1. University of Oxford; Pain Research and Nuffield Department of Clinical Neurosciences (Nuffield Division of Anaesthetics); Pain Research Unit Churchill Hospital Oxford Oxfordshire UK OX3 7LE
2. Helsinki University and Helsinki University Hospital; Department of Anaesthesia, Intensive Care and Pain Medicine; Helsinki Finland
3. Technische Universität München; Department of Neurology, Klinikum Rechts der Isar; Möhlstrasse 28 Munich Germany 81675
4. Aarhus University; Danish Pain Research Center, Department of Clinical Medicine; Building 1A Norrebrogade 44 Aarhus Denmark Dk 8000
5. Assistance Publique - Hôpitaux de Paris; Centre d'évaluation et de traitement de la douleur; Paris France
6. National Hospital for Neurology and Neurosurgery; Department of Neurology and MRC Centre for Neuromuscular Diseases; Queen Square London UK WC1N 3BG