So we aimed to activate cerebellar functions and evaluate its effect on postural control and associated neuroplastic alternations in chronic ankle instability.
Consecutive 22 participants with CAI were randomly allocated to sham and active tDCS groups to receive cerebellar anodal tDCS for 20 min at an intensity of 1.5 mA, as a preliminary randomized controlled trial. The anode and cathode rubber electrodes were positioned within two 5 cm × 5 cm sponges soaked in 14 mL of saline solution. The anode was placed over the cerebellum (approximately 1 cm below the inion of the occipital bone), and the cathode on the middle portion of the right deltoid. Postural control measurements, including center of pressure (CoP) sway and balance error scoring system (BESS) outcomes, and cerebellar resting-state functional magnetic resonance imaging outcomes, including regional intrinsic activity intensity and coherence, were measured before and immediately after the intervention.
The final sample consisted of 10 participants in the sham group and 11 in the active tDCS group. Both groups tolerated the stimulation with minimal adverse effects, and the only significant difference was the higher initial tingling sensation in the sham group compared with the tDCS group (p = 0.024). The blinding integrity assessment indicated that participants in both groups could not accurately discern their allocated intervention (p = 0.561). The tDCS group showed a significant improvement in the CoP length in the mediolateral direction (p = 0.020, Cohen’s d = −0.963; 95% CI: −1.873, −0.054). However, no significant alternations were observed between the sham and tDCS groups in terms of other CoP sway or BESS outcomes (p > 0.05). The tDCS group showed improved coherence in the vermis 1 and 2 subregions (p = 0.029) and superior lobe 3 subregions (p = 0.036) and improved intensity in the vermis 6 subregions (p = 0.043) and inferior lobe 8 subregions (p = 0.029). A strong association was observed between the tDCS-induced improvement in activity coherence in superior lobe 3 and a reduction in mediolateral CoP length (r = −0.709, p = 0.018).
This preliminary study marks the first application of cerebellar tDCS in the rehabilitation of CAI and musculoskeletal injuries. Our study demonstrated that a single session of cerebellar tDCS enhanced postural control in patients with CAI and was correlated with increased coherence in the superior lobe of the cerebellum. However, the observed effects are subtle, which indicates the potential need for more cerebellar tDCS sessions and combined exercise therapy to amplify the observed benefits.
Our preliminary findings contribute to the development of a more integrated, mechanism-focused approach to the treatment of CAI, thereby setting a new direction for sensorimotor rehabilitation research.
Postural Balance
Transcranial Direct Current Stimulation
