Laryngeal ultrasonography in infants and children: a new way of investigating. Normal and pathological findings

Transcutaneous Laryngeal Ultrasound for Assessing Hyaluronic Acid Status in Patients Undergoing Injection Laryngoplasty

OBJECTIVE

Injection laryngoplasty (IL) with hyaluronic acid (HA) is an effective treatment for patients with glottic insufficiency. The duration of HA maintenance in the vocal fold remains unknown. In this study, transcutaneous laryngeal ultrasound (TLUS) was used to evaluate the absorption and migration of HA after IL. Subsequent management might be provided based on the TLUS finding.

METHODS

Patients diagnosed with unilateral vocal fold paralysis (UVFP) or vocal fold atrophy were recruited. All patients underwent IL with HA in an office-based setting along with TLUS to monitor the status of HA. The schedule of TLUS included assessments before and after IL until non-visualization.

RESULTS

The study population comprised 38 women and 17 men. Of the patients, 54.1% underwent IL for UVFP, whereas 45.9% underwent IL for vocal fold atrophy. Multivariate Cox regression analysis for factors affecting HA absorption revealed that the cause of injection was the most important independent predictor (hazard ratio [HR], 2.15; 95% confidence interval [CI], 1.03-4.46; p = 0.040). The duration of HA maintenance was significantly longer in patients with UVFP than in those with vocal fold atrophy (8.77 vs. 4.70 months, HR, 2.33; 95% CI, 5.47-8.18; p = 0.002).

CONCLUSION

TLUS is an objective assessment method for patients undergoing IL with HA. Subsequent tailor-made management could be offered based on the TLUS findings during follow-up. For patients at high risk of upper respiratory tract infection or who are intolerant to flexible nasopharyngoscopy, TLUS can be used as an alternative tool to evaluate the condition of the glottis after IL with HA.

LEVEL OF EVIDENCE

Level 4 Laryngoscope, 2024.

Clinical usefulness of transcutaneous laryngeal ultrasonography in otolaryngology practice during COVID-19 pandemic: a literature review

As a consequence of the outbreak of SARS-CoV-2, the clinical practice of otolaryngologists underwent profound transformations. Non-aerosol-generating procedures have been researched and implemented. Transcutaneous laryngeal ultrasonography (TLUSG) provides a rapid and noninvasive method to assess laryngeal function and can support the management of laryngeal disorders. With the aim of investigating the clinical usefulness of TLUSG in otolaryngology practice, a review of the literature published on PubMed, Cochrane Library and Ovid/ Medline databases was performed up to March 2022. 38 studies were eligible to be included in the review. The selected papers were divided into six topics of interest: evaluation of vocal cords function, diagnosis of laryngeal disorders in infants and children, evaluation of swallowing disorders, assessment of laryngeal cancer and other laryngeal lesions, ultrasound-guided cricothyroidotomy, ultrasound-guided laryngeal electromyography. The results of this review demonstrated that TLUSG, applied to ENT practice, can be a valid method for dynamic laryngeal assessment and airway management, since it is time-efficient, non invasive, well tolerated and easily performed.

Vocal cord dysfunction after pediatric cardiac surgery: A prospective implementation study

Objective

To determine the incidence, outcomes, and evaluate diagnostic modalities for postoperative vocal cord dysfunction (VCD) following cardiothoracic surgery in children.

Methods

A prospective mixed-methods study using principles of implementation science was completed. All patients undergoing surgery involving the aortic arch, ductus, or ligamentum arteriosum and vascular rings from September 2019 to December 2020 were enrolled. Patients underwent speech pathology assessment, laryngeal ultrasound, and flexible direct laryngoscopy.

Results

Ninety-five patients were eligible for inclusion. The incidence of VCD ranged from 18% to 56% and varied according to procedure group. VCD occurred in 42% of neonates. Repair of hypoplastic aortic arch was associated with increased risk of VCD (57%; P = .002). There was no significant difference in duration of intubation, pediatric intensive care unit stay, or hospital stay. Forty percent children were able to achieve full oral feeding. Children with VCD were more likely to require nasogastric supplementary feeding at discharge (60% vs 36%; P = .044). Sixty-eight percent of patients demonstrated complete resolution of VCD at a median of 97 days postoperatively. Laryngeal ultrasound and speech pathology assessment combined had a sensitivity of 91% in comparison to flexible direct laryngoscopy.

