1. Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
2. School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
3. Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
4. Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
5. Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania
6. Division of Neurosurgery, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania