1. Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, Alabama;
2. Department of Neurosurgery, Duke University, Durham, North Carolina;
3. Department of Neurosurgery, Billings Clinic, Billings, Montana;
4. Department of Neurosurgery, Oregon Health Sciences University, Portland, Oregon;
5. Department of Neurosurgery, University of Pittsburgh, Pittsburgh, Pennsylvania;
6. Department of Neurosurgery, Emory University, Atlanta, Georgia;
7. Department of Neurosurgery, University of Colorado, Denver, Colorado;
8. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;
9. Department of Neurosurgery, University of Wisconsin, Madison, Wisconsin;
10. Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona;
11. Section of Neurosurgery, University of Chicago, Chicago, Illinois;
12. Department of Neurosurgery, Stanford University, Palo Alto, California;
13. Department of Neurosurgery, University of California at San Francisco, San Francisco, California;
14. Department of Neurosurgery, University of Illinois, Chicago, Illinois;
15. Department of Neurosurgery, University of Ottawa, Ottawa, Ontario, Canada;
16. Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota; and
17. Department of Neurosurgery, Baylor College of Medicine, Houston, Texas