Visual involvement precedes motor dysfunction in experimental autoimmune encephalomyelitis: evidence from...

The Experimental Autoimmune Encephalomyelitis (EAE) model of Multiple Sclerosis is associated with abnormalities in visual (VEP) and motor (MEP) evoked potentials, together with neuroretinal thinning at optical coherence tomography (OCT). The time course of these deficits is pivotal for testing novel therapeutic strategies. Thus, VEP, MEP, and OCT were performed during the prodromal, acute, and chronic phases of EAE. A group of EAE mice were sacrificed for histological analysis at each timepoint. VEP latency delays at prodromal phases were associated with early optic nerve demyelination. OCT scans revealed subtle retinal pathology before clinical motor onset, while in the chronic phase, MEP dysfunction was detected and validated by demyelination, inflammation and axonal loss. Interestingly, VEP abnormalities appear before electrophysiological or clinical motor involvement, pointing to the relevance of neurophysiological measures to detect early subclinical demyelination, which could be a potential target of novel therapeutic approaches targeting inflammation, demyelination and neuroaxonal loss.