Outcome measures will be assessed the week prior to treatment initiation (T0), the week after the end of treatment (T1) and at 3 months follow-up (T3) to evaluate treatments retention, by a clinician blinded to the treatment. At the end of each session, the subject will complete a questionnaire where report side effects due to stimulation (headache, neck pain, burning, redness and/or itching in the site of stimulation).