1. Department of Neurosurgery, Kure Medical Center and Chugoku Cancer Center, Kure, Hiroshima, Hiroshima, Japan
2. Department of Neurosurgery and Endovascular Neurosurgery, Hiroshima Prefectural Hospital, Hiroshima, Hiroshima, Japan
3. Department of Neurosurgery, Onomichi General Hospital, Onomichi, Hiroshima, Japan
4. Department of Neurosurgery, Onoura Hospital, Hatsukaichi, Hiroshima, Japan