1. Department of Otorhinolaryngology and Head and Neck Surgery; University Hospital Ostrava; 17. listopadu 1790 Ostrava 70852 Czech Republic
2. Department of Neurology; University Hospital Ostrava; 17. listopadu 1790 Ostrava 70852 Czech Republic
3. Department of Neurology and Psychiatry; Faculty of Medicine; University of Ostrava; Dvořákova 7 Ostrava 70103 Czech Republic
4. Epidemiological Studies Center; Faculty of Medicine; University of Ostrava; Dvořákova 7 Ostrava 70103 Czech Republic