1. Department of Physical Medicine & Rehabilitation, Hospital Professor Doutor Fernando da Fonseca, Amadora, Portugal
2. Department of Anesthesiology, Chronic Pain Unit, Centro Hospitalar Universitário Lisboa Norte, Lisbon, Portugal
3. Department of Anesthesiology & Pain Medicine, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, M5T 2S8, Canada
4. Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Jacksonville, FL 32224, USA
5. Department of Pain Medicine, Mayo Clinic, Jacksonville, FL 32224, USA