1. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke;
2. Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
3. Diagnostic Radiology Department, Warren G. Magnuson Clinical Center;
4. Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland;
5. Department of Otolaryngology–Head and Neck Surgery, Georgetown University Medical Center, Washington, D.C