1. Pain Management Center of Paducah, Paducah, KY 42003, USA
2. Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY, 40292, USA
3. Millennium Pain Center, Bloomington, IL 61701, USA
4. Department of Surgery, College of Medicine, University of Illinois, Urbana-Champaign, IL 61801, USA