Preditores clínicos e eletroencefalográficos de resposta à estimulação transcraniana por corrente contínua na fibromialgia

Abstract

Fibromyalgia (FM) is a common cause of chronic widespread pain, associated with a variety of symptoms yet not defined by an explained pathophysiological cause. In recent years, studies assessing the protocols effects of Transcranial Direct Current Stimulation (tDCS) for pain relief in FM have shown satisfactory results regarding its effectiveness. In this sense, biomarkers of response to neuromodulatory techniques have been investigated to obtain better results in clinical practice. However, at this moment, there are no experiments that both analyze the electrophysiological and clinical aspects of the response to neuromodulation in FM. Thus, we aim to analyze the predictive potential of clinical and electroencephalographic variables for a significant response to tDCS. 31 participants, aged between 27 and 58 years old, with a diagnosis of FM for at least three months were submitted to tDCS in the primary motor cortex, with an intensity of 2mA and a duration of 20 minutes. After the intervention protocol, they were divided into two groups: responders (R) and non-responders (NR), based on the minimum significant clinical response of 15% difference on the Visual Analogue Scale (VAS). For prediction analysis, we assessed pain from the VAS; life quality scores from the Health Assessment Questionnaire (HAQ); Age and daily sleep hours, based on sociodemographic and clinical assessment; and eletroencephalogram (EEG) data of both groups to evaluate the alpha 2 mean spectral power for the frontal, parietal and occipital regions. The data were analyzed by the IBM SPSS software version 24. A hierarchical linear regression analysis evidenced a contribution of reduced age, more daily sleep hours and higher quality of life as possible determinants of a better responsiveness to tDCS. Other factors such as baseline pain scores and mean spectral power of alpha2 in the frontal, parietal and occipital regions do not demonstrate a significant contribution to the reduction of post-intervention painful symptoms with tDCS. In conclusion, the clinical predictors were relevant for the prediction of response to tDCS, however the assessment of the alpha-2 mean spectral power with EEG was shown to be limited as a predictor.