1. Department of Neurosurgery, Tufts Medical Center, Boston, Massachusetts;
2. Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;
3. Department of Neurology, University of Virginia Health System, Charlottesville, Virginia;
4. Department of Neurosurgery, University of Miami, Miami, Florida;
5. Department of Neurosurgery, University of Louisville School of Medicine, Louisville, Kentucky; and
6. Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania