1. Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht, the Netherlands,
2. Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands,
3. Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Antwerp, Antwerp, Belgium, and
4. Faculty of Medicine and Life Sciences, University of Antwerp, Antwerp, Belgium