# Effect of cerebellar stimulation on postural control and associated resting-state functional alterations in chronic ankle instability

## TL;DR

A single session of cerebellar tDCS improves postural control in people with chronic ankle instability and is linked to changes in cerebellar activity.

## Contribution

This study shows that cerebellar tDCS can rapidly alter postural control in chronic ankle instability patients.

## Key findings

- tDCS reduced mediolateral center-of-pressure sway (p = 0.020, Cohen's d = -0.963).
- tDCS-induced postural improvements correlated with increased cerebellar coherence (r = -0.709, p = 0.018).
- Clinic-based BESS outcomes did not detect significant tDCS effects.

## Abstract

Cerebellar maladaptive plasticity underlies postural deficits in chronic ankle instability (CAI), and we tested whether cerebellar-targeted transcranial direct current stimulation (tDCS) can provide a rapid, mechanism-specific postural benefit.

Would a single cerebellar tDCS session yield immediate improvements in postural control along with associated alterations in cerebellar activity?

In this randomized, sham-controlled laboratory study, 22 participants with CAI received active or sham cerebellar tDCS (20 min). Pre- and post-intervention assessments included: (1) laboratory-based center-of-pressure (CoP) sway during single-leg stance and clinic-based Balance Error Scoring System (BESS); (2) cerebellar regional homogeneity and amplitude of low-frequency fluctuations on resting-state functional magnetic resonance imaging.

The tDCS group showed a significant reduction in the CoP length in the mediolateral direction (p = 0.020, Cohen's d = −0.963). However, no significant alterations were observed between the sham and tDCS groups in terms of other CoP sway or BESS outcomes. A strong association was observed between the tDCS-induced reduction in mediolateral CoP length and the improvement in activity coherence in superior lobe 3, which is involved in integrating sensory information into postural motor responses (r = −0.709, p = 0.018). Our study indicates that a single session of cerebellar tDCS can immediately alter postural control in patients with CAI and is correlated with increased coherence in the superior lobe of the cerebellum. However, the observed beneficial effects in laboratory-based CoP tests might be too subtle to be detected by clinic-based BESS outcomes.