1. Department of Neurology; St Olavs Hospital, Trondheim University Hospital; Trondheim Norway
2. Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences; Norwegian University of Science and Technology (NTNU); Trondheim Norway
3. Department of Neurosurgery; St. Olavs hospital, Trondheim University Hospital; Trondheim Norway
4. Department of Neurosurgery; Sahlgrenska University Hospital; Gothenburg Sweden
5. Institute of Neuroscience and Physiology; University of Gothenburg, Sahlgrenska Academy; Gothenburg Sweden
6. Department of Neurosurgery; University of Cape Town; Cape Town South Africa
7. Department of Health Registries; Trondheim Norway
8. Department of Neurology; Mayo Clinic; Phoenix Arizona
9. Department of Public Health and General Practice; Norwegian University of Science and Technology (NTNU); Trondheim Norway