healthy males, ages ranging 19–40 years. They were randomized into four equal groups: a-tDCS/saline, s-tDCS/saline, a-tDCS/remifentanil and s-tDCS/remifentanil. tDCS was applied over the primary motor cortex, during 20 min at 2 mA, which was introduced 10 min after starting remifentanil infusion at 0.06 μg⋅kg^-1⋅min^-1 or saline.

Results: An ANCOVA mixed model revealed that during the rCOLDT, there was a significant main effect on the NPS scores (F = 3.81; P = 0.01). The s-tDCS/remifentanil group presented larger pain scores during rCOLDT, [mean (SD) 5.49 (1.04)] and a-tDCS/remifentanil group had relative lower pain scores [4.15 (1.62)]; showing its blocking effect on r-IH. a-tDCS/saline and s-tDCS/saline groups showed lowest pain scores during rCOLDT, [3.11 (1.2)] and [3.15 (1.62)], respectively. The effect of sedation induced by remifentanil during the rCOLDT was not significant (F = 0.76; P = 0.38). Remifentanil groups showed positive scores in the NPS (0–10) during the CPM-task, that is, it produced a disengagement of the DPMS. Also, s-tDCS/Remifentanil compared to a-tDCS showed lower HPT and larger reaction-time during the IPT.

Conclusion: These findings suggest that effects of a-tDCS prevent the summation response induced by r-IH during rCOLDT and the a-tDCS blocked the disengagement of DPMS. Thereby, tDCS could be considered as a new approach to contra-regulate paradoxical mechanisms involved in the r-IH. Clinical trials identification: NCT02432677. URL:https://clinicaltrials.gov/.

Clinimetric properties of the Nepali version of the Pain Catastrophizing Scale in individuals with chronic pain

BACKGROUND

Pain catastrophizing is an exaggerated negative cognitive response related to pain. It is commonly assessed using the Pain Catastrophizing Scale (PCS). Translation and validation of the scale in a new language would facilitate cross-cultural comparisons of the role that pain catastrophizing plays in patient function.

PURPOSE

The aim of this study was to translate and culturally adapt the PCS into Nepali (Nepali version of PCS [PCS-NP]) and evaluate its clinimetric properties.

METHODS

We translated, cross-culturally adapted, and performed an exploratory factor analysis (EFA) of the PCS-NP in a sample of adults with chronic pain (N=143). We then confirmed the resulting factor model in a separate sample (N=272) and compared this model with 1-, 2-, and 3-factor models previously identified using confirmatory factor analyses (CFAs). We also computed internal consistencies, test-retest reliabilities, standard error of measurement (SEM), minimal detectable change (MDC), and limits of agreement with 95% confidence interval (LOA95%) of the PCS-NP scales. Concurrent validity with measures of depression, anxiety, and pain intensity was assessed by computing Pearson's correlation coefficients.

RESULTS

The PCS-NP was comprehensible and culturally acceptable. We extracted a two-factor solution using EFA and confirmed this model using CFAs in the second sample. Adequate fit was also found for a one-factor model and different two- and three-factor models based on prior studies. The PCS-NP scores evidenced excellent reliability and temporal stability, and demonstrated validity via moderate-to-strong associations with measures of depression, anxiety, and pain intensity. The SEM and MDC for the PCS-NP total score were 2.52 and 7.86, respectively (range of PCS scores 0-52). LOA95% was between -15.17 and +16.02 for the total PCS-NP scores.

CONCLUSION

The PCS-NP is a valid and reliable instrument to assess pain catastrophizing in Nepalese individuals with chronic pain.

Translation and validation of Simplified Chinese version of the Pain Catastrophizing Scale in chronic pain patients: Education may matter

Objective

Pain catastrophizing is linked to many aspects of pain perception and defines a unique dimension in predicting pain intensity and physical disability. Pain Catastrophizing Scale (PCS) is an effective, validated,self-report measure, commonly used in clinical trials. Here, we present a Simplified Chinese PCS (SC-PCS) version developed in Chinese patients suffering from chronic pain.

Methods

The SC-PCS was generated in five steps and tested on an initial patient cohort (N = 30). A convenience sample (N = 200) of in-hospital patients with non-malignant pain lasting for more than 12 weeks were recruited for the study, of which 81 completed 5 additional pain questionnaires. A subset (N = 24) of the patients completed an additional SC-PCS, 10 days after the initial query to assess test–retest validation.

Results

Intra-class correlations coefficient indicated high reproducibility and temporal consistency, (0.97), for the total score. Cronbach’s alpha determined high internal consistency across the SC-PCS total score and its three subscales (0.87, 0.85, 0.62, and 0.65). The SC-PCS total score moderately or weakly (R = −0.2 to 0.49), but significantly, correlated with other measurements, such as pain Visual Analog Scale, Beck Depression Inventory, Pain Anxiety Symptoms Scales, Positive and Negative Affect Schedule, and education. We used exploratory factor analysis to examine the dimensionality of the SC-PCS, which indicated instability of the current three-factor model. However, a confirmatory factor analysis indicated that the three-factor model had the best goodness-fitting.

