Safety of Therapeutic Step-down in Neuromyelitis Optica

Inclusion criteria: * Major patients who have received long-term treatment for NMO * Patients with a prospectively diagnosed NMO using the 2015 NMO classification criteria (IPND) * Patients who retrospectively meet the classification criteria of the 2015 NMO (IPND) * Patients who have not expressed their opposition, after information, to the reuse of their data for research purposes. Exclusion criteria: * Patient who expressed his opposition to participating in the study * Lack of data on the assay of anti-AQP4 and anti-MOG antibodies * Less than a year of taking a second-line treatment before the relay * End of follow-up \<1 year following the transfer, this therefore includes patients whose transfer took place less than one year before the date of data extraction