VEP latency delays predicts MRI neurodegenerative outcomes in multiple sclerosis.

BACKGROUND: Visual evoked potential (VEP) P100 latency is routinely used to assess optic nerve demyelination. However, there is no established methodology for disentangling whether shifts in VEP P100 latency may reflect upstream changes in the visual pathway, such as the level of the retina, or whether these delays could be reflective of downstream disturbances in broader brain structure and functioning. OBJECTIVE: To determine the relationship between VEP-based P100 and MRI-based outcomes in people with MS (PwMS) after accounting for structural retinal changes assessed by spectral domain optical coherence tomography (OCT). METHODS: 64 study participants underwent OCT, VEP, and MRI. Standardized VEP assessment derived monocular P100 latency for both eyes. Similarly, OCT performed on Heidelberg Spectralis hardware provided peripapillary retinal nerve fiber layer (pRNFL) thickness. Mediation analyses were performed to assess the relationship between P100 and MRI-based outcomes, adjusting for mediating effects of pRNFL and age. RESULTS: VEP-based P100 was significantly associated with lower whole brain volume (WBV) (p=0.0037), with 87.8% of the total effect being both direct and independent from RNFL and the significant age-WBV covariate effect. Similarly, greater VEP-based P100 latency was directly and independently predictive of lower gray matter volume (GMV) (p=0.015) and greater T2-FLAIR LV (p=0.0036) after adjusting for RNFL and age mediating effects. CONCLUSION: VEP-based P100 latency shows both age- and RNFL-independent associations with MRI-based MS outcomes. In addition to their established diagnostic utility, VEP measures may provide a neurophysiological, objective metric to assess neurodegeneration.