1. Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
2. Vanderbilt Sport Concussion Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
3. School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
4. School of Medicine, Meharry Medical College, Nashville, TN 37208, USA
5. Department of Orthopedic Surgery, Washington University in St Louis, St Louis, MO 63110, USA