1. Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland.
2. R. Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland.
3. Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland.
4. Department of Radiology, University of Maryland School of Medicine, Baltimore, Maryland.
5. Walter Reed National Military Medical Center, Bethesda, Maryland.