Development of a time-dependent numerical model for the assessment of non-stationary pharyngoesophageal tissue vibrations after total laryngectomy

Abstract

Laryngeal cancer due to, e.g., extensive smoking and/or alcohol consumption can necessitate the excision of the entire larynx. After such a total laryngectomy, the voice generating structures are lost and with that the quality of life of the concerning patients is drastically reduced. However, the vibrations of the remaining tissue in the so called pharyngoesophageal (PE) segment can be applied as alternative sound generator. Tissue, scar, and geometric aspects of the PE-segment determine the postoperative substitute voice characteristic, being highly important for the future live of the patient. So far, PE-dynamics are simulated by a biomechanical model which is restricted to stationary vibrations, i.e., variations in pitch and amplitude cannot be handled. In order to investigate the dynamical range of PE-vibrations, knowledge about the temporal processes during substitute voice production is of crucial interest. Thus, time-dependent model parameters are suggested in order to quantify non-stationary PE-vibrations and drawing conclusions on the temporal characteristics of tissue stiffness, oscillating mass, pressure, and geometric distributions within the PE-segment. To adapt the numerical model to the PE-vibrations, an automatic, block-based optimization procedure is applied, comprising a combined global and local optimization approach. The suggested optimization procedure is validated with 75 synthetic data sets, simulating non-stationary oscillations of differently shaped PE-segments. The application to four high-speed recordings is shown and discussed. The correlation between model and PE-dynamics is ≥ 97%.

Influence of spatial camera resolution in high-speed videoendoscopy on laryngeal parameters

“…As depicted in Fig 2, both of the reduced sets were calculated from the original set by averaging over the intensity values of squares of 2×2 (SR2) and 4×4 (SR3) pixels resulting in a mean intensity value for each new pixel, which was rounded to the nearest integer number. The apparent low initial resolution was due to the common clinical settings; since currently used clinical high-speed cameras do not have very high resolutions [46–49].…”

Clinical relevance of endoscopic three‐dimensional imaging for quantitative assessment of phonation

“…The clinical measurement of these irregular and asymmetric vocal fold vibrations is affected by the lack of absolute two‐dimensional (2D) measurements and the lack of 3D imaging techniques that are essential to examine the 3D phonation process appropriately. A direct comparison of absolute sizes and amplitudes is not only highly desirable for an evaluation of the vocal folds, but equally for substitute voice generation in the case of laryngectomy …”

“…A direct comparison of absolute sizes and amplitudes is not only highly desirable for an evaluation of the vocal folds, but equally for substitute voice generation in the case of laryngectomy. [15][16][17][18] Common laryngoscopic examinations are performed by the use of 2D imaging techniques such as stroboscopy, videokymography, and high-speed videoendoscopy (HSV). [19][20][21][22][23][24] As shown in Figure 1, the recordings are intrinsically limited to resolve the lateral and longitudinal view of the vocal folds' behavior.…”

The Pharyngoesophageal Segment After Total Laryngectomy

“…Recent technical progress in HSC, such as the use of a 2-point laser triangulation system, allows measurements of vocal fold displacements during vibration as well as the vocal fold length. 24 In 2014, Huttner et al 25 developed an automated objective quantification of the PES morphology and function with HSC. These advances may add accuracy to future endoscopic evaluation of the neoglottis with HSC.…”