Longitudinal VEP Analysis Reveals Divergent Markers of Inflammation and Neurodegeneration in Multiple Sclerosis

Background Visual evoked potentials (VEPs) are valuable tools for assessing optic pathway integrity in multiple sclerosis (MS), yet the longitudinal implications of P100 latency and amplitude changes remain unclear. The aim of this study was to explore the clinical and prognostic value of serial VEP assessments in MS, focusing on differences between latency and amplitude changes. Methods We retrospectively analyzed 83 MS patients from three centers who underwent ≥ 2 pattern-reversal VEPs at least one year apart. Patients with recent optic neuritis were excluded. Clinical, radiological, and CSF findings were compared between those with and without significant VEP changes. Disability progression was evaluated using EDSS. Results During follow-up, 43.4% developed new P100 latency prolongation, associated with higher relapse rates, RRMS phenotype, and more favorable baseline MRI/CSF profiles. In contrast, 56.6% showed significant P100 amplitude reduction, linked to greater EDSS worsening (p < 0.05). Latency changes were not associated with disability progression. Amplitude decline—especially in the left eye—correlated modestly but significantly with EDSS change (r = − 0.225, p = 0.041). Conclusions Serial VEPs provide distinct insights into MS pathology. While latency prolongation reflects inflammatory activity, amplitude decline may signal silent neurodegeneration and functional decline. Longitudinal VEP monitoring may improve early detection of progression and guide individualized care. Trial Registration Not applicable