Laryngeal Model Research Articles

Novel Image-Guided Simulator for Transcervical Intralaryngeal Injection Training.

To assess the impact of a novel 3D-printed simulation model with Brainlab Image Guidance on enhancing otolaryngology residents' skills and confidence in performing transcervical intralaryngeal injection (TII) compared with conventional training methods. Utilizing a 3D-printed larynx model derived from computed tomography (CT) scans, this study involved 16 otolaryngology residents divided into two groups for TII training: one with Brainlab Image Guidance (LMIG) and the other without (LM). Pre- and post-training evaluations measured participants' confidence while the Brainlab system measured the accuracy of their needle placements. After training, participants exhibited a significant increase in confidence with an average rise from 1.56 to 2.75 on a 5-point scale. The LMIG group outperformed the LM group in accuracy achieving statistically significant reductions in target distances after training (3.5 mm right, 3.6 mm left). The LMIG also demonstrated a significantly greater increase in procedural confidence over the LM group after training. The TII laryngeal model with Brainlab Image Guidance significantly improves procedural confidence and accuracy among otolaryngology residents, signifying potential advantage over a more conventional training approach. The model's realistic tactile and live instrument positioning feedback augments the process of surgical skill refinement in a controlled, risk-free, simulation environment. NA Laryngoscope, 2024.

Upper airway resistance during use of a laryngeal mask airway is flow-dependent and dominated by the laryngeal resistance

During use of a laryngeal mask airway, resistance of the device and larynx contribute to the upper airway resistance. Detailed understanding of this combined resistance is crucial to support spontaneously breathing patients appropriately or to take the right measures during respiratory problems. However, their resistive behavior and which of these components determine the upper airway resistance predominantly, has not been characterized systematically. Pressure-flow-relationships of different sizes of a laryngeal mask airway, of a laryngeal model with vocal cord angles between 10° and 60° and of the combination of a laryngeal mask airway size 4 and the laryngeal model were measured. Results were fitted to the expanded Rohrer’s equation and resistances were calculated. The laryngeal mask airway and the laryngeal model showed a nonlinear flow-dependent resistive behavior. Decreasing size of the laryngeal mask airway, decreasing vocal cord angles, and increasing flow rates resulted in increased resistances (all p < 0.001). Resistance of the laryngeal mask and the laryngeal model added up to the combined resistance in a summative way, where the vocal cord angle determines 59–98% of the combined resistance in adults. The upper airway resistance during the use of a laryngeal mask airway is a summative resistance with a flow-dependent, nonlinear behavior. Upper airway resistance in adults is primarily determined by the vocal cord angle during use of a laryngeal mask.

Validation of a 3D-Printed Silicone-Based Laryngeal Model for Resident Education.

We sought to validate a laryngeal simulation model and subsequently demonstrate its efficacy in improving surgical technique. Pre-post interventional study. Otolaryngology Program at a Tertiary Care Center. A low-cost, high-fidelity laryngeal model was created using a 3-dimensional-printed cast and multilayered silicone to mimic vocal fold lesions. Participants (attendings and trainees) were first given a series of tasks including mucosal vocal fold lesion resection and microflap excision of a submucosal lesion. Trainees were then provided with an instructional video from a laryngologist and asked to repeat the same tasks on the model. Performance data was then assessed using validated surveys and blinded expert reviewers. Eighteen participants completed the simulation. All subjects agreed that the "simulation experience was useful" and 93% agreed "the simulator helped improve my ability to do microsurgical tasks." In the postinstruction self-evaluation, trainees reported a significant decrease in mental demand (95% confidence interval [CI]: 0.37-0.91; P = .038) and significant increase in subjective performance (95% CI: 1.51-51.89; P = .016) compared to the preinstruction self-evaluation. On the postinstruction attempt, there was a significant improvement in all domains of the adapted objective structured assessment of technical skills as measured by 3 blinded, expert reviewers. This study demonstrates the usefulness of a silicone larynx model and the value of instructional video in developing laryngeal microsurgical skills. Participants positively reviewed the laryngeal model and trainees saw both a subjective and objective improvement indicating tangible operative benefits from the use of this laryngeal simulation.

Comparison of Aerodynamic and Elastic Properties in Tissue and Synthetic Models of Vocal Fold Vibrations.

Three laryngeal models were used to investigate the aerodynamic and elastic properties of vocal fold vibration: cadaveric human, excised canine, and synthetic silicone vocal folds. The aim was to compare the characteristics of these models to enhance our understanding of phonatory mechanisms. Flow and medial glottal wall geometry were acquired via particle image velocimetry. Elastic properties were assessed from force-displacement tests. Relatively, the human larynges had higher fundamental frequency values, while canine and synthetic models exhibited greater flow rates. Canine models demonstrated the highest divergence angles and vertical stiffness gradients followed by the human model, both displaying flow separation vortices during closing. Synthetic models, whose advantage is their accessibility and repeatability, displayed the lowest glottal divergence angles and total circulation values compared to tissue models with no flow separation vortices. The elasticity tests revealed that tissue models showed significant hysteresis and vertical stiffness gradients, unlike the synthetic models. These results underscore the importance of model selection based on specific research needs and highlight the potential of canine and synthetic models for controlled experimental studies in phonation.

Comparing cadaveric and 3D-printed laryngeal models in transcutaneous injection laryngoplasty.

There is increasing focus on the development of high-quality simulation models for medical education. Cadaveric models, although considered more realistic, may be difficult to obtain and costly. The advent of three-dimensional (3D) printing has offered a low-cost, reliable, and reproducible alternative. This study sought to compare the utility of 3D-printed to cadaveric models for training in transcutaneous injection laryngoplasty (TIL). A simulation course with a cross-over design was employed. Video laryngoscopes were utilized for both the 3D and cadaveric models to assess the accuracy of injection into the vocal fold. Pre-procedure and post-procedure surveys were administered to evaluate understanding and comfort level on a Likert scale of 1-10. Each model was also rated on a 1-5 Likert scale for self-efficacy, fidelity, and educational value. Pre- and post-survey data were completed by 15 otolaryngology residents and medical students. Mean pre-seminar understanding and comfort level were 3.7 and 2.2, respectively, compared to 6.9 and 5.9 (p < .05) following use of the 3D model and 6.4 and 4.7 (p < .05) following use of the cadaver model. When comparing 3D and cadaveric models, no significant differences were observed regarding self-efficacy, fidelity, and educational value. There was a similar mean increase in understanding and comfort following use of the 3D and cadaveric models. 3D-printing can provide an excellent adjunct to, and eventually a potential replacement for hands-on cadaveric training in medical education, particularly for TIL. Level III.

A computational study of the influence of thyroarytenoid and cricothyroid muscle interaction on vocal fold dynamics in an MRI-based human laryngeal model.

A human laryngeal model, incorporating all the cartilages and the intrinsic muscles, was reconstructed based on MRI data. The vocal fold was represented as a multilayer structure with detailed inner components. The activation levels of the thyroarytenoid (TA) and cricothyroid (CT) muscles were systematically varied from zero to full activation allowing for the analysis of their interaction and influence on vocal fold dynamics and glottal flow. The finite element method was employed to calculate the vocal fold dynamics, while theone-dimensional Bernoulli equation was utilized to calculate the glottal flow. The analysis was focused on the muscle influence on the fundamental frequency (fo). We found that while CT and TA activationincreased the fo in most of the conditions, TA activationresulted in a frequency drop when it was moderately activated. We show that this frequency drop was associated with the sudden increase of the vertical motion when the vibration transited from involving the whole tissue to mainly in the cover layer. The transition of the vibration pattern was caused by the increased body-cover stiffness ratio thatresulted from TA activation.

Experimental Investigation Of The Flow-Acoustic Interaction In Human Phonation

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis. To investigate the amount of two-way coupling between the flow field and the acoustics, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, aeroacoustic source terms were computed. Furthermore, the hydrodynamic pressure in the vocal tract was recorded via wall pressure measurements. The recordings revealed that near a vocal tract resonance frequency, the focal fold oscillation frequency jumps onto the resonance. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. The pressure measurements showed that acoustic anti-resonances of the vocal tract directly dampen the harmonic content of the hydrodynamic pressure field when matching frequencies. This result shows that back-coupling of the acoustics onto the flow field does not only occur in the case where the vocal fold oscillation frequency and a resonance frequency of the vocal tract match, but also under more other conditions.

Register transitions in an in vivo canine model as a function of intrinsic laryngeal muscle stimulation, fundamental frequency, and sound pressure level.

Phonatory instabilities and involuntary register transitions can occur during singing. However, little is known regarding the mechanisms which govern such transitions. To investigate this phenomenon, we systematically varied laryngeal muscle activation and airflow in an in vivo canine larynx model during phonation. We calculated voice range profiles showing average nerve activations for all combinations of fundamental frequency (F0) and sound pressure level (SPL). Further, we determined closed-quotient (CQ) and minimum-posterior-area (MPA) based on high-speed video recordings. While different combinations of muscle activation favored different combinations of F0 and SPL, in the investigated larynx there was a consistent region of instability at about 400 Hz which essentially precluded phonation. An explanation for this region may be a larynx specific coupling between sound source and subglottal tract or an effect based purely on larynx morphology. Register transitions crossed this region, with different combinations of cricothyroid and thyroarytenoid muscle (TA) activation stabilizing higher or lower neighboring frequencies. Observed patterns in CQ and MPA dependent on TA activation reproduced patterns found in singers in previous work. Lack of control of TA stimulation may result in phonation instabilities, and enhanced control of TA stimulation may help to avoid involuntary register transitions, especially in the singing voice.

Influence of airflow and ligament tension on the acoustics of a biomimetic larynx model

The phonation process is a complex interaction involving the airflow from the lungs, the oscillation of the vocal folds’ tissue, and the resultant acoustics. To understand the underlying physical mechanisms, an experimental model has been designed that allow the control of flowrate and longitudinal tension of the vocal folds. A synthetic biomimetic larynx model was applied that features airflow-driven vocal folds’ oscillations. The longitudinal stiffness of the vocal folds is controlled using embedded ligament fibers. The model enables to measure aerodynamic and acoustic signals as function of airflow rate and the fiber tension. Based on the measured signals, the influence of airflow and fiber tension was statistically analyzed using the parameters F0, Psub, CPP, HNR, Shimmer, and Jitter. The statistical analysis revealed that both flowrate and fiber tension significantly influence acoustic and aerodynamic parameters. In general, the parameters showed different trends for increasing flowrate and fiber tension. Increase in fiber tension produced increasing parameters up to a maximum tension level followed by a saturation of the parameters. In contrast, the flowrate showed varying trends depending on the respective parameter. The results clearly show how flowrate and longitudinal tension control the phonation process and the resulting acoustic quality.

Acoustics and aerodynamic effects following glottal and infraglottal medialization in an excised larynx model

ObjectiveThis study aimed to investigate the impact of the implant’s vertical location during Type 1 Thyroplasty (T1T) on acoustics and glottal aerodynamics using excised canine larynx model, providing insights into the optimal technique for treating unilateral vocal fold paralysis (UVFP).MethodsMeasurements were conducted in six excised canine larynges using Silastic implants. Two implant locations, glottal and infraglottal, were tested for each larynx at low and high subglottal pressure levels. Acoustic and intraglottal flow velocity field measurements were taken to assess vocal efficiency (VE), cepstral peak prominence (CPP), and the development of intraglottal vortices.ResultsThe results indicated that the implant's vertical location significantly influenced vocal efficiency (p = 0.045), with the infraglottal implant generally yielding higher VE values. The effect on CPP was not statistically significant (p = 0.234). Intraglottal velocity field measurements demonstrated larger glottal divergence angles and stronger vortices with the infraglottal implant.ConclusionThe findings suggest that medializing the paralyzed fold at the infraglottal level rather than the glottal level can lead to improved vocal efficiency. The observed larger divergence angles and stronger intraglottal vortices with infraglottal medialization may enhance voice outcomes in UVFP patients. These findings have important implications for optimizing T1T procedures and improving voice quality in individuals with UVFP. Further research is warranted to validate these results in clinical settings.

An Investigation of Acoustic Back-Coupling in Human Phonation on a Synthetic Larynx Model.

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis as well as vocal fold oscillation. To investigate the amount of acoustic back-coupling, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, acoustic source terms were computed. Additionally, the sound radiation into the far field was recorded via microphone measurements and the vocal fold oscillation via high-speed camera recordings. The PIV measurements revealed that near a vocal tract resonance frequency fR, the vocal fold oscillation frequency fo (and therefore also the flow field's fundamental frequency) jumps onto fR. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. Furthermore, the measurements show that fo-fR-coupling increases vocal efficiency, signal-to-noise ratio, harmonics-to-noise ratio and cepstral peak prominence. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. All of this results in an improved voice quality and phonation efficiency so that a person phonating with fo-fR-coupling can phonate longer and with better voice quality.

The larynx in 3 dimensions: A digital anatomical model derived from radiographic imaging, refined with peer-reviewed literature, and optimized with medical illustration

ObjectivesDevelopment of an anatomically accurate three-dimensional (3D) digital model of the human larynx derived from published literature and radiographic imaging. Materials and MethodsThe laryngeal framework was segmented from a computed tomography (CT) angiogram of a healthy 29-year-old female. Data derived from published anatomical studies were compiled to provide additional anatomical detail to each structure. Anatomical details beyond the resolution of the imaging study or which could not be elucidated from the study were refined according to descriptions in the anatomic literature. The 3D model was refined by the medical illustrator, and its mesh was reformatted to optimize online viewing and manipulation. ResultsDue to the small size of the laryngeal muscles, there was no attempt to segment these muscles using radiographic imaging. All intrinsic laryngeal muscles were generated de novo, as were the superior laryngeal nerve and recurrent laryngeal nerve. CT imaging was utilized to generate meshes of the hyoid bone, epiglottis, thyroid cartilage, cricoid cartilage, and thyrohyoid membrane. Additionally, the airway space was segmented to provide size and spatial location to the vallecula, false vocal folds, true vocal folds, piriform sinus, subglottis, and a scaffold for the mucosa. These meshes were processed to limit radiographic artifact and serve as a foundation for the construction of the remainder of the laryngeal anatomy. The model was uploaded to a 3D repository, which can be accessed here (https://shorturl.at/nJPYZ). ConclusionThe larynx is a highly specialized organ essential for speech, swallowing, and airway protection. This study describes a digital 3D model of the larynx, created by combining radiographic imaging with critical review of anatomic literature. Utilizing the expertise of neuroradiology, laryngeal surgery, and medical illustration, we highlight surgically-relevant anatomic relationships and important aspects to consider during laryngeal surgery.

A comparative analysis of intraglottal geometry and velocity flow fields: Excised human, canine, and synthetic vocal fold models

Synthetic vocal fold models imitate the characteristics of human vocal folds and offer advantages over tissue models, such as accessibility and prolonged lifespan, all while producing comparable vibration frequencies to those in humans. Nonetheless, due to their simplified design, they may not fully capture the intricate behavior observed in tissue models like the canine larynx model. Canine larynges, like human’s, exhibit a vertical mucosal wave, which yields a phase delay between the inferior and superior edges of the vocal folds free margin. Consequently, a divergent glottis forms during closing, producing intraglottal flow separation vortices (FSVs) that increase voice loudness and intelligibility. To bridge the knowledge gap between silicone and tissue vocal fold models, we compared the intraglottal geometry and velocity flow fields during phonation of these three models. At low subglottal pressures, the synthetic model displayed small divergence angles and no flow separation, where both tissues models exhibited FSVs. At higher pressures, FSVs observed in tissue models were correlated with increased glottal flow waveform skewing and higher MFDR values. These findings highlight why the excised canine larynx model should be the preferred choice over synthetic vocal fold models for studying the aerodynamics and fluid-structure interaction during phonation.

Functional Electrical Stimulation (FES)—Therapeutical potentials for presbyphonia

Presbyphonia, an age-related decrease in voice quality is a consequence of vocal muscle atrophy. Functional Electrical Stimulation (FES) was introduced as a potential treatment to increase the muscle volume. In this study, we analyzed the effects of FES using ex vivo sheep larynx models. To stimulate the thyroarytenoid muscle, electrodes were implanted at the recurrent laryngeal nerve of 12 sheep (10 y). Stimulation was applied to six sheep for 9 weeks. Afterwards, the excised larynges were fixated in a mechanical setup and analyzed. For different elongations of the VFs, the acoustic signal, the subglottal pressure, and the VF motion were recorded simultaneously. The postprocessing was performed with the Glottis Analysis Tools (GAT) software and SPSS. The results show that the vibration characteristics and sound quality improved for the stimulated larynges. The vibration showed a higher degree of glottis closure (GGI) and symmetry (PAI and ASI), as well as a faster glottis closure (MADR) achieved by FES. Consequently, the sound signal exhibited a larger number of tonal sound components (CPP). Furthermore, a higher correlation between acoustic and subglottal pressure was found indicating an enhanced coupling between sub- and supraglottal regions. The results suggest that FES could be a possible therapy for presbyphonia.

Effect of Ligament Fibers on Dynamics of Synthetic, Self-Oscillating Vocal Folds in a Biomimetic Larynx Model.

Synthetic silicone larynx models are essential for understanding the biomechanics of physiological and pathological vocal fold vibrations. The aim of this study is to investigate the effects of artificial ligament fibers on vocal fold vibrations in a synthetic larynx model, which is capable of replicating physiological laryngeal functions such as elongation, abduction, and adduction. A multi-layer silicone model with different mechanical properties for the musculus vocalis and the lamina propria consisting of ligament and mucosa was used. Ligament fibers of various diameters and break resistances were cast into the vocal folds and tested at different tension levels. An electromechanical setup was developed to mimic laryngeal physiology. The measurements included high-speed video recordings of vocal fold vibrations, subglottal pressure and acoustic. For the evaluation of the vibration characteristics, all measured values were evaluated and compared with parameters from ex and in vivo studies. The fundamental frequency of the synthetic larynx model was found to be approximately 200-520 Hz depending on integrated fiber types and tension levels. This range of the fundamental frequency corresponds to the reproduction of a female normal and singing voice range. The investigated voice parameters from vocal fold vibration, acoustics, and subglottal pressure were within normal value ranges from ex and in vivo studies. The integration of ligament fibers leads to an increase in the fundamental frequency with increasing airflow, while the tensioning of the ligament fibers remains constant. In addition, a tension increase in the fibers also generates a rise in the fundamental frequency delivering the physiological expectation of the dynamic behavior of vocal folds.

Validation of a 3D-Printed Percutaneous Injection Laryngoplasty Simulator: A Randomized Controlled Trial.

Simulation may be a valuable tool in training laryngology office procedures on unsedated patients. However, no studies have examined whether existing awake procedure simulators improve trainee performance in laryngology. Our objective was to evaluate the transfer validity of a previously published 3D-printed laryngeal simulator in improving percutaneous injection laryngoplasty (PIL) competency compared with conventional educational materials with a single-blinded randomized controlled trial. Otolaryngology residents with fewer than 10 PIL procedures in their case logs were recruited. A pretraining survey was administered to participants to evaluate baseline procedure-specific knowledge and confidence. The participants underwent block randomization by postgraduate year to receive conventional educational materials either with or without additional training with a 3D-printed laryngeal simulator. Participants performed PIL on an anatomically distinct laryngeal model via trans-thyrohyoid and trans-cricothyroid approaches. Endoscopic and external performance recordings were de-identified and evaluated by two blinded laryngologists using an objective structured assessment of technical skill scale and PIL-specific checklist. Twenty residents completed testing. Baseline characteristics demonstrate no significant differences in confidence level or PIL experience between groups. Senior residents receiving simulator training had significantly better respect for tissue during the trans-thyrohyoid approach compared with control (p < 0.0005). There were no significant differences in performance for junior residents. In this first transfer validity study of a simulator for office awake procedure in laryngology, we found that a previously described low-cost, high-fidelity 3D-printed PIL simulator improved performance of PIL amongst senior otolaryngology residents, suggesting this accessible model may be a valuable educational adjunct for advanced trainees to practice PIL. NA Laryngoscope, 134:318-323, 2024.

Comparing the Scalpel-Bougie-Tube Emergency Front-of-Neck Airway (eFONA) Technique on Conventional Manikins and Ovine Larynges: Evaluating Cost, Realism, and Performance in Anaesthetic Trainees.

Background Emergency front-of-neck airway (eFONA) is a crucial life-saving procedure in "cannot intubate, cannot oxygenate" (CICO) situations. It is essential to teach and maintain eFONA skills for healthcare providers, especially anesthesiologists. This study aims to assess the effectiveness of cost-effective ovine larynx models compared to conventional manikins in teaching eFONA using the scalpel-bougie-tube technique to a group of anaesthesia novices and newly appointed anaesthetic Fellows. Methods and study design The study was conducted at Walsall Manor Hospital, a district general hospital in the Midlands, UK. Participants underwent a pre-survey to assess familiarity with FONA and the ability to perform a laryngeal handshake. After a lecture and demonstration, participants performed two consecutive emergency cricothyrotomies on both ovine models and conventional manikins, followed by a post-survey to assess their confidence in performing eFONA and rate their experience using sheep larynges. Results The training session significantly improved the participants' ability to perform a laryngeal handshake and their confidence in performing eFONA. The majority of participants rated the ovine model higher in terms of realism, difficulty with penetration, difficulty in recognising landmarks, and difficulty in performing the procedure. Additionally, the ovine model was more cost-effective compared to conventional manikins. Conclusion Ovine models provide a more realistic and cost-effective alternative to conventional manikins for teaching eFONA using the scalpel-bougie-tube technique. The use of these models in routine airway teaching enhances the practical skill set of anaesthesia novices and newly appointed anaesthetists, better preparing them for CICO situations. However, further training with objective assessment methods and larger samples is needed to corroborate these findings.

Three-dimensional models of the equine larynx can be used to perform traditional measures of arytenoid abduction and permit the positioning of modeled implants to demonstrate the anatomic feasibility of placing a rigid implant across the cricoarytenoid joint.

To develop 3D models of larynges to compare arytenoid abduction measurements between specimens and models, and to investigate the anatomic feasibility of placing an implant across the cricoarytenoid joint (CAJ) with or without arthrotomy. Cadaveric equine larynges (n = 9). Equine larynges underwent sequential CT scans in a neutral position and with 2 arytenoid treatments: bilateral arytenoid abduction (ABD) and bilateral arytenoid abduction after left cricoarytenoid joint arthrotomy (ARTH). Soft tissue, cartilage, and luminal volume 3-dimensional models were generated. Rima glottidis cross-sectional area (CSA) and left-to-right quotient (LRQ) angles were measured on laryngeal specimens and models. Arytenoid translation, articular contact area, and length of modeled implants placed across the CAJ were measured on models. Data were analyzed using paired t test or ANOVA and Tukey's post hoc test or non-parametric equivalents (P < .05). ARTH CSA was larger for laryngeal specimens than models (P = .0096). There was no difference in all other measures of CSA and LRQ angle between treatment groups or between specimens and models. There was no difference between ABD and ARTH groups for arytenoid cartilage translation, contact area, and implant length. The articular contact area was sufficient for modeled implant placement across the CAJ with a narrow range of implant lengths (17.59 mm to 23.87 mm) across larynges with or without arthrotomy. These results support further investigation of a CT-guided, minimally invasive surgical procedure. Future studies will evaluate the outcomes of the new procedure for technical precision, biomechanical stability, and post-operative success rates for horses with recurrent laryngeal neuropathy (RLN).

Acoustic Screening of the "Wet voice": Proof of Concept in an ex vivo Canine Laryngeal Model.

Current protocols for bedside swallow evaluation have high rates of false negative results. Though experts are not consistently able to screen for aspiration risk by assessing vocal quality, there is emerging evidence that vocal acoustic parameters are significantly different in patients at risk of aspiration. Herein, we aimed to determine whether the presence of material on the vocal folds in an excised canine laryngeal model may have an impact on acoustic and aerodynamic measures. Two ex vivo canine larynges were tested. Three liquids of different viscosities (1:100 diluted glycerin, pure glycerin, and honey-thick Varibar) were placed on the vocal folds at a constant volume. Acoustic and aerodynamic measures were obtained in both adducted and abducted vocal fold configurations. Intraglottal high-speed imaging was used to approximate the maximum divergence angle of the larynges in the studied conditions and examine its relationship to vocal efficiency (VE) and acoustic measures. In glottic insufficiency conditions only, we found that several acoustic parameters could predict the presence of material on the vocal folds. Based on the combination of the aerodynamic and acoustic data, we found that decreased spectral energy in the higher harmonics was associated with decreased VE in the presence of material on the vocal folds and/or glottic insufficiency. Decreased spectral energy in the higher harmonics of the voice was found to be a potential biomarker of swallowing dysfunction, as it correlates with decreased vocal efficiency due to material on the vocal folds and/or glottic insufficiency, both of which are known risk factors for aspiration. NA Laryngoscope, 133:2517-2524, 2023.

Benefits of Side-Firing Optical Fibers in Endoscopic Laser Treatment of the Larynx.

To elucidate potential tissue coverage of side-firing optical fibers in office-based endoscopic laser treatment of larynx, as well as to demonstrate their enhanced ability to address challenging anatomic areas. We performed a comparative study of four different fiber designs: a traditional forward-facing fiber, and three side-firing fibers that emit light at an angle of 45°, 70°, and 90°, respectively. The study was conducted in simulation, using eight three-dimensional models of the human larynx generated from microtomography x-ray scans. A computer program simulated the insertion of the endoscope into the larynx, and the Möller-Trumbore algorithm was used to simulate the application of laser light. Side-firing laser fibers increased potential tissue coverage by a mean of 50.2 (standard deviation [SD] 25.8), 73.8 (SD 41.3), and 84.0 (SD 47.6) percent for angles of 45°, 70°, and 90°, respectively, compared to forward-facing fibers. Angled fibers provided access to areas of the larynx considered difficult to address by traditional methods, including the infraglottis, laryngeal ventricle, and right vocal fold. Simulation results suggest that side-firing optical fibers have the potential to enhance anatomical access during in-office endoscopic laser procedures in the larynx. Further research is needed to better understand the benefits and any potential risks or contraindications of side-firing optical fibers. NA Laryngoscope, 133:1205-1210, 2023.