1. Texas Tech University Health Sciences Center, Lubbock, Texas;
2. Evergreen Medical Consultants, Evergreen, Colorado;
3. Stanford University, Palo Alto, California;
4. Department of Neurology, Mayo Clinic, Rochester, Minnesota;
5. Department of Physical Medicine & Rehabilitation, Loma Linda University, Loma Linda, California;
6. Vanderbilt University, Nashville, Tennessee;
7. Perth, Western Australia;
8. University of Illinois at Chicago, Chicago, Illinois;
9. Cleveland Clinic Pain Management Center, Cleveland, Ohio;
10. Mensana Clinic, Stevenson, Maryland;
11. Pain Management Clinic of Laredo, Laredo, Texas;
12. University of California Medical Center, San Diego, California;
13. Critical Care Medicine and Oncology, Johns Hopkins University, Baltimore, Maryland;
14. The Pain Management Center Cook County Hospital, Chicago, Illinois;
15. Headache and Neurological Rehabilitation Institute of Colorado, Northglenn, Colorado;
16. Department of Neurology, New Orleans VAMC, New Orleans, Louisiana;
17. Department of Anesthesia, Stanford University, Palo Alto, California;
18. University Center for Pain Medicine, University of Texas, Houston, Texas