Conclusions

We demonstrate the successful translational adaptation from English to Simplified Chinese as well as the reliability and validity of SC-PCS. An important discovery was education level significantly correlated with SC-PCS, identifying a future consideration for other cross-cultural development of self-reported measures.

Preoperative transcranial direct current stimulation: Exploration of a novel strategy to enhance neuroplasticity before surgery to control postoperative pain. A randomized sham-controlled study

BACKGROUND

An imbalance in the excitatory/inhibitory systems in the pain networks may explain the persistent chronic pain after hallux valgus surgery. Thus, to contra-regulate this dysfunction, the use of transcranial direct current stimulation (tDCS) becomes attractive.

OBJECTIVE

We tested the hypothesis that two preoperative active(a)-tDCS sessions compared with sham(s)-tDCS could improve the postoperative pain [as indexed by Visual Analogue Scale (VAS) at rest and during walking (primary outcomes)]. To assess their effect on the change in the Numerical Pain Scale (NPS0-10) during Conditioned Pain Modulation (CPM-task), disability related to pain (DRP) and analgesic consumption (secondary outcomes). Also, we assessed if the brain derived neurotrophic factor (BDNF) in the cerebral spinal fluid (CSF) after tDCS could predict the intervention's effect on the DRP.

METHODS

It is a prospective, double blind, sham-controlled, randomized single center, 40 women (18-70 years-old) who had undergone hallux valgus surgery were randomized to receive two sessions (20 minutes each) of anodal a-tDCS or s-tDCS on the primary motor cortex at night and in the morning before the surgery. To assess the DRP was used the Brazilian Profile of Chronic Pain: Screen (B-PCP:S).

RESULTS

A-tDCS group showed lower scores on VAS at rest and during walking (P<0.001). At rest, the difference between groups was 2.13cm (95%CI = 1.59 to 2.68) while during walking was 1.67cm (95%CI = 1.05 to 2.28). A-tDCS, when compared to s-tDCS reduced analgesic doses in 73.25% (P<0.001), produced a greater reduction in B-PCP:S (mean difference of 9.41 points, 95%CI = 0.63 to 18.21) and higher function of descending pain modulatory system (DPMS) during CPM-task.

CONCLUSION

A-tDCS improves postoperative pain, the DRP and the function of DPMS. Also, the CSF BDNF after a-tDCS predicted the improvement in the DRP. In overall, these findings suggest that a-tDCS effects may be mediated by top-down regulatory mechanisms associated with the inhibitory cortical control.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02360462.

The Central Sensitization Inventory validated and adapted for a Brazilian population: psychometric properties and its relationship with brain-derived neurotrophic factor

OBJECTIVES

The primary aim was to assess the psychometric properties (including internal consistency, construct validity, reproducibility, and factor structure) of the Central Sensitization Inventory (CSI), adapted and validated for a Brazilian population (CSI-BP). Additionally, we evaluated the relationship between the CSI-BP and the serum brain-derived neurotrophic factor (BDNF) and determined if the symptoms elicited by the CSI-BP discriminate between subjects who do/do not respond to the conditioned pain modulation (CPM) task, as assessed by change in numeric pain scale (0-10) score.

PATIENTS AND METHODS

A cross-sectional study was conducted in a pain clinic in a tertiary teaching hospital. A total of 222 adults with chronic musculoskeletal pain and 63 healthy control subjects completed the CSI-BP and the Brazilian Portuguese pain-catastrophizing scale (BP-PCS). A team of experts translated the CSI according to the international guidelines. Test-retest, item analysis, convergent validity, and factor analysis were performed. Later, a random subsample (n=77) was used to correlate the CSI-BP adjusted index with change in numeric pain-scale score during the CPM task and a BDNF blood sample.

RESULTS

The CSI-BP presented strong psychometric properties (test-retest reliability 0.91, Cronbach's α=0.91). Confirmatory factor analysis yielded a four-factor structure, supporting the original English version. The CSI-BP adjusted index showed moderate positive correlation with the BP-PCS, and classified more than 80% of patients correctly vs healthy controls. Serum BDNF levels explained 27% of the variation in the CSI-BP adjusted index. Subjects with impairment in the descending modulatory system had higher CSI-BP adjusted index scores than subjects who responded normally to the CPM task: 49.35 (12.1) vs 39.5 (12.33), respectively (P<0.05).

CONCLUSION

The CSI-BP was found to be a psychometrically strong and reliable instrument, with primary evidence of validity. Higher scores on the CSI-BP were correlated positively with serum BDNF and with greater dysfunction of the descending pain-modulatory system.

