The clinical significance of high-speed videoendoscopy in assessing the condition of the pseudoglottis after laryngectomy

The aim of this study was to investigate the anatomical, morphological and dynamic characteristics of the pharyngoesophageal segment mucosa, as well as the features of pseudoglottis deformation during substitute phonation after total laryngectomy.
Material and methods. The study included 90 patients who had undergone laryngectomy and were stratified into 3 groups of 30 participants each, depending on the voice rehabilitation method (esophageal voice (EV, group I), tracheoesophageal voice prosthesis (TEV, group II), and electrolarynx (EL, group III)) from September 2021 to August 2023. All patients underwent endoscopic examination of the pharyngoesophageal segment and pseudoglottis during substitute phonation using a high-speed videoendoscopy system. Analysis of the pseudoglottis vibration parameters was carried out by visual assessment of kymograms and video recordings in slow motion. A number of parameters were assessed: the presence and amount of saliva in the pharyngoesophageal segment in the context of the influence on the visibility of the pseudoglottis, the shape of the pseudoglottis during the opening phase, the localization of visible vibration by prevalence on one or several walls, the presence, severity, and uniformity of the mucosal wave, the displacement of the pharyngoesophageal segment mucosa similar to the displacement of the vocal fold mucosa during physiological phonation, and the presence and relative duration of the pseudoglottis closure phase.
Results. The study revealed 5 different types of pseudoglottis: rounded, triangular, flat with the closure of the front and rear walls, flat with the closure of the lateral walls, and irregular. Comparing the occurrence of various forms of pseudoglottis in the study groups, no statistically significant differences were found between the groups (p-value=0.536). Comparing the groups in terms of the occurrence of various types of pseudoglottic closure (complete, incomplete, absent), no statistically significant differences were revealed (p-value=0.434). Vibration patterns were assessed in 2 study groups: I (EV) and II (TEV). In group 3 (EL), vibrations were not observed in any case due to the different biomechanics of substitute phonation, since the pharyngoesophageal segment is not a vibrating source of sound when an electrolarynx is used. Comparing the occurrence of various types of vibration patterns between groups I and II, no statistically significant differences were revealed in the localization of vibration (p-value=0.877), the strength of the mucosal wave (p-value=0.147), or the pattern of vibration (p-value=0.359).
Conclusion. High-speed videoendoscopy is a modern and effective method for objective assessment of the vibration characteristics of the pseudoglottis, allowing to study biomechanics of substitute phonation in laryngectomized patients. The absence of statistically significant differences between voice rehabilitation methods when comparing the distribution of vibration patterns across the three study groups seems to indicate that certain vibration characteristics, such as the shape and closure of the pseudoglottis, do not depend on the method of substitute phonation. The identified vibration patterns require further study and investigation of the relationships between the pseudoglottis vibration parameters and the acoustic characteristics of the pseudo-voice, as well as the features of the surgical technique, primarily the method of suturing the pharyngoesophageal anastomosis.
Keywords: larynx cancer, total laryngectomy, voice rehabilitation, esophageal voice, tracheoesophageal voice, electrolarynx, voice prosthesis
Conflicts of interest. The authors have no conflicts of interest to declare.
Financing. The study received no funding.