1. Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
2. Department of Otorhinolaryngology–Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
3. Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
4. Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania.
5. Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.