1. Unit of Pain Therapy, Salvatore Maugeri Foundation, Scientific Institute of Pavia, Pavia, Italy
2. Anaesthesia, Intensive Care and Pain Therapy Service, Azienda Ospedaliera Universitaria Parma Hospital, Parma, Italy
3. Department of Surgical Sciences, Azienda Ospedaliera Universitaria Parma Hospital, University of Parma, Parma, Italy