1. Department of Otolaryngology, Toranomon Hospital, Tokyo, Japan
2. Department of Otolaryngology, Takeda General Hospital, Aizu-Wakamatsu, Fukushima, Japan
3. Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
4. Department of Head and Neck Surgery, National Cancer Center Hospital, Tokyo, Japan