1. Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus
2. Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland
3. Department of Otolaryngology–Head and Neck Surgery, Georgetown University Medical Center, Washington, District of Columbia
4. Neuroradiology Section, Diagnostic Radiology, Clinical Center, National Institutes of Health, Bethesda, Maryland
5. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland