1. F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland;
2. Department of Neurosurgery, Baylor College of Medicine, Houston, Texas;
3. Department of Neurosurgery, Temple University, Philadelphia, Pennsylvania;
4. Walter Reed National Military Medical Center, Bethesda, Maryland;
5. Division of Neurosurgery, University of Washington, Seattle, Washington; and
6. Division of Neurosurgery, Department of Surgery, Uniformed Services University, Bethesda, Maryland