1. Neurosurgery, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama 232-0024, Japan
2. Diagnostic Radiology, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama 232-0024, Japan
3. Cardiovascular Surgery, Yokohama Municipal Citizens Hospital, Japan
4. Neurosurgery, Yokohama City University, Postgraduate School of Medicine, Fukuura, Kanazawa-ku, Yokohama, Japan