1. Department of Anesthesiology, Intensive Care, Emergency Medicine and Pain Therapy, Kantonsspital Lucerne, 6000 Lucerne, Switzerland
2. Department of Anesthesiology, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
3. Department of Anesthesiology and Pain Medicine, Swiss Paraplegic Center, 6207 Nottwil, Switzerland
4. Department of Neuroscience, Algesiology and Pediatrics, 90419 Nuremberg, Germany