Cross-cultural adaptation, reliability and construct validity of the Tampa scale for kinesiophobia for temporomandibular disorders (TSK/TMD-Br) into Brazilian Portuguese

Fear of movement (kinesiophobia) seems to play an important role in the development of chronic pain. However, for temporomandibular disorders (TMD), there is a scarcity of studies about this topic. The Tampa Scale for Kinesiophobia for TMD (TSK/TMD) is the most widely used instrument to measure fear of movement and it is not available in Brazilian Portuguese. The purpose of this study was to culturally adapt the TSK/TMD to Brazilian Portuguese and to assess its psychometric properties regarding internal consistency, reliability, and construct and structural validity. A total of 100 female patients with chronic TMD participated in the validation process of the TSK/TMD-Br. The intraclass correlation coefficient (ICC) was used for statistical analysis of reliability (test-retest), Cronbach's alpha for internal consistency, Spearman's rank correlation for construct validity and confirmatory factor analysis (CFA) for structural validity. CFA endorsed the pre-specified model with two domains and 12-items (Activity Avoidance - AA/Somatic Focus - SF) and all items obtained a loading factor greater than 0·4. Acceptable levels of reliability were found (ICC > 0·75) for all questions and domains of the TSK/TMD-Br. For internal consistency, Cronbach's α of 0·78 for both domains were found. Moderate correlations (0·40 < r < 0.60) were observed for 84% of the analyses conducted between TSK/TMD-Br scores versus catastrophising, depression and jaw functional limitation. TSK/TMD-Br 12 items and two-factor demonstrated sound psychometric properties (transcultural validity, reliability, internal consistency and structural validity). In such a way, the instrument can be used in clinical settings and for research purposes.

Anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex modulates attention and pain in fibromyalgia: randomized clinical trial

Cognitive dysfunction in fibromyalgia patients has been reported, especially when increased attentional demands are required. Transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in modulating attention. We tested the effects of a single session of tDCS coupled with a Go/No-go task in modulating three distinct attentional networks: alertness, orienting and executive control. Secondarily, the effect on pain measures was evaluated. Forty females with fibromyalgia were randomized to receive active or sham tDCS. Anodal stimulation (1 mA, 20 min) was applied over the DLPFC. Attention indices were assessed using the Attention Network Test (ANT). Heat pain threshold (HPTh) and tolerance (HPTo) were measured. Active compared to sham tDCS led to increased performance in the orienting (mean difference [MD] = 14.63) and executive (MD = 21.00) attention networks. There was no effect on alertness. Active tDCS increased HPTh as compared to sham (MD = 1.93) and HPTo (MD = 1.52). Regression analysis showed the effect on executive attention is mostly independent of the effect on pain. DLPFC may be an important target for neurostimulation therapies in addition to the primary motor cortex for patients who do not respond adequately to neurostimulation therapies.

The Development and Psychometric Validation of an Arabic-Language Version of the Pain Catastrophizing Scale

Context. The Pain Catastrophizing Scale (PCS) is the most widely used measure of pain-specific catastrophizing. Objectives. The purpose of the present study was to develop and psychometrically evaluate an Arabic-language version of the PCS. Methods. In Study 1, 150 adult chronic nonmalignant pain patients seeking treatment at a hospital setting completed the PCS-A and a number of self-report measures assessing clinical parameters of pain, symptoms of depression, and quality of life. Study 2 employed a cold pressor pain task to examine the PCS-A in a sample of 44 healthy university students. Results. Exploratory factor analyses suggested a two-factor structure. Confirmatory factor analysis comparing the 2-factor model, Sullivan's original 3-factor model, and a 1-factor model based on the total score all provided adequate fit to the data. Cronbach's alpha coefficients across all models met or exceeded accepted standards of reliability. Catastrophizing was associated with higher levels of depression and increased pain intensity and interference. Catastrophizing predicted decreased quality of life, even after controlling for the contribution of gender, employment, depression, and pain interference. PCS-A scores were positively correlated with heightened experimental pain severity and decreased pain tolerance. Conclusion. The present results provide strong support for the psychometric properties of the PCS-A.

Development and validation of Arabic version of the pain catastrophizing scale

Introduction:

The pain catastrophizing scale (PCS) is the most widely used tool to assess pain catastrophizing. The aim of this study was to translate, culturally adapt, and validate the PCS questionnaire in Arabic.

Methods:

A systematic translation process was used to translate the original English PCS into Arabic. After the pilot study, we validated our version among patients with chronic pain at two tertiary care centers. We tested the reliability of our version using internal consistency and test-retest reliability. We examined the validity by assessing construct validity, concurrent validity (by investigating the associations with Brief Pain Inventory [BPI]), and face validity.

Results:

A total of 113 subjects (50 men, 63 women) were included in the study. Cronbach's α was 0.94 (95% confidence interval [CI]: 0.92–0.96), and interclass correlation coefficients was 0.83 (95% CI: 0.77–0.89) for the total scale. There was no statistically significant difference in the total PCS scores between patients who reported experiencing current pain and those who did not. Among patients who reported having current pain, pain severity was weakly associated with the total PCS scores (r = 0.22, P = 0.03). PCS and its subscales were not statistically significantly associated with any of the BPI items. Nonetheless, patients who were diagnosed with neuropathic pain had statistically significantly higher scores on the total PCS, rumination, and helplessness subscales. Most patients found the PCS questions to be clear and easy to understand, and thought the questionnaire items covered all their problem areas regarding their pain catastrophizing.

Conclusion:

Our translated version of PCS is reliable and valid for use among Arabic-speaking patients.

Effects of a Tailored Positive Psychology Intervention on Well-Being and Pain in Individuals With Chronic Pain and a Physical Disability: A Feasibility Trial

OBJECTIVES

To determine the feasibility, acceptability, and efficacy of a computer-based positive psychology intervention in individuals with a physical disability and chronic pain.

