The Effects Of Anodal Transcranial Direct Current Stimulation On Neural Excitability And Function In Individuals With Chronic Ankle Instability: A Preliminary Investigation

Chronic ankle instability (CAI) is common after ankle sprains, characterized by repeated sensations of giving-way existing in 30% of active individuals; high reinjury rates attributed to changes in brain function, suggest current rehabilitation is insufficient. This study attempted to modify these injury-induced brain changes by using anodal transcranial direct current stimulation (aTDCS) with ankle strengthening among individuals with CAI. We implemented a randomized-controlled trial design. Dependent variables included: neural excitability, dynamic balance with muscle activation, side-hop test, and ankle strength tested at baseline, week-2, week-4, and week-6. Twenty-two individuals completed 10 sessions of ankle strengthening over 4-weeks with aTDCS (21.8±2.7yrs, 5M/6F) or sham (22.3±3.1yrs, 3M/8F) stimulation. The aTDCS group received 1.5mA of cortical stimulation for 18-minutes; the sham group received 1-minute of stimulation. Differences were assessed with group-by-time factorial ANOVA (?=0.05). Four-weeks of aTDCS with eccentric exercise enhanced cortical excitability and dynamic balance (baseline to week-6: p=0.024, p=0.026), and improved muscle activation of ankle stabilizers (p=0.044) within 250-ms after landing, compared to sham stimulation. This is the first study using brain stimulation to treat a musculoskeletal injury. Findings support that aTDCS may reverse maladaptive neuroplasticity and subsequently improve function, warranting further investigation into musculoskeletal rehabilitation.