Conclusions

VCD occurred in one-third and resolved in two-thirds of patients at a median of 3 months following cardiac surgery. Aortic arch repair carried the highest risk of VCD. VCD adversely influenced feeding. Forty percent of patients achieved full oral feeding before discharge. VCD did not delay intensive care unit or hospital discharge. Speech pathology assessment and laryngeal ultrasound combined was reliable for diagnosis in most patients and was more patient friendly than flexible direct laryngoscopy.

Ultrasound in paediatric anaesthesia - A comprehensive review

The use of ultrasound is becoming more widespread in anaesthesia. In this review, we discuss the use of ultrasound in various aspects of paediatric anaesthesia and how it can be used to assist diagnostic and therapeutic interventions and the evidence available. We explore the use of ultrasound as an adjunct for regional anaesthesia, vascular access, airway management, bedside cardiac, pulmonary and abdominal imaging and intracranial pressure monitoring.

Application-Based Translaryngeal Ultrasound for the Assessment of Vocal Fold Mobility in Children

Objective

To compare the evaluation of vocal fold mobility between flexible nasal laryngoscopy (FNL) and a handheld application-based translaryngeal ultrasound (TLUS) platform.

Study Design

Prospective analysis included patients with unknown vocal fold mobility status who underwent FNL and TLUS.

Setting

Tertiary referral center.

Subjects and Methods

TLUS was performed on 23 consecutive children (<18 years old) presenting for laryngoscopy due to unknown vocal fold mobility status. After the recording of three 10-second TLUS videos as well as FNL, the study was divided into 2 parts: parental assessment of laryngeal ultrasound at the time of patient evaluation and random practitioner assessment of ultrasound videos.

Results

We describe 23 patients who underwent TLUS and FNL. Ten patients (43.5%) had normal vocal fold function bilaterally, and 13 (56.5%) had either left or right vocal fold immobility. Family members and physicians correctly identified the presence and laterality of impaired vocal fold mobility in 22 of 23 cases (κ = 0.96). The sensitivity, specificity, positive predictive value, and negative predictive value of FLUS in diagnosing vocal fold immobility were 92.3%, 100%, 100%, and 90.9%, respectively. Random practitioners accurately identified the presence and laterality of vocal fold immobility under all circumstances.

Conclusion

A handheld application-based ultrasound platform is both sensitive and specific in its ability to identify vocal fold motion impairment. Portable handheld TLUS has the potential to serve as a validated screening examination, even by inexperienced providers, and in specific cases may obviate the need for an invasive transnasal laryngoscopy.

The role of laryngeal ultrasound in the assessment of pediatric dysphonia and stridor

OBJECTIVES

Dysphonia and stridor are not infrequent in the pediatric population. Awake nasolaryngoscopy (ANL) is the primary diagnostic procedure used to evaluate a child with stridor and/or dysphonia. The major limitation of this technique is poor cooperation in children, resulting in inadequate visualization of the larynx. Ultrasound is a widely used noninvasive imaging modality that has yet to be applied to the laryngeal examination. Our goal was to investigate the feasibility and diagnostic potential of laryngeal ultrasound (LUS) in cases of pediatric stridor and/or dysphonia.

METHODS

Prospective blinded cohort study of infants and children 0-16 years of age referred for ANL due to voice disorders and/or stridor. Prior knowledge of the etiology was considered an exclusion criterion.

RESULTS

LUS concurred with the ANL in the diagnosis of abnormal vs normal larynx in 28/32 children that were recruited. LUS had a sensitivity and specificity of 87% (95% CI: 69%-96%) and 100% (95% CI: 16%-100%) respectively, for diagnosing overall laryngeal disorders in comparison to ANL. LUS also had an area under the receiver operating characteristic (ROC) curve (AUC) of 0.93, (P = 0.04, 95% CI: 0.84-1).

CONCLUSION

LUS may be applied as an adjuvant diagnostic tool for ruling in laryngeal pathologies in children including dysphonia and stridor. As further experience is acquired the value of LUS in diagnosis will be better understood.

Sonographic evaluation of the endochondral ossification process of the thyroid cartilage in children

PURPOSE

To determine the sonographic appearances of the endochondral ossification process of the thyroid cartilage in children.

METHODS

Thyroid cartilage sonography (US) of 420 children was performed with a high-resolution linear-array transducer. Right and left laminae of the thyroid cartilage, including the inferior horns, were examined. Ossification foci were evaluated for their presence, location, shape, size, echo pattern, and number.

RESULTS

Four hundred nineteen children, 239 girls and 180 boys, were enrolled in the study with a mean age of 109.8 ± 60.7 months. Ossification foci were found in 167 children (39.9%). First ossification focus detection age was 72 months in girls and 79 months in boys. On both laminae, the most frequent appearance of the ossification focus was hypoechoic (right: 94.8%, left: 93.5%). Prevalence and number of ossification foci increased with age in each sex. The shape of the ossification foci in both laminae was generally nonexpansile (right: 92.9%, left: 93.5%).

CONCLUSION

Endochondral ossification process of the thyroid cartilage begins in the first decade with extracellular matrix changes, which can be detected as hypoechoic foci by US. These foci can be expansile, and radiologists should be aware of this entity to avoid misdiagnosing them as abnormal masses.

Point-of-Care Sonographic Findings in Acute Upper Airway Edema

We describe a case where a patient presented with acute angiotensin-converting enzyme inhibitor (ACE-I) induced angioedema without signs or symptoms of upper airway edema beyond lip swelling. Point-of-care ultrasound (POCUS) was used as an initial diagnostic test and identified left-sided subglottic upper airway edema that was immediately confirmed with indirect fiberoptic laryngoscopy. ACE-I induced angioedema and the historical use of ultrasound in evaluation of the upper airway is briefly discussed. To our knowledge, POCUS has not been used to identify acute upper airway edema in the emergency setting. Further investigation is needed to determine if POCUS is a sensitive and specific-enough tool for the identification and evaluation of acute upper airway edema.

Noninvasive Assessment of Benign Lesions of Vocal Folds by Means of Ultrasonography

Objectives:

Although ultrasonography (US) has been widely used in various parts of the body, its application in laryngeal examination has been limited. Our objective was to evaluate the significance of US examination in benign lesions of the vocal folds.

Methods:

Ultrasonographic examination of the vocal folds was performed in 14 patients in whom benign lesions of the vocal folds had been diagnosed by videolaryngoscopy and microlaryngoscopy. Microlaryngoscopic surgery was performed after US examination. Each lesion was analyzed for the following US features: Shape, size, and echotexture (echogenicity and homogeneity).

Results:

In total, 16 lesions were diagnosed in 14 patients by means of videolaryngoscopy and microlaryngoscopy. Ultrasonographic examination was capable of diagnosing 14 of the 16 lesions (87.25%). Ultrasonography mainly helped in the diagnosis of sessile polyps, nodules, and leukoplakia that were larger than 2 mm. The lesions were linear hyperechoic, heterogeneous hyperechoic, hypoechoic, and isoechoic if they were leukoplakia, nodules, hemorrhagic polyps, and other polypoid lesions, respectively. The results are better if the diagnosis follows the corresponding US echotexture pattern rather than videolaryngoscopy and microlaryngoscopy.

Conclusions:

Laryngeal US examination appears to be a useful diagnostic tool for supplementing microlaryngoscopy in the assessment of benign lesions of vocal folds. In contrast to these currently used imaging techniques, anesthesia is not necessary in laryngeal US examination. In addition, US is noninvasive, painless, and much less expensive than the other techniques.

Ultrasound: A promising tool for contemporary airway management

Airway evaluation and its management remains an ever emerging clinical science. Present airway management tools are static and do not provide dynamic airway management option. Visualized procedures like ultrasound (US) provide point of care real time dynamic views of the airway in perioperative, emergency and critical care settings. US can provide dynamic anatomical assessment which is not possible by clinical examination alone. US aids in detecting gastric contents and the nature of gastric contents (clear fluid, thick turbid or solid) as well. US can help in predicting endotracheal tube size by measuring subglottic diameter and diameter of left main stem bronchus. US was found to be a sensitive in detecting rotational malposition of LMA in children. Also, US is the fastest and highly sensitive tool to rule out a suspected intraoperative pneumothorax. In intensive care units, US helps torule out causes of inadequate ventilation, determine the tracheal width and distance from the skin to predict tracheotomy tube size and shape and assist with percutaneous dilatational tracheostomy. US can help in confirming the correct tracheal tube placement by dynamic visualisation of the endotracheal tube insertion, widening of vocal cords (children), and bilateral lung-sliding and diaphragmatic movement. Thus, ultrasonography has brought a paradigm shift in the practise of airway management. With increasing awareness, portability, accessibility and further sophistication in technology, it is likely to find a place in routine airway management. We are not far from the time when all of us will be carrying a pocket US machine like stethoscopes to corroborate our clinical findings at point of care.

Synchronous video laryngoscopy and sonography of the larynx in children

Unlike laryngoscopy, laryngeal sonography is easily applicable, well tolerated by young children and less exhausting for the examiner. The aim of this study was to determine if sonography can adequately visualize the laryngeal structures and vocal fold movements of children. Synchronic video laryngoscopy and sonography of the larynx were performed in 35 children (aged 2-8 years) without a laryngeal disease. 10 investigators at differing stages of otolaryngological training were tasked with identifying vocal fold movement and specific anatomical structures after seeing (1) the sonography-only video and (2) the sonography video with a laryngoscopy video overlay. The percentage of correct identification of the structures and the vocal cord movement with and without additional video-overlay was compared. A sonographical view of the larynx could be found and the following anatomical structures were identified: subcutaneous fat tissue, left and right sternohyoid and thyrohyoid muscles, thyroid cartilage, left and right vocal folds, left and right paraglottic spaces, left and right side arytenoid cartilages, and rima glottides. Concerning the evaluation of the videos amongst the investigators: they identified >80 % of vocal fold movement and the targeted anatomical structures except the arytenoid cartilages (only up to 63 %), having the sonography only. In combination with the laryngoscopy video-overlay, investigator detection rates significantly improved (>90 % of vocal fold movement, p < 0.001; >90 % in most anatomical structures, (p < 0,001). Laryngeal sonography is a helpful diagnostic tool to identify laryngeal structures and the movement of the vocal folds in children.

Laryngeal air column width ratio in predicting post extubation stridor

Aim:

Correlation of upper air column width ratio in postextubation stridor patients.

Materials and Methods:

A prospective observational study was conducted in a tertiary hospital between January and December 2013. Patients who were admitted in Intensive Care Unit and intubated for >24 h were included (72 patients). The upper airway air column width ratio (air column width before extubation/air column width after intubation) was calculated and compared in patient with or without postextubation stridor.

Results:

The incidence of stridor was 6.9% (5/72). The duration of mechanical ventilation was 5.60 ± 1.14 days and 3.91 ± 1.45 days in stridor and nonstridor group respectively. In all 5 patients who had stridor, the upper airway air column width ratio was 0.8 or less.

Conclusion:

Air column width ratio of 0.8 or less may be helpful in predicting postextubation stridor, which should be confirmed by large observational studies.

Ultrasound use in the pediatric airway: the time has come

Advancements in ultrasonography and increasing familiarity with its use in the operating room (vascular access and regional neural blockade) suggest its feasibility as an adjunct in pediatric airway evaluation and intervention. We report 3 cases demonstrating the usefulness of ultrasound techniques in this setting. We show key elements of airway anatomy, noninvasive observation of vocal cord motion, and percutaneous periglottic steroid injection via the cricothyroid membrane in 3 different patients. This report reveals the possible usefulness of ultrasound imaging in clinical anesthesia care, specifically airway management, in children.

Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae

OBJECTIVES

To create a state-of-the-art overview of the new and expanding role of ultrasonography in clinical decision-making, intervention and management of the upper and lower airways, that is clinically relevant, up-to-date and practically useful for clinicians.

METHODS

This is a narrative review combined with a structured Medline literature search.

RESULTS

Ultrasonography can be utilised to predict airway difficulty during induction of anaesthesia, evaluate if the stomach is empty or possesses gastric content that poses an aspiration risk, localise the essential cricothyroid membrane prior to difficult airway management, perform nerve blocks for awake intubation, confirm tracheal or oesophageal intubation and facilitate localisation of tracheal rings for tracheostomy. Ultrasonography is an excellent diagnostic tool in intraoperative and emergency diagnosis of pneumothorax. It also enables diagnosis and treatment of interstitial syndrome, lung consolidation, atelectasis, pleural effusion and differentiates causes of acute breathlessness during pregnancy. Patient safety can be enhanced by performing procedures under ultrasound guidance, e.g. thoracocentesis, vascular line access and help guide timing of removal of chest tubes by quantification of residual pneumothorax size.

CONCLUSIONS

Ultrasonography used in conjunction with hands-on management of the upper and lower airways has multiple advantages. There is a rapidly growing body of evidence showing its benefits.

TEACHING POINTS

• Ultrasonography is becoming essential in management of the upper and lower airways. • The tracheal structures can be identified by ultrasonography, even when unidentifiable by palpation. • Ultrasonography is the primary diagnostic approach in suspicion of intraoperative pneumothorax. • Point-of-care ultrasonography of the airways has a steep learning curve. • Lung ultrasonography allows treatment of interstitial syndrome, consolidation, atelectasis and effusion.

Ultrasound measurement of subglottic diameter and an empirical formula for proper endotracheal tube fitting in children

BACKGROUND

The appropriate endotracheal tube (ETT) size is commonly determined using age-based formula; ETT size determination based on ultrasound (US) measurement of subglottic diameter (SD), the narrowest portion of the paediatric upper airway, may provide a better method for accurate fit. We aimed to validate ETT size determination using US measures of SD before intubation to establish an empirical formula for ETT fitting based on SD and biographic parameters.

METHODS

We included 215 children aged 1-72 months undergoing general anaesthesia. US was performed on the anterior neck to measure SD during mask ventilation under anaesthesia. Endotracheal intubation was performed with a cuffed ETT selected by age-based recommendation; the transverse outer diameter (OD) of the ETT within the trachea at the subglottis level (OD-ETT at SD) was measured.

RESULTS

The OD-ETT at SD was correlated with the actual OD-ETT outside the trachea (R(2) = 0.635), showing the validity of ultrasonographic measurement; moreover, the US-measured SD revealed strong correlation with the actual OD-ETT (R(2) = 0.834). US-measured SD and biographic data (age, height and weight) showed little correlation in children less than 12 months but good correlation (age, height) in children older than 12 months (P < 0.01).

CONCLUSIONS

US-measured OD-ETT at SD was in good agreement with the actual OD-ETT, suggesting that US-measured SD helps in choosing the appropriate ETT diameter for children. In children older than 12 months, the equation 'OD (mm) = 0.01 × age (months) + 0.02 × height (cm) + 3.3' may help select the appropriate ETT.

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.

Ultrasonography in the management of the airway

In this study, it is described how to use ultrasonography (US) for real-time imaging of the airway from the mouth, over pharynx, larynx, and trachea to the peripheral alveoli, and how to use this in airway management. US has several advantages for imaging of the airway - it is safe, quick, repeatable, portable, widely available, and it must be used dynamically for maximum benefit in airway management, in direct conjunction with the airway management, i.e. immediately before, during, and after airway interventions. US can be used for direct observation of whether the tube enters the trachea or the esophagus by placing the ultrasound probe transversely on the neck at the level of the suprasternal notch during intubation, thus confirming intubation without the need for ventilation or circulation. US can be applied before anesthesia induction and diagnose several conditions that affect airway management, but it remains to be determined in which kind of patients the predictive value of such an examination is high enough to recommend this as a routine approach to airway management planning. US can identify the croicothyroid membrane prior to management of a difficult airway, can confirm ventilation by observing lung sliding bilaterally and should be the first diagnostic approach when a pneumothorax is suspected intraoperatively or during initial trauma-evaluation. US can improve percutaneous dilatational tracheostomy by identifying the correct tracheal-ring interspace, avoiding blood vessels and determining the depth from the skin to the tracheal wall.

Value of ultrasonography in diagnosis of pediatric vocal fold paralysis

OBJECTIVES

To investigate the appearance of the pediatric larynx on ultrasound images and the diagnostic potential of ultrasound in cases of pediatric vocal fold paralysis.

METHODS

First, we confirmed the ultrasonographic features of the laryngeal landmarks in 2 pediatric cadaveric larynxes. Secondly, 45 children were enrolled in a clinical study (13 patients with vocal fold paralysis and 32 normal children). Quantitative analysis of vocal fold mobility was carried out by measuring the maximum glottic angle (MGA) and vocal fold-arytenoid angle (VAA).

