AQP4 and optic neuritis: Another problem attached to the current nomenclature results from the recent finding that the spectrum of clinical manifestations of AQP4 autoimmunity is wider than previously thought and includes (1) various forms of brainstem encephalitis in adults; (2) a broad variety of cerebral symptoms in children; and (3) abortive forms such as isolated longitudinally extensive transverse myelitis or isolated optic neuritis, which in NMO-IgG-positive patients often convert to NMO [1,9,92,99-104].