Deep Cerebellar Transcranial Direct Current Stimulation of the Dentate Nucleus to Facilitate Standing Balance in Chronic Stroke Survivors

Abstract

Objective: Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide. We hypothesized that cerebellar transcranial direct current stimulation (ctDCS) of the dentate nuclei and the lower-limb representations in the cerebellum can improve standing balance functional reach in chronic (> 6 months’ post-stroke) stroke survivors. Materials and Methods: Magnetic resonance imaging(MRI) based subject-specific electric field was computed across 10 stroke survivors and one healthy MRI template to find an optimal bipolar bilateral ctDCS montage to target dentate nuclei and lower-limb representations (lobules VII-IX). Then, in a repeated-measure crossover study on 5 stroke survivors, we compared 15minutes of 2mA ctDCS based on the effects on successful functional reach(%) during standing balance task. Three-way ANOVA investigated the factors of interest– brain regions, montages, stroke participants, and their interactions.Results: “One-size-fits-all” ctDCS montage for the clinical study was found to be bipolar PO9h – PO10h for dentate nuclei and bipolar Exx7–Exx8 for lobules VII-IX with contalesional anode. Bipolar PO9h–PO10h ctDCS performed significantly (alpha=0.05) better in facilitating successful functional reach (%) when compared to bipolar Exx7–Exx8 ctDCS. Furthermore, a linear relationship between successful functional reach (%) and electric field strength was found where bipolar PO9h–PO10h montage resulted in a significantly (alpha=0.05) higher electric field strength when compared to bipolar Exx7–Exx8 montage for the same 2mA current. Conclusion: We presented a rational neuroimaging based approach to optimize deep ctDCS of the dentate nuclei and lower limb representations in the cerebellum for post-stroke balance rehabilitation.

Transcranial direct current stimulation for balance rehabilitation in neurological disorders: A systematic review and meta-analysis

“…After reviewing titles and abstracts, 51 studies were included, and five additional studies (Forogh et al, 2018;Geroin et al, 2011;Madhavan et al, 2020;Manenti et al, 2016;Tahtis et al, 2014) were included from other systematic reviews on similar topics. After full text review, 19 studies were excluded due to the following reasons: without sham/CG (n = 9) (Alexoudi et al, 2018;Dumont et al, 2015;Hadoush et al, 2018;Mohammadi et al, 2021;Naro et al, 2020;Pilloni et al, 2019;Rezaee et al, 2020;Ricci et al, 2019;Solanki et al, 2021), another population (n = 3) (Jafarzadeh et al, 2019;Maldonado and Bernard, 2021;Manor et al, 2018), another intervention (n = 1) (Koganemaru et al, 2019), and another outcome (n = 6). Finally, 37 articles were included for the systematic reviews and 33 for the meta-analysis (two studies were J o u r n a l P r e -p r o o f 10 excluded from the meta-analysis because of the design (case reports) and two due to incomplete data) (Costa et al, 2020;Forogh et al, 2018;Kaski et al, 2014a;Verheyden et al, 2013).…”