Morphology of the human larynx during the first five years of life studied on whole organ serial sections

Cognitive Mechanisms in Pediatric Voice Therapy - An Initial Examination

INTRODUCTION

Voice disorders are a common communication disorder in children. Behavioral voice therapy is recommended by both Otolaryngologists and Speech-Language Pathologists as a first-line approach for treatment of benign vocal fold lesions that affect children in large numbers. However, the role of cognitive mechanisms critical to voice therapy have not yet been explored.

OBJECTIVE

This proof-of-concept study aims to provide preliminary data on the potential relation between cognitive abilities and behavioral results of voice therapy for children with benign phonotraumatic vocal fold lesions.

METHODS

Six children (4;05 -9;02 years) diagnosed with vocal fold nodules completed a battery of cognitive tests from the NEuroPSYchological (NEPSY-II) Assessment and a standard course of "Adventures in Voice" therapy. Recordings pre and post intervention were analyzed acoustically using the Cepstral Spectral Index of Dysphonia (CSID) and perceptually using visual analog scales (VAS) for severity and resonance separately. Raw and age-corrected scaled scores from the NEPSY-II were then examined for their possible relation to voice outcomes.

RESULTS

Multiple cognitive functions correlated with voice outcomes. Raw score measures for Design Fluency, Inhibition, Fingertip Tapping, and Narrative Memory correlated favorably with all voice outcome measures. Age correlated with all NEPSY-II raw scores and perceptual voice outcome measures. Scaled scores for Auditory Attention, Design Fluency, Fingertip Tapping (Dominant hand), and Narrative Memory correlated with all voice outcome measures.

CONCLUSION

Results suggest that there is merit to further investigation of the relation between cognitive skills and their development and voice treatment outcomes in children with benign phonotraumatic lesions. Future studies with larger samples will build on present findings.

Acoustic Characteristics of Voice in Teachers and Nonteachers

BACKGROUND

Teachers are professional voice users, and the vocal demands in the teaching profession can be considered unique. All teachers will wish to possess a voluminous, strongly-carrying voice that can be maintained for a prolonged time. This necessitated the need to understand and document the voice-acoustic characteristics of teachers.

OBJECTIVES

The specific objectives were to (a) investigate the acoustic characteristics of teachers' voices, (b) compare voice acoustic characteristics between female and male teachers, and (c) compare acoustic characteristics of voice between teachers and nonteachers.

PARTICIPANTS

Four hundred thirty-nine individuals congregated into two groups. Group 1 had 264 female teachers (mean age: 36.8 years) and 42 male teachers (mean age 36.8 years) with a minimum of 5 years of teaching experience. A hundred females (mean age: 37.3 years) and 33 males (mean age: 36.1 years) adults not indulging in additional, prolonged use of voice were in group 2.

MATERIALS AND METHOD

Sustenance of vowel /a/ for 3 seconds at a comfortable pitch and loudness followed by a monologue on "My school" for 1 minute were audio-recorded at the locations of the participants. Multidimensional Voice Profiles and Real Time Pitch were used to analyze the phonation and monologue samples, respectively.

RESULTS

Revealed that most F0 and its related measures, short- and long-term frequency perturbations were higher in female compared to the male participants. The majority of the acoustic parameters were higher in teachers compared to nonteachers of both sexes.

CONCLUSION

The results, in general, confirmed a few evinced findings in females and males, strengthening the nature-controlled biophysical influence on voice. A few acoustic measures discerned voices of teachers and nonteachers and also females and males in teachers. Nonteachers of both sexes showed better acoustic characteristics of voice against teachers signifying that the extended and prolonged voice use, an occupational demand of the teaching profession, led to vocal loading affecting the acoustic characteristics of teachers' voices.

[Paediatric Airway Surgery - Indications and Techniques]

Even in specialised centres, surgical procedures on the airway are only rarely performed in paediatric patients. Moreover, knowledge of various specific anatomical characteristics, diseases and surgical techniques is a prerequisite to treat these patients. Most commonly, sequelae of long-term intubation or tracheostomy in multimorbid patients necessitate surgical repair. Moreover, congenital malformations of the airways might require surgical interventions. However, these are commonly associated with other organ malformations, which adds further complexity to the treatment concept. Thus, cooperation within an interdisciplinary team is absolutely necessary to treat these patients. However, good postoperative outcomes after paediatric airway surgery can be achieved in experienced centres with an appropriate infrastructure. Specifically, this means long-term tracheostomy-free survival with preserved laryngeal functions in most of the patients. This review provides a summary of common indications and surgical techniques in paediatric airway surgery.

Chondrolaryngoplasty

Chondrolaryngoplasty is a surgical procedure that reduces the prominence of the thyroid notch. Although frequently performed on transgender (man to woman) women, anyone wishing to reduce the prominence of their thyroid notch for aesthetic purposes may consider undergoing a chondrolaryngoplasty. Direct visualization of the vocal cords with flexible laryngoscopy and intraoperative needle localization of the anterior commissure directs the extent of resection, helps increase safety, and avoids devastating postoperative voice complications. This procedure can be safely performed in combination with other facial feminization surgeries.

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.

Comparative Analysis of Two Methods of Perceptual Voice Assessment

OBJECTIVES

The primary aim was to compare two methods for perceptual evaluation of voice - paired comparison (PC) and visual analog scale (VAS) ratings. Secondary aims were to assess the correspondence between two dimensions of voice- overall severity of voice quality and resonant voice, and to investigate the influence of rater experience on perceptual rating scores and rating confidence scores.

STUDY DESIGN

Experimental design.

METHODS

Voice samples from six children (pre and post therapy) were rated by 15 Speech-Language Pathologists specialized in voice. Raters completed four tasks corresponding to the two rating methods and voice qualities: PC-severity, PC-resonance, VAS-severity, and VAS-resonance. For PC tasks, raters chose the better of two voice samples (better voice quality or better resonance, depending on the task) and indicated the degree of confidence in each choice. Rating and confidence score were combined to produce a number on a 1-10 scale (PC-confidence adjusted). VAS ratings involved rating voices on a scale for degree of severity and resonance, respectively.

RESULTS

PC-confidence adjusted and VAS ratings were moderately correlated for overall severity and also vocal resonance. VAS ratings were normally distributed and had greater rater consistency than PC-confidence adjusted ratings. VAS scores reliably predicted binary PC choices (choice of voice sample only). Overall severity and vocal resonance were weakly correlated and rater experience was not linearly related to rating scores or confidence.

