1. Rhinology and Skull Base Unit, Department of Otorhinolaryngology, Hospital Clínic, IDIBAPS, CIPERES, Barcelona University. Barcelona
2. Department of Otorhinolaryngology, Clinica Universidad de Navarra, University of Navarra, Pamplona
3. Rhinology and Skull Base Unit, Department of Otorhinolaryngology, Hospital Universitario Ramón y Cajal
4. Unidad Alergo Rino, Centro Médico Teknon, Barcelona, Spain