Asymptomatic myelitis in neuromyelitis optica and autoimmune aquaporin-4 channelopathy

Neuromyelitis optica (NMO) is an autoimmune inflammatory CNS disease associated with pathogenic aquaporin-4 autoantibodies (AQP4-IgG); optic neuritis (ON) and myelitis are required to fulfill diagnostic criteria.1 NMO spectrum disorders (NMOSDs) are defined as one or more typical NMO syndromes accompanied by AQP4-IgG seropositivity but not yet fulfilling NMO diagnostic criteria (e.g., AQP4-IgG–seropositive recurrent ON). Non-Caucasian ethnicity and coexisting autoimmunity are common in NMO/NMOSD.2 Transverse myelitis episodes in patients with NMO/NMOSD are characteristically longitudinally extensive (extending ≥3 vertebral segments on MRI), and the resulting clinical phenotype is typically severe, with paraplegia and wheelchair dependence at nadir a frequent finding.2 In contrast, multiple sclerosis (MS) myelitis episodes are typically mild and often asymptomatic.3 Herein we report 3 AQP4-IgG–seropositive4 women with asymptomatic myelitis in the setting of NMO/NMOSD.