Neuromyelitis optica-IgG (aquaporin-4) autoantibodies in immune mediated optic neuritis.

The clinical course of immune mediated optic neuritis (ON) will depend on the specific underlying inflammatory disease. These disorders have traditionally been classified according to clinical and MRI findings. Aquaporin-4 (AQP4) autoantibodies (neuromyelitis optica-IgG (NMO-IgG)) may have diagnostic and prognostic value in patients who present with isolated ON. In this prospective study, NMO-IgG was evaluated in 114 patients with ON in the following contexts: neuromyelitis optica (NMO), multiple sclerosis (MSON), chronic relapsing inflammatory ON (CRION), relapsing isolated ON (RION) and single isolated ON (SION). The proportion seropositive was 56% for NMO (n = 9), 0% for MSON (n = 28) and 5% for the remaining diagnostic categories (CRION (n = 19), RION (n = 17) and SION (n = 41)). Testing for NMO-IgG in patients with recurrent or severe ON who lack convincing evidence of MS may identify patients who would benefit from immunosuppression rather than MS directed immunomodulatory therapies.