1. Department of Neurosurgery, NTT Medical Center Tokyo, Tokyo, Japan
2. Department of Neurosurgery, Abashiri Neurosurgical Hospital, Abashiri, Japan
3. Carolina Neuroscience Institute, Raleigh, North Carolina, United States
4. Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina, United States
5. Department of Neurosurgery, University of Torino, Torino, Italy
6. Department of Neurosurgery, San Filippo Neri Hospital, Roma, Italy