RESUMEN
Multiple sclerosis (MS) is the most common demyelinating disease affecting the central nervous system of young adults living in the western world. MS should be strongly suspected when a young adult develops one or more neurological episodes consistent with damage to white matter within the central nervous system (CNS), especially when these affect the optic nerves, brainstem, or spinal cord. The patient with relapses, each of which can be attributed to demyelination in the CNS, requires no investigation prior to establishing the diagnosis of clinically definite MS. For a diagnosis of MS, separate anatomical sites within the CNS must have been affected on different occasions, typically three. MS in Asian populations is characterized by the selective and dominant involvement of the optic nerve and spinal cord with some incidence of brainstem lesions. 35-40% of MS cases in Korea are of this optico-spinal type with or without brainstem lesions. Reported cases of neuromyelitis optica spectrum disease (NMOSD), causing severe optic neuritis (ON) and/or longitudinally extensive transverse myelitis, either monophase or with a relapse-remitting pattern, some of which were diagnosed previously as the optico-spinal form of MS in Asia, have increased annually in Korea with the development of the NMO-IgG or aquaporin4-antibody detecting technique. NMO-IgG detection is very important in the diagnosis of early stage of NMOSD and the differentiation of MS and other demyelinating disease. Many new convenient oral drugs or very potent intravenous monoclonal antibodies for targeting VLA-4, CD20, and CD52 may decrease the annual relapse rate and burden of brain-spinal cord lesionsin MS.