1. Leuven Centre for Algology & Pain Management, University Hospitals Leuven, KU Leuven, Leuven, Belgium;
2. Department of Anaesthesiology and Intensive Care Medicine, Charité University Berlin, Campus Virchow Klinikum, Berlin, Germany;
3. Neil Betteridge Associates, London, UK;
4. Pain Clinic, Departments of Anaesthesiology, Intensive Care, and Pain Medicine, Helsinki University Central Hospital, Helsinki, Finland