The main objective of this study is to review and summarize recent findings on electroencephalographic patterns in individuals with chronic pain. We also discuss recent advances in the use of quantitative Electroencephalography (qEEG) for the assessment of pathophysiology and biopsychosocial factors involved in its maintenance over time. Data collection took place from February 2014 to July 2015 in PubMed, SciELO and PEDro databases. Data from cross-sectional studies and longitudinal studies, as well as clinical trials involving chronic pain participants were incorporated into the final analysis. Our primary findings related to chronic pain were an increase of theta and alpha EEG power at rest, and a decrease in the amplitude of evoked potentials after sensory stimulation and cognitive tasks. This review suggests that qEEG could be considered as a simple and objective tool for the study of brain mechanisms involved in chronic pain, as well as for identifying the specific characteristics of chronic pain condition. In addition, results show that qEEG probably is a relevant outcome measure for assessing changes in therapeutic studies.

Chronic pain (CP) is prevalent worldwide. Current reports on its prevalence in developing countries are heterogeneous, and to date, there is no quantitative synthesis providing a general estimation of its magnitude in the developing world. The goal of this study was to estimate the pooled prevalence of CP in the general population in developing countries. This was a PROSPERO-registered CRD42019118680 systematic review including population-based cross-sectional studies on CP from countries with ≤0.8 human developing index. We calculated prevalence using both random effects and fixed effects. Heterogeneity was calculated by the Cochran Q test and the I² statistic. Publication bias was evaluated by visual inspection of the Egger funnel plot, as well as by the Begg rank test and the Egger linear test. Sources of heterogeneity were also explored in subgroup analyses. Twelve studies with a total of 29,902 individuals were included in this meta-analysis, of which 7263 individuals were identified with CP. The overall pooled prevalence of CP after correction for publication bias was 18% (95% confidence interval: 10%–29%), the sample presenting significant heterogeneity (I2 = 100%, P < 0.001). Subgroup analyses demonstrated that year of publication and the adopted threshold for pain chronicity could partially explain the observed heterogeneity (P < 0.05). The proportion of individuals with CP in the general population of developing countries was 18%. However, reports of prevalence have high variability, especially related to year of publication and the threshold level adopted for pain chronicity.

Introduction: Chronic pain (CP) is highly prevalent and generally undertreated health condition. Noninvasive brain stimulation may contribute to decrease pain intensity and influence other aspects related to CP. Objective: To provide consensus-based recommendations for the use of noninvasive brain stimulation in clinical practice. Methods: Systematic review of the literature searching for randomized clinical trials followed by consensus panel. Recommendations also involved a cost-estimation study. Results: The systematic review wielded 24 transcranial direct current stimulation (tDCS) and 22 repetitive transcranial magnetic stimulation (rTMS) studies. The following recommendations were provided: (1) Level A for anodal tDCS over the primary motor cortex (M1) in fibromyalgia, and level B for peripheral neuropathic pain, abdominal pain, and migraine; bifrontal (F3/F4) tDCS and M1 high-definition (HD)-tDCS for fibromyalgia; Oz/Cz tDCS for migraine and for secondary benefits such as improvement in quality of life, decrease in anxiety, and increase in pressure pain threshold; (2) level A recommendation for high-frequency (HF) rTMS over M1 for fibromyalgia and neuropathic pain, and level B for myofascial or musculoskeletal pain, complex regional pain syndrome, and migraine; (3) level A recommendation against the use of anodal M1 tDCS for low back pain; and (4) level B recommendation against the use of HF rTMS over the left dorsolateral prefrontal cortex in the control of pain. Conclusion: Transcranial DCS and rTMS are recommended techniques to be used in the control of CP conditions, with low to moderate analgesic effects, and no severe adverse events. These recommendations are based on a systematic review of the literature and a consensus made by experts in the field. Readers should use it as part of the resources available to decision-making.

To translate and validate the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0) into Brazilian Portuguese. Certified translators translated and back-translated Quest. Content validity (CVI) was determined by 5 experts and, after the final version of B-Quest, a pre-test was applied to users of manual wheelchairs, walkers and crutches. The psychometric properties were tested to assure the validity of items and the reliability and stability of the scale. Data were obtained from 121 users of the above-mentioned devices. Our study showed a CVI of 91.66% and a satisfactory factor analysis referent to the two-dimensional structure of the instrument that ensured the representativeness of the items. The Cron-bach's alpha of the items device, service and total score of B-Quest were 0.862, 0.717 and 0.826, respectively. Test-retest stability conducted after a time interval of 2 months was analyzed using Spearman's correlation test, which showed high correlation (ρ >0.6) for most items. The study suggests that the B-Quest is a reliable, representative, and valid instrument to measure the satisfaction of users of assistive technology in Brazil.

Chronic pain is a public health problem with high impact on various population segments. There are few population studies with the aim of delineating the profile of the chronic pain patient, and generating data for actions to prevent, control and minimize the problem. The aim of this study was to estimate the prevalence of chronic pain in the population of Salvador, Bahia, Brazil and identify independent predictors associated with this morbidity. A cross-sectional study was conducted in a sample population of 2297 individuals of >20 years of age, in Salvador, Brazil. A standardized questionnaire was applied at home to collect data about socio-demographic characteristics, lifestyle, chronic pain and abdominal circumference measurement. The chronic pain was defined as pain with a duration of longer than 6 months. Prevalence of pain and the OR (univariate analysis) were estimated and adjusted (logistic regression), and their ICs at 95% and p<0.05 in the two analyses. The presence of chronic pain was found in 41.4% of the total study population, women being more affected (48.4% against 32.8% in men), with OR of 1.92 IC 95% 1.6-2,28 p<0.001. Among the studied factors, in the gross analysis, the following were shown to be associated with chronic pain: conjugal situation, smoking, excessive alcohol consumption, presence of central obesity and age, all with p<0.05. In the multivariate analysis, female sex, smoking, excessive alcohol consumption, and age were sustained as independent predictors. The presence of chronic pain was predominant in women, the elderly, smokers or ex-smokers and excessive alcohol consumers.

It has been shown that different symptoms or symptom combinations of neuropathic pain (NeP) may correspond to different mechanistic backgrounds and respond differently to treatment. The Neuropathic Pain Symptom Inventory (NPSI) is able to detect distinct clusters of symptoms (i.e. dimensions) with a putative common mechanistic background. The present study described the psychometric validation of the Portuguese version (PV) of the NPSI. Patients were seen in two consecutive visits, three to four weeks apart. They were asked to: (i) rate their mean pain intensity in the last 24 hours on an 11-point (0-10) numerical scale; (ii) complete the PV-NPSI; (iii) provide the list of pain medications and doses currently in use. VAS and Global Impression of Change (GIC) were filled out in the second visit. PV-NPSI underwent test-retest reliability, factor analysis, analysis of sensitivity to changes between both visits. The PV-NPSI was reliable in this setting, with a good intra-class correlation for all items. The factorial analysis showed that the PV-NPSI inventory assessed different components of neuropathic pain. Five different factors were found. The PV-NPSI was adequate to evaluate patients with neuropathic pain and to detect clusters of NeP symptoms. The psychometric properties of the PV-NPSI rendered it adequate to evaluate patients with both central and peripheral neuropathic pain syndromes and to detect clusters of NeP symptoms.