1. Department of Neurosurgery, Saiseikai Wakayama Hospital, Wakayama, Wakayama, Japan
2. Imae Clinic, Wakayama, Wakayama, Japan
3. Department of Neurosurgery, Wakayama Medical University, Wakayama, Wakayama, Japan
4. Department of Neurosurgery, Makita General Hospital, Tokyo, Japan