1. Department of Otorhinolaryngology, Riga Stradiņš University, Pilsonu Street 13, LV-1002 Riga, Latvia
2. Children’s Clinical University Hospital, Vienības Gatve 45, LV-1004 Riga, Latvia
3. Department of Morphology, Institute of Anatomy and Anthropology, Riga Stradiņš University, LV-1007 Riga, Latvia