Twenty-one patients with multiple sclerosis (MS) and onset before 18 years were treated over the past 22 years and their records retrospectively analyzed at the National Taiwan University Hospital, Taipei, and Min-Sheng General Hospital, Taoyuan, Taiwan. Fifteen were female and 6 male, mean age 12.4 +/- 4.5 years. Presenting symptoms or signs in order of frequency were limb weakness (62%), visual loss or field defect (43%), bulbar symptoms (33%), sensory disturbance (29%), headache (29%), ataxia (19%), bowel or sphincter dysfunction (14%), and encephalopathy or encephalitis (14%). Multiple symptoms occurred at onset in 76%. A viral prodrome, usually upper respiratory, was reported 2 weeks before onset of MS symptoms in 43%.
MRI at onset showed lesions in the cerebral white matter in 72%, most commonly in periventricular white matter (56%), in basal ganglia (33%), cerebellum (28%), spinal cord (28%), corpus callosum (22%), and optic nerve (17%). Visual evoked potentials were abnormal in 77%, and a total of 62% had optic nerve involvement. Only one had optico-spinal MS. Of 9 patients receiving periodic subcutaneous interferon beta-la, 4 (44%) had no relapses. The course was relapsing remitting in 86%, and secondary progressive in 14%. The mean interval between the first and second attack was 7.2 +/- 10 months, most occurring within 12 months. Three (14%) patients who were initially diagnosed with acute disseminated encephalomyelitis developed MS after 4 months, 2 and 6 years intervals. 
COMMENT. Compared with the West, Asian populations appear to be less susceptible to MS, suggesting a genetic racial factor in susceptibility. The concordance rate for MS among monozygotic twins is 26% compared to 2% for dizygotic twins . A 50-fold increase in risk for daughters is noted in female MS patients . The female to male sex ratio has increased over the past 50 years and now exceeds 3.2:1 in Canada . An environmental factor is suspected. Similar changes in sex ratio are observed in USA, Australia, and Japan. In the above Taiwan series, the female to male ratio is 2.5:1. An MS phenotype may be defined by its association with other autoimmune diseases; 26% index MS cases reported coexisting Hashimoto thyroiditis in 10%, psoriasis (6%), and rheumatoid arthritis (2%). 
The differentiation of ADEM and MS is difficult, and in the above report, a viral prodrome and polysymptomatic presentation, characteristic of ADEM, were common in MS. Dale RC et al. (Ped Neur Briefs June 2005;19:47-48)  found that the disseminated demyelinative lesions on MRI are cortical and in deep grey matter in ADEM and periventricular/callosal in location in MS. In another study  the risk of MS is significantly higher with MRI callosal lesions, while basal ganglia lesions are equally frequent in ADEM and MS. The risk of relapse, and subsequent diagnosis of MS in patients initially considered ADEM is 10% in one previous study.