Upper Esophageal Sphincter Response to Laryngeal Adductor Reflex Elicitation in Humans

Computational Analysis of the Droplet-Stimulated Laryngeal Adductor Reflex in High-Speed Sequences

OBJECTIVES/HYPOTHESIS

The laryngeal adductor reflex (LAR) is an important protective mechanism of the airways. Its physiology is still not completely understood. The available methods for LAR evaluation offer limited reproducibility and/or rely on subjective interpretation. A new approach, termed Microdroplet Impulse Testing of the LAR (MIT-LAR), was recently introduced. Here, the LAR is elicited by a droplet and a laryngoscopic high-speed recording is acquired simultaneously. In the present work, image-processing algorithms for autonomous MIT-LAR sequence analysis were developed. This allowed the automated approximation of kinematic LAR parameters in humans.

STUDY DESIGN

Development and testing of computational methods.

METHODS

Computational image processing enabled the autonomous estimation of the glottal area, the glottal angle, and the vocal fold edge distance in MIT-LAR sequences. A suitable analytical representation of these glottal parameters allowed the extraction of seven relevant LAR parameters. The obtained values were compared to the literature.

RESULTS

A generalized logistic function showed the highest average goodness of fit among four different analytical approaches for each of the glottal parameters. Autonomous sequence analysis yielded bilateral LAR response latencies of (229 ± 116) ms and (182 ± 60) ms for cases of complete and incomplete glottal closure, respectively. The initial/average/maximum angular vocal fold adduction velocity was estimated at (157 ± 115) °s^-1 /(891 ± 516) °s^-1 /(929 ±  583) °s^-1 and (88 ± 53) °s^-1 /(421 ± 221) °s^-1 /(520 ± 238) °s^-1 for complete and incomplete glottal closure, respectively.

CONCLUSION

The automated extraction of LAR parameters from laryngoscopic high-speed sequences can potentially increase the objectiveness of optical LAR characterization and reduce the associated workload. The proposed methods may thus be helpful for future research on this vital reflex.

LEVEL OF EVIDENCE

NA Laryngoscope, 132:2412-2419, 2022.

Phonation-induced Upper Esophageal Sphincter Contraction Caused by Different Phonation Types

INTRODUCTION

The upper esophageal sphincter (UES) has been reported to show activity during phonation. As it is still unknown whether the phonation-induced UES contraction represents a reflex or a simultaneous activation phenomenon, i.e. co-innervation, this study aims to investigate and characterize the phonation-induced contraction of the UES in healthy individuals by analyzing the influence of various phonation tasks on pressure parameters of the UES.

METHODS

Twenty-five healthy volunteers produced the German neutral vowel [ə] in five different phonation tasks (modal voice, whispering, voiceless speech, creaky voice, and whispery voice). Simultaneously, they underwent high resolution manometry and electroglottography for measurement of pressure parameters in the region of the UES and latencies between larynx and UES activation.

RESULTS

During all types of phonation, the maximum pressures of the UES increased significantly (maximum pressure increases of 72%-132%). With regard to mean pressures this was valid for modal voice and whispering (mean pressure increases of 20%-25%). Differences concerning total pressure changes reached statistical significance when comparing whispering and voiceless speech as well as whispery voice. However, differences concerning the total pressure change between modal voices on the one hand and voiceless speech and whispery voice on the other hand turned out to be small. The averaged time delay between larynx and UES activation ranged from approximately -15 ms (whispery voice) to +15 ms (whispering).

CONCLUSION

A phonation induced pressure increase of the UES was confirmed in this study and did exist for different types of phonation. The extent of total pressure changes in the UES increases in relation with laryngeal muscle activity necessary for the phonation type. Next to varying effects of different types of phonation on UES activation, very short latencies indicate that a phonation induced contraction of the UES exists most likely due to co-innervation of UES and laryngeal muscles by the vagus nerve.