1. Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA;
2. Department of Neurosurgery, David Geffen UCLA School of Medicine, Los Angeles, California, USA;
3. Department of Neurosurgery, University Hospitals/Case Western Reserve University School of Medicine, Cleveland, Ohio, USA;
4. Department of Neurosurgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA;
5. Department of Neurological Surgery, Keck School of Medicine of USC, Los Angeles, California, USA;
6. Office of Training & Workforce Development, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA