1. Department of Neurosurgery; University of Pittsburgh School of Medicine; Pittsburgh Pennsylvania
2. Department of Otolaryngology; University of Pittsburgh School of Medicine; Pittsburgh Pennsylvania
3. Department of Pathology; Allegiance Health; Jackson Michigan
4. Department of Radiation Oncology; University of Florida; Gainesville Florida
5. Department of Otolaryngology; Hospital Universitario Central de Asturias; Oviedo Spain
6. Instituto Universitario de Oncología del Principado de Asturias; Oviedo Spain
7. ENT Clinic; University of Udine; Udine Italy