1. Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8654, Japan
2. Department of Otolaryngology, Mitsui Memorial Hospital, Tokyo 101-8643, Japan
3. Department of Otolaryngology, Nagasaki Harbor Medical Center, Nagasaki 850-0842, Japan
4. Department of Otolaryngology and Head and Neck Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan
5. Department of Otolaryngology, Faculty of Medicine, Kindai University, Osaka 589-0014, Japan
6. Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
7. Department of Otolaryngology, Faculty of Medicine, Teikyo University, Tokyo 173-8605, Japan