Bilateral Anodal Cerebellar tDCS for Multidomain Dysfunctions in Patients With Multiple Sclerosis

Multiple sclerosis (MS) is a chronic immune-mediated neurological disorder characterized by demyelination and neurodegeneration within the central nervous system. Disruption of cerebro-cerebellar networks is a key feature of MS and contributes to impairments in motor coordination, balance, gait, fatigue, and cognitive performance. Cerebellar involvement is particularly associated with ataxia and postural instability, which significantly affect functional independence and quality of life. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique capable of modulating cortical and cerebellar excitability. Previous studies investigating cerebellar tDCS in MS have reported variable findings, which may be related to heterogeneity in stimulation protocols, the predominant use of unilateral stimulation approaches, and the frequent combination of stimulation with task-oriented rehabilitation. These factors limit the ability to isolate the independent effects of neuromodulation. The cerebellum operates through bilateral cerebro-cerebellar loops, suggesting that bilateral stimulation may provide more comprehensive modulation of these distributed networks compared to unilateral approaches. In addition, the effects of tDCS are influenced by state-dependent factors, including concurrent motor activity. Delivering stimulation as a standalone intervention allows for clearer evaluation of its direct neuromodulatory effects without the confounding influence of concurrent rehabilitation. This study is designed as a randomized, double-blind, sham-controlled trial to evaluate the effects of bilateral cerebellar tDCS on multidomain dysfunction in individuals with MS. Participants will be randomly assigned to receive either active or sham stimulation. The intervention consists of repeated sessions of bilateral cerebellar stimulation delivered over a two-week period using a standardized protocol. The study aims to evaluate the effects of this intervention on motor and non-motor domains and to explore associated neurophysiological changes. By isolating the effects of bilateral cerebellar stimulation, this trial seeks to provide a clearer understanding of its therapeutic potential and to inform the development of targeted neuromodulation strategies in MS rehabilitation.