1. Department of Neurology; Seoul National University Hospital; Seoul; Korea
2. Department of Neurology; Inha University Hospital; Incheon; Korea
3. Department of Neurology; Dongguk University Ilsan Hospital; Goyang; Korea
4. Biostatistical Consulting Unit; Soonchunhyang University Medical Center; Seoul; Korea
5. Department of Neurology; Seoul National University Bundang Hospital; Seongnam; Korea
6. Department of Neurology; Seoul Municipal Boramae Hospital; Seoul; Korea