1. Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia, USA
2. Department of Neurosurgery, University of Louisville, Louisville, Kentucky, USA
3. Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, Alabama, USA
4. Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
5. Department of Neurosurgery, Pennsylvania State University, Hershey, Pennsylvania, USA