Comparative Study of TIS Efficacy Across Different Targets

This prospective, randomized, participant- and outcome-assessor-blinded, parallel-group exploratory trial will compare the target-dependent clinical, neuroimaging, and electrophysiological effects of temporal interference stimulation (TIS) targeting the subthalamic nucleus (STN) or globus pallidus internus (GPi) in patients with Parkinson's disease (PD). Eighteen participants with idiopathic PD will be randomly assigned in a 1:1 ratio to the STN-TIS or GPi-TIS group. Participants will receive one 20-minute TIS session daily for 7 consecutive days. Motor symptoms will be assessed using the MDS-UPDRS Part III immediately before and after each daily stimulation session. Resting-state functional magnetic resonance imaging (fMRI) and 64-channel electroencephalography (EEG) will be performed before the first stimulation session and immediately after completion of the 7-day intervention. The primary outcomes are: (1) change in MDS-UPDRS Part III score from Day 1 before stimulation to Day 7 after stimulation; and (2) changes in regional spontaneous brain activity and seed-based functional connectivity measured using resting-state fMRI. Secondary outcomes are: (1) daily immediate changes in MDS-UPDRS Part III scores and the proportion of participants achieving at least 30% improvement at Day 7; and (2) changes in resting-state 64-channel EEG relative bandpower. Safety and tolerability will be evaluated by monitoring adverse events and local skin reactions throughout the intervention. This study aims to provide preliminary evidence regarding target-dependent functional response patterns associated with STN- and GPi-targeted TIS in PD.