In Reply We thank Gao and colleagues for their comments regarding our article.1 We agree that the spectrum of neuromyelitis optica (NMO) is much wider than originally thought and that it is now recognized that the term NMO is not synonymous with aquaporin-4 antibody (AQP4-Ab) disease. In our experience, the presence of AQP4-Ab indicates a generally severe, frequently relapsing central nervous system inflammatory disease and we manage AQP4-Ab–positive patients with early and long-term immunosuppression regardless of the clinical phenotype. Conversely, patients referred to our UK AQP4-Ab assay service and those seen within our specialist clinical NMO service are a heterogeneous group, despite many having features considered typical of NMO such as longitudinally extensive transverse myelitis or severe/bilateral optic neuritis. We consider AQP4-Ab–negative patients separately from those with AQP4-Ab, even if fulfilling diagnostic criteria for NMO. In general, we treat such patients less aggressively but their management is difficult because of the clinical heterogeneity. Myelin-oligodendrocyte glycoprotein Abs appear to offer an alternative biomarker in patients presenting with features of NMO and its spectrum who are negative for AQP4-Ab and this biomarker appears to be helpful in making decisions regarding patient management and prognosis. We agree that the current NMO diagnostic criteria need updating to reflect the fact that AQP4-Ab–negative NMO/NMO spectrum disorder is not a clear entity and that such patients should be considered separately from those with AQP4-Ab disease.
Kitley J, Waters P, Vincent A, Palace J. Features of Neuromyelitis Optica Spectrum Disorders and Aquaporin-4 With Myelin-Oligodendrocyte Glycoprotein Antibodies—Reply. JAMA Neurol. 2014;71(7):924. doi:10.1001/jamaneurol.2014.940