Jan Van Zundert MD, PhD, FIPPAnesthesiologist, Department of Anesthesiology and Multidisciplinary Pain Centre, Ziekenhuis Oost-Limburg, Genk, Belgium.Jacob Patijn MD, PhDNeurologist, Department of Anesthesiology and Pain Management, Maastricht University Pain Centre, Maastricht, The Netherlands.Craig T. Hartrick MD, DABPM, FIPPAnesthesiologist, Departments of Anesthesiology, Biomedical Sciences, and Health Sciences, Oakland University William Beaumont School of Medicine, Rochester, MI, USA.Arno Lataster MScAnatomist, Department of Anatomy and Embryology, Maastricht University, Maastricht, The Netherlands.Frank J.P.M. Huygen MD, PhD, FIPPAnesthesiologist, Department of Anesthesiology and Pain Management, Erasmus Medical Centre, Rotterdam, The Netherlands.Nagy Mekhail MD, PhD, FIPPCarl E. Wasmuth Professor and Chair, Department of Pain Management, Cleveland Clinic, Cleveland, OH, USA.Maarten Van Kleef MD, PhD, FIPPNeurologist, Department of Anesthesiology and Pain Management, Maastricht University Medical Centre, Maastricht, The Netherlands.