1. Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
2. Department of Rehabilitation, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
3. Department of Neurosurgery, Martini Hospital Groningen, Groningen, The Netherlands
4. Care and Public Health Research Institute School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands
5. Department of Neurosurgery, Zuyderland Medical Center, Heerlen, The Netherlands
6. Department of Neurosurgery, Maastricht University Medical Center, Maastricht, The Netherlands
7. Department of Neurosurgery, Medical Center Haaglanden, The Hague, The Netherlands
8. Department of Neurosurgery, Elisabeth Tweesteden Ziekenhuis, Tilburg, The Netherlands
9. Department of Neurosurgery, Radboud University Medical Center Nijmegen, Nijmegen, The Netherlands
10. Department of Neurosurgery, Haaglanden Medical Center, The Hague, The Netherlands
11. Department of Neurosurgery, Haga Teaching Hospital, The Hague, The Netherlands
12. Department of Neurosurgery, Leiden University Medical Center, Leiden, The Netherlands
13. Department of Neurosurgery, Northwest Clinics, Alkmaar, The Netherlands
14. Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
15. Department of Anesthesiology, Groninger Pain Center, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
16. mProve Hospitals, Zwolle, The Netherlands