1. Spine and Nerve Center of the Virginias, Charleston, West Virginia
2. Department of Neurosurgery, Neurosurgical Associates of Lancaster, Lancaster, Pennsylvania
3. Department of Neurosurgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
4. Department of Functional Neurosurgery and Stereotaxy, Heinrich Heine University, Dusseldorf, Germany
5. Department of Neurosurgery, Albany Medical College, Albany, New York
6. Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
7. UK HealthCare Pain Services, Department of Anesthesiology, University of Kentucky College of Medicine, Lexington, Kentucky
8. Department Neurosurgery, NYU Langone Medical Center, New York, New York, USA