Effects of Priming Intermittent Theta Burst Stimulation With High-Definition tDCS on Upper Limb Function in Hemiparetic Patients With Stroke: A Randomized Controlled Study

Background Preconditioning with cathodal high-definition transcranial direct current stimulation (HD-tDCS) can potentiate cortical plasticity induced by intermittent theta burst stimulation (iTBS) and enhance the after-effects of iTBS in healthy people. However, it is unclear whether this multi-modal protocol can enhance upper limb function in patients with stroke. Objective The aim of this study was to investigate whether priming iTBS with cathodal HD-tDCS over the ipsilesional M1 can augment upper limb motor recovery in poststroke patients. Methods A total of 66 patients with subacute stroke were randomly allocated into 3 groups. Group 1 received priming iTBS with HD-tDCS (referred to as the tDCS + iTBS group), Group 2 received non-priming iTBS (the iTBS group), and Group 3 received sham stimulation applied to the ipsilesional M1. One session was performed per day, 5 days per week, for 3 consecutive weeks. In Group 1, iTBS was preceded by a 20-minute session of cathodal HD-tDCS at a 10-minute interval. The primary outcome measure was the Fugl-Meyer Assessment-Upper Extremity (FMA-UE) score. Moreover, the secondary outcome measures for muscle strength and spasticity were the Motricity Index-Upper Extremity (MI-UE) and the Modified Ashworth Scale Upper-Extremity (MAS-UE), respectively, and the Hong Kong Version of the Functional Test for the Hemiplegic Upper Extremity (FTHUE-HK) and the Modified Barthel Index (MBI) for activity and participation. Results Significant differences were detected in the changes in FMA-UE, MI-UE, and MBI scores between the 3 groups from baseline to post-intervention (χ 2 FMA-UE = 10.856, P = .004; χ 2 MI-UE = 6.783, P = .034; χ 2 MBI = 9.608, P = .008). Post hoc comparisons revealed that the priming iTBS group demonstrated substantial improvements in FMA-UE ( P = .004), MI-UE ( P = .028), and MBI ( P = 0.006) compared with those in the sham group. However, no significant difference was observed between the iTBS group and the sham group. Moreover, no significant differences were found in the changes in MAS-UE or FTHUE-HK between the groups. Conclusions Priming iTBS with HD-tDCS over the ipsilesional M1 cortex had beneficial effects on augmenting upper limb motor recovery and enhancing daily participation among subacute stroke patients.