Basic and functional effects of transcranial Electrical Stimulation (tES)-An introduction.

Non-invasive brain stimulation (NIBS) has been gaining increased popularity in human neuroscience research during the last years. Among the emerging NIBS tools is transcranial electrical stimulation (tES), whose main modalities are transcranial direct, and alternating current stimulation (tDCS, tACS). In tES, a small current (usually less than 3mA) is delivered through the scalp. Depending on its shape, density, and duration, the applied current induces acute or long-lasting effects on excitability and activity of cerebral regions, and brain networks. tES is increasingly applied in different domains to (a) explore human brain physiology with regard to plasticity, and brain oscillations, (b) explore the impact of brain physiology on cognitive processes, and (c) treat clinical symptoms in neurological and psychiatric diseases. In this review, we give a broad overview of the main mechanisms and applications of these brain stimulation tools.

Five-year review of an international clinical research-training program.

The exponential increase in clinical research has profoundly changed medical sciences. Evidence that has accumulated in the past three decades from clinical trials has led to the proposal that clinical care should not be based solely on clinical expertise and patient values, and should integrate robust data from systematic research. As a consequence, clinical research has become more complex and methods have become more rigorous, and evidence is usually not easily translated into clinical practice. Therefore, the instruction of clinical research methods for scientists and clinicians must adapt to this new reality. To address this challenge, a global distance-learning clinical research-training program was developed, based on collaborative learning, the pedagogical goal of which was to develop critical thinking skills in clinical research. We describe and analyze the challenges and possible solutions of this course after 5 years of experience (2008-2012) with this program. Through evaluation by students and faculty, we identified and reviewed the following challenges of our program: 1) student engagement and motivation, 2) impact of heterogeneous audience on learning, 3) learning in large groups, 4) enhancing group learning, 5) enhancing social presence, 6) dropouts, 7) quality control, and 8) course management. We discuss these issues and potential alternatives with regard to our research and background.

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 (ß = 0.05 and ß = 0.04, respectively) and negatively correlated to the cortical silent period (CSP) (ß = -1.17 and ß = -1.23, respectively) (P <0.05 for all comparisons). After QST evoked pain, the DRP was positively correlated to ICF (ß = 0.02) (P < 0.05). Pain scores during CPM were positively correlated with trait-anxiety when it was concurrently with high DRP (ß = 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.

Analgesic and sedative effects of melatonin in temporomandibular disorders: a double-blind, randomized, parallel-group, placebo-controlled study.

CONTEXT: The association between myofascial temporomandibular disorder (TMD) and nonrestorative sleep supports the investigation of therapies that can modulate the sleep/wake cycle. In this context, melatonin becomes an attractive treatment option for myofascial TMD pain. OBJECTIVES: To investigate the effects of melatonin on pain (primary aim) and sleep (secondary aim) as compared with placebo in a double-blind, randomized, parallel-group trial. METHODS: Thirty-two females, aged 20-40 years, with myofascial TMD pain were randomized into placebo or melatonin (5mg) treatment groups for a period of four weeks. RESULTS: There was a significant interaction (time vs. group) for the main outcomes of pain scores as indexed by the visual analogue scale and pressure pain threshold (analysis of variance; P<0.05 for these analyses). Post hoc analysis showed that the treatment reduced pain scores by -44% (95% CI -57%, -26%) compared with placebo, and it also increased the pressure pain threshold by 39% (95% CI 14%, 54%). The use of analgesic doses significantly decreased with time (P<0.01). The daily analgesic doses decreased by -66% (95% CI -94%, -41%) when comparing the two groups. Additionally, melatonin improved sleep quality, but its effect on pain was independent of the effect on sleep quality. CONCLUSION: This study provides additional evidence supporting the analgesic effects of melatonin on pain scores and analgesic consumption in patients with mild-to-moderate chronic myofascial TMD pain. Furthermore, melatonin improves sleep quality but its effect on pain appears to be independent of changes in sleep quality.

Cross-cultural adaptation and validation of the profile of chronic pain: screen for a Brazilian population.

OBJECTIVE: To translate the original English version of the Profile of Chronic Pain: Screen (PCP:S) into Brazilian Portuguese and examine basic psychometric properties of the translated version. We investigated ceiling and floor effects, internal consistency, factor structure, convergent validity, and the ability of the Brazilian PCP:S (B-PCP:S) to discriminate persons with pain who were either employed or not working, or in treatment or not in treatment. METHODS: The Brazilian Portuguese version of the Profile of Chronic Pain: Screen (B-PCP:S) was administered to a sample of 414 adults (men = 67). Pain catastrophizing was also assessed. Subsamples with special conditions (working despite pain [N = 116] vs not working due to pain [N = 122], and not receiving treatment for pain [N = 119] vs receiving treatment [N = 119]) were identified to investigate the discriminative properties of B-PCP:S. RESULTS: For the B-PCP:S, Cronbach's α values were 0.76 (severity), 0.88 (interference), and 0.87 (emotional burden). Confirmatory factor analysis supported the original, English language three-factor structure, with the comparative fit index = 0.93, root mean square error of approximation = 0.075, and normed fit index = 0.93. Significant correlations were found between pain intensity, pain interference, and emotional burden, and a criterion measure of catastrophizing (correlation coefficients ranged from 0.48 to 0.66, P < 0.01). B-PCP:S scores (severity, interference, and emotional burden) were higher in subjects under a doctor's care for pain and in those not working due to pain. CONCLUSION: This B-PCP:S version was found to be a reliable instrument, with basic evidence of validity for the evaluation of pain severity, interference, and emotional burden in Brazilian Portuguese adults. The profile of B-PCP:S scores was similar to that observed in the original version.

