Autoimmune aquaporin channelopathies and mogopathies; Propinquity and divergence

Abstract

Neuromyelitis optica spectrum disorder (NMOSD) is a profound inflammatory disease of the central nervous system characterized, in particular, by disabling attacks of optic neuritis and longitudinal extensive transverse myelitis. The diagnostic criteria has been refined, to a broader spectrum of symptoms since 2015, according to the antibody serostatus. The main pathogenic characteristic is the presence of anti-aquaporin-4 antibodies (AQP4-Abs), considering it as autoimmune astrocytopathy. However, a proportion of patients with the typical NMOSD phenotype are, in fact, negative (seronegative) for AQP4-Abs, but positive for antibodies to myelin oligodendrocyte glycoprotein (MOG-Abs), which is now recognised as a nosological entity with specific clinical and paraclinical features. Aquaporin channelopathies and autoimmune mogopathies might share similar presentations, like optic neuritis, extensive myelitis. Although, the clinical and paraclinical features might differ. Perhaps, age group at onset, disease course, and residual disability. Also MRI characteristics can help in differentiating anti-MOG-myelitis from neuromyelitis optica. Randomised control trials are limited, for treating both conditions, but observational open-label experience suggests a role for high-dose steroids and plasma exchange in the treatment of acute attacks, and for immunosuppressive therapies, such as steroids, oral immunosuppressants and rituximab as maintenance treatment. In this talk, we will identify similarities and differences between both disease groups.