1. Department of Neurosurgery, Duke University School of Medicine, Durham, North Carolina, USA;
2. Department of Neurosurgery, Duke University Hospital, Durham, North Carolina, USA;
3. Department of Neurosurgery, Washington University, St. Louis, Missouri, USA;
4. Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts, USA;
5. Department of Radiology, Duke University Hospital, Durham, North Carolina, USA