1. Department of Anaesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
2. Department of Anaesthesiology and Pain Medicine, Chungnam National University College of Medicine, Daejeon, Korea.
3. Department of Information Statistics, Chungnam National University, Daejeon, Korea.
4. Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
5. Department of Neurology, Seoul National University Bundang Hospital, Seongnam, Korea.