fMRI Study on Cerebral Localization and Network Mechanisms of rTMS in Chronic Ankle Instability Treatment

Condition(s) studied

Investigational drug(s) / intervention(s)

repetitive transcranial magnetic stimulation, rTMS: Participants underwent rTMS intervention prior to daily ankle stability training. The interventional targets were the key cortical brain regions identified in preliminary studies, with stimulation applied to the contralateral cortical areas corresponding to the affected ankle joint. Parameters included a figure-of-8 coil, 10 Hz frequency, 2-second stimulation duration, 8-second inter-train intervals, 60 repetitions, totaling 1,200 pulses per session, with each session lasting 10 minutes. Ankle stability training commenced within 10 minutes post-rTMS, following the same duration and intensity as the Ankle Stability Training Group + Sham rTMS Group. The treatment was conducted three times per week for a total of 4 weeks.

ankle stability training: The ankle stability training protocol comprised three modalities: neuromuscular training, balance training, and proprioceptive training. Specific exercises included single-leg stance, balance pad training, heel raises, resistive ankle inversion/eversion exercises, MOBO board balance exercises, alphabet tracing (toe-writing), lateral walking, heel walking, toe walking, and jump and landing control drills. The training progressed from stable to unstable surfaces, starting at low intensity and gradually increasing in difficulty and intensity. The training was conducted three times per week for a total of 4 weeks.

Sham repetitive transcranial magnetic stimulation, SrTMS: Before each session of ankle stability training, participants received sham rTMS intervention. The sham stimulation mimicked the sensory experience of real rTMS but did not produce any physiological effects.

Study summary

Chronic ankle instability (CAI) is a common sports injury that often leads to recurrent injuries and functional deficits. While conventional rehabilitation can restore ankle stability, the underlying neurophysiological mechanisms remain poorly understood, and the long-term efficacy of current treatments is limited. This study aims to investigate the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS) in combination with conventional ankle stability training for CAI and to evaluate its impact on ankle-stabilizing muscle activation and cerebral cortex excitability.

The study design is a single-center, randomized, single-blind, parallel-controlled trial. Participants with CAI will be randomly assigned to either an ankle stability training plus real rTMS group or an ankle stability training plus sham rTMS group. The primary outcome measure is the Cumberland Ankle Instability Tool (CAIT) score, which assesses the severity of ankle instability. Secondary outcomes include the Karlsson-Peterson Ankle Function Score (KPAFS), American Orthopedic Foot and Ankle Society Score (AOFAS), surface electromyography (sEMG) data, and task-based functional magnetic resonance imaging (fMRI) data. These secondary outcomes will provide a comprehensive evaluation of ankle function, muscle activation patterns, and neural activity changes.

The intervention will consist of a 4-week program, with participants receiving rTMS sessions three times per week. Each rTMS session will target key brain regions. The ankle stability training will include exercises designed to improve strength, balance, and proprioception. The sham rTMS group will receive identical ankle stability training but with a placebo rTMS protocol to ensure blinding.

Data will be collected at baseline, 2 weeks, and 4 weeks. The primary outcome, CAIT score, will be used to assess the overall improvement in ankle stability. The KPAFS and AOFAS scores will provide additional measures of ankle function and pain. sEMG data will be collected during specific functional tasks to evaluate the activation patterns of the tibialis anterior, peroneus longus, and other relevant muscles. Task-based fMRI will be used to assess changes in brain activity in motor and sensory areas before and after the intervention.

Statistical analyses will be performed using SPSS 22.0. Data will be presented as mean ± standard deviation. Between-group differences will be compared using independent samples t-tests, and overall differences across time points will be assessed via two-way repeated-measures ANOVA or mixed-effects models. Post-hoc analyses will be conducted to identify specific time points and conditions where significant differences occur.

The study timeline spans from March 2025 to December 2026, including participant recruitment, intervention implementation, data collection, and analysis, as well as manuscript drafting. This research aims to provide new insights into the neurophysiological mechanisms of CAI and to offer a novel, evidence-based approach to the rehabilitation of CAI, potentially improving long-term outcomes and reducing the risk of recurrent injuries.

Eligibility

Primary outcome measure(s)

• Cumberland Ankle Instability Tool score, CAIT — Before treatment, 2 week after treatment and 4 weeks after treatment
  A self-reported questionnaire designed to assess functional ankle instability. It consists of 9 items with a total score ranging from 0 to 30, where higher scores indicate better ankle stability.

Trial sites (1)

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