RESULTS

All the paralyzed vocal folds showed abnormal mobility, and were flaccid during breathing and phonation. The rima glottis appeared as a hyperechoic air-column band in ultrasound images during phonation. The mean value of the MGA was 61.47 ± 9.00 in the normal larynx and 42.25 ± 10.41 in the paralyzed larynx. In the affected side of the paralyzed larynx, the VAA in maximum abduction was smaller than that in the normal larynx or in the unaffected side. The median difference of the VAA between maximum abduction and maximum adduction was less than that in the normal larynx. The kappa value was 0.96.

CONCLUSION

MGA and VAA are quantitative indicators of vocal fold immobility. Ultrasound is a reliable method of diagnosis of pediatric VFP. To diagnose VFP from an ultrasound image, the criteria are: (1) abnormal mobility (this was the most important and direct evidence), (2) hyperechoic air-column band of the glottic rima during phonation, (3) flaccid vocal fold and (4) asymmetry of the glottal structures.

Applications of ultrasonography in ENT: airway assessment and nerve blockade

This article presents a comprehensive narrative review of the published literature relating to ultrasound imaging relevant to anesthesia for ear, nose, and throat (ENT) surgery. The review comprises 2 main subject areas: the use of ultrasonography related to assessment and management of the airway, and the use of ultrasonography related to nerve blockade for ENT surgery. The relevant sonoanatomy and suitable probe placement are illustrated in relation to applicable regional anatomy (they are not discussed). The possible value of the use of ultrasonography to improve existing clinical practice in these areas is explored.

Use of sonography for airway assessment: an observational study

OBJECTIVE

The purpose of this study was to evaluate the feasibility of sonography in identifying the anatomic structures of the upper airway and to describe their appearance on sonography.

METHODS

We enrolled 24 healthy volunteers, placed them supine with their head extended and neck flexed (the "sniffing" position), and performed a systematic sonographic examination of their upper airway from the floor of the mouth to the suprasternal notch.

RESULTS

We were able to visualize all relevant anatomic structures in all of the participants using either a linear or curved transducer oriented in 1 of 3 planes: sagittal, parasagittal, and transverse. Bony structures (eg, the mandible and hyoid) were brightly hyperechoic with an underlying hypoechoic acoustic shadow. Cartilaginous structures (eg, the epiglottis, thyroid cartilage, cricoid cartilage, and tracheal rings) were hypoechoic, and their intraluminal surface was outlined by a bright air-mucosa interface. The vocal cords were readily visualized through the thyroid cartilage. However, the posterior pharynx, posterior commissure, and posterior wall of the trachea could not be visualized because of artifacts created by an intraluminal air column.

CONCLUSIONS

Sonography of the upper airway is capable of providing detailed anatomic information and has numerous potential clinical applications.

Non-invasive assessment of benign vocal folds lesions in children by means of ultrasonography

OBJECTIVES

Flexible fiberoptic endoscopes have made pediatric laryngeal examinations an everyday practice, even though fiberoptic-flexible laryngoscopy (FFL) is not always well tolerated in young children because of limited cooperation. Laryngeal ultrasonography (LUS) has been applied to normal and pathological findings in infants and children, allowing the assessment of subglottic hemangiomas, laryngeal stenosis and paralysis. No previous study assessed benign vocal folds lesions by LUS in children. The aim of this study is to evaluate the possibility of LUS to detect benign vocal fold lesions in children by comparing the results of FFL in 16 children with those of LUS.

METHODS

Sixteen children (9 males and 7 females) with a mean age of 7.5+/-4.0 years were included in the study. Each child underwent FFL performed by a skilled phoniatrician and LUS performed blindly by an expert radiologist.

RESULTS

On FFL bilateral vocal folds nodules were found in 9 patients, vocal fold cyst in 2 other patients, while in 2 children the vocal folds appeared normal. Laryngeal papyllomatosis, vocal fold polyp and vocal fold irregularity were found in only one patient. LUS enabled the diagnosis in all the 14 patients with vocal fold lesions. Bilateral hyperechoic lesions were visible in 10 patients, while hypoechoic lesions were found in three patients. No lesion were found in two children, while one patient presented with a monolateral hyperechoic lesion.

