Summary

Aquaporin-4 (AQP4) autoantibodies are specific for neuromyelitis optica (NMO) and related spectrum disorders; the specificity exceeds 90%. NMO and multiple sclerosis (MS) share transverse myelitis and optic neuritis as typical symptom complexes, but they tend to be more severe in NMO and often are associated with longitudinally extensive lesions in the corresponding affected central nervous system structures, which are rarely found in MS. While interferon beta and natalizumab benefit MS patients, they appear to exacerbate NMO.