1. Department of Neurosurgery, Guro Teun Teun Hospital, Seoul, Korea.
2. Department of Neurosurgery, Daegu Teun Teun Hospital, Daegu, Korea.
3. Department of Radiology, Guro Teun Teun Hospital, Seoul, Korea.
4. Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.