Evaluation of Vertical Level Differences Between Left and Right Vocal Folds Using Artificial Intelligence System in Excised Canine Larynx.

OBJECTIVES: This study aimed to establish an artificial intelligence (AI) system to classify vertical level differences between vocal folds during vocalization and to evaluate the accuracy of the classification. METHODS: We designed models with different depths between the right and left vocal folds using an excised canine larynx. Video files for the data set were obtained using a high-speed camera system and a color complementary metal oxide semiconductor camera with global shutter. The data sets were divided into training, validation, and testing. We used 20,000 images for building the model and 8000 images for testing. To perform deep learning multiclass classification and to estimate the vertical level difference, we introduced DenseNet121-ConvLSTM. RESULTS: The model was trained several times using different numbers of epochs. We achieved the most optimal results at 100 epochs, and the batch size used during training was 16. The proposed DenseNet121-ConvLSTM model achieved classification accuracies of 99.5% and 88.0% for training and testing, respectively. After verification using an external data set, the overall accuracy, precision, recall, and f1-score were 90.8%, 91.6%, 90.9%, and 91.2%, respectively. CONCLUSIONS: The newly developed AI system may be an easy and accurate method for classifying superior and inferior vertical level differences between vocal folds. Thus, this AI system can be applied and may help in the assessment of vertical level differences in patients with unilateral vocal fold paralysis.

Excised larynx evaluation of subthyroid cartilage approach to medialization thyroplasty.

OBJECTIVES/HYPOTHESIS: To describe an alternative approach to medialization thyroplasty involving dissection underneath the thyroid cartilage with placement of a Gore-Tex implant, and to evaluate its effect on a range of phonatory measures using an excised canine larynx model. STUDY DESIGN: Animal model. METHODS: On each of eight excised canine larynges, the conditions of normal, paralysis, medialization thyroplasty by standard transthyroid cartilage approach, and medialization thyroplasty by experimental subthyroid cartilage approach were performed. Aerodynamic, acoustic, and mucosal wave parameters were measured for each condition. RESULTS: Compared to the vocal fold paralysis state, both the transthyroid and subthyroid approaches for Gore-Tex insertion resulted in significant decreases in phonation threshold pressure and phonation threshold flow. Both approaches also significantly decreased percent jitter, decreased percent shimmer, and improved signal-to-noise ratio. The mucosal wave was preserved after insertion of the Gore-Tex implant for both approaches. For all the phonatory measures except phonation threshold flow, there were no significant differences between the transthyroid and subthyroid approaches. CONCLUSIONS: Gore-Tex implantation via a subthyroid approach in an excised canine larynx model can produce effective medialization, preserve the mucosal wave, and significantly improve aerodynamic and acoustic parameters without meaningful difference compared to a traditional transthyroid approach. The subthyroid approach does not require creation of a thyroid cartilage window and could be a potentially valuable alternative method of performing medialization thyroplasty. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:675-681, 2018.

The First Application of the Two-Dimensional Scanning Videokymography in Excised Canine Larynx Model.

OBJECTIVE: Evaluation of the vibratory pattern of vocal folds is of paramount importance to diagnose vocal fold disorders. Currently, laryngeal videokymography (VKG) and digital kymography from high-speed videolaryngoscopy are the available techniques for studying aperiodic vibrations of vocal folds. But VKG has the fundamental limitation that only linear portion of the vocal fold mucosa can be visualized. Digital kymography has the disadvantages of no immediate feedback during examination, considerable waiting time before kymographic visualization, recoding duration limited to seconds, and extreme demands on storage space. We developed a new system--two-dimensional (2D) scanning VKG--for evaluation of the vibratory pattern of vocal folds, and the method provided a possible alternative with its advantages and disadvantages. Thus, we aimed to evaluate the feasibility of the new device for the vocal fold vibration in excised canine larynx model. METHODS: The vibrating pattern for vocal folds was evaluated using high-speed videolaryngoscopic and 2D scanning videokymographic system in the excised canine larynx model. RESULTS: The images of canine vocal folds were captured with high-speed videolaryngoscopic system and converted to the kymographic images using the software. The kymographic image acquired by 2D scanning VKG was comparable with multi-line digital kymography at multiple locations. CONCLUSIONS: The vocal fold vibration could be evaluated in the excised canine larynx model using 2D scanning VKG. And this new device is expected to be a promising tool to evaluate the vocal fold vibration for clinical practice and voice research.

Voice Outcome of Modified Frontolateral Partial Laryngectomy in Excised Canine Larynges and Finite Element Model.

OBJECTIVE: To evaluate vocal parameters after modified frontolateral partial laryngectomy (MFLPL) and frontolateral partial laryngectomy (FLPL) in both excised canine and finite element models. STUDY DESIGN: FLPL and MFLPL were compared, using a prospective paired case control laboratory study with excised canine larynx and computational modeling. SETTING: Basic science study conducted in university laboratory. METHODS: FLPL and MFLPL were performed serially on 9 excised canine larynges. The excised larynx bench apparatus was used to collect phonation threshold pressure (PTP) and high-speed video data. A finite element model was built to compare a normal vocal fold with applied tension, a cut fold with no applied tension (simulating FLPL), and a cut fold with applied tension (simulating MFLPL). Stress values and distributions across the 3 conditions were computed. RESULTS: The mean PTP increase after MFLPL (15.45-17.46 cmH2O) was not statistically significant. In the excised canine model, fundamental frequency (F0) showed a significant increase for the MFLPL (P = .039). Differences in vibration amplitudes were not statistically significant. Von Mises stress distribution was most similar between the MFLPL model and the normal fold. Maximum von Mises stresses at the midline were 17.56, 21.63, and 5.10 kPa for the normal, MFLPL, and FLPL, respectively, and 47.57, 63.98, and 101.97 kPa at the peripheries. CONCLUSIONS: From these results, we conclude that MFLPL has the potential to give a better voice outcome while avoiding tracheotomy in partial laryngectomy patients. In vivo study in canines to examine the healing process would lend further evidence-based support for this surgical method.

