1. Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; UPMC Sports Medicine Concussion Program, Pittsburgh, Pennsylvania, USA
2. Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
3. Department of Kinesiology and Recreation Administration, Cal Poly Humboldt, Arcata, California, USA
4. UPMC Sports Medicine Concussion Program, Pittsburgh, Pennsylvania, USA
5. Health Science Library System, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
6. Inova Sports Concussion Program, Annandale, Virginia, USA
7. Department of Pediatrics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Children’s Hospital of Pittsburgh Division of Emergency Medicine, Pittsburgh, Pennsylvania, USA
8. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
9. Pediatric Emergency Medicine, George Washington School of Medicine, Washington, DC, USA; Children’s National Health System, Fairfax, Virginia, USA
10. Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Pediatric Emergency Medicine, Children’s Wisconsin, Wauwatosa, Wisconsin, USA)
11. Investigation performed at University of Pittsburgh Medical Center Sports Concussion Program and University of Pittsburgh Department of Orthopaedic Surgery, Pittsburgh, Pennsylvania, USA