Neuromyelitis optica - an update: 2007–2009

Neuromyelitis optica is an inflammatory demyelinating disorder of the central nervous system. The discovery of a specific antibody (NMO IgG /aquaporin-4 antibody) in patients with this condition has led to a marked revival of research on the disease. This article summarizes the major advances in neuromyelitis optica, particularly in the last 2 years, and supplements the previous review published in this Journal in 2007. Important among these developments are: the epidemiological studies, which have provided estimates of incidence and prevalence; identification of mutations in the aquaporin-4 gene; improved understanding of the effects of anti-aquaporin-4 antibody on astrocytes; roles of excitatory amino acid transporter type 2 and glutamate; requirement of aquaporin-4 to be in orthogonal arrays to be antigenic; recognition of the presence of aquaporin-4 antibody in patients with cancer and posterior reversible encephalopathy syndrome; possibility of monitoring the disease using the antibody, and the effectiveness of rituximab and mycophenolate in preventing relapses.