1. Department of Neurology, College of Medicine, Ewha Womans University, Seoul, Korea.
2. Department of Neurology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
3. Department of Neurology, Chuncheon Sacred Heart Hospital, Hallym University College of Medicine, Chuncheon, Korea.
4. Department of Statistics, Dongguk University, Seoul, Korea.
5. Department of Neurology, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Korea.