Glottal opening and closing events investigated by electroglottography and super-high-speed video recordings.

Previous research has suggested that the peaks in the first derivative (dEGG) of the electroglottographic (EGG) signal are good approximate indicators of the events of glottal opening and closing. These findings were based on high-speed video (HSV) recordings with frame rates 10 times lower than the sampling frequencies of the corresponding EGG data. The present study attempts to corroborate these previous findings, utilizing super-HSV recordings. The HSV and EGG recordings (sampled at 27 and 44 kHz, respectively) of an excised canine larynx phonation were synchronized by an external TTL signal to within 0.037 ms. Data were analyzed by means of glottovibrograms, digital kymograms, the glottal area waveform and the vocal fold contact length (VFCL), a new parameter representing the time-varying degree of 'zippering' closure along the anterior-posterior (A-P) glottal axis. The temporal offsets between glottal events (depicted in the HSV recordings) and dEGG peaks in the opening and closing phase of glottal vibration ranged from 0.02 to 0.61 ms, amounting to 0.24-10.88% of the respective glottal cycle durations. All dEGG double peaks coincided with vibratory A-P phase differences. In two out of the three analyzed video sequences, peaks in the first derivative of the VFCL coincided with dEGG peaks, again co-occurring with A-P phase differences. The findings suggest that dEGG peaks do not always coincide with the events of glottal closure and initial opening. Vocal fold contacting and de-contacting do not occur at infinitesimally small instants of time, but extend over a certain interval, particularly under the influence of A-P phase differences.

Aerodynamic and acoustic effects of ventricular gap.

PURPOSE: Supraglottic compression is frequently observed in individuals with dysphonia. It is commonly interpreted as an indication of excessive circumlaryngeal muscular tension and ventricular medialization. The purpose of this study was to describe the aerodynamic and acoustic impact of varying ventricular medialization in a canine model. METHODS: Subglottal air pressure, glottal airflow, electroglottograph, acoustic signals, and high-speed video images were recorded in seven excised canine larynges mounted in vitro for laryngeal vibratory experimentation. The degree of gap between the ventricular folds was adjusted and measured using sutures and weights. Data were recorded during phonation when the ventricular gap was narrow, neutral, and large. Glottal resistance was estimated by measures of subglottal pressure and glottal flow. RESULTS: Glottal resistance increased systematically as ventricular gap became smaller. Wide ventricular gaps were associated with increases in fundamental frequency and decreases in glottal resistance. Sound pressure level did not appear to be impacted by the adjustments in ventricular gap used in this research. CONCLUSIONS: Increases in supraglottic compression and associated reduced ventricular width may be observed in a variety of disorders that affect voice quality. Ventricular compression may interact with true vocal fold posture and vibration resulting in predictable changes in aerodynamic, physiological, acoustic, and perceptual measures of phonation. The data from this report supports the theory that narrow ventricular gaps may be associated with disordered phonation. In vitro and in vivo human data are needed to further test this association.

Laringe canina y humana: un estudio para establecer homología / Laringe canina e humana: um estudo para estabelecer homologia / Canine and human larynx: a study to establish homologies

En este trabajo se describen las características anatómicas de la laringe canina y humana, con el objeto de encontrar rasgos relevantes que permitan hacer una homologación entre ambas especies. Se trabajó con cuatro laringes caninas y cinco humanas. Nuestros resultados muestran similitudes y diferencias en líneas generales y semejanzas entre las estructuras asociadas a los cartílagos tiroides y aritenoides. La articulación cricotirohidea y cricoaritenoídea son muy parecidas entre ambas especies. Una situación similar se observa en la musculatura intrínseca y extrínseca. Las diferencias más notables corresponden al tipo de articulación que se establece en el perro entre los cartílagos aritenoides, corniculados y cuneiformes que es una sincondrosis. Nuestros hallazgos permiten apoyar el hecho de que la laringe del perro puede ser usada con fines experimentales para resolver problemas animales y humanos.

Neste trabalho se descrevem as características anatômicas das lanringes do cão e do homem, com o objetivo de encontrar características relevantes que permitam fazer uma comparação entre ambas espécies. Trabalhou-se com quatro laringes caninas e cinco humanas. Os resultados mostram semelhanças e diferenças em linhas gerais e semelhanças entre as estruturas associadas às cartilagens tiróides e aritenóides. A articulação cricotiroidea e cricoaritenoidea são muito parecidasem ambas espécies. Uma situação similar se observa na musculatura intrínseca e extrínseca. As diferenças mais notáveis correspondem ao tipo de articulação que se estabelece no cão entre as cartilagens aritenóides, corniculados e cuneiformes que é uma sincondrose. As descobertas permitem apoiar o fato de que a laringe do cão pode ser usada com fi ns experimentais para resolver problemas animais e humanos.

In this paper the anatomical characteristics of canine and human larynx are described, with the purpose to detect relevant features that allows to fi nd homologies in both species. Four canine and fi ve human larynges were employed. The results shown resemblances and differences between the structures associated to general aspects but resemblance at level of thyroid and arytenoid cartilages. The cricothyroid and cricoarytenoid articulation are very similar in both species. A similar situation is observed in the intrinsic and extrinsic muscles. The most outstanding differences correspond with the articulation type, which is established between arytenoid, corniculate and cuneiform cartilages which corresponds to a synchondrosis in the dog. Findings probably allow to use the dog larynx be used with experimental purpose in order to solve surgical problems in animal and human beings.