1. Department of Neurosurgery, University of Toyama;
2. Department of Neurosurgery, Chiba University Graduate School of Medicine, Chiba;
3. Department of Neurosurgery, Saitama Medical University International Medical Center, Hidaka;
4. Department of Neurosurgery, Nippon Medical School, Tokyo;
5. Department of Neurosurgery, Tokyo Medical University, Tokyo;
6. Department of Neurosurgery, The Jikei University School of Medicine, Tokyo;
7. Department of Neurosurgery, Juntendo University, Tokyo;
8. Brain Research Institute, University of Niigata;
9. Department of Neurosurgery, Keio University School of Medicine, Tokyo;
10. Department of Neurosurgery, Okayama University Graduate School of Medicine, Okayama; and
11. Department of Neurosurgery, University of Tsukuba, Japan