1. Columbia University College of Physicians and Surgeons, New York, New York
2. Vanderbilt University, Nashville, Tennessee
3. University of California at San Francisco, San Francisco, California
4. Beth Israel Deaconess Medical Center, Boston, Massachusetts
5. Henry Ford Health System, Detroit, Michigan
6. Affordable Pain Management, Chicago, Illinois
7. Spine Intervention Society, Hinsdale, Illinois, USA
8. Manning Pain Management, Mayo Private Hospital, Taree, New South Wales, Australia