1. Department of Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.
2. Department of Anesthesiology, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.
3. Department of Neurological Surgery, Gyeongsang National University School of Medicine, Jinju, Korea.
4. Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.