Relevance and safety of non-invasive brain stimulation in patients with systemic autoimmune myopathies: a randomized, double-blind, sham-controlled cross-over clinical trial

Background: Systemic autoimmune myopathies comprise a heterogeneous group of rare rheumatic diseases divided into dermatomyositis, polymyositis, antisynthetase syndrome, and immune-mediated necrotizing myopathy. In addition to therapeutic advances and options, chronic pain and fatigue are common symptoms in these patients. Current studies show that the association between aerobic exercise training and noninvasive brain stimulation may promote additional benefits in chronic pain and fatigue improvement. However, no studies have assessed the prevalence of pain and chronic fatigue; for example, there is no evidence regarding the potential effects of aerobic exercise training associated with non-invasive brain stimulation on pain and fatigue in patients with systemic autoimmune myopathy. Objectives: To assess the perception and intensity of pain and fatigue in patients with systemic autoimmune myopathies. Nonetheless, to evaluate the potential efficacy of noninvasive brain-stimulation for pain and fatigue perception, impact, and severity. Methods: This was a two-phase study, divided by a) an observational cross-sectional study; b) randomized, double-blind, sham-controlled, crossover clinical trial. 75 patients were included in the first phase, which was compared with 79 individuals without any disease as a control group. Of the eligible patients, 17 were included in the intervention with transcranial current electrical stimulation (tDCS) at an intensity of 2 mA and duration of 20 minutes associated with moderate aerobic exercise training for 30 minutes. The patients were evaluated using uni-multidimensional questionnaires and physical function tests before and after the intervention. Results: In the first stage, 31 (41.3%) patients were diagnosed with dermatomyositis, 26 (34.6%) antisynthetase syndrome, six (8.0%) clinically amyopathic dermatomyositis, seven (9.0%) with immune-mediated necrotizing myopathy, and five (6.0%) with polymyositis. Patients were relatively stable in the disease with a median glucocorticoid use of 0.0 (0.0-5.0) mg/day, and there were no differences between the demographic and anthropometric characteristics in the patients and the control group. There were differences in the perception and intensity of mild, moderate, and severe pain, whereas regarding the perception of fatigue, only differences were noted in mild intensity, intensity, and fatigue severity scores. After the intervention, there was a reduction in the general scores of the multidimensional pain and fatigue questionnaires as well as in the intensity of pain. However, there were no differences in the domains of the fatigue and pain questionnaires. Therefore, 88.8% of patients in the present study showed adherence and no serious adverse events. Conclusion: Patients with MAS had a higher perception of pain and fatigue than those with CTR did. The association of tDCS with aerobic training promoted additional effects in relation to the group subjected to sham stimulation combined with aerobic training on general pain and fatigue scores, as well as on pain intensity. However, there were no changes in the subdomains of the pain and fatigue questionnaire (AU)