1. Department of Neurosurgery and Division of Interventional Neuroradiology, University of Pennsylvania Medical Center, and Division of Neurosurgery, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
2. Department of Neurosurgery, University of Pennsylvania Medical Center, and Division of Neurosurgery, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
3. Department of Neurosurgery, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania
4. Division of Interventional Neuroradiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania
5. Department of Neurosurgery and Division of Interventional Neuroradiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania