1. 1Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon;
2. 2Wright Patterson Air Force Base, Ohio;
3. 3Department of Neurosurgery, Wilford Hall Medical Center, Lackland Air Force Base, Texas;
4. 4Department of Neurosurgery, David Grant Medical Center, Travis Air Force Base, California; and
5. 5Department of Surgery, R. Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, Maryland