1. Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-Akita
2. Department of Neurosurgery, Hokkaido University Graduate School of Medicine
3. Sapporo Azabu Neurosurgical Hospital
4. Department of Neurosurgery, Keiwa-kai Ebetsu Hospital
5. Department of Neurosurgery, Teine Keijinkai Hospital