1. Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania.
2. Physical Medicine and Rehabilitation Alliance of Baylor College of Medicine and the University of Texas-Houston Medical School
3. Department of Neurology, Baylor College of Medicine, Houston, Texas.
4. Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas
5. Department of Emergency Medicine, University of Texas Health Science Center, Houston, Texas.