Pragmatic Feasibility Study Combining Cerebello-spinal Neuromodulation and Exercise in Spinocerebellar Ataxia Type 3: A 20-session Single-arm Protocol.

Spinocerebellar ataxia type 3 (SCA3) is a hereditary neurodegenerative disorder that progressively impairs balance and gait, without effective pharmacological treatments available. Cerebellar and cerebello-spinal transcranial direct current stimulation (tDCS) have shown neuromodulatory potential. However, extended protocols combined with exercise have not yet been tested in these individuals in a public health service. To assess the feasibility and safety of 20 sessions of cerebello-spinal tDCS combined with exercise in individuals with SCA3 in real-world conditions, and to explore preliminary changes in ataxia severity, balance, and mobility. In this single-arm, open-label pragmatic feasibility study, 39 participants [67% female; 46 ± 10 (23-70) years-old; mean ± SD (min.-max.)] with mild-to-moderate SCA3 completed 20 sessions over four weeks under real-world public-health conditions. Feasibility was evaluated through adherence and tolerability, and safety was assessed by monitoring adverse events. Secondary outcomes included disease severity (SARA), balance (Berg Balance Scale), and mobility (Timed Up and Go), assessed at baseline, post-intervention, and one-month follow-up. Analyses included between-moments standardized individual differences (SID) and multiple linear regression adjusted for baseline values. Adherence was 97.3%, with no serious adverse events. Significant improvements were observed in SARA (SID - 0.72 ± 1.00; mean ± SD; P < 0.001), BBS (SID 0.47 ± 1.00; P < 0.001), and TUG (SID - 0.49 ± 1.00; P = 0.011). Improvements were maintained at one month (P > 0.171). A combination of multiple sessions of cerebello-spinal tDCS and exercise in a public health service was feasible, safe, and may improve ataxia severity, balance, and mobility in individuals with SCA3. As a study without a control group, these findings should be confirmed in randomized controlled trials but encourage further investigation of the proposed intervention as a potential rehabilitation strategy for cerebellar neurodegeneration.