1. Department of Medicine, Graduate School of Yonsei University, Seoul, Korea.
2. Department of Rehabilitation Medicine, Gangnam Severance Hospital, Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Physical Medicine and Rehabilitation, Research Institute of Clinical Medicine of Chonbuk National University–Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea.