Evaluation of vestibular tests, assessment of otolith organs in virtual reality environment, and investigation of their relationship with magnetic resonance imaging findings and serum glial fibrillary acidic protein levels in relapsing-remitting multiple sclerosis patients

This study aimed to explore vestibular system functioning in individuals with Relapsing-Remitting Multiple Sclerosis (RRMS) through a combination of conventional assessments and virtual reality (VR)–based otolith tests. The study also examined whether vestibular findings might be associated with magnetic resonance imaging (MRI) features and serum Glial Fibrillary Acidic Protein (sGFAP) levels. A total of 71 participants (36 RRMS patients and 35 healthy controls) underwent videonystagmography (VNG), cervical vestibular-evoked myogenic potentials (cVEMP), Subjective Visual Vertical (SVV), Subjective Visual Horizontal (SVH), Dynamic SVV (DSVV), and Dynamic SVH (DSVH). The results indicated that SVV values tended to differ significantly between the RRMS and control groups (p = 0.042). Similarly, SVH deviations were more pronounced in the RRMS group (p = 0.012). Dynamic tests (DSVV and DSVH) did not show statistically significant differences (p > 0.05), although subtle trends toward impairment in the RRMS group were observed. In the cVEMP analysis, amplitudes appeared comparable between groups; however, the Asymmetry Ratio (AR) was higher in RRMS participants (p = 0.0276), suggesting a possible imbalance in sacculo-collic pathways. Additionally, P1–N1 interpeak latencies were longer in RRMS patients (p < 0.05), which may reflect slowed conduction at the brainstem level. VNG findings showed patterns that may be consistent with central vestibular involvement, including less consistent saccadic accuracy and smooth pursuit performance. MRI observations suggested that RRMS patients with brainstem lesions tended to show more vestibular abnormalities, with the most noticeable association appearing between cVEMP interpeak latency and brainstem involvement. Although serum GFAP levels were generally higher in the RRMS group, no statistically significant associations were found between GFAP and vestibular test parameters (p > 0.05). A trend toward a potential relationship between GFAP levels and SVH deviation was observed (p = 0.082). In conclusion, the findings of this study suggest that RRMS may influence vestibular functioning at both otolithic and central processing levels. cVEMP interpeak latency and AR may represent potential markers of brainstem involvement, while VR-based otolith assessments may offer complementary insights into gravitational perception. Further research with larger sample sizes and longitudinal designs is needed to more definitively clarify these relationships.