1. Department of Neurosurgery, Naval Medical Center San Diego, San Diego, CA 92134, USA
2. Department of Neurosurgery, Washington University in Saint Louis, St. Louis, MO 63110, USA
3. Department of Brain & Spine Surgery, Naval Medical Center, Portsmouth, VA 23708, USA
4. Department of Neurosurgery, Columbia University, New York, NY 10032, USA
5. Departments of Neurosurgery and Political Science, University of Southern Alabama, University of South Alabama, Mobile, AL 36604, USA
6. Department of Neurosurgery, Ascension St. John, Tulsa, OK 74104, USA
7. Department of Neurosurgery, Walter Reed National Military Medical Center, Bethesda, MD 20814, USA
8. Department of Surgery, US Naval Hospital Okinawa, Chatan, Okinawa 904-0103, Japan