1. Division of Emergency Medicine, Boston Children's Hospital, Boston, Massachusetts, USA.
2. Medical College of Georgia, Augusta, Georgia, USA.
3. Departments of Pediatrics and Emergency Medicine, University of Ottawa, and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
4. Department of Psychology, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
5. Division of Emergency Medicine, Center for Injury Research and Prevention, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
6. Micheli Center for Sports Injury Prevention, Division of Sports Medicine and Department of Pediatrics Boston Children's Hospital, Boston, Massachusetts, USA.
7. UBMD Department of Orthopedics and Sports Medicine, State University of New York at Buffalo, Buffalo, New York, USA.
8. Sports Medicine and Performance Center, Center for Injury Research and Prevention, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
9. Mind Research Network/LBERI and Departments of Psychology, Neurology, and Psychiatry, University of New Mexico, Albuquerque, New Mexico, USA.
10. Children's Hospital Colorado Sports Medicine Center and Department of Orthopedics University of Colorado School of Medicine, Aurora, Colorado, USA.
11. Departments of Neurosurgery, Cell Biology, Neurobiology and Anatomy, and Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.