1. Servicio ORL, Hospital Central Cruz Roja, Madrid, Spain.
2. Department of Otolaryngology, Alexandria School of Medicine, Alexandria, Egypt.
3. Division of Head and Neck Surgery, University of California at Los Angeles (UCLA), Los Angeles, California.
4. ENT Department, Military Medical Academy, Cairo, Egypt.
5. Gruppo Otologico, Via Emmanueli, 42, Piacenza, Italy.