1. Department of Clinical Sciences, Otorhinolaryngology Umeå University Sundsvall Sweden
2. Department of Otorhinolaryngology, Surgical Division County Council of Västernorrland, Sundsvall Hospital Sundsvall Sweden
3. Division of CLINTEC, Department of Otorhinolaryngology Karolinska Institutet Stockholm Sweden
4. MU ENT, Hearing and Balance Karolinska University Hospital Stockholm Sweden
5. Department of Research and Development, County Council of Västernorrland Sundsvall Hospital Sundsvall Sweden
6. Dept of Surgical Sciences, Otorhinolaryngology Uppsala University Hospital Uppsala Sweden