1. The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA;
2. Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
3. Division of Neurosurgery, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA;
4. Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
5. Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA