1. Department of Neurosurgery, IRCCS Policlinico S. Matteo, University of Pavia, Pavia, Italy (Locatelli)
2. Department of Otorhinolaryngology, IRCCS Policlinico S. Matteo, University of Pavia, Pavia, Italy (Canevari)
3. Neurosurgical Department, Ospedale “SS. Antonio e Biagio e Cesare Arrigo,” Alessandria, Italy (Acchiardi)
4. Department of Otorhinolaryngology, University of Insubria, Varese, Italy (Castelnuovo)