METHODS

Individuals with spinal cord injury, multiple sclerosis, neuromuscular disease, or postpolio syndrome and chronic pain were randomly assigned to a positive psychology or a control condition. Participants in the intervention group were instructed to practice 4 personalized positive psychology exercises. Participants in the control group were instructed to write about life details for 8 weeks. Participants completed online well-being and pain-related questionnaires at baseline, posttreatment, and at the 2.5-month follow-up, and rated treatment satisfaction at posttreatment.

RESULTS

Ninety-six participants were randomized and 68 (70%) completed follow-up assessments. Participants in the positive psychology intervention group reported significant pretreatment to posttreatment improvements in pain intensity, pain control, pain catastrophizing, pain interference, life satisfaction, positive affect, and depression. Improvements in life satisfaction, depression, pain intensity, pain interference, and pain control were maintained to the 2.5-month follow-up. Participants in the control group reported significant pretreatment to posttreatment improvements in life satisfaction, and pretreatment to follow-up improvements in pain intensity and pain control. Significant between-group differences, favoring the treatment group, emerged for pretreatment to posttreatment improvements in pain intensity and pain control. Participants were similarly satisfied with both treatments.

DISCUSSION/CONCLUSIONS

The results support the feasibility, acceptability, and potential efficacy of a computer-based positive psychology intervention for improving well-being and pain-related outcomes in individuals with physical disabilities and chronic pain, and indicate that a full trial of the intervention is warranted.

Injustice Experience Questionnaire, Japanese Version: Cross-Cultural Factor-Structure Comparison and Demographics Associated with Perceived Injustice

OBJECTIVE

The Injustice Experience Questionnaire (IEQ) assesses injury-related perceived injustice. This study aimed to (1) develop a Japanese version (IEQ-J), (2) examine its factor structure, validity, and reliability, and (3) discover which demographic variable(s) positively contributed to prediction of IEQ-J scores.

METHODS

Data from 71 patients (33 male, 38 female; age = 20+) with injury pain were employed to investigate factor structure by exploratory and confirmatory factor analyses. Concurrent validity was examined by Pearson correlation coefficients among the IEQ-J, Brief Pain Inventory (BPI), and Pain Catastrophizing Scale (PCS). Internal consistency was investigated by Cronbach's alpha, and test-retest reliability was indicated with intra-class correlations (ICCs) in 42 of 71 patients within four weeks. Relations between demographic variables and IEQ-J scores were examined by covariance analysis and linear regression models.

RESULTS

IEQ-J factor structure differed from the original two-factor model. A three-factor model with Severity/irreparability, Blame/unfairness, and Perceived lack of empathy was extracted. The three-factor model showed goodness-of-fit with the data and sufficient reliability (Cronbach's alpha of 0.90 for total IEQ-J; ICCs = 0.96). Pearson correlation coefficients among IEQ-J, BPI, and PCS ranged from 0.38 to 0.73. Pain duration over a year (regression coefficient, 11.92, 95%CI; 5.95-17.89) and liability for injury on another (regression coefficient, 12.17, 95%CI; 6.38-17.96) predicted IEQ-J total scores.

CONCLUSIONS

This study evidenced the IEQ-J's sound psychometric properties. The three-factor model was the latter distinctive in the Japanese version. Pain duration over a year and injury liability by another statistically significantly increased IEQ-J scores.

Motor Cortex Excitability and BDNF Levels in Chronic Musculoskeletal Pain According to Structural Pathology

The central sensitization syndrome (CSS) encompasses disorders with overlapping symptoms in a structural pathology spectrum ranging from persistent nociception [e.g., osteoarthritis (OA)] to an absence of tissue injuries such as the one presented in fibromyalgia (FM) and myofascial pain syndrome (MPS). First, we hypothesized that these syndromes present differences in their cortical excitability parameters assessed by transcranial magnetic stimulation (TMS), namely motor evoked potential (MEP), cortical silent period (CSP), short intracortical inhibition (SICI) and short intracortical facilitation (SICF). Second, considering that the presence of tissue injury could be detected by serum neurotrophins, we hypothesized that the spectrum of structural pathology (i.e., from persistent nociception like in OA, to the absence of tissue injury like in FM and MPS), could be detected by differential efficiency of their descending pain inhibitory system, as assessed by the conditioned pain modulation (CPM) paradigm. Third, we explored whether brain-derived neurotrophic factor (BDNF) had an influence on the relationship between motor cortex excitability and structural pathology. This cross-sectional study pooled baseline data from three randomized clinical trials. We included females (n = 114), aged 19-65 years old with disability by chronic pain syndromes (CPS): FM (n = 19), MPS (n = 54), OA (n = 27) and healthy subjects (n = 14). We assessed the serum BDNF, the motor cortex excitability by parameters the TMS measures and the change on numerical pain scale [NPS (0-10)] during CPM-task. The adjusted mean (SD) on the SICI observed in the absence of tissue injury was 56.36% lower than with persistent nociceptive input [0.31(0.18) vs. 0.55 (0.32)], respectively. The BDNF was inversely correlated with the SICI and with the change on NPS (0-10)during CPM-task. These findings suggest greater disinhibition in the motor cortex and the descending pain inhibitory system in FM and MPS than in OA and healthy subjects. Likewise, the inter-hemispheric disinhibition as well as the dysfunction in the descending pain modulatory system is higher in chronic pain without tissue injury compared to a structural lesion. In addition, they suggest that a greater level of serum BDNF may be involved in the processes that mediate the disinhibition of motor cortex excitability, as well as the function of descending inhibitory pain modulation system, independently of the physiopathology mechanism of musculoskeletal pain syndromes.

