1. Department of Neurosurgery, University of Tennessee, and Semmes-Murphey Clinic, Memphis, Tennessee;
2. Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota;
3. Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan;
4. Columna Institute, Belo Horizonte, Minas Gerais, Brazil; and
5. Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona