1. Department of Otorhinolaryngology, Mitsui Memorial Hospital, Tokyo 101-8643, Japan
2. Department of Otorhinolaryngology and Head and Neck Surgery, The University of Tokyo, Tokyo 113-8655, Japan
3. Department of Otorhinolaryngology, Tokyo Metropolitan Police Hospital, Tokyo 164-8541, Japan
4. Department of Otorhinolaryngology, Tokyo Teishin Hospital, Tokyo 102-8798, Japan