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.

High spinal cord injured patients (SCI) are susceptible to respiratory muscle impairments.Transcranial direct current stimulation (tDCS) and peripheral electrical stimulation (PES) may influence the diaphragm's central control, but until now they are not described as a therapeutic resource for difficult weaning. We present two case reports of SCI patients (P1 and P2) with long-term tracheostomy (>40 days) and hospital stay (>50 days). In association with respiratory exercise, P1 received a combined application of anodal tDCS over the supplementary motor area plus sensory PES in the thoracic-abdominal muscles, and P2 received isolated excitatory PES in the abdominal muscles, applied daily except on weekends. Maximum inspiratory/expiratory pressure, peak cough flow, diaphragm excursion, and thickening fraction were measured in the first and last days of the protocol. Both patients had improvements, with clinical impact such as cough effectiveness, decannulated after 15 applications of stimulation.Augmentation of neural respiratory drive and corticospinal excitability is suggested.

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Chronic pain is one of the most common symptoms of temporomandibular disorders (TMD). Although its pathophysiology is still a challenge, TMD has been associated with changes in central nervous system activity related to pain modulatory capacity. This study was conducted to examine the cortical activity of patients with temporomandibular disorders and chronic pain of myofascial origin using quantitative electroencephalography (qEEG). Individuals with TMD and chronic pain and healthy controls were evaluated using qEEG in four consecutive conditions, all with closed eyes: 1) initial resting condition; 2) non-painful motor imagery task of hand movement; 3) painful motor imagery task of clenching the teeth; 4) final resting condition. Participants with TMD and chronic pain overall presented decreased alpha power density during baseline at rest, and non-painful and painful motor imagery tasks when compared to healthy controls. Furthermore, functional brain connectivity was distinct between groups, with TMD and chronic pain showing lower small-world values for the delta (all conditions), theta (eyes closed, painful and non-painful motor imagery task), and alpha bands (painful motor imagery task), and an increase in the beta band (all conditions). These results suggest that TMD and related chronic pain is associated with maladaptive plasticity in the brain, which may correspond to a reduced ability to modify brain activity during different mental tasks, including painful and non-painful imagery. These changes can be detected by qEEG, a method which may be very important because of its characteristics of good temporal resolution and the possibility to be performed in naturalistic setups.