1. Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
2. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
3. Department of Otorhinolaryngology, Head and Neck Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
4. Department of Oncology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
5. Department of Pathology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
6. Service de Neurochirurgie, Département des Neurosciences Cliniques, Hopitaux Universitaires de Genève, Geneva, Switzerland
7. Faculty of Medicine, University of Geneva, Geneva, Switzerland