A Framework for Understanding the Relationship between Descending Pain Modulation, Motor Corticospinal, and Neuroplasticity Regulation Systems in Chronic Myofascial Pain

Myofascial pain syndrome (MPS) is a leading cause of chronic musculoskeletal pain. However, its neurobiological mechanisms are not entirely elucidated. Given the complex interaction between the networks involved in pain process, our approach, to providing insights into the neural mechanisms of pain, was to investigate the relationship between neurophysiological, neurochemical and clinical outcomes such as corticospinal excitability. Recent evidence has demonstrated that three neural systems are affected in chronic pain: (i) motor corticospinal system; (ii) internal descending pain modulation system; and (iii) the system regulating neuroplasticity. In this cross-sectional study, we aimed to examine the relationship between these three central systems in patients with chronic MPS of whom do/do not respond to the Conditioned Pain Modulation Task (CPM-task). The CPM-task was to immerse her non-dominant hand in cold water (0-1°C) to produce a heterotopic nociceptive stimulus. Corticospinal excitability was the primary outcome; specifically, the motor evoked potential (MEP) and intracortical facilitation (ICF) as assessed by transcranial magnetic stimulation (TMS). Secondary outcomes were the cortical excitability parameters [current silent period (CSP) and short intracortical inhibition (SICI)], serum brain-derived neurotrophic factor (BDNF), heat pain threshold (HPT), and the disability related to pain (DRP). We included 33 women, (18-65 years old). The MANCOVA model using Bonferroni's Multiple Comparison Test revealed that non-responders (n = 10) compared to responders (n = 23) presented increased intracortical facilitation (ICF; mean ± SD) 1.43 (0.3) vs. 1.11 (0.12), greater motor-evoked potential amplitude (μV) 1.93 (0.54) vs. 1.40 (0.27), as well a higher serum BDNF (pg/Ml) 32.56 (9.95) vs. 25.59 (10.24), (P < 0.05 for all). Also, non-responders presented a higher level of DRP and decreased HPT (P < 0.05 for all). These findings suggest that the loss of net descending pain inhibition was associated with an increase in ICF, serum BDNF levels, and DRP. We propose a framework to explain the relationship and potential directionality of these factors. In this framework we hypothesize that increased central sensitization leads to a loss of descending pain inhibition that triggers compensatory mechanisms as shown by increased motor cortical excitability.

Descending Control of Nociceptive Processing in Knee Osteoarthritis Is Associated With Intracortical Disinhibition: An Exploratory Study

Based on the hypothesis that an imbalance in excitatory and inhibitory input is a central mechanism of knee osteoarthritis chronic pain (KOACP), this exploratory study had the following aims: to compare whether the function of the descending inhibitory pain pathway is associated with the state of inhibition in the corticospinal system indexed by the motor-evoked potential (MEP) and the cortical salient period (CSP) in patients with severe osteoarthritis (OA) and healthy controls; and to determine if there is correlation between the measures of intracortical inhibition (CSP, MEP) with changes on the numerical pain scale (NPS [0-10]) in KOACP during a conditioned pain modulation (CPM)-task considering the effect of self-reported function assessed by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and analgesic use.In a cross-sectional study, we included females (n = 21), with disability by pain or stiffness due to KOACP and healthy controls (n = 10), aged 19 to 75 years. The motor cortex excitability parameters (MEP and CSP) were assessed using the transcranial magnetic stimulation. We assessed the pain and disability by the WOMAC, and change on NPS (0-10) during CPM-task.A Multivariate analysis of covariance revealed that the adjusted mean (SD) on the MEP amplitude was 13.53% higher in the OA than in healthy subjects (1.33 [0.49] vs 1.15 [0.13]), respectively (P = 0.16). The adjusted mean (SD) on the CSP observed in OA patients was 23.43% lower than in healthy subjects (54.54 [16.10] vs 70.94 [22.87]), respectively (P = 0.01). The function of the descending pain modulatory system assessed by change on NPS (0-10) during a CPM-task was negatively correlated with the cortical excitability parameter indexed by the CSP (P = 0.001). Also, the CSP was negatively correlated with the pain and disability assessed by the WOMAC index.These findings support the hypothesis that the change in cortical plasticity in KOACP is associated with less intracortical inhibition, as measured by the CSP. These results show that the neural change in the motor cortex in KOACP is associated with pain and disability levels, and also with decreased activation of the endogenous pain-modulating system by a CPM-task.

