Investigation the concurrent effects of multi-session anodal tDCS and postural training on postural stability and functional balance in patients with multiple sclerosis: cerebellum versus dorsolateral prefrontal cortex stimulation.

Individuals with multiple sclerosis (MS) often encounter challenges with postural stability and balance. This research investigated the impact of anodal trans-cranial direct current stimulation (a-tDCS) to either dorsolateral prefrontal cortex (DLPFC) or cerebellum concurrent with postural training on postural stability and functional balance in MS individuals. In this study that was double-blind, randomized, and sham control, 57 participants with an Expanded Disability Status Scale (EDSS) score ranging from 3.5 to 5 were allocated randomly into three groups: One group a-tDCS over cerebellum, another a-tDCS over DLPFC, and the third sham a-tDCS. Subjects in the a-tDCS experimental groups underwent 1.5 mA stimulation over a 20-minute duration alongside postural training. However, in the group receiving sham a-tDCS, the stimulation was stopped following 30 seconds. Treatment was conducted for ten sessions over four weeks. Before and after the intervention, postural stability or center of pressure (COP) sways, and functional balance were evaluated utilizing force plate, Berg Balance Scale (BBS) and Timed Up and Go (TUG(, respectively. It was reported that the combination of postural training and cerebellar a-tDCS resulted in improved postural stability including sway speed in anterior-posterior (AP) and mediolateral (ML) directions with eyes closed and opened, sway area in ML direction with eyes closed and opened (p < 0.05), BBS (p < 0.05) and TUG scores (p < 0.05) when contrasted with the other groups. Additionally, the impact of DLPFC a-tDCS was higher than sham a-tDCS on postural stability, BBS and TUG scores, while the variations were not significant (P >0.05). Moreover, no variables exhibited changes in the sham group. The results showed that a-tDCS targeting the cerebellum could enhance balance and postural stability in MS patients.Trial registration number: This study was part of thesis that underwent registration within the Iranian Center for Clinical Trials' registry (Registration Number: IRCT20220111053689N2,  www.irct.ir ).