High-speed digital imaging and electroglottography of tracheoesophageal phonation by Amatsu's method

Comparison of electroglottographic variability index in euphonic and pathological voice

In a recent study we introduced a new approach for analysis of the electroglottographic (ECG) signal. This method is based on the evaluation of variation of the EGG signal and its first derivative, through new software developed by the Pisan phoniatric school. This software is designed to extract quantitative indices related to the contacting and decontacting phases of the vocal folds during phonation. The software allows us to study the combined variability of vibration amplitude and velocity (i.e. the first derivative of the EGG signal). Pathological voices show a much more variable EGG signal compared to normal voices, since cordal vibration is made irregular due to the presence of glottis plane pathologies. With the aim of demonstrating the differences between normal and pathological voices relevant to combined vibration amplitude and velocity variability, we have introduced a new quantitative parameter named “variability index, VI”. We studied 95 subjects (35 normal and 60 with pathological voice); among pathologic subjects, 15 showed functional dysphonia and 45 showed organic dysphonia. Subjects affected by organic dysphonia presented: 15 bilateral vocal nodules, 15 unilateral polyps and 15 unilateral cysts. All subjects were studied with videolaryngostroboscopy; electro-acoustic parameters of the voice were analysed with the KayPENTAX CSL (Model 4500) system. The EGG signal was recorded using KAY Model 6103 connected to the CSL system. The new software for the analysis of the EGG signal allows us to obtain not only a VI total value relevant to variability during all the recording, but also partial VI values relevant to the different glottis cycle phases. In fact, plotting the amplitude variation and its first derivative on a Lissajous graph, it is possible to divide the whole glottis cycle into four phases (each represented by four quadrants on the graph): the initial vocal folds contacting activity (VI-Q1), the last phase of vocal folds contacting (VI-Q2), the first phase of vocal folds decontacting (VI-Q3) and the last phase, up to the complete decontacting of vocal folds (VI-Q4). For each quadrant, it is also possible to work out the percent variability index. By comparing the variability indices in the normal and pathological groups, we obtained the following results: the total VI was significantly higher in the pathological subjects (0.25 vs 0.18; p = 0.01); the absolute value of VI was higher in pathological subjects, although the difference was not significant (VI-Q2, 0.041 vs 0.029; VI-Q3, 0.065 vs 0.058; VI-Q4, 0.054 vs 0.052). The percent variability in the Q2 quadrant (VI-Q2%) was significantly higher in pathological subjects compared to normal subjects (0.22 vs 0.16) (p = 0.01). The results of this study confirm that our new software for analysis of EGG signal can distinguish normal voice from pathological voice based on the new quantitative parameter VI. Moreover, this study emphasises that the final contact phase of vocal folds is the most representative of the difference between the normal and pathological voice and shows a wider variability in terms of amplitude and vibration velocity. Further studies on larger groups of subjects will be required to confirm these results and assess differences in the EGG signal among the various vocal fold pathologies.

High-speed digital imaging laryngoscopy of the neoglottis following supracricoid laryngectomy with cricohyoidoepiglottopexy

OBJECTIVES

This study aimed to analyse vocal performance and to investigate the nature of the neoglottal sound source in patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy, using a high-speed digital imaging system.

METHODS

High-speed digital imaging analysis of neoglottal kinetics was performed in two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy; laryngotopography, inverse filtering analysis and multiline kymography were also undertaken.

RESULTS

In case one, laryngotopography demonstrated two vibrating areas: one matched with the primary (i.e. fundamental) frequency (75 Hz) and the other with the secondary frequency (150 Hz) at the neoglottis. In case two, laryngotopography showed two vibrating areas matched with the fundamental frequency (172 Hz) at the neoglottis. The interaction between the two areas was considered to be the sound source in both patients. The waveform of the estimated volume flow at the neoglottis, obtained by inverse filtering analysis, corresponded well to the neoglottal vibration patterns derived by multiline kymography. These findings indicated that the specific sites identified at the neoglottis by the present method were likely to be the sound source in each patient.

CONCLUSIONS

High-speed digital imaging analysis is effective in locating the sites responsible for voice production in patients who have undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. This is the first study to clearly identify the neoglottal sound source in such patients, using a high-speed digital imaging system.

