Neuromyelitis optica spectrum disorders (NMOSD) are a spectrum of autoimmune diseases characterized by acute inflammation of the optic nerve (optic neuritis, ON) and the spinal cord (myelitis).[1][2][3] Episodes of ON and myelitis can be simultaneous or successive. A relapsing disease course is common, especially in untreated patients.[1][4]
Neuromyelitis optica (NMO) is a particular disease within the NMOSD spectrum. It is characterised by optic neuritis and longitudinally extensive myelitis. In more than 80% of NMO cases, the cause is immunoglobulin Gautoantibodies to aquaporin 4 (anti-AQP4), the most abundant water channel protein in the central nervous system.[5][1][4]
Less common diseases with other manifestations are also part of the NMOSD spectrum.[6][4]
^Banerjee S, Butcher R. Rituximab for the Treatment of Neuromyelitis Optica Spectrum Disorder [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2021 Feb. Available from: https://www.ncbi.nlm.nih.gov/books/NBK571350/