1. Department of Neurosurgery, Medical University Innsbruck, Innsbruck, Austria
2. Department of Neurosurgery, Donauisar Klinikum Deggendorf, Deggendorf, Germany
3. Department of Neurosurgery, St Bonifatius Hospital, Lingen, Germany
4. Department of Neurosurgery, OLVG-West and Academic Medical Center, Amsterdam, the Netherlands
5. Department of Neurosurgery, University Hospital Düsseldorf, Düsseldorf, Germany
6. Department of Neurosurgery, OLV Ziekenhuis, Aalst, Belgium
7. Department of Neurosurgery, University Hospital Bochum, Bochum, Germany
8. Department of Neurosurgery, HMC Westeinde, Den Hague, the Netherlands
9. Miller Scientific, Johnson City, Tennessee
10. Department of Neurosurgery, Charité Universitätsmedizin, Berlin, Germany
11. Department of Neurosurgery, AZ Klina, Brasschaat, Belgium
12. Department of Neurosurgery, Medical University Graz, Graz, Austria
13. Department of Neurosurgery, Isala Klinieken, Zwolle, the Netherlands
14. Department of Neurosurgery, Asklepios Westklinikum Hamburg, Hamburg, Germany
15. Department of Neurosurgery, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
16. Department of Neurosurgery, AZ Nikolaas, Sint-Niklaas, Belgium & Faculty of Medicine and Health Sciences, Antwerp University, Wilrijk, Belgium
17. Department of Neurosurgery, Centre Hospitalier Régional Universitaire de Lille, Lille, France
18. Department of Neurosurgery, Kantonsspital Aarau, Aarau, Switzerland