[1] “La Paz” University Hospital,Department of Otolaryngology, IdiPaz Research Institute
[2] “Gregorio Marañon” University Hospital,Department of Otolaryngology
[3] “Rey Juan Carlos” Hospital,Department of Otolaryngology
[4] University of Chieti,Department of Otology and Skull Base Surgery, Gruppo Otologico Piacenza
[5] University of Parma,Rome