ABSTRACT
OBJECTIVES: Diplophonia is the voice of two separate tones through quasi-periodic variations in the vocal cord vibration when an imbalance in the tension and the level applied to the vocal cords. The purpose of this study is to investigate the relationship between the occurrence of the diplophonia and the endoscopic findings in the unilateral vocal cord paralysis. MATERIALS AND METHOD: A retrospective review was employed using video recorded images of larynx with unilateral vocal cord paralysis. A total 104 patients selected for this study complained of voice change due to unilaterally paralyzed vocal cord. Video-recordings were obtained using a laryngeal telescope. The paralyzed positions, bowing, shapes of the paralyzed arytenoids and level differences between two vocal folds were evaluated according to whether diplophonia. existed or not. RESULTS: A large number of patients of paramedian paralysis showed diplophonia when the bowing of paralyzed vocal fold was shown. However, diplophonia was shown in a small number of patients with median and intermediate paralysis. Diplophonia also seems to occur when the vertical mismatch was shown. CONCLUSION: Occurene of diplophonia depends largely on the paralyzed position, adequate glottal gap such as paramedian position, with the presence of bowing of paralyzed vocal cord.