1. aKaiser Foundation Rehabilitation Center, Kaiser Permanente Vallejo Medical Center, Vallejo, California
2. bThe Permanente Medical Group, Oakland, California
3. cDivision of Research, Kaiser Permanente, Oakland, California
4. dNapa-Solano Sports Concussion Clinic, Kaiser Permanente Vacaville Medical Center, Vacaville, California; and
5. eDivision of Injury Prevention, National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia