1. Department of Neurology, Nowon Eulji Medical Center, Eulji University School of Medicine, Seoul, Korea.
2. Department of Neurology, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Korea.
3. Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. The Saitama International Headache Center, Saitama, Japan.
5. Mayo Clinic College of Medicine, Scottdale, PA, USA.
6. Department of Neurology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.