The effect of multi-session cerebellar transcranial direct current stimulation on balance function in adults with chronic vestibular hypofunction

Transcranial Direct Current Stimulation (tDCS) has demonstrated efficacy in restoring vestibular function and in stabilizing stance and gait in patients with vestibular dysfunction. The current study was conducted to investigate the synergistic effects of cerebellum tDCS (ctDCS) combined with vestibular rehabilitation therapy (VRT) on static and dynamic postural stability in adults with chronic vestibular hypofunction. In a double-blinded, sham-controlled trial, 48 adults diagnosed with bilateral vestibular hypofunction were randomly assigned to receive either active ctDCS (i.e., ctDCS + VRT) or sham ctDCS (i.e., VRT alone). Outcome measurements were assessed at baseline, and at 1, 2 and 4 weeks of follow-up and included the Dizziness Handicap Inventory (DHI), the Berg Balance Scale (BBS) and the Dynamic Gait Index (DGI). For the primary outcome measure, DHI score, a significant main effect was observed for group ( p = 0.003) and time ( p < 0.001) factors. In addition, there was a significant reduction in the overall DHI score with time for both the groups, which was more pronounced in the in the active ctDCS group compared to the sham ctDCS group across different times post-intervention. In terms of the DGI change scores, we found a significant main effect of time ( p < 0.001), a main effect of group ( p = 0.042), and a group-by-time interaction effect ( p = 0.003). Post-hoc analysis revealed that the DGI score was reduced in the active ctDCS compared to the sham ctDCS group at the 2-week (19.58 vs. 17.88, p = 0.026) and 4-week (22.58 vs. 19.59, p = 0.007) follow-up phases. For the BSS score, we found a significant main effect of time ( p < 0.001), but no evidence for the main effect of the group and group-by-time interaction effect. Post-hoc analysis also revealed no significant group difference in the BBS score at any time points. Cerebellar tDCS shows promising effects on vestibular symptoms as well as static and dynamic postural stability in patients with chronic vestibular hypofunction.