1. Department of Neurosurgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
2. Department of Radiation Oncology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
3. Department of Neurosurgery, Osaka General Medical Center, 3-1-56 Mandaihigashi, Sumiyoshi-ku, Osaka, Osaka 558-8558, Japan
4. Department of Respiratory medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan