1. Department of Neurological Surgery, Wakayama Rosai Hospital, Wakayama;
2. Department of Neurological Surgery, Wakayama Medical University, Wakayama;
3. Department of Neurosurgery, Ishioka Cardiology and Neurosurgery Hospital, Ishioka, Ibaragi; and
4. Department of Neurological Surgery, Kishiwada Tokushukai Hospital, Kishiwada, Japan