Focal Vibration Therapy for Upper Extremity Dysfunction

Inclusion Criteria: * Aged over 18 years * Confirmed diagnosis of RRMS according to the McDonald criteria (33) * No MS relapse or exacerbation within the past 6 months (ensuring stability of symptoms) * Self-report on clinical evidence of UEx impairment (including reduced arm/hand function, muscle weakness, spasticity, or pain). * Stable on MS treatment for at least four weeks before recruitment, with no plans to initiate new treatments (participants may continue current treatments during the study) * Agree and are able to use the FVT device after training. * Sufficient proficiency in English to participate in interviews and follow instructions * Able to visit the laboratory for assessments * Able to provide written informed consent Exclusion Criteria: * Evidence of cognitive impairment that could interfere with following instructions (Mini-Montreal Cognitive Assessment score (Mini-MoCA) \< 12) * Comorbid neurological or psychiatric conditions affecting the UEx (including stroke and severe carpal tunnel syndrome) that would confound results or make FVT unsafe * Unstable cardiac disease or any major medical illness that would preclude participation * Any known contraindications to vibration therapy (pregnancy, acute deep vein thrombosis, severe osteoporosis, chronic migraines, epilepsy, active malignancy in the target area, unstable cardiac disease, or an implanted pacemaker without clearance)