^*Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona;

^‡Department of Neurosurgery, and

^¶Department of Orthopaedics, University of Maryland, Baltimore, Maryland;

^§Department of Neurosurgery, Emory University, Atlanta, Georgia;

^‖Department of Clinical Neurosciences, University of Calgary Spine Program, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada;

^#Division of Neurological Surgery, and

^§§Division of Neurological Surgery, Children’s Hospital of Alabama, University of Alabama at Birmingham, Birmingham, Alabama;

^**Iowa Spine & Brain Institute, University of Iowa, Waterloo/Iowa City, Iowa;

^‡‡Department of Neurosciences, Inova Health System, Falls Church, Virginia

Correspondence: Mark N. Hadley, MD, FACS, UAB Division of Neurological Surgery, 510 – 20^th Street South, FOT 1030, Birmingham, AL 35294-3410. E-mail: [email protected]