1. Department of Anesthesiology and Perioperative Medicine, Division of Pain Medicine Mayo Clinic Rochester Minnesota USA
2. Department of Anesthesiology Brown University Providence Rhode Island USA
3. University Pain Medicine Center Somerset New Jersey USA
4. West Virginia School of Medicine Charleston West Virginia USA
5. Mayo Clinic Alix School of Medicine Rochester Minnesota USA
6. Department of Anesthesiology and Pain Medicine University of Kansas Medical Center Kansas City Kansas USA
7. Southwest Spine & Pain Center Provo Utah USA
8. The Spine and Nerve Center of the Virginias Charleston West Virginia USA