1. Department of Physical Medicine & Rehabilitation, Hospital Professor Doutor Fernando Fonseca. Amadora, 2720-276, Portugal
2. Department of Anesthesiology & Pain Medicine, Toronto Western Hospital, University Health Network, University of Toronto. Toronto, ON, M5T 2S8, Canada
3. Department of Pain Medicine, Mayo Clinic. Jacksonville, FL 32224, USA
4. Department of Anesthesiology & Perioperative Medicine, Mayo Clinic. Rochester, MN 55905, USA
5. Department of Anesthesiology & Perioperative Medicine, Mayo Clinic. Jacksonville, FL 32224, USA