1. Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
2. Department of Neurosurgery, Inazawa Municipal Hospital, Inazawa, Aichi, Japan
3. Division of Pathology, Konan Kosei Hospital, Konan, Aichi, Japan
4. Division of Neurosurgery, St. Michael’s Hospital, University of Toronto, Toronto, Canada