CONCLUSIONS

Results suggest that the VAS rating method holds advantages over PC, including normally distributed ratings, superior consistency of ratings, and the ability to provide more finely grained detail regarding the auditory perception of voice. Overall severity and vocal resonance were not redundant in the current data set, suggesting that resonant voice and overall severity are not isomorphic. Finally, the number of years of clinical experience was not linearly related to perceptual ratings or rating confidence.

Pädiatrische Atemwegschirurgie: Indikationen und Techniken

In der pädiatrischen Atemwegschirurgie sind zahlreiche anatomische Besonderheiten, spezifische Krankheitsbilder sowie spezielle Operationstechniken zu beachten. Auch an spezialisierten Zentren sind diese Eingriffe bei pädiatrischen Patienten eher selten. Ätiologisch handelt es sich meist um erworbene Stenosen als Folge von Frühgeburtlichkeit, Langzeitintubation oder -tracheotomie, welche typischerweise in Kindern mit zahlreichen Komorbiditäten auftreten. Kongenitale Fehlbildungen der Atemwege gehen häufig mit weiteren Malformationen einher, welche die erfolgreiche Behandlung zusätzlich erschweren. Voraussetzung zur Behandlung dieser Kinder sollte daher ein multidisziplinäres Team sein. An erfahrenen Zentren mit entsprechender Infrastruktur kann die chirurgische Behandlung dieser Kinder mit sehr guten Ergebnissen durchgeführt werden. So wird bei den meisten Patienten nach chirurgischer Behandlung eine sehr gute Lebensqualität ohne Notwendigkeit einer Langzeittracheostomie erreicht. Diese Übersichtsarbeit fasst die wichtigsten Indikationen, sowie die häufigsten Operationstechniken in der pädiatrischen Atemwegschirurgie zusammen.

Computational Fluid Dynamic Modeling Reveals Nonlinear Airway Stress during Trachea Development

Normative trachea dimensions and aerodynamic information during development was collected to establish clinical benchmarks and showed that airway development seems to outpace respiratory demands. Infants and toddlers' trachea exhibit higher aerodynamic stress that significantly decreases by teenage years. This implies large airway pathology in younger children may have a more substantial clinical impact.

High-resolution magnetic resonance and mass spectrometry imaging of the human larynx

High-resolution, noninvasive and nondestructive imaging of the subepithelial structures of the larynx would enhance microanatomic tissue assessment and clinical decision making; similarly, in situ molecular profiling of laryngeal tissue would enhance biomarker discovery and pathology readout. Towards these goals, we assessed the capabilities of high-resolution magnetic resonance imaging (MRI) and matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) imaging of rarely reported paediatric and adult cadaveric larynges that contained pathologies. The donors were a 13-month-old male, a 10-year-old female with an infraglottic mucus retention cyst and a 74-year-old female with advanced polypoid degeneration and a mucus retention cyst. MR and molecular imaging data were corroborated using whole-organ histology. Our MR protocols imaged the larynges at 45-117 μm² in-plane resolution and capably resolved microanatomic structures that have not been previously reported radiographically-such as the vocal fold superficial lamina propria, vocal ligament and macula flavae; age-related tissue features-such as intramuscular fat deposition and cartilage ossification; and the lesions. Diffusion tensor imaging characterised differences in water diffusivity, primary tissue fibre orientation, and fractional anisotropy between the intrinsic laryngeal muscles, mucosae and lesions. MALDI-MS imaging revealed peptide signatures and putative protein assignments for the polypoid degeneration lesion and the N-glycan constituents of one mucus retention cyst. These imaging approaches have immediate application in experimental research and, with ongoing technology development, potential for future clinical application.

Age and Sex Comparison of Aerodynamic Phonation Measurements Using Noninvasive Assessment

Purpose The goal of this study was to present vocal aerodynamic measurements from pediatric and adult participant pools. There are a number of anatomical changes involving the larynx and vocal folds that occur as children age and become adults. Data were collected using two methods of noninvasive aerodynamic assessment: mechanical interruption and labial interruption. Method A total of 154 participants aged 4-24 years old took part in this study. Ten trials were performed for both methods of airway interruption. To perform mechanical interruption, participants phonated /α/ for 10 s trials while a balloon valve interrupted phonation 5 times. For labial interruption, participants said /pα/ 5 times at comfortable and quiet volumes. Aerodynamic measures included subglottal pressure, phonation threshold pressure, mean airflow, laryngeal resistance, and others. Results One hundred one participants (51 females) successfully completed testing with both methods. Eight out of 20 measurements were found to have a statistically significant effect of participant age on measurements. Sex alone had a significant effect on vocal efficiency for the labial quiet method. Conclusions The data discussed here can be used to view age and sex trends in vocal aerodynamic measurements. When using either method of mechanical or labial interruption, participant age needs to be taken into account to properly interpret several aerodynamic parameters. A participant's sex is not as important when using these methods.

Treatment of tracheal stenosis with extracorporeal membrane oxygenation support in infants and newborns

Tracheal stenosis in children is a challenge for the healthcare team, since it is a rare disease. Patients usually have other clinical comorbidities, mainly previous cardiac surgical interventions. This retrospective single-center study included infants with tracheal stenosis (congenital or acquired) operated between 2016 and 2020 on venoarterial extracorporeal membrane oxygenation (VA ECMO). Five patients were operated and the median age of detection of the tracheal disease was 3.7 months, and the median age at the operation was 5 months. All patients had associated cardiac anomalies. Four patients had congenital tracheal stenosis; two with associated pig bronchus. One patient had acquired subglottic stenosis with concomitant stenosis at the carina. After the operation, the patients were referred to ICU on ECMO with an open chest. Minor ECMO-related complications occurred in two patients (hemothorax and wound infection). All patients required endoscopic evaluation during the postoperative care; median of 3.2 procedures. Two patients are currently in follow-up and three have died. Slide tracheoplasty with VA-ECMO can be successfully performed in infants with prior cardiac surgery. Nevertheless, a difficult postoperative course should be anticipated, with possible prolonged ECMO use, readmissions, and higher morbidity and mortality than in children with tracheal stenosis alone.

Analyzing Longitudinal Data on Singing Voice Parameters of Boys and Girls Aged 8 to 12.5 and Possible Effects of a Music Pedagogical Intervention

OBJECTIVE

Controlled and randomized study to analyze longitudinal voice data of boys and girls aged 8-12.5, to describe their physiological development and to evaluate the influence of a one-year music pedagogical interventional program focused on the singing voice.

METHODS

Singing voice profiles of 116 children (52 boys, 64 girls) aged 8-12.5 years were collected longitudinally at the beginning and the end of the third school year and the end of the fourth school year. 64 of the 116 children received a music pedagogical program during their third school year (interventional group). Maximum and minimum voice intensity, highest and lowest frequency, maximum phonation time (MPT) and Jitter were investigated.

RESULTS

In two years' time highest frequency increased on average by 100.23 Hz from G1 up to A1 for boys and for girls. Lowest frequency decreased by 18.36Hz from Gis-1 to G-1 (boys: Gis-1-Fis-1; girls: A-1-G-1). There was no clinically relevant development of the intensity parameters for both sexes. However, after the interventional year, minimum voice intensity significantly decreased in the interventional group compared to the control group. The MPT increased by 2.41 seconds from 10.67 seconds up to 13.09 seconds in two years. Here the increase was higher for boys (+3.2 seconds) than for girls (+1.77 seconds). Jitter was found to be 0.84%-1.11%, showing no clinically relevant changes in two years.

CONCLUSION

To the best of our knowledge, for the first time this study presents longitudinal data on singing voice parameters of the voice range profile of boys and girls aged 8-12.5 years. While frequency and intensity parameters develop equally for boys and girls, the MPT is found to develop more distinctly within boys. A music pedagogical intervention of a small extent has a positive effect on the ability to sing as soft as possible.

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.

Keyhole anesthesia-Perioperative management of subglottic stenosis: A case report

Any narrowing in the airway presents as obstruction and with features of noisy breathing. The presence of subglottic stenosis poses a great challenge to the anesthesiologist. Diagnostic and corrective procedures by Otolaryngologist require rigid endoscopy which demands apneic ventilation. Hence, the goal of general anesthesia in the presence of subglottic stenosis requires a patent airway to maintain oxygenation and ventilation and avoid hypoxia. We present an interesting case of a preterm neonate with subglottic stenosis who was managed successfully with endoscopic release.

Developmental changes of upper airway dimensions in children

BACKGROUND

Knowledge about airway dimensions during child growth is of paramount importance for pediatric clinical practice. Decisions about airway management in children are based on relatively limited, imprecise, or incomplete data about airway size.

AIMS

The aim of this work was to determine the anatomical development and size of airway structures from birth to adolescence using high-resolution computed tomography scans and to study the correlation between airway measurements and biometric data.

METHODS

We conducted a retrospective study of all high-resolution computed tomography scans including the respiratory tract, performed in our tertiary pediatric center (for reasons unrelated to airway symptoms) between June 1, 2016, and October 15, 2017, on children aged from 1 day to 14 years old. On each scan, 23 measurements of the larynx, trachea, and mainstem bronchi were performed. Patients were stratified into 16 groups according to their age. We calculated median value for each measurement in each group. Statistical models were calculated to explore correlation between measurements and age or weight.

RESULTS

A total of 192 scans were included (127 boys/65 girls). The mean age was 7 years. The correlations between airway measurements and age or weight were always significant. The relationship between measurements and age was found to be suitably represented by a cubic polynomial equation suggesting that the airway has a rapid growth phase in the first 3 years, followed by a slow growth phase and a second rapid growth phase during adolescence. The most relevant biometric parameter was age concerning 21 of the measurements.

CONCLUSION

This comprehensive anatomical database of upper airway dimensions provides important data in the field of pediatric airway anatomy, particularly relating to the cricoid. We demonstrated that laryngeal, tracheal, and bronchial parameters correlate better to age and have three different growth phases.

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.

Pediatric airway dimensions-A summary and presentation of existing data

BACKGROUND

Age-related pediatric airway dimension reference values for cricoid, tracheal, and bronchial diameters as well as tracheal and bronchial lengths are essential for distinguishing normal from pathological airway findings and for manufacturing and selecting appropriately sized airway equipment.

AIM

The aim of this work was to summarize and present existing pediatric airway dimension data for the larynx, trachea, and main stem bronchi from fetus to adolescence.

METHODS

A systematic literature search was carried out using PubMed, Scopus, Embase, and Google Scholar. Publications containing original data on pediatric airway dimensions as mean or median in tabular form and spanning narrow age groups of 1 or 2 years were included in our study. Original data such as diameters, lengths, and cross-sectional areas of trachea, cricoid, left and right main bronchi in fetuses and children were collected and presented as figures.

RESULTS

Pediatric airway dimension data were gathered and compiled from 15 studies fulfilling the inclusion criteria. Data were obtained from different measurement methods such as autopsy, chest X-ray, computed tomography, magnetic resonance imaging, rigid and flexible bronchoscopy as well as ultrasound examinations. There was considerable variation among age-related data due to biologic heterogeneity, different presentation of data, different definitions, and various measurement techniques.

CONCLUSION

This investigation revealed heterogeneous data on pediatric airway dimensions, making it impossible to compile them into standard reference values for airway dimensions. New studies with structured and standardized measurements and data presentation in large populations of children are required to provide more valid pediatric airway dimension data.

The influence of premature birth on laryngeal development for phonation

INTRODUCTION

Dysphonia is a known consequence of premature birth, and is usually associated with endotracheal intubation in the neonatal period or surgical ligation of persistent patent ductus arteriosus. Recently, cases of dysphonia, in the absence of these causative factors, have been reported.

OBJECTIVES

This review seeks to identify literature pertaining to those aspects of laryngeal development that may potentially be disrupted by premature birth. The purpose of the review is to determine whether there is any possible anatomical or physiological explanation for dysphonia to arose solely from premature birth.

METHODS

This scoping review was conducted in accordance with the guidelines prescribed by Arskey and O'Malley (2005). Fifteen relevant papers were identified. Results were categorized into age-related categories, to identify changes in the developmental trajectory. Based on the results of the literature search, a further category of unphonated larynges was added.

