1. Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine, Oita University, Oita 879-5593, Japan
2. Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine, Miyazaki University, Miyazaki 889-1601, Japan
3. Department of Otolaryngology-Head and Neck Surgery, Miyazaki Prefectural Miyazaki Hospital, Miyazaki 880-0017, Japan