Dimensions of the laryngeal framework in adults

Development of a continuum manipulator with variable bending length and piecewise stiffness for transoral laryngeal surgery

PURPOSE

Continuum manipulators (CMs) show great potential in transoral laryngeal surgery due to their flexibility. However, CMs for transoral surgery face several issues: large size, which reduces practicality; intersegment coupling, which causes undesired deflection; and a lack of versatility that limits their applicability across different patient groups.

METHODS

This work combines a rod-driven proximal segment and a cable-driven distal segment to achieve piecewise stiffness, alleviating the issue of intersegment coupling. A rigid constraint tube is integrated into the proximal segment to diversify its bending behavior. Preliminary experiments are conducted to validate the design concept.

RESULTS

The proposed CM has an overall diameter of only 6.5 mm. The proximal segment can achieve a 90° bending with various curvatures. At the working configuration, the coupling error between the proximal segment and the distal segment is less than 1 mm. The effectiveness of the proposed CM is successfully validated using a human model.

CONCLUSION

The proposed continuum manipulator possesses the desirable characteristics of small size, low coupling, and high versatility, indicating its great potentialities for the diagnosis and treatment of laryngeal lesion.

Laryngeal photobiomodulation: application sites, interferences from body mass index and skin phototype

PURPOSE

Establish points on the neck, correspondent to the laryngeal topography, where to apply Low Level Light therapy (LLLT), to evaluate the incidence of light through variables such as skin phototype and body mass index (BMI).

METHODS

This is a cross-sectional, analytical, observational study, carried out with 15 vocally healthy women, between 18 and 50 years of age, who were divided into three groups, according to BMI and skin phototype. Six anatomical reference points were established to locate the larynx and its musculature, with visual monitoring by videonasolaryngoscopy, to assess light reach (present/absent) and degree of illumination (from very weak to very strong) in the larynx during the LASER application at doses of 3J, 6J and 9J. A flexible endoscope was used for visual monitoring during the LASER application, and subsequent image analysis.

RESULTS

The light reached the larynx at doses of 3J, 6J and 9J, in the anterior commissure of the vocal folds, membranous (thyroarytenoid muscle) and cartilaginous portions of the vocal fold and the cricothyroid muscle. The degree of LASER light illumination decreased in overweight and obese participants and increased in moderate brown and dark brown skin phototypes.

CONCLUSION

Data suggest that the LLLT penetrates differently according to skin phototype and BMI, being more evident in individuals with Fitzpatrick IV and V phototypes and less evident with higher BMI levels. The evidence that the LASER light reaches the larynx in specific anatomical points provides direction for the standardization of its use in voice practice.

Oropharyngeal and Aryepiglottic Narrowing for Twang: A Magnetic Resonance Imaging Study

OBJECTIVE

This study aimed to compare vocal tract configurations between speech and twang qualities.

METHODS

Magnetic resonance imaging data were acquired from five professional vocalists while producing the sustained vowel /i/. Width and area measurements were obtained from the axial (ie, transverse) images to evaluate oropharyngeal narrowing and aryepiglottic (AES) narrowing.

RESULTS

Four out of five participants exhibited a smaller vocal tract area for twang than for speech at the oropharyngeal level, with the extent of narrowing ranging from 18.8% to 49.6%. Only one participant showed a meaningful decrease in oropharyngeal anteroposterior (AP) width, while three participants showed meaningful decreases in oropharyngeal mediolateral (ML) width for twang compared to speech. At the AES level, all participants showed a smaller vocal tract area for twang than for speech, with the extent of narrowing ranging from 11.8% to 52.4%. Two participants exhibited meaningful decreases in AES AP width, while three participants showed meaningful decreases in AES ML width for twang compared to speech.

CONCLUSIONS

Axial imaging revealed oropharyngeal and AES narrowing associated with twang, more prominent in the ML than the AP dimension. Notable individual variations in the mechanism and degree of narrowing at the oropharyngeal and AES levels were observed. The degree of narrowing varied among participants, highlighting the complexity of physiological maneuvers involved in twang production. Future research is necessary to identify broader patterns in twang production for effective pedagogic and therapeutic applications.

Morphometry of the thyroid cartilage, epiglottis and piriform sinus: An anatomical study

Background

The goal was to measure the piriform sinus, epiglottis, and thyroid cartilage in our sample population.

Methods

This study included 22 adult embalmed cadavers available in the Department of Anatomy. Dimensions were measured using a digital Vernier caliper.

Results

The mean height of the thyroid laminae was 27 ± 1.4 mm at the right side and 25.5 ± 1.4 mm at the left side. Mean width of the thyroid lamina was 27.1 ± 1.3 mm at the right side and 27.4 ± 0.9 mm at the left side. The mean thickness of thyroid cartilage was found to be 4.4 ± 0.4 mm and 3.9 ± 0.5 mm over the right and left sides. The mean length, width and thickness of the epiglottis were 29.1 ± 0.5 mm, 22.2 ± 0.6 mm and 2.6 ± 0.3 mm correspondingly. The height, width and thickness of the right piriform sinus were 25 ± 0.5 mm, 14.2 ± 0.5 mm and 12.6 ± 0.5 mm, the same parameters were 25.3 ± 1.3 mm, 15.1 ± 0.7 mm and 13.3 ± 0.4 mm for the left side.

Conclusions

The height and thickness of the thyroid cartilage were greater on the right side than on the left side (p<0.05). It was statistically observed that the width and thickness were greater on the left side than on the right side (p < 0.05). The data about the height, width and thickness of the thyroid cartilage, epiglottis and piriform sinus are essential during the laryngeal and other neck surgeries. They guide in the preoperative positioning, predicting the difficulty of intraoperative exposure and retractor pulling.

Direct Transvestibular Feminization Thyroid Laryngochondroplasty

BACKGROUND

Feminization laryngochondroplasty (FLC) methods have evolved from using a midcervical incision to a submental, less visible incision. The scar may be unacceptable to the patient because it signals gender reassignment surgery. An endoscopic transoral approach to FLC inspired by transoral endoscopic thyroidectomy was recently suggested to avoid the neck scar; however, it requires special equipment and has a long learning curve. A vestibular incision is used to approach the chin in lower-third facial feminization surgery. The authors propose that this incision may be extended to the thyroid cartilage in performing direct FLCs. The authors describe their experience with a novel, minimally invasive, direct transvestibular use of the chin-reshaping incision.

METHODS

The medical records of all patients who underwent direct transvestibular FLC (DTV-FLC) from December of 2019 to September of 2021 were retrieved and reviewed for this retrospective cohort study. Data on the operative, postoperative, and follow-up courses, complications, and functional and cosmetic results were retrieved.

RESULTS

Nine transgender women were included. Seven DTV-FLCs were performed during lower-third facial feminization surgery, and two were isolated DTV-FLCs. One was a revision DTV-FLC. Transient minor complications were encountered and resolved by the postoperative visit at 1 to 2 months. Vocal fold function and voice quality remained intact. Eight available patients were satisfied with the surgical results. A blinded assessment by eight plastic surgeons determined that seven procedures were successful.

CONCLUSION

The novel DTV-FTLC approach either in isolation or as part of lower-third facial feminization surgery facilitated scar-free FLC with satisfactory cosmetic and functional results.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Role of ultrasonography in upper airway assessment: A comparison with computerized tomography measurements

INTRODUCTION

This study aimed to compare ultrasonography (US) measurements of the upper airway to computerized tomography (CT) measurements. Our study's primary outcome is to research the accuracy of US measurements in the evaluation of upper airway diameters when CT is taken as the gold standard; the secondary outcome is to determine the time required to obtain US measurements.

METHODS

This prospective study included patients ≥18 years old that had undergone thoracic or neck CT due to current clinical necessity. The US measurement for each patient was performed by two researchers with different levels of experience, both of whom were blinded to each other and the CT measurements. Measurements were obtained from the vocal cords and subglottic region. The duration of the US performance was also recorded.

RESULTS

The US and CT measurements were obtained from 94 patients. Concordance between US and CT measurements was found in the Bland-Altman analysis, with a mean -0.05 mm difference for vocal cord diameter and -1.2 mm for subglottic diameter. The intra-class correlation coefficients (ICC) between the CT and US measurements were 0.993, and 0.609 for vocal cord and subglottic diameter measurements, respectively. The ICC between US performers was 0.992 for vocal cord diameter and 0.959 for subglottic diameter. The US's mean time for vocal cord diameter measurement was 38 ± 23 s, and the mean time for subglottic diameter measurement was 49 ± 30 s.

CONCLUSION

The concordance between US and CT measurements is high and the measurements of different practitioners with different experience levels are compatible with each other.

Novel and pragmatic exploration of variation in glottic parameters in non-parallel versus parallel vocal cord CT planes with potential reporting pitfalls

Oblique orientation of vocal cord demands strict compliance, by technicians and clinicians, to the recommended parallel plane CT scan of larynx. Repercussions of non-compliance has never been investigated before. We aimed to observe influence of non-parallel vocal cord plane CT scan on qualitative and quantitative glottic parameters, keeping parallel plane CT as a standard for comparison. Simultaneous identification of potential suboptimal imaging sequelae as a result of unformatted CT plane was also identified. In this study we included 95 normal adult glottides and retrospectively analyzed their anatomy in two axial planes, non-parallel plane ① and parallel to vocal cord plane ②. Qualitative (shape, structures at glottic level) and quantitative (anterior commissure ACom, vocal cord width VCw, anteroposterior AP, transverse Tr, cross-sectional area CSA) glottic variables were recorded. Multivariate statistical analysis was used to predict pattern and their impact on glottic anatomy. Plane ① displayed supraglottic features in glottis; adipose (90.5%) and split thyroid laminae (70.6%). Other categorical variables: atypical shape, submental structures and multilevel vertebral crossing were also in majority. All glottic dimensions varied significantly between two planes with most in ACom (-5.8mm) and CSA (-15.0 mm2). In contrast, plane ② manifested higher VCw (>73%), Tr (66.3%), CSA (64.2%) and AP (44.2%) measurements. On correlation analysis, variation in ACom, CSA, Tr was positively associated with VC or plane obliquity (p<0.05). This variability was more in obese and short necked subjects. Change in one parameter also modified other significantly i.e., ACom versus AP and CSA versus Tr. Results indicated statistically significant change in subjective and objective anatomical parameters of glottis on non-application of appropriate CT larynx protocol for image analysis hence highlighting importance of image reformation.

Laryngeal Framework Surgical Anatomy: A Radiological Study

PURPOSE

Awareness of variations in laryngeal anatomy among different age and gender groups is crucial during laryngeal framework surgery. The aim of this study is to demonstrate the relationship between gender and laryngeal radiologic morphometrics among different age groups and the applicability of important anatomical landmarks of laryngeal surgery.

METHODS

Laryngeal images of 180 adult patients older than 18 years of age were obtained by computed tomography and assessed. A total of 11 measurements of important laryngeal landmarks were taken from the patients' computed tomography images. Results were subgrouped according to gender and age, and these groups were compared for each measurement.

RESULTS

The majority of laryngeal measurements obtained in the study were higher in males than females, with the exception of the interlaminar angle. The mean interlaminar angle value was 88.27°± 14.99 for males and 103.04°± 14.81 for females (P <0.005). The distance from the anterior commissure to the inferior border of the thyroid cartilage was 10.46 ± 2.5 mm for males and 7.72 ± 1.9 mm for females. The anterior commissure locates slightly higher than the midpoint of the distance from the thyroid notch to the thyroid inferior border. The shortest distance between the muscular process of the arytenoid cartilage and the thyroid cartilage was found to be 9.60 ± 3.47 mm for males and 7.72 ± 2.33 mm for females (P <0.001).

CONCLUSION

Observation of obvious diversities in the size and distance of the important laryngeal structures between the gender groups is an important factor to be considered for successful laryngeal framework surgery. Also, using the midpoint of the thyroid cartilage as a landmark for anterior commissure is a practical method during surgery, especially for thyroplasty.

Post-pubertal developmental trajectories of laryngeal shape and size in humans

Laryngeal morphotypes have been hypothesized related to both phonation and to laryngeal pathologies. Morphotypes have not been validated or demonstrated quantitatively and sources of shape and size variation are incompletely understood but are critical for the explanation of behavioral changes (e.g., changes of physical properties of a voice) and for therapeutic approaches to the larynx. This is the first study to take this crucial step and results are likely to have implications for surgeons and speech language pathologists. A stratified human sample was interrogated for phenotypic variation of the vocal organ. First, computed tomography image stacks were used to generate three-dimensional reconstructions of the thyroid cartilage. Then cartilage shapes were quantified using multivariate statistical analysis of high dimensional shape data from margins and surfaces of the thyroid cartilage. The effects of sex, age, body mass index (BMI) and body height on size and shape differences were analyzed. We found that sex, age, BMI and the age-sex interaction showed significant effects on the mixed sex sample. Among males, only age showed a strong effect. The thyroid cartilage increased in overall size, and the angulation between left and right lamina decreased in older males. Age, BMI and the age-height interaction were statistically significant factors within females. The angulation between left and right lamina increased in older females and was smaller in females with greater BMI. A cluster analysis confirmed the strong age effect on larynx shape in males and a complex interaction between the age, BMI and height variables in the female sample. The investigation demonstrated that age and BMI, two risk factors in a range of clinical conditions, are associated with shape and size variation of the human larynx. The effects influence shape differently in female and male larynges. The male-female shape dichotomy is partly size-dependent but predominantly size-independent.

Recommended Maximum Laryngeal Prominence Size in Adult Females: A Cross-Sectional Study Proposing a Laryngeal Prominence Size Standard for Chondrolaryngoplasty in Male-to-Female Transgender Individuals

BACKGROUND

Although the World Professional Association for Transgender Health has provided international, multidisciplinary, evidence-based standards of care for various aspects of transgender health care, there is a lack of evidence-based guidelines for facial feminization surgery, including chondro laryngoplasty. The aim of this study was to define the recommended maximum laryngeal prominence size in adult females to propose an evidence-based laryngeal prominence size standard for chondrolaryngoplasty in male-to-female transgender individuals.

METHODS

This cross-sectional study was conducted in a tertiary care hospital. The study sample consisted of cisgender patients aged 18 to 60 years old with no history of surgery or radiotherapy in the head and neck area who visited the Otolaryngology/Head and Neck Surgery outpatient clinic. Laryngeal prominence size data were collected using three-dimensional scanning of the head and neck area.

RESULTS

Seventy-nine participants, 43 males and 36 females, were included in data analysis. Laryngeal prominence size was larger in male participants (median, 0.16 mm; range, 0 to 9.40 mm) than in female participants (median, 0.00 mm; range, 0 to 1.24 mm) (p < 0.001). The proportion of participants with a laryngeal prominence size larger than 0 mm was greater in male participants (55.81 percent) than in female participants (22.22 percent) (p = 0.002).

CONCLUSIONS

To the authors' knowledge, this is the first study to assess laryngeal prominence size in the general population. Their results suggest that 2 mm would be the recommended maximum laryngeal prominence size in females. Therefore, a laryngeal prominence size standard of 2 mm could be considered for chondrolaryngoplasty in male-to-female transgender individuals.

Contributions of biomass/solid fuel burning to blood pressure modification in women: A systematic review and meta-analysis

OBJECTIVES

Approximately 2½ billion people worldwide rely on solid/biomass fuel as fuel for cooking/heating the home. Environmental exposure to the smoke associated with biomass fuel burning has been associated respiratory diseases, cardiac disorders, and altered blood pressure. Therefore, a systematic review and meta-analysis was conducted to study this relationship across multiple studies.

METHODS

Searches were performed using PRISMA guidelines for articles using Web of Science, PubMed, Toxline, and Web of Science of peer reviewed papers with no beginning time restriction until February 2017. The search yielded 10 manuscripts after application of inclusion criteria, which encompassed 93 724 participants. Outcomes included (a) the proportion of people with a clinical diagnosis of hypertension in an exposed (vs. unexposed) population or (b) correlation coefficients examining degree of exposure and systolic/diastolic blood pressure.

RESULTS

The four studies reporting effect sizes for hypertension (N = 92 042) had a weighted mean effect size of r = .12 [-0.02, 0.27], z = 1.66, p = 0.097. The six studies reporting effect sizes for systolic and diastolic blood pressure (N = 1682) had weighted mean effect sizes of r = .15 [0.06, 0.24], p = 0.001, and r = .09 [0.03, 0.15], p = 0.002, respectively.

CONCLUSION

These analyses revealed that there is a small-but-significant relationship between biomass fuel exposure and an increase in both systolic and diastolic blood pressure, but the relationship between biomass fuel and hypertension specifically remains unclear.

Quantification of the effect of body mass index on cricothyroid membrane depth: a cross-sectional analysis of clinical CT images

OBJECTIVES

The recommended front of neck access procedure in can't intubate, can't oxygenate scenarios relies on palpation of the cricothyroid membrane (CTM), or dissection of the neck down to the larynx if CTM is impalpable. CTM palpation is particularly challenging in obese patients, most likely due to an increased distance between the skin and the CTM (CTM depth). The aims of this study were to measure the CTM depth in a representative clinical sample, and to quantify the relationship between body mass index (BMI) and CTM depth.

METHODS

This is a retrospective analysis of 355 clinical CT scans performed at a teaching hospital over an 8-month period. CTM depth was measured by two radiologists, and mean CTM depth calculated. Age, gender, height and weight were recorded, and BMI calculated. Linear relationships between patient characteristics and CTM depth were assessed in order to derive a predictive equation for calculating CTM depth. The variables included for this model were those with a strong association with CTM depth, that is, a p value of 0.10 or less.

RESULTS

Mean CTM depth was 8.12 mm (IQR 6.36-11.70). There was no association between CTM depth and sex (β -0.33, 95% CI -1.33 to 0.68, p=0.53), height (cm) (β 0.01, 95% CI -0.05 to 0.06, p=0.79) or age (years) (β -0.01, 95% CI 0.10 to 0.15, p=0.62). Increasing weight (kg) (β 0.12, 95% CI 0.10 to 0.15, p<0.001) and BMI (kg/m³) (β 0.52, 95% CI 0.44 to 0.60, p<0.001) were strongly associated with CTM depth. Predicted CTM depth increased from 6.4 mm (95% CI 4.9 to 8.1) at a BMI of 20 kg/m² to 16.8 (95% CI 13.7 to 20.1) at BMI 40 kg/m².

CONCLUSION

CTM depth was strongly associated with BMI in a retrospective analysis of patients having clinical CT scans.

Postnatal Development of the Mouse Larynx: Negative Allometry, Age-Dependent Shape Changes, Morphological Integration, and a Size-Dependent Spectral Feature

Purpose The larynx plays a role in swallowing, respiration, and voice production. All three functions change during ontogeny. We investigated ontogenetic shape changes using a mouse model to inform our understanding of how laryngeal form and function are integrated. We understand the characterization of developmental changes to larynx anatomy as a critical step toward using rodent models to study human vocal communication disorders. Method Contrast-enhanced micro-computed tomography image stacks were used to generate three-dimensional reconstructions of the CD-1 mouse (Mus musculus) laryngeal cartilaginous framework. Then, we quantified size and shape in four age groups: pups, weanlings, young, and old adults using a combination of landmark and linear morphometrics. We analyzed postnatal patterns of growth and shape in the laryngeal skeleton, as well as morphological integration among four laryngeal cartilages using geometric morphometric methods. Acoustic analysis of vocal patterns was employed to investigate morphological and functional integration. Results Four cartilages scaled with negative allometry on body mass. Additionally, thyroid, arytenoid, and epiglottic cartilages, but not the cricoid cartilage, showed shape change associated with developmental age. A test for modularity between the four cartilages suggests greater independence of thyroid cartilage shape, hinting at the importance of embryological origin during postnatal development. Finally, mean fundamental frequency, but not fundamental frequency range, varied predictably with size. Conclusion In a mouse model, the four main laryngeal cartilages do not develop uniformly throughout the first 12 months of life. High-dimensional shape analysis effectively quantified variation in shape across development and in relation to size, as well as clarifying patterns of covariation in shape among cartilages and possibly the ventral pouch. Supplemental Material https://doi.org/10.23641/asha.12735917.

Rapid evolution of the primate larynx?

Tissue vibrations in the larynx produce most sounds that comprise vocal communication in mammals. Larynx morphology is thus predicted to be a key target for selection, particularly in species with highly developed vocal communication systems. Here, we present a novel database of digitally modeled scanned larynges from 55 different mammalian species, representing a wide range of body sizes in the primate and carnivoran orders. Using phylogenetic comparative methods, we demonstrate that the primate larynx has evolved more rapidly than the carnivoran larynx, resulting in a pattern of larger size and increased deviation from expected allometry with body size. These results imply fundamental differences between primates and carnivorans in the balance of selective forces that constrain larynx size and highlight an evolutionary flexibility in primates that may help explain why we have developed complex and diverse uses of the vocal organ for communication.

A Dissectional Study of the Level of Anterior Commissure of the Larynx

PURPOSE

Precise knowledge of the level of the vocal fold as projected on the external thyroid cartilage is of critical importance for the performance of many surgical approaches. This study aims to identify the level of the anterior commissure, as well as the lengths of the vocal muscle and arytenoid cartilage in Turkish population.

MATERIALS AND METHOD

Specimens were collected after autopsy from the Council of Forensic Medicine. One hundred human larynges (52 men, 48 women; age range: 25-80 years) were dissected under a stereomicroscope. Projection of the vocal fold was analyzed in relation to the superior thyroid (A) and the inferior border of the thyroid cartilage (B). Then, the larynx was dissected parallel to the level of the vocal fold to measure the length of the vocal muscle (C) and the length of the interarytenoid space (D).

RESULTS

The mean value of the "a" was 9.15 ± 1.99 mm in male and 9.38 ± 3.43 mm in female. Mean value of the "b" was 10.54 ± 1.73 mm and 8.88 ± 1.81 mm in male and female, respectively. The mean value of the parameter corresponding the length of vocal muscle which was "c" was found 15.00 ± 3.18 mm in male and 12.88 ± 4.12 mm in female. The mean value of the interarytenoid space "d" was 8.31 ± 1.76 mm in male and 8.13 ± 1.90 mm in female. Comparing between genders, no statistical differences were observed in parameters of a, c, d, a + b, a + b/2 (P > .05). However, the difference with female and male for the parameters of b and c + d was statistically significant (P < .05).

CONCLUSION

Our results indicate that the anterior commissure projects slightly above the midline height for male and at the level to slightly below in female subjects in Turkish population.

Vocal Feminization for Transgender Women: Current Strategies and Patient Perspectives

Voice feminization for transgender women is a highly complicated comprehensive transition process. Voice feminization has been thought to be equal to pitch elevation. Thus, many surgical procedures have only focused on pitch raising for voice feminization. However, voice feminization should not only consider voice pitch but also consider gender differences in physical, neurophysiological, and acoustical characteristics of voice. That is why voice therapy has been the preferred choice for the feminization of the voice. Considering gender difference of phonatory system, the method for voice feminization consists of changing the following four critical elements: fundamental frequency, resonance frequency related to vocal tract volume and length, formant tuning, and phonatory pattern. Voice feminizing process can be generally divided into non-surgical feminization and surgical feminization. As a non-surgical procedure, feminization voice therapy consists of increasing fundamental frequency, improving oral and pharyngeal resonance, and behavioral therapy. Surgical feminization usually can be achieved by external approach or endoscopic approach. Based on three factors (length, tension and mass) of vocal fold for pitch modulation, surgical procedure can be classified as one-factor, two-factors and three-factors modification of vocal folds. Recent systematic reviews and meta-analysis studies have reported positive outcomes for both the voice therapy and voice feminization surgery. The benefits of voice therapy, as it is highly satisfactory, mostly increase vocal pitch, and are noninvasive. However, the surgical voice feminization of three-factors modification of vocal folds is also highly competent and provides a maximum absolute increase in vocal pitch. Voice feminization is a long transition journey for physical, neurophysiological, and psychosomatic changes that convert a male phonatory system to a female phonatory system. Therefore, strategies for voice feminization should be individualized according to the individual’s physical condition, the desired change in voice pitch, economic conditions, and social roles.

Proposing an Endotracheal Tube Selection Tool Based on Multivariate Analysis of Airway Imaging

OBJECTIVES

We aimed to comprehensively investigate different upper airway segments in adults, determine the predictors of the size of each segment, and identify an appropriate endotracheal tube (ETT) size chart.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary care center.

MATERIALS AND METHODS

The data for patients aged >18 years who underwent neck computed tomography were screened. Patients with existing tumors, trauma, or any pathology that can alter the normal airway anatomy and those with intubation, tracheostomy, or nasogastric tubes were excluded. Computed tomography software was used to measure the anteroposterior diameter (APD), transverse diameter (TD), and cross-sectional area (CSA) at the glottic, proximal subglottic, distal subglottic, and tracheal levels. Multiple regression analysis was used to identify the predictors of the airway size.

RESULTS

One hundred patients were reviewed. The TD was consistently smaller than or equal to the APD at each level in all but 3 patients. The mean CSA and TD (170 mm² and 11.3 mm, respectively) of the glottis indicated that the glottis was most often the narrowest level, followed by the proximal subglottis where the mean CSA and TD were 192.1 mm² and 12.7 mm, respectively. Moreover, the mean APD was the smallest at the level of the trachea (20.1 mm). Multiple regression analysis confirmed that height and sex were the predominant predictors of measurements for the 4 airway segments. In addition, age was associated with the TD and CSA of the distal subglottic and tracheal segments, respectively.

CONCLUSION

One-third of our participants exhibited a proximal subglottic diameter that was equal to or smaller than the glottic diameter. Our findings also suggested that the height and sex of the patients are important variables for the selection of an appropriate ETT size.

Euclidean distances of laryngopharyngeal structures obtained from CT data for preclinical development of laryngoscopic devices

PURPOSE

This study aims to determine Euclidean distances between landmark structures in the larynx and pharynx to optimize endoscope shaft designs with regard to gentle and patient-oriented handling.

METHODS

Four Euclidean distances between landmarks in the larynx and pharynx were analyzed based on CT data of 66 patients. Distance (1): labium inferius oris-posterior pharyngeal wall at the cervical vertebra C1 (atlas), anterior edge of the tuberculum anterius atlantis. Distance (2): posterior pharyngeal wall adjacent to C1-entrance of pyriform sinus. Distance (3): inferior edge of the uvula-superior edge of the epiglottis. Distance (4): base of the vallecula-posterior pharyngeal wall. The minimum angular field of view α required to observe the glottis with a rigid transoral laryngoscope was derived trigonometrically from distances (2) and (4).

RESULTS

Average Euclidean distances measured: Distance (1): 90.7 mm ± 6.9 mm in men and 86.9 mm ± 5.9 mm in women. (2): 73.7 mm ± 13.4 mm and 56.2 mm ± 7.6 mm. (3): 25.2 mm ± 8.6 mm and 18.5 mm ± 6.8 mm. (4): 20.8 mm ± 4.6 mm and 16.5 mm ± 3.4 mm. α: 16.0° ± 3.9° and 16.6 ± 4.3°.

CONCLUSIONS

As expected, statistically significant sex-related differences could be observed for distances (1)-(4). The results indicate that the length of transoral laryngoscopes should not be below 110 mm and that a minimum angular field of view of α = 17° is required to fully observe the laryngeal inlet.

An actuated larynx phantom for pre-clinical evaluation of droplet-based reflex-stimulating laryngoscopes

The laryngeal adductor reflex (LAR) is an important protective function of the larynx to prevent aspiration and potentially fatal aspiration pneumonia by rapidly closing the glottis. Recently, a novel method for targeted stimulation and evaluation of the LAR has been proposed to enable non-invasive and reproducible LAR performance grading and to extend the understanding of this reflexive mechanism. The method relies on the laryngoscopically controlled application of accelerated water droplets in association with a high-speed camera system for LAR stimulation site and reflex onset latency identification. Prototype laryngoscopes destined for this method require validation prior to extensive clinical trials. Furthermore, demonstrations using a realistic phantom could increase patient compliance in future clinical settings. For these purposes, a model of the human larynx including vocal fold actuation for LAR simulation was developed in this work. The combination of image processing based on a custom algorithm and individual motorization of each vocal fold enables spatio-temporal droplet impact detection and controlled vocal fold adduction. To simulate different LAR pathologies, the current implementation allows to individually adjust the reflex onset latency of the ipsi- and contralateral vocal fold with respect to the automatically detected impact location of the droplet as well as the maximum adduction angle of each vocal fold. An experimental study of the temporal offset between desired and observed LAR onset latency due to image processing was performed for three average droplet masses based on highspeed recordings of the phantom. Median offsets of 100, 120 and 128 ms were found (n=16). This offset most likely has a multifactorial cause (image processing delay, inertia of the mechanical components, droplet motion). The observed offset increased with increasing droplet mass, as fluid oscillations after impact may have been detected as motion. In future work, alternative methods for droplet impact detection could be explored and the observed offset could be used for compensation of this undesirable delay.

Biomechanical study of the thyroid cartilage: A model of bi-digital strangulation

The presence of fracture on neck elements is an indication of violence. Both the hyoid bone and the larynx can be damaged by a strangulation mechanism. Thyroid cartilage, more specifically, may present lesions in response to this mechanical stress. These lesions result in fractures at the bases of the horns of the thyroid cartilage. This study focuses on the thyroid cartilage behavior in cases of bi-digital strangulation, using an anthropometric and biomechanical approach. To develop a biomechanical model, we performed an anthropometric study taking into account 14 distances measurements as well as 3 measurements of angles. These measures allowed us to determine a significant sexual dimorphism between individuals. Then, we define 6 morphologies models, composed of 3 females and 3 males individuals. In order to visualize the ossification of the cartilage, each model has been tested with bone properties. Strangulation cases were simulated by applying an imposed velocity of 0.4m/s then 1m/s. We observed different behaviors of the thyroid cartilage according to the sex and the morphology.

Unilateral and bilateral agenesis of the upper thyroid horns - A morphometric analysis of the larynx

The agenesis of one or both upper thyroid horns (UTH) cannot be considered rare with an incidence ranging between 0.8-9.4%. Studies so far have mostly described frequencies, yet surveys on its morphology and traumatology are missing. It is unknown to what extent this anatomical variant impacts the overall symmetry of the larynx. For the trauma reconstruction after cervical trauma this knowledge is required as an asymmetric larynx can show a different fracture pattern. In this investigation, larynxes with unilateral (n=21)/bilateral (n=5) agenesis of the upper thyroid horn(s) and a control group with regular larynxes (n=23) were juxtaposed. Various measurements were taken after μ-CT scanning. In total 10 distances/angles for the thyroid cartilage and 8 for the cricoid cartilage were compared. Using intra-individual and matched pair comparisons the symmetry was assessed. The results of this investigation showed significant differences in the intra-individual and pairwise comparison for the opening angle and the length of the thyroid alae although the lateral inclination of the thyroid alae showed no significant difference. Combining these three parameters into one symmetry score, the comparison was not significant. This research demonstrates that neither unilateral nor bilateral agenesis of the UTH is related to a structural disbalance of the larynx. Thus, different fracture patterns or vulnerabilities are not to be expected.

Individualized Patient Vocal Priorities for Tailored Therapy

PURPOSE

The purposes of this study are to introduce the concept of vocal priorities based on acoustic correlates, to develop an instrument to determine these vocal priorities, and to analyze the pattern of vocal priorities in patients with voice disorders.

METHOD

Questions probing the importance of 5 vocal attributes (vocal clarity, loudness, mean speaking pitch, pitch range, vocal endurance) were generated from consensus conference involving speech-language pathologists, laryngologists, and voice scientists, as well as patient feedback. The responses to the preliminary items from 213 subjects were subjected to exploratory factor analysis, which confirmed 4 of the predefined domains. The final instrument consisted of a 16-item Vocal Priority Questionnaire probing the relative importance of clarity, loudness, mean speaking pitch, and pitch range.

RESULTS

The Vocal Priority Questionnaire had high reliability (Cronbach's α = .824) and good construct validity. A majority of the cohort (61%) ranked vocal clarity as their highest vocal priority, and 20%, 12%, and 7% ranked loudness, mean speaking pitch, and pitch range, respectively, as their highest priority. The frequencies of the highest ranked priorities did not differ by voice diagnosis or by sex. Considerable individual variation in vocal priorities existed within these large trends.

CONCLUSIONS

A patient's vocal priorities can be identified and taken into consideration in planning behavioral or surgical intervention for a voice disorder. Inclusion of vocal priorities in treatment planning empowers the patient in shared decision making, helps the clinician tailor treatment, and may also improve therapy compliance.

Comparative Anatomy of Pig Arytenoid Cartilage and Human Arytenoid Cartilage

OBJECTIVE

This study aims to investigate the feasibility of pig arytenoid cartilage as an animal model for simulating arytenoidectomy under microlaryngoscope by comparing the similarities and differences between pig arytenoid cartilage and human arytenoid cartilage.

STUDY DESIGN

This is a methodological study on the excised pig arytenoid cartilage and human arytenoid cartilage.

METHODS

Five excised human adult cadaver larynges and five adult excised porcine larynges were dissected and all the soft tissue and mucous membrane attached to the arytenoid and cricoarytenoid joint were removed. The anatomical structure and morphology of the arytenoid cartilage were observed and measured with a vernier caliper. Measurements included cricoarytenoid articular facet major and minor diameter, cricoarytenoid articular facet center distance, cricoarytenoid facet major and minor diameter, length of vocal process and muscular process, and distance between tip of vocal process, muscular process, and junction/apex of arytenoid cartilage. Data were then compared across these major anatomic markers using student t test.

RESULTS

The gross anatomy of the pig arytenoid cartilage was similar to the human. However, the size of the pig larynx arytenoid cartilage was obviously larger in total, and there was statistical significance for almost all measurements (P < 0.05), except the mean value of cricoarytenoid articular facet center distance, the cricoarytenoid facet minor diameter, and the length of vocal process of pig and human, without statistically significant difference (P > 0.05). Moreover, the biggest differences between the pig arytenoid cartilage and the human arytenoid cartilage were that the pig arytenoid cartilage apex had the angle winding structure toward the back, and that the posterior part of the bilateral arytenoid cartilages was partially connected. Whereas after the angle winding was removed from the junction, pig arytenoid cartilage and human arytenoid cartilage were shaped both like a triangular pyramid.

CONCLUSION

The data of this metric comparative study indicate that pig arytenoid, after resecting the angle winding structure and incising the interarytenoid cartilage, is similar to the human's. Therefore, pig larynx is an appropriate experimental model for endoscopic arytenoidectomy. In addition, regarding the pig laryngeal angle winding structure, we still require further basic and clinical research to clarify its physiological function and significance.

Linear Measurements of Vocal Folds and Laryngeal Dimensions in Freshly Excised Human Larynges

INTRODUCTION

Understanding the morphology of the larynx, one of the most complex organs of the human body, is an important step toward understanding the detailed laryngeal anatomy, and physiology. Different studies have described the linear measurements of the larynx in different measuring methods, but no studies have been structured to describe vocal fold length in freshly excised larynges.

OBJECTIVES

The aim of this study was to describe exact anatomical measurements of vocal folds and some laryngeal structures in freshly excised larynges, and to compare such measurements between males and females. This can help improve the diagnostic and therapeutic procedures in the laryngology field.

SUBJECTS AND METHODS

This study was applied on 21 patients having different types of laryngeal carcinoma: 11 males and 10 females with the age range 41-75 years old. Every patient was assessed using laryngeal endoscopy and photography, and the length of the membranous vocal fold was measured using a millimeter-graded ruler that was photographed with focus with the same magnification used in the video laryngoscopy of the glottis. Then patients were exposed to total laryngectomy, and excised larynges were used for a direct measuring of the membranous and cartilaginous vocal folds. Then measures of men and women were compared statistically. Measures of excised larynges were also compared with those of the video endoscopy using a video-printed ruler.

CONCLUSION

Freshly excised larynges can be used for accurate quantitative measuring of the vocal fold length and laryngeal dimensions. There are considerable differences in all measured dimensions between males and females.

Difficulty in inserting left double-lumen endobronchial tubes at the cricoid level in small-statured women: A retrospective study

BACKGROUND AND AIMS

Left double-lumen endobronchial tube (DLT) sizes are selected using tracheal diameters and left mainstem bronchial diameters (LMBDs) determined from chest radiographs or computed tomography (CT) scans. In Western women, 35-Fr or 37-Fr DLTs are often selected. However, difficulties can be encountered when inserting 32-Fr or 35-Fr DLTs in Japanese women. We investigated success rates for 32-Fr or 35-Fr DLT insertion in Japanese women and determined the causes of unsuccessful DLT insertion.

METHODS

We searched anaesthesia records of Japanese women aged ≥20 years who underwent thoracic surgery with 32-Fr or 35-Fr DLTs between April 2010 and March 2015 in our hospital. In the successful group (SG), patients were intubated using the initially selected DLTs. By contrast, in the unsuccessful group (UG), the DLT size had to be changed. The Mann-Whitney U-test and Fisher's exact test were used to compare groups.

RESULTS

The SG included 149 (96.1%) of 155 cases of 32-Fr DLT use and 119 (95.2%) of 125 cases of 35-Fr DLT use. Patient height was significantly lower in the UG than in the SG for the 35-Fr DLT (P = 0.0036). In seven of 12 UG patients (three for 32-Fr and four for 35-Fr), the transverse diameters of cricoid cartilages were smaller than the DLTs' tracheal diameters, thereby preventing passage through the cricoid cartilages.

CONCLUSION

Along with LMBDs, transverse diameters of cricoid cartilages based on CT scans or ultrasonogram findings may help in selecting the appropriate left DLT size.

A Comparative Study of Tracheal Diameter in Caucasian and Chinese Patients

Ethnicity may be considered a factor when considering what size endotracheal tube to insert. In particular it has been suggested that Chinese patients have a smaller tracheal diameter, justifying the selection of smaller endotracheal tubes. We systematically evaluated transverse tracheal diameters in Chinese and Caucasian patients, utilising archived computer tomography images. A convenience sample of 100 Caucasian patients from Australia was compared with 100 Chinese patients from Hong Kong. Patients over 18 years of age who had undergone a computerised tomography scan of the neck and thorax, and also had accurate body height and weight recorded, were studied. The mean transverse diameter of the trachea measured at three levels was similar between the Chinese and Caucasian patients. At the narrowest measurement point, the immediate subcricoid transverse diameter, the unadjusted mean difference between male Chinese and Caucasian patients was small (1 mm, standard deviation 0.83 mm, P=0.01), and similarly small between female Chinese and Caucasian patients (1.5 mm, standard deviation 0.8 mm, P <0.01). Multivariate analysis demonstrated only a small influence related to ethnicity (12% relative contribution to the overall variance [R2] of the model), but substantial influence of height (40%) and sex (41%). Our findings do not support the practice of routinely selecting a smaller endotracheal tube size for Chinese patients on the basis that there is a difference related to the Chinese ethnic phenotype. Considerations regarding choice of endotracheal tube size should rather focus on patient sex and height.

Shape of Thyroid Cartilage Influences Outcome of Montgomery Medialization Thyroplasty: A Gender Issue

OBJECTIVE

This study aimed to determine whether the shape of the thyroid cartilage and gender influence voice outcomes after a Montgomery thyroplasty implant system (MTIS).

METHODS

A retrospective cohort study was performed on 20 consecutive patients who underwent MTIS. Voice outcome variables were the relative decrease in Voice Handicap Index (%) and the absolute increase in maximum phonation time (MPT) (in seconds). Material variables were the angle between the thyroid cartilage laminae (α-angle), the size of the prosthesis, and a combination of both (the α-ratio). Continuous variables were analyzed using medians and were compared between groups using the Mann-Whitney U test. Factors associated with the outcome variables were assessed by multivariable linear regression. A Pearson coefficient was calculated between material variables.

RESULTS

The absolute increase in MPT between the pre- and postoperative period was significantly different between men and women, with a median absolute increase of 11.0 seconds for men and of 1.3 seconds for women (P < 0.001). A strong inverse correlation between the α-ratio and the absolute increase in MPT is observed in all patients, with a Pearson correlation coefficient R = -0.769 (P < 0.001). No factors were significantly associated with the relative Voice Handicap Index decrease in univariable or multivariable analyses. A better Pearson coefficient between the α-angle and the prosthesis size was found for females (0.8 vs 0.71).

CONCLUSION

The MTIS is a good thyroplasty modality for male patients, but inadequate design of MTIS female implants leads to poor MPT outcomes. This represents a gender issue that needs to be further studied and eventually tackled.

Total deposition of ultrafine particles in the lungs of healthy men and women: experimental and theoretical results

BACKGROUND

Inhaled ultrafine particles (UFP) may induce greater adverse respiratory effects than larger particles occurring in the ambient atmosphere. Due to this potential of UFP to act as triggers for diverse lung injuries medical as well as physical research has been increasingly focused on the exact deposition behavior of the particles in lungs of various probands. Main purpose of the present study was the presentation of experimental and theoretical data of total, regional, and local UFP deposition in the lungs of men and women.

METHODS

Both experiments and theoretical simulations were carried out by using particle sizes of 0.04, 0.06, 0.08, and 0.10 µm [number median diameters (NMD)]. Inhalation of UFP took place by application of predefined tidal volumes (500, 750, and 1,000 mL) and respiratory flow rates (150, 250, 375, and 500 mL·s(-1)). For male subjects a functional residual capacity (FRC) of 3,911±892 mL was measured, whereas female probands had a FRC of 3,314±547 mL. Theoretical predictions were based on (I) a stochastic model of the tracheobronchial tree; (II) particle transport computations according to a random walk algorithm; and (III) empirical formulae for the description of UFP deposition.

RESULTS

Total deposition fractions (TDF) are marked by a continuous diminution with increasing particle size. Whilst particles measuring 0.04 µm in size deposit in the respiratory tract by 40-70%, particles with a size of 0.10 µm exhibit deposition values ranging from 20% to 45%. Except for the largest particles studied here TDF of female probands are higher than those obtained for male probands. Differences between experimental and theoretical results are most significant for 0.10 µm particles, but never exceed 20%. Predictions of regional (extrathoracic, tracheobronchial, alveolar) UFP deposition show clearly that females tend to develop higher tracheobronchial and alveolar deposition fractions than males. This discrepancy is also confirmed by airway generation-specific deposition, which is permanently higher in women than in men.

CONCLUSIONS

From the experimental data and modeling predictions it can be concluded that females bear a slightly higher potential to develop lung insufficiencies after exposure to UFP than males. Besides higher deposition fractions occurring in female subjects, also total lung deposition dose is noticeably enhanced.

Novel Anatomic Characteristics of the Laryngeal Framework

Objective

The thyroid cartilage (TC) in men has a more prominent thyroid notch and a narrower interlaminae angle (ILA) as compared with women. Anatomy textbooks classically stipulate that the ILA is 90° in men and 120° in women. Our observation, based on thyroid chondroplasty operations, of a much narrower angle led to the current investigation.

Study Design

Cohort imaging study.

Setting

Tertiary academic referral center.

Subjects and Methods

Computed tomography angiography neck images of adult patients were studied. The ILA was measured on 2 axial planes: at the level of the vocal processes (and the upper portion of thyroarytenoid muscles) and 5 mm superior and parallel to the former. The anterior projection of the TC and the vertical dimensions of the midline cricothyroid membrane (CTM) were also measured.

Results

A total of 126 patients were included in the study. The average ILAs were 63.5°±20.6° and 93.3°±16.6° for men and women, respectively ( P < 10−14), and were significantly narrower at the upper level in comparison with the vocal process level ( P < 10−7 for men, P = .004 for women). The anterior projection of the TC in men was more prominent as compared with women ( P = .0003) and significantly correlated with the ILA ( P = .0159). The length of the midline CTM was 11.1±2.3 mm in men and 10.3±1.7 mm in women ( P = .0355).

Conclusions

The ILA is narrower than that reported in the classic anatomy textbooks. In male patients, the upper part of the TC becomes narrower and projects anteriorly like a “jug’s spout.” The mean vertical dimension of the midline CTM was 10 to 11 mm.

[The size of the vocal folds in the children during the first years of life]

The objective of the present study was to determine the size of the vocal folds in the children during the first several years of life. The study included 137 children at the age from the birth up to 3 years who were referred to our clinic for the pre-planned surgical intervention with the use of endotracheal intubation. The length and the width of the vocal folds from the muscle tubercle to the anterior commissure in abduction were measured using a probe specially designed and adapted for this purpose. In all the cases, the endoscope was positioned at the same distance from the vocal folds. The fold length (ab) and width (cd) were expressed in millimeters. These parameters were measured in the following age groups of the patients: from the birth to 1 month 29 days (group 1), from 12 mo to 23 mo 29 d (group 2), from 24 mo to 35 mo 29 d (group 3), and above 36 months (group 4). The length and the width of the vocal folds varied from 2.6 mm to 7.8 mm and from 1.3 mm to 3.2 mm respectively. The length of the vocal folds increased at a rate of 1.025 mm per year showing marked variations within each age group, from the maximum value of 1.79 mm during the second year of life to the minimum of 0.48 mm during the fourth year. The authors conclude that these data may be of use for the improvement of the quality of the surgical treatment and subsequent rehabilitation of the respiratory and voice-generating functions of the larynx.

Assessment of the subglottic region by ultrasonography for estimation of appropriate size endotracheal tube: A clinical prospective study

Background:

Endotracheal intubation is important to carry out various surgical procedures. The estimation of endotracheal tube size is governed by narrowest diameter of the upper airway. The objective of the study was to assess the narrowest tracheal diameter by ultrasound for selection of the appropriate size endotracheal tube.

Materials and Methods:

After the approval of institution ethical committee and written informed consent, 112 patients aged 3 to 18 years of both genders with normal airways, scheduled for surgery under general anesthesia and intubation, were enrolled for this prospective clinical observational study. Preanesthetic ultrasonography of the subglottic region was performed by experienced ultrasonologist with a high-resolution linear array transducer in sniffing position for every patient and the subglottic tracheal diameter was estimated to select the appropriate-size endotracheal tube. The endotracheal tube, calculated on the basis of physical indices and by ultrasound, was statistically correlated with the appropriate size endotracheal tube used clinically for intubation.

Results:

The ultrasound guided selection criterion has estimated the appropriate-sized endotracheal tube better than physical indices (age or height)-based formulas. The estimated endotracheal tube size by ultrasound was significantly correlated with the clinically used endotracheal tube.

Conclusion:

Ultrasonography may be used for the assessment of the subglottic diameter of trachea in children to estimate the appropriate size endotracheal tube for intubation.

Cancer etiology. Variation in cancer risk among tissues can be explained by the number of stem cell divisions

Some tissue types give rise to human cancers millions of times more often than other tissue types. Although this has been recognized for more than a century, it has never been explained. Here, we show that the lifetime risk of cancers of many different types is strongly correlated (0.81) with the total number of divisions of the normal self-renewing cells maintaining that tissue's homeostasis. These results suggest that only a third of the variation in cancer risk among tissues is attributable to environmental factors or inherited predispositions. The majority is due to "bad luck," that is, random mutations arising during DNA replication in normal, noncancerous stem cells. This is important not only for understanding the disease but also for designing strategies to limit the mortality it causes.

The accuracy of locating the cricothyroid membrane by palpation - an intergender study

Background

The cricothyroid membrane (CTM) is the recommended site of access to the airway during cricothyrotomy to provide emergency oxygenation. We sought to compare the ability of physicians to correctly identify the CTM in male and female patients.

Methods

In a prospective observational study, anaesthetists were asked to locate the CTM by palpation which was then identified using ultrasound and the distance between the actual and estimated margin of the CTM was measured. Participants assessed the ease of CTM palpation using a visual analog scale. In a second series, the angulation of the posterior junction of the thyroid laminae was measured using ultrasound.

Results

23 anaesthetists and 44 subjects participated. A total of 36 assessments were carried out in each gender. Incorrect identification of the CTM was more common in females (29/36 vs. 11/36, P < 0.001) and the distance from the CTM in the vertical plane was greater (11.0 [6.5–20.0] vs. 0.0 [0.0–10.0] mm, P < 0.001). In females distance from the CTM correlated positively with neck circumference (P = 0.005) and BMI (P = 0.00005) and negatively with subject height (P = 0.01). Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02). VRS palpation correlated with decreased posterior thyroid cartilage angulation (P = 0.04).

Conclusions

CTM localisation is more difficult in female subjects irrespective of body habitus. It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.

