1. Multidisciplinary Pain Centre, Department of Anaesthesiology, University of Munich, Germany.
2. Department of Physical Medicine, Rehabilitation and Prevention, Staedtisches Klinikum City of Munich/Harlaching, Munich, Germany.
3. Department of Otorhinolaryngology, BKH Kufstein, Austria.
4. Department of Otolaryngology–Head and Neck Surgery, Salzburg University Medical School, Salzburg, Austria.