1. Department of Neurosurgery, School of Medicine, Saga University, Saga;
2. Department of Pediatric Surgery, Reproductive and Developmental Medicine, Faculty of Medical Sciences, Kyushu University, Fukuoka;
3. Department of Neurosurgery, School of Medicine, International University of Health and Welfare, Chiba; and
4. Department of Neurosurgery, Saga-ken Medical Centre Koseikan, Saga, Japan