1. Department of Pain Management and Research, Oslo University Hospital, Oslo, Norway
2. Department of Anaesthesia, Karlstad Central Hospital, Karlstad, Sweden
3. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
4. Department of Radiology, Oslo University Hospital-Rikshospitalet, Oslo, Norway
5. Department of Geriatrics and Internal Medicine, Sørlandet Hospital, Arendal, Norway