1. Departments of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
2. Departments of Orthopedics and Sports Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
3. The Pittsburgh Steelers Football Organization, Pittsburgh, Pennsylvania
4. Department of Behavioral Services, Henry Ford Health System, Detroit, Michigan
5. Michigan State University, East Lansing, Michigan
6. Department of Neurosurgery, Cornell University, New York, New York