RESULTS

Potential differences in the laryngeal framework (e.g., the development of the cricoid cartilage and the shape of the glottis) and vocal fold histology, depending on gestational age and post-natal phonation were identified. Much literature focused on the macula flavae, however, the layers of the lamina propria were also discussed.

DISCUSSION

It is unclear whether the process of differentiation of the layers of the lamina propria, which commences in the second to third months of life in term-born infants, is disrupted by prematurity. Further, development of the macula flavae continues until at least 28 weeks' gestation. Preterm children may not phonate immediately after birth, which may also affect laryngeal development.

The pediatric airway: Historical concepts, new findings, and what matters

New observations from novel imaging techniques regarding the anatomy, dimensions, and shape of the pediatric airway have emerged and provide insight for potential changes in the clinical management of the airway in infants and children. These new findings are challenging the historical concepts of a funnel-shaped upper airway with the cricoid ring as the narrowest dimension. Although these tenets have been accepted and used to guide clinical practice in airway management, there are limited clinical investigations in children to support the validity of these concepts. Imaging modalities such as magnetic resonance imaging, computed tomography (CT) scanning, multi-detector CT imaging, and videobronchoscopy suggest the need to revisit the historical view of the pediatric airway. This manuscript reviews the historical evolution of pediatric airway studies, summarizes important scientific observations from recent investigations relevant to our clinical understanding of pediatric airway anatomy, and discusses the importance of these findings for pediatric airway management.

Medialization Laryngoplasty in Pediatric Patients With Unilateral Vocal Fold Immobility: A Case Series

Objectives:

The aims of this study were to describe the impact of laryngoplasty in pediatric unilateral vocal fold immobility (UVFI) and to determine the impact of etiology and technique on voice and swallowing.

Methods:

A retrospective review was conducted of all children with UVFI undergoing medialization laryngoplasty at a pediatric hospital (2010-2017). Data including demographics, etiology, subjective voice quality, and swallowing function were collected.

Results:

The median age at first surgery among 25 patients with UVFI was 11 years (range, 1.2-25 years). The causes of UVFI were iatrogenic (76%), congenital (16%), and idiopathic (8%). A total of 38 laryngoplasties (24 injections, 11 Silastic implants, 3 Gore-Tex) were performed. Postoperatively, 78% of patients reported improvements in voice and 81% in swallowing. The median duration of voice improvement was 1.0 years (range, 0.1-10 years), with no significant difference by etiology or laryngoplasty technique. Patients who were ⩾10 years of age at surgery reported voice improvement significantly more often than patients <10 years of age at surgery (94% vs 61%, P = .04).

Conclusions:

UVFI has a significant impact on health and quality of life. In this study we found that laryngoplasty is an effective way to address both voice and swallowing in pediatric UVFI. A greater proportion of children with improved voice quality were older at injection. Surprisingly, there was no difference in duration of voice improvement between permanent and absorbable materials. Although this duration would be considered acceptable for many injectable materials, the limited duration in permanent implantation techniques may represent the challenges of managing UVFI in the growing larynx of the pediatric population. Injection laryngoplasty with absorbable materials may serve as an adequate method of addressing UVFI in this population.

Selection of cuffed endotracheal tube for children with congenital heart disease based on an ultrasound-based linear regression formula

It remains to be discovered whether a formula predicting the subglottic transverse diameter measured by ultrasound (SGD_formula) for the selection of an appropriate endotracheal tube (ETT) for children without congenital heart disease (CHD) is useful for children with CHD. A formula for predicting SGD was established after assessing 60 children ≤ 8 years without CHD and validated on 60 children with CHD. We selected the cuffed ETT size based on the SGD by ultrasound (SGD_ultra). Subsequently, the fit of the ETT cuff in 60 children with CHD was examined via air-leak test. The maximum allowed difference between the SGD_formula and the ETT size that fit was 0.2 mm. The agreement among and accuracy of SGD_ultra, SGD_formula, and the ETT used in children was analyzed. For children without CHD, we adopted a linear formula, given by SGD_formula (mm) = 0.4 × age + 5.3. For children with CHD, allometric formula was adopted, given by SGD_formula (mm) = 5.4 × age^0.18. A stronger agreement exists between SGD_ultra and ETT size compared to that between SGD_formula and ETT size. And the mean bias (SGD_formula-ETT size and SGD_ultra-ETT size) was 0.21 mm (95% confidence interval, - 0.59 to 1.01 mm) and 0.00 mm (- 0.79 to 0.84 mm). For the CHD group, the ultrasound-based method yielded a 78% success rate of ETT size choice, while the formula-based method permitted an appropriate ETT size in only 32% of subjects (P < 0.001). Our analysis showed that measuring the SGD_ultra was more accurate in predicting the correct OD of the ETT in children with CHD undergoing cardiovascular surgery, based on the correlation and agreement with ETT OD.

Airway dimensions from fetal life to adolescence-A literature overview

BACKGROUND

Data on airway dimensions in pediatric patients are important for proper selection of pediatric airway equipment such as endotracheal tubes, double-lumen tubes, bronchial blockers, or stents. The aim of the present work was to provide a synopsis of the available data on pediatric airway dimensions.

METHODS

A systematic literature search was carried out in the PubMed database, Scopus, Embase, Web of Science, Prisma, and Google Scholar and secondarily completed by a reference search. Based on inclusion and exclusion criteria, a final selection of 109 studies with data on pediatric airway dimensions published from 1923 to 2018 were further analyzed.

RESULTS

Six different airway measurement methods were identified. They included anatomical examinations, chest X-ray, computed tomography, magnetic resonance tomography, bronchoscopy, and ultrasound. Anatomical studies were more abundant compared to other methods. Data provided were very heterogeneously presented and powered. In addition, due to different study conditions, they are hardly comparable. Among all, anatomical and computer tomography studies are thought to provide the most reliable data. Ultrasound is an upcoming technique to estimate airway parameters of fetus and premature infants. There was, in general, a lack of comprehensive studies providing a complete range of airway dimensions in larger groups of patients from birth to adolescence.

CONCLUSIONS

This work revealed a large heterogeneity of studies providing data on pediatric airway dimensions, making it impossible to compare, or assemble them to normograms for clinical use. Comprehensive studies in large population of children are needed to provide full range nomograms on pediatric airway dimensions.

