1 From the Department of Anesthesiology and Pain Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea.
2 Biomedical Research Institute, Chung-Ang University Hospital, Seoul, Republic of Korea.
3 Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
4 Department of Anesthesiology and Pain Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.