1. Department of Neurology, Eulji University School of Medicine, Seoul, Korea.
2. Department of Neurology, Hallym University College of Medicine, Anyang, Korea.
3. Brain-Lee Headache/Neurology Center, Seoul, Korea.
4. Department of Neurology, Chungnam National University College of Medicine, Daejeon, Korea.
5. Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
6. Department of Neurology, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.