Temporal changes in vocal functions of human scarred vocal folds after cordectomy

Objectives/Hypothesis: The maturation process of scarred vocal folds has previously been investigated using animal models. However, in human models the features of scarred vocal folds have rarely been described, and the process by which the scar changes with time is not well known. The present study aimed to investigate the maturation process of human vocal folds scarred by cordectomy in terms of vibratory and aerodynamic functions. Study Design: Prospective case series. Methods: Eight patients with early glottic carcinoma and two patients with leukoplakia of the vocal fold underwent endoscopic cordectomy at Kyoto University Hospital between 2006 and 2008. The temporal changes in their vocal functions were evaluated using acoustic and aerodynamic analyses and videostroboscopic examination. Results: Normalized mucosal wave amplitude, mean flow rate, and the amplitude perturbation quotient appear to stabilize about 6 months after the procedure. Although there were individual variations in the changes in normalized glottal gap and maximum phonation time, it appears to take at least 6 months to reach plateau. The other parameters - pitch perturbation quotient and noise to harmonic ratio - varied by individual, and thus it was difficult to identify commonalities in the healing process. Conclusions: Some individual variation was observed in the temporal changes of vocal function of scarred vocal folds after cordectomy. However, in terms of vibratory and aerodynamic functions, this study suggests that it takes at least 6 months for maturation of vocal fold scarring.