1. Department of Otolaryngology, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
2. Department of Otorhinolaryngology, National Center for Geriatrics and Gerontology, Aichi 474-8511, Japan
3. Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan