3.1. Participant characteristics and flow of the trial
Thirty-four subjects were selected to participate in the electrophysiological study. In therapeutic study, nineteen subjects, who participated in the electrophysiological study, were included (10 in the experimental group and 9 in the control group). Four patients (all of the control group) dropped out during the study. One, after six sessions, reported that personal reasons prevented him from complying with the session schedule. The other patient justified the decision by lack of noticeable improvement after six tDCS sessions and two reported worsening of headache after second session. Fifteen participants completed all of the study procedures. Fig. 1 shows the flow of individuals through the study. In the electrophysiological and therapeutic study, no significant differences were found between groups regarding their demographic and clinical characteristics