Analysis of the functionally-narrowest portion of the pediatric upper airway in sedated children

The narrowest portions of the pediatric larynx are the glottis and subglottic region. However, the pliable and paralyzed subglottic region, acting like a curtain, is no resistance when passing an endotracheal tube. Therefore, the 'functionally' portion of the pediatric upper airway, which may be the most vulnerable to damage during intubation, is the unyielding portion below the cricoid cartilage. We investigated the functionally-narrowest portion below the cricoid cartilage.Computed tomography (CT) was performed under deep sedation. CT images were used for measurement of dimensions and cross-sectional area (CSA) of the larynx at the level of the cricoid, subcricoid, and trachea. We analyzed the anteriorposterior (AP) diameter, transverse diameter, and CSA below the cricoid cartilage (at the cricoid, subcricoid, and tracheal levels).CT images of 46 children from 8 months to 96 months were reviewed from electric medical record (EMR). The mean ± SD of AP diameter was the shortest at the subcricoid level (cricoid, 105.7 ± 15.8 mm; subcricoid, 94.6 ± 15.3 mm; and trachea, 101.5 ± 15.7 mm; P < .001). The mean ± SD of transverse diameter was the shortest at the trachea level (cricoid, 99.8 ± 12.2 mm; subcricoid, 102.5 ± 13.7 mm; and trachea, 98.8 ± 10.7 mm; P = .01). The mean ± SD of CSA was the smallest at the subcricoid level (cricoid, 8781.5 ± 1963.3 mm; subcricoid, 8425.0 ± 2025.7 mm; and trachea, 8523.7 ± 1791.1 mm; P = .02). The AP diameter at the subcricoid level was narrower than the transverse diameter at trachea level (mean difference: 4.2 mm, 95% confidence interval [CI]: 0.7-7.7, P = .02).Since the most susceptible portion for airway damage is unyielding portion, our findings suggest that, functionally, the narrowest portion of the pediatric larynx is located in the subcricoid region.

Volume relationships between cricoid and main stem bronchi in children using three-dimensional computed tomography imaging

BACKGROUND

There are limited data to guide the selection of the appropriate sized endobronchial tube for main stem intubation to provide one-lung ventilation in children. The relationship between the cricoid and the main bronchi (right and left) has been previously evaluated using two-dimensional computed tomography (CT) imaging and video-bronchoscopic images. The present study defines the three-dimensional, CT-derived volume-based relationships between the right main-stem bronchus (RMB), left main-stem bronchus (LMB), and the cricoid ring.

METHODS

The three-dimensional CT images of 35 children, less than 8 years of age, undergoing radiological evaluation unrelated to airway or mediastinal symptomatology were examined. The images of the airway column were evaluated at the level of the cricoid and main stem bronchi (right and left). Volumes were calculated and comparisons made between these levels.

RESULTS

There was no statistically significant difference based on gender for the cricoid and main stem bronchi volumes. A statistically significant difference was observed between the cricoid and left main stem bronchi volumes as well as between the right and left main stem bronchi.

CONCLUSION

The relationship (ratio) between the volumes of the cricoid and main stem bronchi remains constant by age. The cricoid dimensions can be used to predict the main stem bronchi dimensions.

The anatomy of the pediatric airway: Has our knowledge changed in 120 years? A review of historic and recent investigations of the anatomy of the pediatric larynx

BACKGROUND

There is disagreement regarding the anatomy of the pediatric airway, particularly regarding the shape of the cricoid cartilage and the location of the narrowest portion of the larynx.

AIMS

The aim of this review is to clarify the origin and the science behind these differing views.

METHODS

We undertook a review of published literature, University Libraries, and authoritative textbooks with key search words and phrases.

RESULTS

In vivo observations suggest that the narrowest portion of the airway is more proximal than the cricoid cartilage. However, in vitro studies of autopsy specimens measured with rods or calipers, confirm that the nondistensible and circular or near circular cricoid outlet is the narrowest level. These anatomic studies confirmed the classic "funnel" shape of the pediatric larynx. In vivo studies are potentially misleading as the aryepiglottic, vestibular, and true vocal folds are in constant motion with respiration. These studies also do not consider the effects of normal sleep, inhalation agents, and comorbidities such as adenoid or tonsil hypertrophy that cause some degree of pharyngeal collapse and alter the normal movement of the laryngeal tissues. Thus, the radiologic studies suggesting that the narrowest portion of the airway is not the cricoid cartilage may be the result of an artifact depending upon which phase of respiration was imaged.

CONCLUSION

In vivo studies do not take into account the motion of the highly pliable laryngeal upper airway structures (aryepiglottic, vestibular, and vocal folds). Maximal abduction of these structures with tracheal tubes or bronchoscopes always demonstrates a larger opening of the glottis compared to the outlet of the cricoid ring. Injury to the larynx depends upon ease of tracheal tube or endoscope passage past the cricoid cartilage and not passage through the readily distensible more proximal structures. The infant larynx is funnel shaped with the narrowest portion the circular or near circular cricoid cartilage confirmed by multiple in vitro autopsy specimens carried out over the past century.

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.

Pediatric airway surgery

The management of pediatric airway pathology can be challenging and requires a dedicated team, consisting of thoracic surgeons, phoniatricians, logopedics, pediatricians and anesthetists. It necessitates a tailored treatment approach for each individual patient in order to address the minor variances that exist between cases. The majority of pediatric airway problems are a sequela of prematurity and prolonged post-partal intubation/tracheostomy. Surgical repair is often complicated by additional malformation or severe comorbidities. This comprehensive review should give an overview on most common airway problems in neonates and children as well as available surgical techniques.

Vibratory onset and offset times in children: A laryngeal imaging study

OBJECTIVES

The aim of the study was to evaluate the differences in vibratory onset and offset times across age (adult males, adult females, and children) and waveform types (total glottal area waveform, left glottal area waveform, and right glottal area waveform) using high-speed videoendoscopy.

METHODS

In this prospective study, vibratory onset and offset times were evaluated in a total of 86 participants. Forty-three children (23 girls, 18 boys) between 5 and 11 years and 43 gender matched vocally normal young adults (23 females and 18 males) in the age range (21-45 years) were recruited. Vibratory onset and offset times were calculated in milliseconds from the total, left, and right Glottal Area Waveform (GAW). A two-factor analysis of variance was used to compare the means among the subject groups (children, adult male, and adult female) and waveform type (total GAW, left GAW, right GAW) for onset and offset variables. Post hoc analyses were performed using the Fishers Least Significant Different test with Bonferroni correction for multiple comparisons.

