Diplophonia in unilateral vocal fold paralysis and intracordal cyst

TLDR

Diplophonia is the production of two distinct tones due to quasiperiodic variations in vocal fold vibration, commonly observed in patients with unilateral vocal fold paralysis, intracordal cysts, or granulomas that cause incomplete glottal closure. In 16 patients with unilateral vocal cord paralysis or intracordal cysts, diplophonia was observed; after surgery, tension‑imbalance cases showed improved perceptual scores, fewer vibratory cycles, and lower diplophonic occurrence, while mass‑imbalance cases showed no diplophonia, indicating that diplophonia depends on glottal conditions during tension imbalance but not mass imbalance. References include Ward et al.

Abstract

Diplophonia is the production by the voice of 2 separate tones through quasiperiodic variations in the vocal fold vibration (Ward PH, Moore GP. Ann Otol Rhinol Laryngol 1969;78:771‐7). Clinically, diplophonia can be observed in patients with unilateral vocal fold paralysis with incomplete glottal closure and a mass lesion of the vocal fold, intracordal cyst, and granuloma (Kiritani S, et al. Ann Bull RILP 1991; 25:55‐62; Hirano M, et al. Ann Otol Rhinol Laryngol 1989;98:791‐5). In this study we report 16 subjects with unilateral vocal cord paralysis or an intracordal cyst characterized perceptually by diplophonia. Diplophonia during tension imbalance may occur after surgery and is characterized by an improved perceptual score, a reduced number of vibratory cycles in each quasiperiodic waveform, and a reduced occurrence rate of the diplophonic waveform. During mass imbalance, no diplophonia occurred after surgery. Regarding the relationship of diplophonia with glottal condition at production of stops, in our study diplophonia varied significantly according to the different phonologic environments of stops during tension imbalance. We presume that there is a close relationship between the occurrence of diplophonia and the glottal conditions in tension imbalance, but not in mass imbalance.