Corticospinal Integrity and Motor Impairment Predict Outcomes After Excitatory Repetitive Transcranial Magnetic Stimulation: A Preliminary Study

Abstract

ObjectiveTo identify the effective predictors for therapeutic outcomes based on intermittent theta-burst stimulation (iTBS). DesignA sham-controlled, double-blind parallel study design. SettingA tertiary hospital. ParticipantsPeople with stroke (N=72) who presented with unilateral hemiplegia. InterventionsTen consecutive sessions of real or sham iTBS were implemented with the aim of enhancing hand function. Patients were categorized into 4 groups according to the presence (MEP+) or absence (MEP−) of motor-evoked potentials (MEPs) and grip strength according to the Medical Research Council (MRC) scale. Main Outcome MeasuresCortical excitability, Wolf Motor Function Test (WMFT), finger-tapping task (FT), and simple reaction time were performed before and after the sessions. ResultsMEPs and the MRC scale were predictive of iTBS therapeutic outcomes. Group A (MEP+, MRC>1) exhibited the greatest WMFT change (7.6±2.3, P<.001), followed by group B (MEP−, MRC>1; 5.2±2.2 score change) and group C (MEP−, MRC=0; 2.3±1.5 score change). These improvements were correlated significantly with baseline motor function and ipsilesional maximum MEP amplitude. ConclusionsThe effectiveness of iTBS modulation for poststroke motor enhancement depends on baseline hand grip strength and the presence of MEPs. Our findings indicate that establishing neurostimulation strategies based on the proposed electrophysiological and clinical criteria can allow iTBS to be executed with substantial precision. Effective neuromodulatory strategies can be formulated by using electrophysiological features and clinical presentation information as guidelines.