Dmitry Tretiakow1, Andrzej Skorek2. 1. Department of Otolaryngology, Medical University of Gdansk, Smoluchowskiego str. 17, 80-214, Gdansk, Poland. d.tret@gumed.edu.pl. 2. Department of Otolaryngology, Medical University of Gdansk, Smoluchowskiego str. 17, 80-214, Gdansk, Poland.