Does cerebellar non-invasive brain stimulation affect corticospinal excitability in healthy individuals? A systematic review of literature and meta-analysis

•This systematic review indicates that the effects of different type of cerebellar noninvasive brain stimulation (NIBS) on the Corticospinal Excitability (CSE) is different.•This review showed cerebellar PAS 6, a-tDCS + PAS25, and cTBS decrease the CSE level.•This review showed there is an increase in the CSE after using cerebellar PAS 2, PAS 21.5 + a-tDCS, and 1 Hz rTMS.•This review gives a good understanding of the effects of different cerebellar NIBS techniques affect the CSE, and help us to select the best NIBS technique for researches in cerebellar stimulation field, based on the effects that we need. Numerous studies have indicated that non-invasive brain stimulation (NIBS) of the cerebellum could modulate corticospinal excitability (CSE) in young healthy individuals. However, there is no systematic review and meta-analysis that clarifies the effects of cerebellar NIBS on CSE. The aim of this study was to provide a meta-analytic summary of the effects of cerebellar NIBS on CSE. Seven search engines were used to identify any trial evaluating CSE before and after one session of cerebellar NIBS in healthy individuals up to June 2018. Twenty-six studies investigating the corticospinal responses following cerebellar NIBS were included. Meta-analysis was used to pool the findings from included studies. Effects were expressed as mean differences (MD) and the standard deviation (SD). Risk of bias was assessed with the Cochrane tool. Meta-analysis found that paired associative stimulation (PAS) with 2 ms interval, a combination of PAS with 21.5 ms interval and anodal transcranial direct current stimulation, and repetitive transcranial magnetic stimulation with a frequency of < 5 Hz increase CSE (P PAS2 < 0.00001, P PAS21.5 +a-tDCS = 0.02, P rTMS = 0.04). However, continuous theta burst stimulation, a combination of PAS with 25 ms interval and anodal transcranial direct current stimulation, and PAS with a 6 ms interval decreased CSE (P PAS6 < 0.00001, P cTBS < 0.00001, P PAS25 +a-tDCS = 0.003). The results of this review show that cerebellar NIBS techniques are a promising tool for increasing CSE