Transcranial direct current stimulation is safe and effective in autoimmune myopathies: a randomised, double-blind, sham-controlled trial

Objective We aimed to assess the safety and efficacy of transcranial direct current stimulation (tDCS) in patients with systemic autoimmune myopathies (SAMs).Methods This prospective, randomised, sham-controlled, double-blind, study included 20 patients with SAMs allocated to receive sham or active tDCS (2mA, 20 minutes, 3 days). Electrodes were positioned with the anode over the C1 or C2, whereas the cathode was placed over the Fp2 or Fp1, respectively. The groups were evaluated in four periods with specific questionnaires and functional tests: pre-stimulation and after 30 minutes, three weeks, and eight weeks post-tDCS.Results Two patients from the sham group withdrew after the three sessions. The demographic data, type of myositis, disease duration, and disease status were comparable between the active and sham tDCS groups. After interventions, in the active tDCS group, the physical aspects of SF-36 in week eight, mean and better timed up-and-go test at each evaluation, peak torque of stimulated inferior limb extension improved significantly (p<0.05). The emotional aspect of SF-36 decreased only in the active tDCS group (p<0.001). The patients' adherence to the protocol was 100% and no serious adverse event was reported, including disease relapses.Conclusion This study evidences the safety of tDCS, as well as its potential efficacy in improving muscle strength and function in SAMs patients. More studies with a larger sample and longer tDCS sessions are necessary to corroborate the results of the present study.