title: Response to Dr. Freo and Dr. Calldero.
authors.affiliation: Department of Anesthesiology and Pain Management, Maastricht University Medical Center, MUMC, Maastricht, The Netherlands.|Department of Anesthesiology, Critical Care and Multidisciplinary Pain Center, ZOL, Genk/Lanaken, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Van Boxem
authors.affiliation: Department of Anesthesiology and Pain Management, Maastricht University Medical Center, MUMC, Maastricht, The Netherlands.
authors.forename: Nelleke
authors.initials: N
authors.lastname: de Meij
authors.affiliation: Department of Anesthesiology and Pain Management, Maastricht University Medical Center, MUMC, Maastricht, The Netherlands.
authors.forename: Jacob
authors.initials: J
authors.lastname: Patijn
authors.affiliation: Department of Radiology, Maastricht University Medical Center MUMC, Maastricht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Wilmink
authors.affiliation: Department of Anesthesiology and Pain Management, Maastricht University Medical Center, MUMC, Maastricht, The Netherlands.|Department of Anesthesiology and Pain Management, VUMC, Amsterdam, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: van Kleef
authors.affiliation: Department of Anesthesiology, Critical Care and Multidisciplinary Pain Center, ZOL, Genk/Lanaken, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Van Zundert
authors.affiliation: Clinical Epidemiology and Medical Technology Assessment, University Hospital Maastricht, Maastricht, The Netherlands.
authors.forename: Alfons
authors.initials: A
authors.lastname: Kessels