The aim of this study is to investigate the acute effects of virtual reality-based optokinetic stimulation on postural sway and motion sickness symptoms in individuals with multiple sclerosis (MS)

This study will be conducted at Hacettepe University, Faculty of Physical Therapy and Rehabilitation. It will investigate the acute effects of virtual reality-based optokinetic stimulation (OKS) on postural sway and motion sickness symptoms in individuals with multiple sclerosis (MS). Participants will include MS patients with and without central vestibular dysfunction, as well as age- and sex-matched healthy controls. MS participants will first undergo vestibular function assessment using videonystagmography (VNG). Postural control will then be measured via a force platform under four conditions (bipodal/monopodal, eyes open/closed) before and after a 10-minute OKS session using Oculus Quest 2. Healthy participants will follow the same postural and OKS assessment protocol without VNG.Motion sickness and virtual reality effects will be evaluated using the Simulator Sickness Questionnaire. Data will be analyzed using appropriate parametric or non-parametric tests to compare postural sway and VR-related symptoms across groups, with significance set at p < 0.05.

Inclusion Criteria:

• Be an adult aged 18-55 years
• Have a confirmed diagnosis of MS by a neurologist (for MS groups)
• Not have had a relapse in the last 3 months (for MS patients)
• Have an Expanded Disability Status Scale (EDSS) score of ≤ 4 (for MS patients)
• Be a healthy control with no condition preventing participation

Exclusion Criteria:

• Have peripheral vestibular dysfunction (for MS groups)
• Be older than 55 years
• Have any cardiovascular, orthopedic, neurological, or other condition preventing assessments
• Have a history of neurological disorders, head trauma, or chronic psychiatric conditions (for healthy controls)