1. Department of Neurosurgery, Mayo Clinic, Phoenix, Arizona;
2. Department of Neurosurgery, Kentucky College of Osteopathic Medicine, University of Pikeville, Pikeville, Kentucky;
3. Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
4. Department of Neurosurgery, Duke University, Durham, North Carolina;
5. Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota; and
6. Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona