Towards Fully Automated Determination of Laryngeal Adductor Reflex Latencies through High-Speed Laryngoscopy Image Processing

Fast, Jacob Friedemann; Ptok, M.; Jungheim, M.; Szymanski, Robin; Ortmaier, Tobias; Kahrs, Lüder A.

doi:10.1007/978-3-662-56537-7_41

Cited by 3 publications

(7 citation statements)

References 8 publications

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“…We propose a standardized definition of the instant

t_{2}

of LAR onset, based on the temporal evolution of

d_{50}

. This represents a step forward with respect to our previous work, 8 in which the global optical flow was used to automatically estimate

t_{2}

. This unspecific approach was susceptible to artifacts caused by unrelated motion.…”

Section: Discussionmentioning

confidence: 99%

“…The instant

t_{2}

of LAR onset must also be known to enable calculating the LAR onset latency

normalΔ t_{LAR}

according to Equation (). In contrast to the instant

t_{1}

of droplet impact, a high inter‐rater variability has been reported for

t_{2} .

8 Shock et al defined

t_{2}

as the time stamp associated with the frame preceding the onset of VF adduction 4 . To avoid bias introduced by human involvement, we propose a standardized, automatic method for

t_{2}

identification: we define

t_{2}

as the instant at which the fit function representing

d_{50} ((), t)

decreases to

98 %

of its total span.…”

Section: Methodsmentioning

confidence: 99%

“…However, their use was thus far restricted by the amount of experience required to apply the available methods for LAR evaluation and by a limited reproducibility of these methods. Recent developments in the field of LAR analysis focus on a more controlled reflex stimulation with a calibrated aesthesiometer 5,6 or standardized air bursts, 7 and on computer‐assisted approaches for optical LAR assessment 7–10 . The LAR can also be evoked by droplet impact; this is the principle of Microdroplet Impulse Testing of the LAR , or MIT‐LAR for short 11 .…”

Section: Introductionmentioning

confidence: 99%

“…Recent developments in the field of LAR analysis focus on a more controlled reflex stimulation with a calibrated aesthesiometer 5,6 or standardized air bursts, 7 and on computer-assisted approaches for optical LAR assessment. [7][8][9][10] The LAR can also be evoked by droplet impact; this is the principle of Microdroplet Impulse Testing of the LAR, or MIT-LAR for short. 11 A droplet is similar to the physiological triggers of the LAR, such as food particles or saliva, and avoids the invasiveness associated with electrical methods.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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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

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“…We propose a standardized definition of the instant

t_{2}

of LAR onset, based on the temporal evolution of

d_{50}

. This represents a step forward with respect to our previous work, 8 in which the global optical flow was used to automatically estimate

t_{2}

. This unspecific approach was susceptible to artifacts caused by unrelated motion.…”

Section: Discussionmentioning

confidence: 99%

“…The instant

t_{2}

of LAR onset must also be known to enable calculating the LAR onset latency

normalΔ t_{LAR}

according to Equation (). In contrast to the instant

t_{1}

of droplet impact, a high inter‐rater variability has been reported for

t_{2} .

8 Shock et al defined

t_{2}

as the time stamp associated with the frame preceding the onset of VF adduction 4 . To avoid bias introduced by human involvement, we propose a standardized, automatic method for

t_{2}

identification: we define

t_{2}

as the instant at which the fit function representing

d_{50} ((), t)

decreases to

98 %

of its total span.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…These structures could also be tracked, paving the way for a robotic MIT-LAR system which would autonomously stimulate predefined targets of interest in the larynx. By addition of an adequate algorithm for the analysis of the high-speed frame sequence recorded after LAR stimulation, the LAR latency of a given individual could ultimately be determined with very limited human involvement [53], thus drastically increasing the efficiency and objectiveness of routine aspiration risk screening.…”

Section: B Suggestions For Future Workmentioning

confidence: 99%

Stereo Laryngoscopic Impact Site Prediction for Droplet-Based Stimulation of the Laryngeal Adductor Reflex

et al. 2021

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The laryngeal adductor reflex (LAR) is a vital reflex of the human larynx. LAR malfunctions may cause life-threatening aspiration events. An objective, noninvasive, and reproducible method for LAR assessment is still lacking. Stimulation of the larynx by droplet impact, termed Microdroplet Impulse Testing of the LAR (MIT-LAR), may remedy this situation. However, droplet instability and imprecise stimulus application thus far prevented MIT-LAR from gaining clinical relevance. We present a system comprising two alternative, custom-built stereo laryngoscopes, each offering a distinct set of properties, a droplet applicator module, and image/point cloud processing algorithms to enable a targeted, dropletbased LAR stimulation. Droplet impact site prediction (ISP) is achieved by droplet trajectory identification and spatial target reconstruction. The reconstruction and ISP accuracies were experimentally evaluated. Global spatial reconstruction errors at the glottal area of (0.3 ± 0.3) mm and (0.4 ± 0.3) mm and global ISP errors of (0.9 ± 0.6) mm and (1.3 ± 0.8) mm were found for a rod lens-based and an alternative, fiberoptic laryngoscope, respectively. In the case of the rod lens-based system, 96 % of all observed ISP error values are inferior to 2 mm; a value of 80 % was found with the fiberoptic assembly. This contribution represents an important step towards introducing a reproducible and objective LAR screening method into the clinical routine.INDEX TERMS Aspiration, biomedical engineering, computer aided diagnosis, endoscopes, image guidance, laryngeal closure reflex, reflex latency, stereo endoscopy.

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Laryngeal Adductor Reflex Movement Latency Following Tactile Stimulation

Strohl¹,

Chang²,

Dwyer³

et al. 2021

Otolaryngol.--head neck surg.

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Objective To measure the latency of laryngeal adductor reflex (LAR) motion onset at 2 laryngopharyngeal subsites using calibrated aesthesiometers. Study Design Cross-sectional. Setting Academic institution. Methods Twenty-one asymptomatic, healthy subjects (11 male, 10 female) underwent laryngopharyngeal sensory testing with tactile stimuli delivered to the aryepiglottic fold and medial pyriform sinus using 30-mm Cheung-Bearelly monofilaments (4-0 and 5-0 nylon sutures) via channeled flexible laryngoscope. The LAR onset latency, defined as the first visual detection of ipsilateral vocal fold adduction following tactile stimulation, was measured with frame-by-frame analysis of video recordings. Results The overall mean LAR latency across both subsites and stimulation forces was 176.6 (95% CI, 170.3-183.0) ms, without significant difference between subsites or forces. The critical value for LAR response latency prolongation at the .01 significance level was 244 ms. At 30 frames/s video capture resolution, LAR response latency ≥8 frame intervals would indicate abnormal prolongation. Conclusion Aesthesiometer-triggered LAR latency appears to be invariant over an 8.7-dB force range and between the aryepiglottic fold and medial pyriform sinus subsites in controls. Laryngeal adductor reflex latency incongruences between stimulation forces or laryngopharyngeal subsites may serve as pathophysiological features to dissect mechanisms of upper aerodigestive tract disorders. Level of Evidence Level 3B.

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Towards Fully Automated Determination of Laryngeal Adductor Reflex Latencies through High-Speed Laryngoscopy Image Processing

Cited by 3 publications

References 8 publications

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

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

Stereo Laryngoscopic Impact Site Prediction for Droplet-Based Stimulation of the Laryngeal Adductor Reflex

Laryngeal Adductor Reflex Movement Latency Following Tactile Stimulation

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