1. Department of Neurosurgery Memorial Sloan Kettering Cancer Center New York New York
2. Department of Orthopedics University Medical Center Utrecht Utrecht the Netherlands
3. Department of Neurosurgery Duke University Medical Center Durham North Carolina
4. Department of Radiation Oncology Sunnybrook Odette Cancer Center and University of Toronto Toronto Ontario Canada
5. Department of Neurosurgery The University of Texas MD Anderson Cancer Center Houston Texas
6. Department of Neurosurgery Johns Hopkins University School of Medicine Baltimore Maryland
7. Department of Neurosurgery Hospital of the University of Pennsylvania Philadelphia Pennsylvania
8. Division of Surgery McGill University and Montreal General Hospital Montreal Quebec Canada
9. National Center for Spinal Disorders and Buda Health Center Budapest Hungary
10. Division of Neurosurgery and Spine Program University of Toronto and Toronto Western Hospital Toronto Ontario Canada
11. Department of Neurosurgery Mayo Clinic Rochester Minnesota
12. Department of Neurosurgery University of Kansas Hospital Kansas City Kansas
13. Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS (Institute of Hospitalization and Scientific Care)) Galeazzi Orthopedic Institute Milan Italy
14. Department of Neurosurgery Warren Alpert Medical School of Brown University, Rhode Island Hospital, and Miriam Hospital Providence Rhode Island
15. Division of Spine, Department of Orthopedics University of British Columbia and Vancouver General Hospital Vancouver British Columbia Canada