1. Department of Otolaryngology, University Hospital Ostrava, 17 Listopadu 1790, 708 52 Ostrava, Czech Republic
2. Faculty of Medicine, University of Ostrava, Syllabova 19, 703 00 Ostrava, Czech Republic
3. ENT University Department, Medical School, Comenius University, Bratislava, Antolska 11, 85107 Bratislava, Slovakia
4. University Hospital of Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK