Feasibility and safety of neuromodulação cerebelo-espinhal combinada ao exercício na ataxia espinocerebelar tipo 3: um protocolo de 20 sessões

Abstract

Spinocerebellar ataxias (SCA) are a group of progressive degenerative diseases that result in gait and balance disorders, significantly affecting patients' quality of life. Despite the severity of symptoms, available therapeutic options remain limited. In this context, transcranial direct current stimulation (tDCS) has emerged as a potentially effective approach due to its ability to modulate neural plasticity and promote motor function improvements. The application of anodal tDCS over the cerebellum has been explored as a strategy to compensate for functional deficits, aiming to improve balance and gait. Protocols combining tDCS with motor exercises have shown promising results, indicating benefits in motor coordination and postural stability. However, some questions remain unanswered. Objective: To investigate: (i) whether specific characteristics in individuals with SCA can predict improvements in postural control and gait after 20 consecutive tDCS sessions;(ii) the feasibility, safety, and acceptability of administering more than the typical five to ten tDCS sessions, applied alongside progressively challenging exercises;(iii) the potential benefits of this combined intervention on clinical scores, postural control, and mobility in a public health outpatient setting, inviting the general population with SCA; and (iv) whether the benefits are maintained one month after completing the protocol. Methods: This is a pragmatic clinical trial involving 39 individuals with SCA3. Trans-spinal tDCS was applied at an intensity of 2mA, with the anodal electrode positioned over the cerebellar region and the cathodal electrode placed on the spinal cord at T11. Each session lasted 20 minutes. Participants simultaneously received 20 minutes of tDCS combined with a progressively challenging gait and balance exercise protocol. The intervention was applied over four weeks on weekdays, totaling 20 sessions. All participants received real stimulation. The severity of ataxia (Scale for the Assessment and Rating of Ataxia - SARA), postural control (Berg Balance Scale - BBS), and mobility (Timed- Up-and-Go - TUG) were assessed before, after 20 sessions, and one-month post- intervention. Statistical analysis followed an intention-to-treat approach, with multiple imputations used to handle missing data (8.3%). Standardized individual differences (SID) were calculated and compared to zero to verify significant changes after the intervention. Analyses were performed using Python 3.11.7, with a statistical threshold set at 5%. Results and Discussion: The attendance rate was 97.31%. Some falls occurred but had no adverse consequences. The intervention significantly reduced SARA scores (p < 0.001), increased BBS scores (p = 0.005), and reduced TUG time (p = 0.011) compared to baseline values. Improvements were maintained one month after the intervention (p > 0.171 for SID comparison between post-intervention and follow-up). Conclusion: The proposed intervention was feasible, well-accepted, and safe, promoting improvements in ataxia severity, mobility, and balance. Controlled studies are needed to confirm these findings.