Mucosal wave measurement and visualization techniques

Organized vibration of the vocal folds is critical for high-quality voice production. When the vocal folds oscillate, the superficial tissue of the vocal fold is displaced in a wave-like fashion, creating the so-called "mucosal wave." Because the mucosal wave is dependent on vocal fold structure, physical alterations of that structure cause mucosal wave abnormalities. Visualization and quantification of mucosal wave properties have become useful parameters in diagnosing and managing vocal fold pathology. Mucosal wave measurement provides information about vocal fold characteristics that cannot be determined with other assessment techniques. Here, we discuss the benefits, disadvantages, and clinical applicability of the different mucosal wave measurement techniques, such as electroglottography, photoglottography, and ultrasound and visualization techniques that include videokymography, stroboscopy, and high-speed digital imaging. The various techniques and their specific uses are reviewed with the intention of helping researchers and clinicians choose a method for a given situation and understand its limitations and its potential applications. Recent applications of these techniques for quantitative assessment demonstrate that additional research must be conducted to realize the full potential of these tools. Evaluations of existing research and recommendations for future research are given to promote both the quantitative study of the mucosal wave through accurate and standardized measurement of mucosal wave parameters and the development of reliable methods with which physicians can diagnose vocal disorders.

High-speed digital imaging of the neoglottis after supracricoid laryngectomy with cricohyoidoepiglottopexy

OBJECTIVE

To determine the utility of high-speed digital imaging (HSDI) in evaluating vocal kinetics of the neoglottis after supracricoid laryngectomy with cricohyoidoepiglottopexy (SCL-CHEP).

STUDY DESIGN

Case series.

SETTING

The University of Tokyo Hospital.

SUBJECTS AND METHODS

High-speed digital recordings of laryngeal images were obtained from six patients after SCL-CHEP to clarify the vocal kinetics of the postoperative neoglottis. Simultaneous recording of electroglottograms (EGGs) were obtained and multiline kymograms were generated on the basis of the recorded images. The distribution of frequency, amplitude, and phase in the neoglottis were visualized by using gradients of colors superimposed onto the glottal and supraglottal areas of laryngeal images to produce laryngeal topograms. Furthermore, waveforms of estimated laryngeal sound source (ELSS) were obtained on the basis of glottal inverse filtering of the vocal signal to reflect vibratory motions in the neoglottis. The vibratory part of the neoglottis was determined as a possible sound source when the frequencies of the ELSS, EGG, and laryngeal topograms, as well as the waveforms of ELSS, EGG, and kymograms, were consistent with each other.

RESULTS

Spaces between the arytenoid(s) and epiglottis (5 patients) or pyriform sinus mucosa (1 patient) were estimated as the major source of sound during postoperative vocalization. The possible sound source could be determined by HSDI, even in the neoglottis, with more than one vibratory position.

CONCLUSION

HSDI could be useful for evaluating the vocal kinetics of the neoglottis after SCL-CHEP.

Laryngeal function after supracricoid laryngectomy

Objective: The purpose of this study was to assess laryngeal function after supracricoid laryngectomy.

Study Design: Case series.

Subjects and Methods: Supracricoid laryngectomy (SCL) has been performed in our institution for 24 selected patients with laryngeal cancer since December 2000. Reconstruction was performed through cricohyoidoepiglottopexy for 23 patients and cricohyoidopexy for 1 patient. Seven patients had ipsilateral arytenoid removal, and 15 patients underwent SCL as salvage surgery. A retrospective chart review was performed to assess postoperative speech and swallowing function. Stroboscopy and/or fiberscopy of the neoglottis were used to assess postoperative speech kinetics. Acoustic parameters were measured to evaluate vocal function, and several questionnaires were used to evaluate postoperative quality of life (QOL).

Results: In the absence of postoperative complications, stoma closure and normal diet intake were achieved 1 month after surgery. The neoglottis comprises the arytenoid(s), epiglottis, and pyriform sinus mucosa. Several different combinations of vibrating regions were observed among patients during phonation. Although vocalization sounded rough and breathy, vocal communication was possible with little inconvenience.

Conclusion: Acceptable functional recovery and tolerable QOL can be achieved after SCL.