Cross-cultural adaptation and validation of the Brazilian Portuguese version of the pain catastrophizing scale.

OBJECTIVE: Catastrophizing is a maladaptive response to pain and is one of the factors that contribute to the chronicity of some pain syndromes. The Pain Catastrophizing Scale (PCS) assists both treatment planning and outcome assessment. Its use is limited in Portuguese-speaking countries because of the lack of a validated translated version. We conducted the validation of the Brazilian Portuguese (BP)-PCS and explored its psychometric properties. This study reports the internal consistency, factor structure, and its capability to discriminate pain reported by patients with specific chronic pain conditions. METHODS: Three hundred eighty-four patients, 317 women (82.55%), aged 18-79 years with chronic nonmalignant pain attending an outpatient multidisciplinary pain center participated in this cross-sectional study. The instruments were the BP-PCS, pain intensity, pain interference in functional capacity, and a sociodemographic questionnaire. One subsample with chronic tensional headache (CTH) according to the criteria of the International Headache Society (N = 19), and another with a diagnosis of fibromyalgia according to the American College of Rheumatology criteria (N = 50) were selected to assess the discriminative properties of BP-PCS. RESULTS: We observed good internal consistency (Cronbach's α values of 0.91 for the total BP-PCS, and 0.93 [helplessness], 0.88 [magnification], and 0.86 [rumination] for the respective subdomains). The item-total correlation coefficients ranged from 0.91 to 0.94. Confirmatory factor analysis (CFA) supported the three factors structure, with the comparative fit index = 0.98, root mean square error of approximation = 0.09, and normed fit index = 0.98. Significant correlations were found for pain intensity, pain interference, and patient's mood (correlation coefficients ranged from 0.48 to 0.66, P < 0.01). No significant gender difference was observed for BP-PCS scores. When comparing scores of BP-PCS scale and subscales between the selected control group (patients with pain scores on visual analog scale equal or lower than 40 mm in the most part of the day in the last 6 months) and patients with fibromyalgia or CTH, we observed lower scores for the former group. CONCLUSION: Our findings support the validity and reliability of the BP-PCS. The scale showed satisfactory psychometric properties. CFA provides support for the three-factor structure reported in previous studies. This factor structure presented good discriminative properties to identify catastrophizers who present with mild chronic pain, fibromyalgia, and CTH. The BP-PCS is a valuable tool for use in scientific studies and in the clinical setting in patients with chronic pain in Brazilian Portuguese-speaking countries.

Neurobiological effects of transcranial direct current stimulation: a review.

Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that is affordable and easy to operate compared to other neuromodulation techniques. Anodal stimulation increases cortical excitability, while the cathodal stimulation decreases it. Although tDCS is a promising treatment approach for chronic pain as well as for neuropsychiatric diseases and other neurological disorders, several complex neurobiological mechanisms that are not well understood are involved in its effect. The purpose of this systematic review is to summarize the current knowledge regarding the neurobiological mechanisms involved in the effects of tDCS. The initial search resulted in 171 articles. After applying inclusion and exclusion criteria, we screened 32 full-text articles to extract findings about the neurobiology of tDCS effects including investigation of cortical excitability parameters. Overall, these findings show that tDCS involves a cascade of events at the cellular and molecular levels. Moreover, tDCS is associated with glutamatergic, GABAergic, dopaminergic, serotonergic, and cholinergic activity modulation. Though these studies provide important advancements toward the understanding of mechanisms underlying tDCS effects, further studies are needed to integrate these mechanisms as to optimize clinical development of tDCS.

Dor miofascial ou síndrome de Eagle? A importância do diagnóstico diferencial / Myofascial pain or Eagle´s syndrome? The importance of the differential diagnosis

A síndrome do processo estiloide alongado ou síndrome de Eagle e a dor miofascial fazem parte das disfunções craniomandibulares. Vários relatos de casos clínicos encontrados na literatura enfatizam as anormalidades do complexo estiloideo associadas a vários sintomas, como dor muscular, tender points, trigger points, que confundem o diagnóstico ou associam esses sintomas a outras enfermidades. Nesse sentido, é importante a obtenção de um diagnóstico preciso, em virtude de sintomatologia confundente. Este artigo relata um caso de dor miofascial no qual a paciente se apresentava com dor em região de cabeça e pescoço com o processo estiloide alongado em torno de 78 mm (observado em radiografia panorâmica). O diagnóstico final foi obtido por meio de exame clínico investigatório associado a imagens.