Stimulation and Training for Adaptive Balance and Locomotor Enhancement in Multiple Sclerosis

INTERVENTION: Group 1: Arm 1: Anodal tDCS + Balance Training (Intervention group) Participants will undergo a 3‐week intervention consisting of balance training combined with anodal transcranial direct current stimulation (tDCS). Training sessions will be conducted three times per week (total of 9 sessions). Each session will include approximately 35 minutes of standardized balance training following the clinical protocol of Kliniken Schmieder (e.g., Romberg stance, tandem stance, one‐leg stance, and gait exercises). Prior to each training session, participants will receive 20 minutes of anodal tDCS (2 mA) over the primary motor corte X(M1), using a Cz–Fp2 electrode montage based on the international 10–20 EEG system. In addition to the study intervention, participants will receive standard multidisciplinary rehabilitation at the clinic. Group 2: Arm 2: Sham tDCS + Balance Training (Control group) Participants will undergo the same 3‐week balance training program (3 sessions per week, total of 9 sessions) as the intervention group. Prior to each training session, participants will receive sham tDCS using the same electrode montage (Cz–Fp2). The stimulation will be ramped up and down, but the current will only be applied for approximately 30 seconds to mimic the sensation of active stimulation without inducing neurophysiological effects. Participants will also receive standard multidisciplinary rehabilitation at the clinic. CONDITION: ; G35 Multiple sclerosis PRIMARY OUTCOME: Balance performance, assessed using static posturography (center of pressure sway path) and the Mini‐Balance Evaluation Systems Test (Mini‐BESTest), measured at baseline (pre‐intervention) and immediately after the 3‐week intervention (post‐intervention). SECONDARY OUTCOME: Gait performance (velocity and step length), assessed using the OptoGait system during single‐ and dual‐task walking; central sensorimotor integration, assessed using a model‐based systems identification approach with virtual reality–based or platform‐based perturbations; fear of falling, assessed using the Falls Efficacy Scale–International (FES‐I); mental health, assessed using the Hospital Anxiety and Depression Scale (HADS) and the General Health Questionnaire (GHQ‐28); quality of life, assessed using the Multiple Sclerosis Quality of Life‐54 (MSQOL‐54); and adherence to balance training, assessed using self‐reported questionnaires, measured at baseline (pre‐intervention), immediately after the 3‐week intervention (post‐intervention), and during follow‐up at 2, 4, and 6 months after the intervention. INCLUSION CRITERIA: Diagnosis of multiple sclerosis (according to established clinical criteria); Expanded Disability Status Scale (EDSS) = 6.0; no relapse within the last 3 months; ability to stand and walk independently (with or without assistive devices); indication for balance training as determined by clinical assessment; ability to understand study procedures and provide written informed consent.