1. Department of Neurosurgery, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
2. Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
3. Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.