Mapeamento metabólico cortical por espectroscopia funcional em sujeitos saudáveis submetidos a estimulação elétrica do nervo acessório

A estimulação elétrica periférica (PES), que abrange diversas técnicas com respostas fisiológicas diversas, tem apresentado em alguns casos resultados clínicos promissores para o tratamento da dor e reabilitação clínica. No entanto, as respostas encontradas são heterogêneas, principalmente porque há uma falta de compreensão em relação ao seu mecanismo de ação. Neste estudo, buscamos avaliar os efeitos da PES através da medição da ativação cortical cerebral utilizando a espectroscopia funcional por infravermelho (fNIRS). A fNIRS é um método de imagem óptica funcional que avalia mudanças hemodinâmicas nas concentrações de hemoglobina oxigenada (HbO) e desoxigenada (HbR), relacionadas à atividade cortical. Nós hipotetizamos que a PES do nervo acessório espinal (ASN) pode promover a ativação do córtex motor (MC) e do córtex pré-frontal dorsolateral (DLPFC), relacionados ao processamento da dor. Quinze voluntários saudáveis receberam estimulação elétrica ativa e sham em um ensaio clínico randomizado cruzado. A resposta hemodinâmica à estimulação elétrica unilateral direita do nervo acessório com 10 Hz foi medida pela espectroscopia funcional por um sistema de 40 canais. A variação de HbO nas áreas corticais de interesse mostrou ativação do DLPFC direito (p=0,025) e do MOTOR esquerdo (p=0,042) no grupo ativo comparado com sham. Em relação ao DLPFC esquerdo (p=0,610) e ao MOTOR direito (p=0,154), não houve diferença estatística entre os grupos. Como na modulação top-down, a estimulação bottom-up do nervo acessório parece ativar as mesmas áreas corticais, relacionadas às dimensões sensório-discriminativas e afetivo-motivacionais da dor. Esses resultados fornecem evidência adicional para desenvolver e otimizar o uso clínico da estimulação elétrica periférica.Peripheral electrical stimulation (PES), which encompasses several techniques with heterogeneous physiological responses, has shown in some cases remarkable outcomes for pain treatment and clinical rehabilitation. However, results are still mixed, mainly because there is a lack of understanding regarding its neural mechanisms of action. In this study, we aimed to assess its effects by measuring cortical activation as indexed by functional near infrared spectroscopy (fNIRS). fNIRS is a functional optical imaging method to evaluate hemodynamic changes in oxygenated (HbO) and de-oxygenated (HbR) blood hemoglobin concentrations in cortical capillary networks that can be related to cortical activity. We hypothesized that PES of accessory spinal nerve (ASN) can promote cortical activation of motor cortex (MC) and dorsolateral prefrontal cortex (DLPFC) pain processing cortical areas. Fifteen healthy volunteers received both active and sham ASN electrical stimulation in a crossover design. The hemodynamic response to unilateral right ASN burst electrical stimulation with 10 Hz was measured by a 40- channel fNIRS system. The effect of ASN electrical stimulation over HbO concentration in cortical areas of interest was observed through the activation of right- DLPFC (p=0.025) and left-MOTOR (p=0.042) in the active group but not in sham group. Regarding left-DLPFC (p=0.610) and right-MOTOR (p=0.174) there was no statistical difference between groups. As in non-invasive brain stimulation (NIBS) topdown modulation, bottom-up electrical stimulation to the accessory spinal nerve seems to activate the same critical cortical areas on pain pathways related to sensorydiscriminative and affective-motivational pain dimensions. These results provide additional mechanistic evidence to develop and optimize the effects of peripheral neural electrical stimulation

Longer cortical silent period length is associated to binge eating disorder : an exploratory study