RESULTS

Children exhibited significantly shorter vibratory onset and offset times compared to adult males and females. Differences in vibratory onset and offset times were not statistically significant between adult males and females. Across all waveform types (i.e. total GAW, left GAW, and right GAW), no statistical significance was observed among the subject groups.

CONCLUSION

This is the first study reporting vibratory onset and offset times in the pediatric population. The study findings lay the foundation for the development of a large age- and gender-based database of the pediatric population to aid the study of the effects of maturation of vocal fold vibration in adulthood. The findings from this study may also provide the basis for evaluating the impact of numerous lesions on tissue pliability, and thereby has potential utility for the clinical differentiation of various lesions.

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.

Formant measurement in children's speech based on spectral filtering

Children's speech presents a challenging problem for formant frequency measurement. In part, this is because high fundamental frequencies, typical of a children's speech production, generate widely spaced harmonic components that may undersample the spectral shape of the vocal tract transfer function. In addition, there is often a weakening of upper harmonic energy and a noise component due to glottal turbulence. The purpose of this study was to develop a formant measurement technique based on cepstral analysis that does not require modification of the cepstrum itself or transformation back to the spectral domain. Instead, a narrow-band spectrum is low-pass filtered with a cutoff point (i.e., cutoff "quefrency" in the terminology of cepstral analysis) to preserve only the spectral envelope. To test the method, speech representative of a 2-3 year-old child was simulated with an airway modulation model of speech production. The model, which includes physiologically-scaled vocal folds and vocal tract, generates sound output analogous to a microphone signal. The vocal tract resonance frequencies can be calculated independently of the output signal and thus provide test cases that allow for assessing the accuracy of the formant tracking algorithm. When applied to the simulated child-like speech, the spectral filtering approach was shown to provide a clear spectrographic representation of formant change over the time course of the signal, and facilitates tracking formant frequencies for further analysis.

Learning to Produce Syllabic Speech Sounds via Reward-Modulated Neural Plasticity

At around 7 months of age, human infants begin to reliably produce well-formed syllables containing both consonants and vowels, a behavior called canonical babbling. Over subsequent months, the frequency of canonical babbling continues to increase. How the infant's nervous system supports the acquisition of this ability is unknown. Here we present a computational model that combines a spiking neural network, reinforcement-modulated spike-timing-dependent plasticity, and a human-like vocal tract to simulate the acquisition of canonical babbling. Like human infants, the model's frequency of canonical babbling gradually increases. The model is rewarded when it produces a sound that is more auditorily salient than sounds it has previously produced. This is consistent with data from human infants indicating that contingent adult responses shape infant behavior and with data from deaf and tracheostomized infants indicating that hearing, including hearing one's own vocalizations, is critical for canonical babbling development. Reward receipt increases the level of dopamine in the neural network. The neural network contains a reservoir with recurrent connections and two motor neuron groups, one agonist and one antagonist, which control the masseter and orbicularis oris muscles, promoting or inhibiting mouth closure. The model learns to increase the number of salient, syllabic sounds it produces by adjusting the base level of muscle activation and increasing their range of activity. Our results support the possibility that through dopamine-modulated spike-timing-dependent plasticity, the motor cortex learns to harness its natural oscillations in activity in order to produce syllabic sounds. It thus suggests that learning to produce rhythmic mouth movements for speech production may be supported by general cortical learning mechanisms. The model makes several testable predictions and has implications for our understanding not only of how syllabic vocalizations develop in infancy but also for our understanding of how they may have evolved.

Whats special in a child's larynx?

What's special in a child's larynx? Many of us know only a few specialties of the pediatric larynx, but there are much more features, which are unique and often not highlighted. To understand the pediatric larynx, we have reviewed the development, the functions in-utero and new born period and peculiarities.

Kinematic measurements of the vocal-fold displacement waveform in typical children and adult populations: quantification of high-speed endoscopic videos

PURPOSE

This article presents a quantitative method for assessing instantaneous and average lateral vocal-fold motion from high-speed digital imaging, with a focus on developmental changes in vocal-fold kinematics during childhood.

METHOD

Vocal-fold vibrations were analyzed for 28 children (aged 5-11 years) and 28 adults (aged 21-45 years) without voice disorders. The following kinematic features were analyzed from the vocal-fold displacement waveforms: relative velocity-based features (normalized average and peak opening and closing velocities), relative acceleration-based features (normalized peak opening and closing accelerations), speed quotient, and normalized peak displacement.

RESULTS

Children exhibited significantly larger normalized peak displacements, normalized average and peak opening velocities, normalized average and peak closing velocities, peak opening and closing accelerations, and speed quotient compared to adult women. Values of normalized average closing velocity and speed quotient were higher in children compared to adult men.

CONCLUSIONS

When compared to adult men, developing children typically have higher estimates of kinematic features related to normalized displacement and its derivatives. In most cases, the kinematic features of children are closer to those of adult men than adult women. Even though boys experience greater changes in glottal length and pitch as they mature, results indicate that girls experience greater changes in kinematic features compared to boys.

Subglottic stenosis and socio-economic deprivation: a 6-year review of the Scottish National Service for Paediatric Complex Airway Reconstruction

OBJECTIVE

Subglottic stenosis is the third most common cause of stridor in children, and severe cases may need surgical reconstruction. Babies born to parents in high-deprivation areas are at increased risk of prematurity and low birth weight. This may require intensive care admission with prolonged intubation, hence, putting them at increased risk of subglottic stenosis. We aimed to review cases of subglottic stenosis requiring surgical intervention in the Scottish population and its association with socio-economic deprivation.

METHODS

We collected retrospective data on all children who underwent open reconstructive surgery for subglottic stenosis between January 2005 and January 2011 at the Royal Hospital for Sick Children, Yorkhill, which provides the national complex airway reconstruction service for Scotland. The Scottish Index of Multiple Deprivation (SIMD) was used to categorise deprivation based on the child's home postal code. Incidence figures were calculated based on the total number of births in each deprivation category over the time period.

