1. Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan;
2. Department of Neurosurgery, Japanese Red Cross Kitami Hospital, Kitami, Japan;
3. Department of Medical Informatics and Hospital Management, Asahikawa Medical University Hospital, Asahikawa, Japan;
4. Department of Neurosurgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan;
5. Furano Kyokai Hospital, Furano, Japan; and
6. Faculty of Health Sciences, Hokkaido University, Sapporo, Japan