1. Department of Neurology, Movement Disorder Center, Neuroscience Research Institute, College of Medicine, Seoul National University Hospital, Seoul, Korea
2. Parkinson Disease Study Group, Seoul National University Hospital, Seoul, Korea
3. Department of Neurology, College of Medicine, Seoul National University, Metropolitan Boramae Hospital, Seoul, Korea
4. Department of Neurosurgery, Movement Disorder Center, Neuroscience Research Institute, College of Medicine, Seoul National University Hospital, Seoul, Korea