Affiliation: | a Department of Anesthesiology and Pain Medicine, Soonchunhyang University Hospital Cheonan, Chungcheongnam-do, Korea;b Department of Neurosurgery, Soonchunhyang University Hospital Cheonan, Chungcheongnam-do, Korea;c Department of Orthopaedic Surgery, Soonchunhyang University Hospital Cheonan, Chungcheongnam-do, Korea. |