1. Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Neurosurgery, Korea University Medical Center, Korea University College of Medicine, Seoul, Korea.
3. Center of Innovative Cell Therapy and Research, Anam Hospital, Korea University College of Medicine, Seoul, Korea.
4. Department of Neurosurgery, Dongrae Wooridul Hospital, Busan, Korea.