Clinical characteristics and outcome of multiple sclerosis in Korea: Does multiple sclerosis in Korea really differ from that in the Caucasian populations?

Background: Multiple sclerosis (MS) in Asia is thought to have different clinical characteristics from MS in Western countries; however, previous studies in Asia were performed without properly differentiating neuromyelitis optica (NMO) from MS. Objectives: To evaluate the clinical characteristics of MS in Korea after careful exclusion of potential explanations other than MS, particularly NMO spectrum disorder (NMOSD). Methods: This study is a retrospective review of consecutive MS patients attending five referral hospitals in Korea. All patients MS diagnoses were re-evaluated. Results: Of the 105 patients, 70 were female and 35 were male. The mean age of onset was 30.4 years and the mean disease duration was 5.4 years. On initial magnetic resonance imaging (MRI), 58% and 64% fulfilled the criteria for dissemination in space for the 2005 and 2010 McDonald criteria, respectively. Spinal cord lesions were observed in 78% of patients, primarily present as multiple small lesions with a mean length of 0.9 vertebral segments. The median time from disease onset to an Expanded Disability Status Scale 6 was 20 years. Conclusions: After careful exclusion of NMOSD, we found that the clinical pattern of MS in Korea does not fundamentally differ from that seen in Western countries.