RESULTS

There were a total of 53 cases of subglottic stenosis undergoing surgery in Scotland over the last 6 years, of which 31 were acquired and 22 were congenital. The most common procedure performed was laryngotracheal reconstruction with cartilage grafts (46 cases). No association was found between deprivation and the incidence of acquired or congenital subglottic stenosis.

CONCLUSION

Our data is the first attempt to review the incidence of subglottic stenosis in the Scottish population and its association with deprivation. Perhaps surprisingly, we found no association.

Spatiotemporal analysis of vocal fold vibrations between children and adults

OBJECTIVES/HYPOTHESIS

Aim of the study is to quantify differences in spatiotemporal features of vibratory motion in typically developing prepubertal children and adults with use of high speed digital imaging.

STUDY DESIGN

Prospective case-control study.

METHODS

Vocal fold oscillations of 31 children and 35 adults were analyzed. Endoscopic high-speed imaging was performed during sustained phonation at typical pitch and loudness. Quantitative technique of Phonovibrogram was used to compute spatiotemporal features. Spatial features are represented by opening and closing angles along the anterior and posterior parts of the vocal folds, as well as by left-right symmetry ratio. Temporal features are represented by the cycle-to-cycle variability of the spatial features. Group differences (adult females, adult males, and children) were statistically investigated.

RESULTS

Statistical differences were more pronounced in the temporal behavior compared to the spatial behavior. Children demonstrated greater cycle-to-cycle variability in oscillations compared to adults. Most differences between children and adults were found for temporal characteristics along the anterior parts during closing phase. The spatiotemporal features differed more between children and males than between children and females. Both adults and children showed equally high left-right symmetry.

CONCLUSIONS

Results suggest a more unstable phonation in children than in adults, yielding increased perturbation in periodicity. Children demonstrated longer phase delay in the anterior/posterior and medio-lateral parts during the opening phase compared to adults. The data presented may provide the bases for differentiating normal vibratory characteristics from the disordered in the pediatric population, and eventually assist in aiding the clinical utility of high speed imaging.

Pediatric high speed digital imaging of vocal fold vibration: a normative pilot study of glottal closure and phase closure characteristics

OBJECTIVE

The aim of the study is to characterize normal vibratory patterns of both glottal closure and phase closure in the pediatric population with the use of high speed digital imaging.

METHODS

For this prospective study a total of 56 pre-pubertal children, 5-11 years (boys=28, girls=28) and 56 adults, 21-45 years (males=28, females=28) without known voice problems were examined with the use of a new technology of high speed digital imaging. Recordings were captured at 4000 frames per second for duration of 4.094 s at participants' typical phonation. With semi-automated software, montage analysis of glottal cycles was performed. Three trained experienced raters, rated features of glottal configuration and phase closure from glottal cycle montages.

RESULTS

Posterior glottal gap was the predominant glottal closure configuration in children (girls=85%, boys=68%) with normal voice. Other glottal configurations observed were: anterior gap (girls=3.6%, boys=0%), complete closure (girls=7%, boys=10%) and hour glass (girls=0%, boys=11%). Adults with normal voice also demonstrated predominantly higher percentage of posterior glottal gap configuration (females=75% male=54%) compared to the configurations of anterior gap (females=0% male=7%), complete closure (females=2% male=39%), hour glass (females=3.6% male=3.6%). A predominantly open phase (51-70% of the glottal cycle) was observed in 86% girls and 71% boys. Compared to children, adult females showed a predominantly balance phased closure 46%, followed by open phase (39%) and predominantly closed phase (14%). Adult males showed a predominantly closed phase (43%), followed by predominantly open phase (39%), followed by a balanced phase (18%).

CONCLUSIONS

This is a first study investigating characteristics of normal vibratory motion in children with high speed digital imaging. Glottal configuration and phase closure for children with normal voices are distinctly different compared to adults. The results suggest that posterior glottal gap and a predominantly open phase of the glottal cycle should be considered as normal glottal configuration in children during modal pitch and loudness. This study provides preliminary information on the vibratory characteristics of children with normal voice. The data presented here may provide the bases for differentiating normal vibratory characteristics from the disordered in the pediatric population.

Laser projection imaging for measurement of pediatric voice

OBJECTIVES/HYPOTHESIS

The aim of the study was to present the development of a miniature laser projection endoscope and to quantify vocal fold length and vibratory amplitude of the pediatric glottis using high-speed digital imaging coupled with the laser endoscope.

STUDY DESIGN

For this prospective study, absolute measurement of entire vocal fold length, membranous length of the vocal fold, and vibratory amplitude during phonation were obtained in one child (9 years old), one adult male (36 years old), and one adult female (20 years old) with the use of high-speed digital imaging, coupled with a custom-developed laser projection endoscope.

METHODS

The laser projection system consists of a module slip-fit sleeve with two 3-mW 650-nm laser diodes in horizontal orientation separated by a distance of 5 mm. Calibration involved projecting the laser onto grid patterns at depths ranging from 6 to 10 cm and tilt angles of 15 to -5 degrees to obtain pixel-to-millimeter conversion templates. Measurements of vocal fold length and vibratory amplitude were extracted based on methods of image processing.

RESULTS

The system demonstrated a method for estimating vocal fold length and vibratory amplitude with a single laser point with high measurement precision. First measurements of vocal fold length (6.8 mm) and vibratory amplitude (0.25 mm) during phonation in a pediatric participant are reported.

CONCLUSIONS

The proposed laser projection system can be used to obtain absolute length and vibratory measurements of the pediatric glottis. The projection system can be used with stroboscopy or high-speed digital imaging systems with a 70-degree rigid endoscope.

Prenatal and early postnatal morphogenesis and growth of human laryngotracheal structures

Advances in neonatal medicine have resulted in increased care of fetal and neonatal airways. These advances have required an exhaustive knowledge of fetal airway anatomy and development. The aim of this study was to determine the anatomical development of laryngotracheal structures during the fetal and immediate postnatal period and to correlate these observations with other fetal biometric parameters to estimate developmental particularities of the fetal airway. An anatomical prospective study was based on examination of larynx and trachea from 300 routine autopsies of fetuses and infants, free of malformation and never intubated. Anatomical measurements of cricoid cartilage, thyroid cartilage, glottis, arytenoid cartilage and trachea were performed using a precision calliper and precision divider. Statistical analysis was performed to represent the growth of anatomical structures and to evaluate the correlation with biometric data. Raw data and 10th and 90th percentile curves were fitted satisfactorily with a linear model for gestational age. A linear relationship between laryngotracheal measurement and body weight and height was observed except for glottis length, interarytenoid distance and anterior cricoid height. The diameter of the cricoid lumen was significantly less than that of the trachea and glottis lumen. A sexual dysmorphism was noted for thyroid cartilage measurements and interarytenoid distance, with measurements significantly smaller in females. This study reports the anatomical development of normal laryngotracheal structures during the fetal period. Despite the fact that this study was performed during postmortem examination, these observations can be useful to develop criteria, materials and surgical procedures adapted to fetal and neonatal airways as well as for the purposes of early diagnosis and management of laryngotracheal malformations.