Introduction: Although binge eating disorder (BED) is an eating disorder and obesity is a clinical disease, it is known that both conditions present overlapped symptoms related to, at least partially, the disruption of homeostatic and hedonistic eating behavior pathways. Therefore, the understanding of neural substrates, such as the motor cortex excitability assessed by transcranial magnetic stimulation (TMS), might provide new insights into the pathophysiology of BED and obesity. Objectives: (i) To compare, among BED, obesity, ex-obese, and HC (healthy control) subjects, the cortical excitability indexed by TMS measures, such as CSP (cortical silent period; primary outcome), SICI (intracortical inhibition), and ICF (intracortical facilitation; secondary outcome). (ii) To explore the relationship of the CSP, eating behavior (e.g., restraint, disinhibition, and hunger), depressive symptoms, and sleep quality among the four groups (BED, obesity, ex-obese, and HC). Methods: Fifty-nine women [BED (n = 13), obese (n = 20), ex-obese (n = 12), and HC (n = 14)] comprise the total sample for this study. Assessments: cortical excitability measures (CSP, SICI, and ICF), inhibition response task by the Go/No-go paradigm, and instruments to assess the eating psychopathology (Three-Factor Eating Questionnaire, Eating Disorder Examination Questionnaire, and Binge Eating Scale) were used. Results: A MANCOVA analysis revealed that the mean of CSP was longer in the BED group compared with other three groups: 24.10% longer than the obesity group, 25.98% longer than the HC group, and 25.41% longer than the ex-obese group. Pearson's correlations evidenced that CSP was positively associated with both eating concern and binge eating scores. Conclusion: The findings point out that BED patients present longer CSP, which might suggest an upregulation of intracortical inhibition. Additionally, CSP was positively correlated with Binge Eating Scale and eating concern scores. Further studies are needed

The fear of pain questionnaire : psychometric properties of a Brazilian version for adolescents and its relationship with brain-derived neurotrophic factor (BDNF)

Objectives: The primary aim was to assess the psychometric properties (including internal consistency, construct validity, criterion validity, criterion-group validity and responsiveness) of the Fear of Pain Questionnaire (FOPQ) for adolescents (FOPQ-A) and parents (FOPQ-P) translated to Brazilian Portuguese (BrP). The secondary aim was to analyze the factor structures and their ability to identify subjects with chronic pain conditions and identify the relationship of the BrP FOPQ-A with saliva brain-derived neurotrophic-factor (BDNF). Methods: A cross-sectional study was conducted with 286 adolescents aged 11 to 18 (257 healthy adolescents [157 females] and 29 adolescents with chronic pain [16 females]). Parents and adolescents completed the BrP-FOPQ. A team of experts translated the FOPQ according to international guidelines. Convergent validity and factor analysis were performed. Later, a subsample (n=146) was used to correlate the BrP-FOPQ-A with saliva BDNF. Results: The BrP-FOPQ for adolescents and parents presented strong psychometric properties (Cronbach’s α equal to 0.92 and 0.91, respectively). BrP-FOPQ-A confirmatory factor analysis yielded a two-factor structure while the factorial analyses of BrP-FOPQ-P demonstrated that the best solution was a three-structure factorial. The BrP-FOPQ-P scores in healthy adolescents and those in chronic pain conditions was 34.13 (16.71) vs 43.14 (18.08), respectively. A generalized mixed model demonstrated that the scores in the BrP-FOPQ-A are higher in those with chronic pain conditions compared to healthy subjects (29.20 [12.77] vs 33.80 [10.76], respectively; Wald χ2= 17.80; df=1, P<0.0001). The model revealed that the BDNF was positively correlated with the score of BrP-FOPQ-A and subjects with chronic pain showed higher levels of BDNF. Conclusion: The BrP-FOPQ scores for adolescents and parents were found to be psychometrically robust and reliable instruments, with primary evidence of validity. Higher scores on the BrP-FOPQ-A were correlated positively with saliva BDNF and permitted the identification of subjects with chronic pain conditions

Longer cortical silent period length is associated to binge eating disorder : an exploratory study