Three-dimensional reconstruction of human vocal folds and standard laryngeal cartilages using computed tomography scan data

Three-dimensional (3D) computer models of the human larynx are useful tools for research and for eventual clinical applications. Recently, computed tomography (CT) scanning and magnetic resonance imaging (MRI) have been used to recreate realistic models of human larynx. In the present study, CT images were used to create computer models of vocal folds, vocal tract, and laryngeal cartilages, and the procedure to create solid models are explained in details. Vocal fold and vocal tract 3D models of healthy and postsurgery larynges during phonation and respiration were created and morphometric parameters were quantified. The laryngeal framework of eight patients was also reconstructed from CT scan images. For each cartilage, morphometric landmarks were measured on the basis of their importance for biomechanical modeling. A quantitative comparison was made between measured values from the reconstructions and those from human excised larynges in literature. The good agreement between these measurements supports the accuracy of CT scan-based 3D models. Generic standard models of the laryngeal framework were created using known features in modeling softwares. They were created based on the morphometric landmark dimensions previously defined, preserving all biomechanically important dimensions. These models are accessible, subject independent, easy to use for computational simulations, and make the comparisons between different studies possible.

Multiplanar 3D ultrasound imaging to assess the anatomy of the upper airway and measure the subglottic and tracheal diameters in adults

OBJECTIVE

To evaluate the feasibility of using three-dimensional (3D) ultrasound to assess the anatomy of the airway.

METHODS

11 young volunteers were recruited for 3D ultrasound and MRI of the airway. 3D ultrasound data were obtained from the level of the true vocal cords, cricoid cartilage and upper trachea. Multiplanar 3D ultrasound images were rendered and compared visually with corresponding MRI and cadaver anatomical sections. The anteroposterior (AP) and transverse diameter of the subglottic space and transverse diameter of the upper trachea were also measured in the 3D ultrasound and MR images and compared.

RESULTS

The airway anatomy was clearly delineated in the multiplanar 3D ultrasound images. It was also possible to identify the cricothyroid junction, and a simple method to measure the AP diameter of the subglottic space using this landmark is described. We were also able to accurately measure the transverse diameter of the upper trachea, but the transverse diameter of the subglottic space was overestimated using ultrasound. There was a strong correlation for the AP diameter measurement (r=0.94, p<0.05) and moderate correlation for the transverse diameter measurement (r=0.82, p=0.002) of the subglottic space, and a strong correlation for the transverse diameter measurement (r=0.91, p<0.05) of the upper trachea, in the ultrasound and MR images.

CONCLUSION

The anatomy of the adult airway can be assessed using 3D ultrasound. It can also be used to accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

ADVANCES IN KNOWLEDGE

This is the first report to describe the use of 3D ultrasound to evaluate the anatomy of the upper airway and accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

Real-time ultrasonographic assessment of true vocal fold length in professional singers

PURPOSE

To assess changing true vocal fold (TVF) length with ultrasonography.

MATERIALS

Thirty-five professional singers (12 tenors and 23 sopranos) were included in this study. Each subject had a documented TVF length with laryngeal ultrasonography (SonoAce X6 scanner; Samsung Medison, Seoul, Korea) during respiration, phonation, and singing.

RESULTS

The average TVF lengths could be measured in each situation with real-time laryngeal ultrasonography. The mean (standard deviation [SD]) of TVF length was 1.71 cm (0.29) at inspiration, 1.56 cm (0.26) at expiration, 1.70 cm (0.21) at comfort phonation, 2.00 cm (0.22) at the highest tone, and 1.47 cm (0.19) at the lowest tone in tenors. In sopranos, the mean (SD) was 1.35 cm (0.12) at inspiration, 1.17 cm (0.12) at expiration, 1.42 cm (0.12) at comfort phonation, 1.65 cm (0.12) at the highest tone, and 1.14 cm (0.15) at the lowest tone. All variables had significant differences between both sexes (P<0.01). The lengths showed statistically significant differences in each phase (P<0.01). The differences in length between each phase were evaluated as well. When analyzed in each sex, all variables were statistically different except few of them. In both sexes, the highest tone and comfort phonation showed no difference (P=0.081 in tenors and P=0.289 in sopranos). The inspiratory phase and comfort phonation had significant difference only in sopranos (P<0.01) in contrast to tenors (P=0.905).

CONCLUSION

Ultrasonographic measurement of TVF could be used to assess physiological variation of TVF. To reach a high-pitched voice, the professional singers used similar range of TVF length at comfort phonation. TVF length was affected more by inspiration in tenors. In sopranos, TVF at comfort phonation was significantly lengthened than in tenors.

Morphometric study of cricoid cartilages in Western India

BACKGROUND

It is important to determine the size and proportion of the larynx as such information is useful in procedures such as intubation, endoscopy and surgical manipulations. Recent interest in the cases of subglottic stenosis and postintubational stenosis of the lower respiratory tract has led to renewed interest in ascertaining the measurements of the various laryngeal cartilages. The aim of the present study was to collect morphometric data of cricoid cartilage from a regional population.

METHOD

Fifty laryngeal preparations from adult cadavers of Western India were assessed. Sections were prepared via dissection and the removed cricoid cartilages then measured and weighed.

RESULTS

The mean antero-posterior diameter (19.29±2.47) of the cricoid cartilage was greater than the average transverse diameter (18.33±2.26). The height of arch of cricoid cartilage was 6.54±1.23mm and height of lamina was 21.45±1.97mm. Mean weight of cricoid cartilage was 4.53±1.27grams. The shape of the cricoid cartilage was ovoid in 46% of cases, oval in 38%, pear shaped in 12% and narrow-oblong in 4% of cases.

CONCLUSION

Inter-subject variability in the dimensions of cricoid cartilages was observed. The large difference in almost all sizes and shapes of the cricoid cartilage makes it difficult to standardise the rigid stents used in these organs. Endotracheal tubes of the appropriate size should therefore be based on the measurements of individual patients. Clinicians should therefore be aware of morphological variations as they are of fundamental clinical importance.

Respiratory deposition model of an inhaled aerosol bolus

The bolus delivery method is designed to deliver a dose to the desired location in the lung, and it has the advantage of fewer side effects and a more efficient way of delivery. Based upon the lung deposition model developed for continuously inhaling aerosols of constant concentration, a mathematical model of aerosol bolus deposition is proposed. The calculated results show that the recovery depends on the bolus penetration depth, flow rate, particle size, breath holding time and bolus volume. Three sets of published experimental data with different controlling factors (particle size, flow rate and breath holding time) are adopted to make the quantitative comparisons with the calculated results. The predictions and data for the low intrinsic motion particles (∼1 μm) have good agreement, as do the coarse particles in the shallow airways region. For females, the recovery was found to be consistently lower than that for males.

Superior thyroid cornu anatomical variation causing globus pharyngeous and Dysphagia

Objective. Rare case presentation of thyroid cartilage variation causing globus sensation and dysphagia. Method. Case report and review of the literature concerning thyroid cartilage variant of clinical significance. Results. Middle-aged male patient presented with globus sensation and painful swallow without previous injury of the larynx. Clinical examination and diagnostic procedures revealed a rare anatomic aberrance of the thyroid cartilage. Surgical treatment was declined by the patient who accepted a yearly followup. Conclusion. Morphometric studies do not report the dislocation of the superior thyroid cornu, and very few cases have been described either of which were attributed to trauma or to unknown cause. The present case is to be added to the very few cases of superior thyroid cornu dislocation of unknown aetiology. Clinicians should be aware of this rare variation using CT neck as the imaging study of choice. Direct endoscopy rules out any synchronous disease or malignancies.