Intermittent Theta-Burst Stimulation for Stroke: Primary Motor Cortex Versus Cerebellar Stimulation: A Randomized Sham-Controlled Trial

BACKGROUND: Stroke survivors with impaired balance and motor function tend to have relatively poor functional outcomes. The cerebellum and primary motor cortex (M1) have been suggested as targets for neuromodulation of balance and motor recovery after stroke. This study aimed to compare the efficacy and safety of intermittent theta-burst stimulation (iTBS) to the cerebellum or M1 on balance and motor recovery in patients with stroke.METHODS: In this randomized, double-blind, sham-controlled clinical trial, patients with subacute stroke were randomly divided into 3 groups: M1-, cerebellar-, and sham-iTBS (n=12 per group; 15 sessions, 3 weeks). All outcomes were evaluated before intervention (T0), after 1 week of intervention (T1), after 3 weeks of intervention (T2), and at follow-up (T3). The primary outcome was the Berg balance scale score at T2. Secondary outcomes include the Fugl-Meyer assessment scale for lower extremities, the trunk impairment scale, the Barthel index, the modified Rankin Scale, the functional ambulation categories, and cortical excitability.RESULTS: A total of 167 inpatients were screened, 36 patients (age, 57.50 +/- 2.41 years; 10 women, 12 ischemic) were enrolled between December 2020 and January 2023. At T2, M1- or cerebellar-iTBS significantly improved Berg balance scale scores by 10.7 points ([95% CI, 2.7-18.6], P=0.009) and 14.2 points ([95% CI, 1.2-27.2], P=0.032) compared with the sham-iTBS group. Moreover, the cerebellar-iTBS group showed a significantly greater improvement in Fugl-Meyer assessment scale for lower extremities scores by 5.6 points than the M1-iTBS ([95% CI, 0.3-10.9], P=0.037) and by 7.8 points than the sham-iTBS ([95% CI, 1.1-14.5], P=0.021) groups at T2. The motor-evoked potential amplitudes of the M1- and cerebellar-iTBS groups were higher than those of the sham-iTBS group (P<0.001).CONCLUSIONS: Both M1- and cerebellar-iTBS could improve balance function. Moreover, cerebellar-iTBS, but not M1-iTBS, induced significant effects on motor recovery. Thus, cerebellar-iTBS may be a valuable new therapeutic option in stroke rehabilitation programs.