Cross-cultural adaptation and validation of the Turkish version of the pain catastrophizing scale among patients with ankylosing spondylitis

[Purpose] This study describes the cultural adaptation, validation, and reliability of the Turkish version of the Pain Catastrophizing Scale in patients with ankylosing spondylitis. [Methods] The validity of the Turkish version of the Pain Catastrophizing Scale was assessed by evaluating data quality (missing data and floor and ceiling effects), principal components analysis, internal consistency (Cronbach’s alpha), and construct validity (Spearman’s rho). Reproducibility analyses included standard measurement error, minimum detectable change, limits of agreement, and intraclass correlation coefficients. [Results] Sixty-four adult patients with ankylosing spondylitis with a mean age of 42.2 years completed the study. Factor analysis revealed that all questionnaire items could be grouped into two factors. Excellent internal consistency was found, with a Chronbach’s alpha value of 0.95. Reliability analyses showed an intraclass correlation coefficient (95% confidence interval) of 0.96 for the total score. There was a low correlation coefficient between the Turkish version of the Pain Catastrophizing Scale and body mass index, pain levels at rest and during activity, health-related quality of life, and fear and avoidance behaviors. [Conclusion] The results of this study indicate that the Turkish version of the Pain Catastrophizing Scale is a valid and reliable clinical and research tool for patients with ankylosing spondylitis.

Neuroplastic Effects of Transcranial Direct Current Stimulation on Painful Symptoms Reduction in Chronic Hepatitis C: A Phase II Randomized, Double Blind, Sham Controlled Trial

Introduction: Pegylated Interferon Alpha (Peg-IFN) in combination with other drugs is the standard treatment for chronic hepatitis C infection (HCV) and is related to severe painful symptoms. The aim of this study was access the efficacy of transcranial direct current stimulation (tDCS) in controlling the painful symptoms related to Peg-IFN side effects.

Materials and Methods: In this phase II double-blind trial, twenty eight (n = 28) HCV subjects were randomized to receive either 5 consecutive days of active tDCS (n = 14) or sham (n = 14) during 5 consecutive days with anodal stimulation over the primary motor cortex region using 2 mA for 20 min. The primary outcomes were visual analogue scale (VAS) pain and brain-derived neurotrophic factor (BDNF) serum levels. Secondary outcomes were the pressure-pain threshold (PPT), the Brazilian Profile of Chronic Pain: Screen (B-PCP:S), and drug analgesics use.

Results: tDCS reduced the VAS scores (P < 0.003), with a mean pain drop of 56% (p < 0.001). Furthermore, tDCS was able to enhance BDNF levels (p < 0.01). The mean increase was 37.48% in the active group. Finally, tDCS raised PPT (p < 0.001) and reduced the B-PCP:S scores and analgesic use (p < 0.05).

Conclusions: Five sessions of tDCS were effective in reducing the painful symptoms in HCV patients undergoing Peg-IFN treatment. These findings support the efficacy of tDCS as a promising therapeutic tool to improve the tolerance of the side effects related to the use of Peg-IFN. Future larger studies (phase III and IV trials) are needed to confirm the clinical use of the therapeutic effects of tDCS in such condition.

Trial registration: Brazilian Human Health Regulator for Research with the approval number CAAE 07802012.0.0000.5327.

Psychometric properties of the Brazilian version of the Pain Catastrophizing Scale for acute low back pain

Measurement instruments of pain catastrophizing for middle-aged and elderly individuals are needed to understand its impact on low back pain. The goals were to cross-culturally adapt the Pain Catastrophizing Scale, assess the construct validity through Rasch analysis, and verify reliability and convergent validity of pain catastrophizing with psychosocial factors. 131 individuals aged 55 years and older with acute low back pain were interviewed . The intra-rater reliability was Kp = 0.80 and interrater Kp = 0.75. The Rasch analysis found adequate reliability coefficients (0.95 for items and 0.90 for individuals ). The separation index for the elderly was 2.95 and 4.59 items. Of the 13 items, one did not fit the model, which was justified in the sample evaluated. The pain catastrophizing correlated with most psychosocial factors. The instrument proved to be clinically useful. Subsequent studies should carry out the same analysis in different populations.

Combined neuromodulatory interventions in acute experimental pain: assessment of melatonin and non-invasive brain stimulation

Transcranial direct current stimulation (tDCS) and melatonin can effectively treat pain. Given their potentially complementary mechanisms of action, their combination could have a synergistic effect. Thus, we tested the hypothesis that compared to the control condition and melatonin alone, tDCS combined with melatonin would have a greater effect on pain modulatory effect, as assessed by quantitative sensory testing (QST) and by the pain level during the Conditioned Pain Modulation (CPM)-task. Furthermore, the combined treatment would have a greater cortical excitability effect as indicated by the transcranial magnetic stimulation (TMS) and on the serum BDNF level. Healthy males (n = 20), (aged 18-40 years), in a blinded, placebo-controlled, crossover, clinical trial, were randomized into three groups: sublingual melatonin (0.25 mg/kg) + a-tDCS, melatonin (0.25 mg/kg) + sham-(s)-tDCS, or sublingual placebo+sham-(s)-tDCS. Anodal stimulation (2 mA, 20 min) was applied over the primary motor cortex. There was a significant difference in the heat pain threshold (°C) for melatonin+a-tDCS vs. placebo+s-tDCS (mean difference: 4.86, 95% confidence interval [CI]: 0.9 to 8.63) and melatonin+s-tDCS vs. placebo+s-tDCS (mean: 5.16, 95% CI: 0.84 to 8.36). There was no difference between melatonin+s-tDCS and melatonin+a-tDCS (mean difference: 0.29, 95% CI: -3.72 to 4.23). The mean change from the baseline on amplitude of motor evocate potential (MEP) was significantly higher in the melatonin+a-tDCS (-19.96% ± 5.2) compared with melatonin+s-tDCS group (-1.36% ± 5.35) and with placebo+s-tDCS group (3.61% ± 10.48), respectively (p < 0.05 for both comparisons). While melatonin alone or combined with a-tDCS did not significantly affect CPM task result, and serum BDNF level. The melatonin effectively reduced pain; however, its association with a-tDCS did not present an additional modulatory effect on acute induced pain.

