1. Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway
2. Department of Otorhinolaryngology, Mayo Clinic School of Medicine, Rochester, Minnesota
3. Department of Otorhinolaryngology, Head and Neck Surgery, Haukeland University Hospital, Bergen, Norway
4. Department of Neurologic Surgery, Mayo Clinic School of Medicine, Rochester, Minnesota
5. Department of Clinical Medicine, University of Bergen, Bergen, Norway