Sample size calculation. The dependent variable (the primary outcome measure) is the score of the N-FOG Questionnaire. Sample size has been calculated considering a repeated measures mixed ANOVA of the primary outcome measure, with the software G*Power 3. The result gives a sample size of 20 patients: 10 for each group (experimental and active comparator group). The sizing of the sample is justified by similar protocols evaluations that with an identical sample size (n = 10 per group) found statistically significant results.