1. Department of Otolaryngology–Head and Neck Surgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
2. Department of Otolaryngology, Sanokousei General Hospital, Tochigi, Japan.
3. Center for Kampo Medicine, Keio University School of Medicine, Tokyo, Japan.
4. Tokyo Voice Center, International University of Health and Welfare, Tokyo, Japan.
5. Department of Otolaryngology–Head and Neck Surgery, National Defense Medical College, Saitama, Japan.