Multiple sclerosis NMO

After the discovery of anti-aquaporin-4 (AQP4) antibody (Ab) in neuromyelitis optica (NMO) and related disorders, the diagnosis and treatment in NMO has dramatically changed with unique pathomechanism of autoimmune astrocytopathy distinct from multiple sclerosis (MS). Moreover, in AQP4-Ab negative cases, there are various types of disseminated encephalomyelitis (DEM), often misdiagnosed as classical MS, such as tumefactive disease, Balo’ disease and acute DEM. Now it was revealed that anti-myelin oligodendrocyte glycoprotein (MOG) Ab were found in about half of ADEM cases especially in paediatric cases. The role of this antibody has long been controversial because of non-specific detection in previous studies, but now specific antibody against conformational epitope of extracellular domain is considered as pathogenic antibody. There were some cases of anti-MOG-Ab positive opticomyelitis with bilateral optic neuritis and long spinal cord lesions, like monophasic Devic’s NMO disease. However, the clear difference of anti-MOG-Ab syndrome from anti-AQP4-ab syndrome is the lack of elevated CSF GFAP and the relatively mild prognosis. In adult MOG-positive cases, there are some cases of unique cortical encephalitis with epileptic seizure revealed in our cohort study. The specific features including unilateral cerebral cortical FLAIR hyper-intense lesions, which were swollen and hyper-perfused on SPECT. In pathology, there are diffuse inflammatory lesions at the cortical meningeal areas with dominant loss of MOG, but other myelin and AQP4, suggesting MOG spectrum. Until now, there have been several kinds of DEM with unknown etiology probably distinct from MS, which is promising to clarify each specific pathomechanism in near future.