Neuromyelitis optica spectrum disorders are a set of clinical syndromes, dominated by optic neuritis and myelitis, but diverse in clinical manifestations and autoantibodyassociation. It is critical to recognize these disorders and to avoid confusion with multiple sclerosis and other conditions which they may mimic. This symposium will be case-based. It will emphasize current diagnosis, including unusual presentations, such as brain/brainstem syndromes, limited syndromes (e.g. recurrent optic neuritis), and co-association with other autoimmune diseases and cancer. It will also consider issues pertinent to serologic diagnosis including recognition of false positive and negative test results. Finally, the symposium will discuss acute and maintenance treatment in this era of new treatments emerging from successful phase 3 clinical trials. Special circumstances such as pregnancy, management of aggressive disease and treatment failure will be discussed.