Trans-spinal Electrical Stimulation in Individuals With Spinocerebellar Ataxia

The main goal of this pragmatic clinical trial is to investigate the effects of trans-spinal tDCS in individuals with spinocerebellar ataxia (SCA) over some parameters of gait and postural control in real-world conditions, reflecting daily clinical practice. The main questions it aims to answer are: * If an extended number of tDCS sessions, beyond the typical 5 to 10 sessions described in scientific literature, applied concomitantly with exercises with progressive challenges, to yield positive outcomes over some parameters of gait and postural control in individuals with SCA and if there is retention of possible benefits one month later the end of this protocol. * If there is specific characteristics (including balance, gait, mobility, severity of ataxia, DNA test characteristics and non-ataxic signs) in individuals with SCA that can predict their improvement in postural control and gait following the 20 tDCS sessions. * Participants will receive 20 tDCS sessions concomitantly with exercises for gait and postural control with progressive challenges. * Postural control and gait of the participants will be assessed in two big sessions before (#assessment 1) and after the 20 sessions (#assessment 5) and 3 small sessions after every 5 sessions (#assessments 2, 3 and 4). Also, as a follow-up, they will be assessed a month after the end of the intervention (#assessment 6).