1. Apeldoorn Dizziness Centre, Gelre Hospital, Apeldoorn, The Netherlands
2. Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, The Netherlands
3. Department of Primary and Community Care, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
4. Department of Radiology, Gelre Hospital, Apeldoorn, The Netherlands.