1. Department of Orthopedic Surgery and Neurological Surgery, Vanderbilt Spine Center, Vanderbilt University Medical Center, Nashville, Tennessee;
2. Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota;
3. Department of Neurological Surgery, Carolina Neurosurgery and Spine Associates and Neurological Institute, Carolinas Healthcare System, Charlotte, North Carolina;
4. Department of Physical Medicine and Rehabilitation, Vanderbilt University Medical Center, Nashville;
5. Department of Neurosurgery, University of Tennessee Health Sciences Center, Semmes Murphey Neurologic and Spine Institute, Memphis, Tennessee;
6. Department of Neurological Surgery, University of California, San Francisco, California;
7. Department of Neurologic Surgery, University of Utah, Salt Lake City, Utah;
8. Atlantic Neurosurgical Specialists, Morristown, New Jersey; and
9. Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, Virginia