CONCLUSIONS

LUS was accurate, safe, well accepted and tolerated. LUS appears to be a useful diagnostic tool for supplementing FFL in the assessment of benign vocal fold lesions in children and may represent an interesting alternative in everyday clinical practice.

The Feasibility of Ultrasound to Assess Subglottic Diameter

BACKGROUND

In healthy patients, the narrowest diameter of the subglottic upper airway is the width of the air-column at the level of the cricoid cartilage. This diameter governs the selection of the endotracheal tube size, as excessive tube diameter may damage the tracheal mucosa leading to postextubation stridor or subglottic stenosis. Unfortunately, selecting endotracheal tube size based on height, weight, or age does not reliably lead to the proper tube. The knowledge of airway diameter, especially using a bedside noninvasive tool, could therefore be helpful in anesthesia and intensive care.

METHODS

We studied 19 healthy volunteers (27 +/- 3 yr, nine females) to compare the transverse diameter of the cricoid lumen assessed by ultrasonography and magnetic resonance imaging.

RESULTS

We found a strong correlation between the two techniques (r = 0.99, P < 0.05) confirmed by Bland-Altman analysis with a bias of 0.14 mm, a precision of 0.33 mm, and limits of agreement of -0.68 mm/0.96 mm.

CONCLUSION

In young healthy adults, ultrasonography appeared to be a reliable tool to assess the diameter of the subglottic upper airway.

The potential role of ultrasound in differentiating solid and cystic swellings of the true vocal fold

This study was designed to investigate the potential role of ultrasound in the diagnosis of cysts of the true vocal fold.

MATERIALS AND METHODS

Grayscale ultrasound of the larynx was carried out in 29 patients with a swelling of the true vocal fold and dysphonia. The findings were then compared with those at subsequent microlaryngoscopy, in the majority of cases.

RESULTS AND CONCLUSIONS

Whereas preoperative laryngeal ultrasound correctly predicted the surgical findings of a cystic lesion in only 5 of 11 cases, it correctly identified that no cyst was present in 15 of 16 instances when this had been queried. This study suggests that ultrasound may have some role in investigation of unilateral vocal fold pathology, but that further fine-tuning of the technique may be necessary.

Evaluation of the upper airway

The evaluation of infants and children with upper airway obstruction always involves a history and physical examination, which in many cases allow a diagnosis to be made. Assessment of severity and response to treatment relies on subjective parameters. Flow-volume loop analysis is a rapid, simple and effective method of evaluating patients with upper airway obstruction non-invasively. Imaging studies are complementary to endoscopy, and include plain radiography as well as computed tomography and magnetic resonance imaging, with the latter two being increasingly used in the evaluation of the paediatric airway. The ultimate diagnostic test for evaluation of upper airway obstruction, however, is flexible endoscopy.

[Sonography of the larynx--an alternative to laryngoscopy?]

PROBLEM

The aim of this study was to determine whether the pictorial results obtained from B-mode ultrasonography duplicate those of laryngeal endoscopy and whether there are any additional advantages when using ultrasonography.

PATIENTS AND METHODS

A total of 22 patients with various diseases of the larynx were examined ultrasonically with the ultrasound plusing a Sonoline Elegra as well as with a '7.5 L40' and a 'VF 13/5' linear array. In order to compare both methods directly, reference data were prepared and contrasted.

RESULTS

All of the laryngeal lesions recognised in the endoscopic investigation were also demonstrable by the use of ultrasound, although minor changes were difficult to detect. In one case, ultrasonography suggested the presence of an infiltration of the thyroid cartilage, otherwise no additional information was available using this method.

CONCLUSIONS

Using ultrasonography, the image quality of the larynx is worse than that of the soft tissue of the neck, which is determined by the air-mucous membrane boundary as well as the (ossified) cartilaginous skeleton. Thus, ultrasonography is useful in cases of larger laryngeal lesions, while there is no advantage in the detection of small processes.

The role of ultrasound in the assessment of laryngeal paralysis in the dog

Forty dogs with clinical signs suggestive of upper respiratory tract disease underwent echolaryngography and laryngoscopy. Laryngoscopy was used as the definitive technique to diagnose laryngeal paralysis. The ultrasound investigation accurately indicated the presence of the paralysis and confirmed the uni- or bilateral nature of the disorder. Findings indicative of laryngeal paralysis included asymmetry or absence of motion of the cuneiform processes (30/30), abnormal arytenoid movement (16/30), paradoxical movement (9/30), caudal displacement of the larynx (2/30) and laryngeal collapse (1/30). Thirty dogs were found to be afflicted with laryngeal paralysis and ten had normal laryngeal motility.

