1. Department of Neurosurgery, Akita University Graduate School of Medicine
2. Department of Neurosurgery, Teine Keijinkai Hospital
3. Department of Neurosurgery, Gifu University Graduate School of Medicine
4. Department of Neurosurgery, National Cerebral and Cardiovascular Center
5. Department of Neurological Surgery, Faculty of Medicine, Kagawa University
6. Department of Environmental Health Science and Public Health, Akita University Graduate School of Medicine