Pediatric laryngeal dimensions: an age-based analysis

BACKGROUND

In children, the cricoid is considered the narrowest portion of the "funnel-shaped" airway. Growth and development lead to a transition to the more cylindrical adult airway. A number of airway decisions in pediatric airway practice are based on this transition from the pediatric to the adult airway. Our primary aim in this study was to measure airway dimensions in children of various ages. The measures of the glottis and cricoid regions were used to determine whether a transition from the funnel-shaped pediatric airway to the cylindrical adult airway could be identified based on images obtained from video bronchoscopy.

METHODS

One hundred thirty-five children (ASA physical status 1 or 2) aged 6 mo to 13 yr were enrolled for measurement of laryngeal dimensions, including cross-sectional area (G-CSA), anteroposterior and transverse diameters at the level of the glottis and the cricoid (C-CSA), using the video bronchoscopic technique under general anesthesia.

RESULTS

Of the 135 children enrolled in the study, seven patients were excluded from the analysis mainly because of poor image quality. Of the 128 children studied (79 boys and 49 girls), mean values (+/-standard deviation) for the demographic data were age 5.9 (+/-3.3) yr, height 113.5 (+/-22.2) cm and weight 23.5 (+/-13) kg. Overall, the mean C-CSA was larger than the G-CSA (48.9 +/- 15.5 mm(2) vs 30 +/- 16.5 mm(2), respectively). This relationship was maintained throughout the study population starting from 6 mo of age (P < 0.001, r = 0.45, power = 1). The mean ratio for C-CSA: G-CSA was 2.1 +/- 1.2. There was a positive correlation between G- and the C-CSA versus age (r = 0.36, P < 0.001; r = 0.27, P = 0.001, respectively), height (r = 0.34, P < 0.001; r = 0.29, P < 0.001, respectively), and weight (r = 0.35, P < 0.001; r = 0.25, P = 0.003, respectively). No significant gender differences in the mean values of the studied variables were observed.

CONCLUSION

In this study of infants and children, the glottis rather than cricoid was the narrowest portion of the pediatric airway. Similar to adults, the pediatric airway is more cylindrical than funnel shaped based on these video bronchoscopic images. Further studies are needed to determine whether these static airway measurements in anesthetized and paralyzed children reflect the dynamic characteristics of the glottis and cricoid in children.

Normal Voice in Children Between 6 and 12 Years of Age: Database and Nonlinear Analysis

This study was carried out using a transversal design. It aimed to investigate possible changes of the normal voice in children before mutation, to create a database for the parameters used in the study, and to examine the use of fractal dimension and the largest Lyapunov exponent (LLE) in the assessment of nonpathological phenomena. Two hundred twelve children were enrolled: 111 females and 101 males; and 9 six-year-olds, 24 seven-year-olds, 18 eight-year-olds, 25 nine-year-olds, 27 ten-year-olds, 55 eleven-year-olds, and 54 twelve-year-olds. Fundamental frequency (Fo) decreased with age and was lower in boys than in girls. Jitter and shimmer did not significantly differ with age or gender. Fractal dimension and LLE were significantly lower in boys; LLE decreased with age. The present series confirmed the established findings that Fo is lower in boys than in girls, even before mutation, and decreases with age; two other classical voice analysis parameters, jitter and shimmer, also showed the same behavior as described in the literature. The study of nonlinear parameters (fractal dimension and LLE) showed that laryngeal dynamics is more stable in boys than in girls, and that stability is correlated with age.

Upper airway dimensions in children using rigid video-bronchoscopy and a computer software: description of a measurement technique

BACKGROUND

Pediatric airway management decisions are based primarily on results derived from indirect measures of laryngeal and tracheal dimensions. More recent methods could provide more direct information about absolute and relative changes in airway dimensions associated with growth and development.

STUDY OBJECTIVES

The aims of this study were (i) to determine whether a 'video-bronchoscopic' measurement method could be used to reliably measure airway dimensions in children and (ii) to provide a preliminary assessment of dimensions of the glottis and cricoid in children of various ages.

METHODS

Following approval from the institutional review board, validation experiments were performed to determine whether measurements obtained from the video image from the bronchoscope provided accurate measurements of tubular objects of known dimensions. The reliability of the measurements was determined by using two independent trained observers to measure video-bronchoscopic images of the larynx at the level of the glottis and the cricoid in 11 children. The observers measured the video-bronchoscopic images and airway measurements were obtained in 16 additional children to determine the utility of the measurement method.

RESULTS

There was good agreement between the direct and video-bronchoscopic measurement techniques (Bland and Altman plot) for both the cross-sectional area (CSA) and the diameter of objects. The interobserver measures for cricoid and glottis were reproducible as indicated by the concordance correlation coefficient (CCC) for cricoid anteroposterior diameter (CCC = 0.98, r = 0.98, accuracy = 0.99) and transverse diameter (CCC = 0.93, r = 0.8, accuracy = 0.99) as well as for the glottic anteroposterior diameter (r = 0.8, accuracy = 0.8, CCC = 0.6) and the glottic transverse diameter(r = 0.8, accuracy = 0.74, CCC = 0.6). Overall, for the 27 children studied [mean age 73 months (+/-24.7, range 30-140], the mean value of the cricoid CSA [45.3 mm(2) (+/-13.9)] was found to be greater than the glottic CSA [16.2 mm(2) (+/-10.1)].

CONCLUSIONS

The video-bronchoscopic imaging method provided an accurate, reliable measure of pediatric airway dimensions. This technique could be applied to assess absolute and relative airway size associated with growth and development. The relationship between glottic and cricoid dimensions during growth and development in children needs further investigation across various age groups.