Within the group of inflammatory idiopathic demyelinating diseases, there is a great number of diseases that have an initial attack in common, including visual. Multiple sclerosis (MS) is a chronic, demyelinating, immune‐mediated disease, with considerably varying prevalence and incidence. Neuromyelitis optica (NMO), which until recently was considered a variant of MS, is currently considered an independent entity. However, it resembles MS, because it is an immune‐mediated disease characterized by the simultaneous or sequential involvement in time of optic neuritis and extensive demyelinating myelitis. Fifty percent of patients with MS have isolated optic neuritis. However, the frequency of abnormalities ranges from 57 to 100% in visual evoked potential (VEP). Several studies have evaluated the clinical, evolutive, and demographic characteristics of idiopathic optic neuritis and demonstrated their differences among the cases related to MS and NMO. The most common changes in VEP studies in multiple sclerosis are as follows: increased interocular differential latency of P100 wave and the absolute increase in latency of P100 wave. New studies indicate that VEP pattern in NOM spectrum syndromes is different from that of MS.
Part of the book: Event-Related Potentials and Evoked Potentials