Melatonin analgesia is associated with improvement of the descending endogenous pain-modulating system in fibromyalgia: a phase II, randomized, double-dummy, controlled trial

BACKGROUND

Central disinhibition is a mechanism involved in the physiopathology of fibromyalgia. Melatonin can improve sleep quality, pain and pain threshold. We hypothesized that treatment with melatonin alone or in combination with amitriptyline would be superior to amitriptyline alone in modifying the endogenous pain-modulating system (PMS) as quantified by conditional pain modulation (CPM), and this change in CPM could be associated with serum brain-derived neurotrophic factor (BDNF). We also tested whether melatonin improves the clinical symptoms of pain, pain threshold and sleep quality.

METHODS

Sixty-three females, aged 18 to 65, were randomized to receive bedtime amitriptyline (25 mg) (n = 21), melatonin (10 mg) (n = 21) or melatonin (10 mg) + amitriptyline (25 mg) (n = 21) for a period of six weeks. The descending PMS was assessed with the CPM-TASK. It was assessed the pain score on the Visual Analog Scale (VAS 0-100 mm), the score on Fibromyalgia Impact Questionnaire (FIQ), heat pain threshold (HPT), sleep quality and BDNF serum. Delta values (post- minus pre-treatment) were used to compare the treatment effect. The outcomes variables were collected before, one and six weeks after initiating treatment.

RESULTS

Melatonin alone or in combination with amitriptyline reduced significantly pain on the VAS compared with amitriptyline alone (P < 0.01). The delta values on the VAS scores were-12.85 (19.93),-17.37 (18.69) and-20.93 (12.23) in the amitriptyline, melatonin and melatonin+amitriptyline groups, respectively. Melatonin alone and in combination increased the inhibitory PMS as assessed by the Numerical Pain Scale [NPS(0-10)] reduction during the CPM-TASK:-2.4 (2.04) melatonin + amitriptyline,-2.65 (1.68) melatonin, and-1.04 (2.06) amitriptyline, (P < 0.05). Melatonin + amitriptyline treated displayed better results than melatonin and amitriptyline alone in terms of FIQ and PPT improvement (P < 0.05, fort both).

CONCLUSION

Melatonin increased the inhibitory endogenous pain-modulating system as assessed by the reduction on NPS(0-10) during the CPM-TASK. Melatonin alone or associated with amitriptyline was better than amitriptyline alone in improving pain on the VAS, whereas its association with amitriptyline produced only marginal additional clinical effects on FIQ and PPT.

TRIAL REGISTRATION

Current controlled trail is registered at clinical trials.gov upon under number NCT02041455. Registered January 16, 2014.

Higher serum S100B and BDNF levels are correlated with a lower pressure-pain threshold in fibromyalgia

BACKGROUND

Fibromyalgia (FM) is conceptualized as a central sensitization (CS) condition, that presents high serum brain-derived neurotrophic factor (BDNF) and neuroglia activation. Although the S100B protein regulates neuroglia functions, it has been traditionally used as a proxy of central nervous system damage. However, neither BDNF nor S100B association with the clinical picture of FM has been elucidated. To explore their association with the pressure-pain threshold (PPT) in FM, we performed a cross-sectional study, including 56 females with confirmed FM aged 18-65 years. Linear regression models were used to adjust for potential confounding factors between serum BDNF, S100B and PPT.

RESULTS

Serum BDNF and S100B were correlated (Spearman's Rho = 0.29). Serum BDNF (log) and S100B (log) were correlated with the PPT (log) (Partial η2 = 0.129, P = 0.012 for the BDNF (log), and Partial η2 = 0.105, P = 0.025 for the S100B (log)). Serum BDNF (log) was inversely associated with PPT (log) (β = -1.01, SE = 0.41), age (β = -0.02, SE = 0.15) and obsessive compulsive disorder (β = -0.36, SE = 0.15), while serum S100B (log) was inversely associated with PPT (log) (β = -1.38, SE = 0.50), only.

CONCLUSIONS

Both neuroglia key mediators in the CS process were inversely correlated with the PPT. Serum assessment of BDNF and S100B deserve further study to determine its potential as a proxy for the CS spectrum in FM.

