1. Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia;
2. Department of Otorhinolaryngology–Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania;
3. Department of Otolaryngology–Head and Neck Surgery, University of South Florida, Tampa, Florida;
4. Division of Neurosurgery, Children’s Hospital of Philadelphia, Pennsylvania;
5. Department of Otorhinolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts; and
6. Department of Radiology, Children’s Hospital of Philadelphia, Pennsylvania