Introduction: Although binge eating disorder (BED) is an eating disorder and obesity is a clinical disease, it is known that both conditions present overlapped symptoms related to, at least partially, the disruption of homeostatic and hedonistic eating behavior pathways. Therefore, the understanding of neural substrates, such as the motor cortex excitability assessed by transcranial magnetic stimulation (TMS), might provide new insights into the pathophysiology of BED and obesity. Objectives: (i) To compare, among BED, obesity, ex-obese, and HC (healthy control) subjects, the cortical excitability indexed by TMS measures, such as CSP (cortical silent period; primary outcome), SICI (intracortical inhibition), and ICF (intracortical facilitation; secondary outcome). (ii) To explore the relationship of the CSP, eating behavior (e.g., restraint, disinhibition, and hunger), depressive symptoms, and sleep quality among the four groups (BED, obesity, ex-obese, and HC). Methods: Fifty-nine women [BED (n = 13), obese (n = 20), ex-obese (n = 12), and HC (n = 14)] comprise the total sample for this study. Assessments: cortical excitability measures (CSP, SICI, and ICF), inhibition response task by the Go/No-go paradigm, and instruments to assess the eating psychopathology (Three-Factor Eating Questionnaire, Eating Disorder Examination Questionnaire, and Binge Eating Scale) were used. Results: A MANCOVA analysis revealed that the mean of CSP was longer in the BED group compared with other three groups: 24.10% longer than the obesity group, 25.98% longer than the HC group, and 25.41% longer than the ex-obese group. Pearson's correlations evidenced that CSP was positively associated with both eating concern and binge eating scores. Conclusion: The findings point out that BED patients present longer CSP, which might suggest an upregulation of intracortical inhibition. Additionally, CSP was positively correlated with Binge Eating Scale and eating concern scores. Further studies are needed

The fear of pain questionnaire : psychometric properties of a Brazilian version for adolescents and its relationship with brain-derived neurotrophic factor (BDNF)

Objectives: The primary aim was to assess the psychometric properties (including internal consistency, construct validity, criterion validity, criterion-group validity and responsiveness) of the Fear of Pain Questionnaire (FOPQ) for adolescents (FOPQ-A) and parents (FOPQ-P) translated to Brazilian Portuguese (BrP). The secondary aim was to analyze the factor structures and their ability to identify subjects with chronic pain conditions and identify the relationship of the BrP FOPQ-A with saliva brain-derived neurotrophic-factor (BDNF). Methods: A cross-sectional study was conducted with 286 adolescents aged 11 to 18 (257 healthy adolescents [157 females] and 29 adolescents with chronic pain [16 females]). Parents and adolescents completed the BrP-FOPQ. A team of experts translated the FOPQ according to international guidelines. Convergent validity and factor analysis were performed. Later, a subsample (n=146) was used to correlate the BrP-FOPQ-A with saliva BDNF. Results: The BrP-FOPQ for adolescents and parents presented strong psychometric properties (Cronbach’s α equal to 0.92 and 0.91, respectively). BrP-FOPQ-A confirmatory factor analysis yielded a two-factor structure while the factorial analyses of BrP-FOPQ-P demonstrated that the best solution was a three-structure factorial. The BrP-FOPQ-P scores in healthy adolescents and those in chronic pain conditions was 34.13 (16.71) vs 43.14 (18.08), respectively. A generalized mixed model demonstrated that the scores in the BrP-FOPQ-A are higher in those with chronic pain conditions compared to healthy subjects (29.20 [12.77] vs 33.80 [10.76], respectively; Wald χ2= 17.80; df=1, P<0.0001). The model revealed that the BDNF was positively correlated with the score of BrP-FOPQ-A and subjects with chronic pain showed higher levels of BDNF. Conclusion: The BrP-FOPQ scores for adolescents and parents were found to be psychometrically robust and reliable instruments, with primary evidence of validity. Higher scores on the BrP-FOPQ-A were correlated positively with saliva BDNF and permitted the identification of subjects with chronic pain conditions