Repetitive transcranial magnetic stimulation increases the corticospinal inhibition and the brain-derived neurotrophic factor in chronic myofascial pain syndrome: an explanatory double-blinded, randomized, sham-controlled trial

Chronic myofascial pain syndrome has been related to defective descending inhibitory systems. Twenty-four females aged 19 to 65 years with chronic myofascial pain syndrome were randomized to receive 10 sessions of repetitive transcranial magnetic stimulation (rTMS) (n = 12) at 10 Hz or a sham intervention (n = 12). We tested if pain (quantitative sensory testing), descending inhibitory systems (conditioned pain modulation [quantitative sensory testing + conditioned pain modulation]), cortical excitability (TMS parameters), and the brain-derived neurotrophic factor (BDNF) would be modified. There was a significant interaction (time vs group) regarding the main outcomes of the pain scores as indexed by the visual analog scale on pain (analysis of variance, P < .01). Post hoc analysis showed that compared with placebo-sham, the treatment reduced daily pain scores by -30.21% (95% confidence interval = -39.23 to -21.20) and analgesic use by -44.56 (-57.46 to -31.67). Compared to sham, rTMS enhanced the corticospinal inhibitory system (41.74% reduction in quantitative sensory testing + conditioned pain modulation, P < .05), reduced the intracortical facilitation in 23.94% (P = .03), increased the motor evoked potential in 52.02% (P = .02), and presented 12.38 ng/mL higher serum BDNF (95% confidence interval = 2.32-22.38). No adverse events were observed. rTMS analgesic effects in chronic myofascial pain syndrome were mediated by top-down regulation mechanisms, enhancing the corticospinal inhibitory system possibly via BDNF secretion modulation.

PERSPECTIVE

High-frequency rTMS analgesic effects were mediated by top-down regulation mechanisms enhancing the corticospinal inhibitory, and this effect involved an increase in BDNF secretion.

Association of anxiety with intracortical inhibition and descending pain modulation in chronic myofascial pain syndrome

Background

This study aimed to answer three questions related to chronic myofascial pain syndrome (MPS): 1) Is the motor cortex excitability, as assessed by transcranial magnetic stimulation parameters (TMS), related to state-trait anxiety? 2) Does anxiety modulate corticospinal excitability changes after evoked pain by Quantitative Sensory Testing (QST)? 3) Does the state-trait anxiety predict the response to pain evoked by QST if simultaneously receiving a heterotopic stimulus [Conditional Pain Modulation (CPM)]? We included females with chronic MPS (n = 47) and healthy controls (n = 11), aged 19 to 65 years. Motor cortex excitability was assessed by TMS, and anxiety was assessed based on the State-Trait Anxiety Inventory. The disability related to pain (DRP) was assessed by the Profile of Chronic Pain scale for the Brazilian population (B:PCP:S), and the psychophysical pain measurements were measured by the QST and CPM.

Results

In patients, trait-anxiety was positively correlated to intracortical facilitation (ICF) at baseline and after QST evoked pain (β = 0.05 and β = 0.04, respectively) and negatively correlated to the cortical silent period (CSP) (β = -1.17 and β = -1.23, respectively) (P <0.05 for all comparisons). After QST evoked pain, the DRP was positively correlated to ICF (β = 0.02) (P < 0.05). Pain scores during CPM were positively correlated with trait-anxiety when it was concurrently with high DRP (β = 0.39; P = 0.02). Controls’ cortical excitability remained unchanged after QST.

Conclusions

These findings suggest that, in chronic MPS, the imbalance between excitatory and inhibitory descending systems of the corticospinal tract is associated with higher trait-anxiety concurrent with higher DRP.

The relationship between cortical excitability and pain catastrophizing in myofascial pain

Pain catastrophizing regularly occurs in chronic pain patients. It has been suggested that pain catastrophizing is a stable, person-based construct. These findings highlight the importance of investigating catastrophizing in conceptualizing specific approaches for pain management. One important area of investigation is the mechanism underlying pain catastrophizing. Therefore, this study explored the relationship between a neurophysiological marker of cortical excitability, as assessed by transcranial magnetic stimulation, and catastrophizing, as assessed by the Brazilian Portuguese Pain Catastrophizing Scale, in patients with chronic myofascial pain syndrome. The Pain Catastrophizing Scale is a robust questionnaire used to examine rumination, magnification and helplessness that are associated with the experience of pain. We include 24 women with myofascial pain syndrome. The Brazilian Portuguese Pain Catastrophizing Scale and cortical excitability were assessed. Functional and behavioral aspects of pain were evaluated with a version of the Profile of Chronic Pain scale and by multiple pain measurements (eg, pain intensity, pressure pain threshold, and other quantitative sensory measurements). Intracortical facilitation was found to be significantly associated with pain catastrophizing (β = .63, P = .001). Our results did not suggest that these findings were influenced by other factors, such as age or medication use. Furthermore, short intracortical inhibition showed a significant association with pressure pain threshold (β = .44, P = .04). This study elaborates on previous findings indicating a relationship between cortical excitability and catastrophizing. The present findings suggest that glutamatergic activity may be associated with mechanisms underlying pain catastrophizing; thus, the results highlight the need to further investigate the neurophysiological mechanisms associated with pain and catastrophizing.

PERSPECTIVE

This study highlights the relationship between cortical excitability and catastrophizing. Cortical measures may illuminate how catastrophizing responses may be related to neurophysiological mechanisms associated with chronic pain.