Efficacy of sensorimotor cortical paired associative magnetic stimulation prior to exercise on balance and gait in Parkinson's disease: study protocol for a randomised controlled trial in China.

INTRODUCTION: Balance and gait dysfunction in Parkinson's disease (PD) involves impairments in both motor execution and sensory processing. Conventional transcranial magnetic stimulation (TMS) protocols targeting only the motor cortex may not fully address these complex deficits. A dual-site TMS protocol targeting the sensorimotor network could be more effective. METHODS AND ANALYSIS: This three-arm, double-blind, randomised controlled trial will recruit 72 participants with PD. Participants will be randomly assigned to receive sensorimotor cortical paired associative TMS (sm-PAS) followed by exercise, single-site motor cortex TMS followed by exercise or sham TMS followed by exercise. All participants will complete a 2-week intervention with five sessions per week. The sm-PAS protocol delivers paired stimuli to the supplementary motor area and the temporoparietal junction with an individualised interstimulus interval. The primary outcome is balance and gait measured by the Mini-Balance Evaluation Systems Test. Secondary outcomes include motor symptoms, quality of life and mechanistic measures. The latter include cortical excitability measured by paired-pulse TMS and cortical activation measured by functional near-infrared spectroscopy. Assessments will be conducted at baseline, after 1 and 2 weeks of intervention and at 1 month follow-up. The primary estimate is the between-group difference in the change of Mini-Balance Evaluation Systems Test scores from baseline to Week 2, comparing sm-PAS group with both sham TMS and single-site motor cortex TMS groups. Data will be analysed using linear mixed-effects models following intention-to-treat principle. ETHICS AND DISSEMINATION: Ethics approval has been obtained from the Biomedical Ethics Committee of West China Hospital, Sichuan University (No. 2025-2041). Findings will be disseminated through peer-reviewed publications. TRIAL REGISTRATION NUMBER: ChiCTR2600116787.