1. Department of Physical Medicine and Rehabilitation, Penn Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
2. Division of Pain Medicine, Department of Anesthesiology, Reanimation, and Pain Medicine, Hospital Clínic de Barcelona, University of Barcelona, Barcelona, Catalonia, Spain
3. Department of Pain Medicine, Mayo Clinic, Jacksonville, Florida, USA
4. Department of Physical Medicine and Rehabilitation, Hospital Professor Doutor Fernando Fonseca, Amadora, Portugal