1. Department of Neurosurgery, Carver College of Medicine, University of Iowa, Iowa City, IA
2. Department of Neurosurgery, Thomas Jefferson University and Jefferson Hospital for Neuroscience, Philadelphia, PA
3. Department of Radiology, Carver College of Medicine, University of Iowa, Iowa City, IA
4. Department of Neurological Surgery, University of California San Francisco, San Francisco, CA
5. Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, CA
6. Department of Neurosurgery, Hofstra University and Lenox Hill Hospital, New York City, NY
7. Departments of Internal Medicine and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA