1 Faculty of Medicine, University of Oslo, Oslo, Norway. chrmja@gmail.com.
2 Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. chrmja@gmail.com.
3 Division of Clinical Neuroscience, Department of Research and Innovation, Oslo University Hospital, P.O. Box 4956, 0424, Oslo, Nydalen, Norway. chrmja@gmail.com.
4 Institute of Clinical Medicine, The Arctic University of Norway, Tromsø, Norway.
5 Department of Neurosurgery and The Norwegian Registry for Spine Surgery (NORspine), The University Hospital of North Norway, Tromsø, Norway.
6 Faculty of Medicine, University of Oslo, Oslo, Norway.
7 Division of Clinical Neuroscience, Department of Research and Innovation, Oslo University Hospital, P.O. Box 4956, 0424, Oslo, Nydalen, Norway.
8 Department of Rehabilitation and Technology, Faculty of Health Science, Oslo Metropolitan University, St. Olavs Plass, P.O. Box 4, 0130, Oslo, Norway.
9 Department of Neurosurgery, Oslo University Hospital, Oslo, Norway.