Quantitative endoscopy: initial accuracy measurements

The geometric optics of an endoscope can be used to determine the absolute size of an object in an endoscopic field without knowing the actual distance from the object. This study explores the accuracy of a technique that estimates absolute object size from endoscopic images. Quantitative endoscopy involves calibrating a rigid endoscope to produce size estimates from 2 images taken with a known traveled distance between the images. The heights of 12 samples, ranging in size from 0.78 to 11.80 mm, were estimated with this calibrated endoscope. Backup distances of 5 mm and 10 mm were used for comparison. The mean percent error for all estimated measurements when compared with the actual object sizes was 1.12%. The mean errors for 5-mm and 10-mm backup distances were 0.76% and 1.65%, respectively. The mean errors for objects <2 mm and > or =2 mm were 0.94% and 1.18%, respectively. Quantitative endoscopy estimates endoscopic image size to within 5% of the actual object size. This method remains promising for quantitatively evaluating object size from endoscopic images. It does not require knowledge of the absolute distance of the endoscope from the object, rather, only the distance traveled by the endoscope between images.

Ultrasonographic examination of the pharynx and larynx of the normal dog

Real-time ultrasonographic examination of the canine larynx was performed in 12 normal dogs using a 7.5-mHz mechanical sector scanner combined with a stand-off. A variety of breeds and ages were examined. All examinations were performed in nonsedated, conscious animals. Transverse scans were found to provide the most reliable and interpretable images. Identification of laryngeal structures included the epiglottis, laryngeal and cricoid cartilages, and the vocal cords. In conscious animals, abduction and adduction of the vocal cords associated with respiration could be identified if the animal was made to pant during the examination. Movement of the vocal cords could also be quantified by pulse-wave Doppler recording. In all animals, recordings were made during inspiration only, with muscular vibration at a rate less than 0.1 m/s.

Ultrasonography of laryngeal masses in six cats and one dog

Ultrasonography of laryngeal abnormalities in small animals allows the identification of laryngeal masses because of the resulting distortion of normal structural/anatomical relationships. It also allows fine-needle aspirates to be taken with minimal risk of causing hemorrhage or edema affecting the already narrowed laryngeal lumen. Findings in six cats and one dog with laryngeal abnormalities are described.

Changes in the male voice at puberty: vocal fold length and its relationship to the fundamental frequency of the voice

Ultrasound measurements of the vocal folds were taken for a number of boys passing through puberty. The boys were grouped according to their pubertal stage as defined by Tanner and there was a gradual increase in the length of the vocal folds as puberty progressed. The fundamental frequency of the boys' speaking voice was recorded via laryngography and a good correlation between the length of the vocal folds and the frequency of the voice was seen. The sudden drop in frequency seen between Tanner stages 3 and 4 did not correlate with similar changes in the length of the vocal folds at this time but stroboscopic findings suggest a change in the structure and mass of the vocal folds at this time of maximum frequency change.

Use of ultrasonography in the diagnosis of tracheal collapse

Ultrasonographic imaging of the cervical trachea was performed with the neck in both a neutral and a hyperextended position in 10 dogs with tracheal collapse. Tracheoscopy was used to confirm a diagnosis of tracheal collapse. The ultrasound investigation was repeated in 10 dogs of similar size but without tracheal abnormality. The ultrasonographic findings of the affected dogs were compared with those of the normal group and showed an alteration in the shape of the tracheal lumen in the ventrodorsal projection. This study highlights the possibility of identifying changes in the shape of the tracheal lumen during ultrasound investigations as an aid to the diagnosis of tracheal collapse.

Ultrasonographic imaging of the tongue and larynx in normal dogs

Ultrasonographic imaging of the tongue and larynx was performed in 10 dogs with no previous history of upper airway disease. The ultrasonographic findings were compared with the normal canine anatomy of this area and with the results described in the human literature. This study shows that the anatomical features of the canine larynx are adequately detectable using ultrasonography. This finding is in accordance with the findings described in the human literature. It is concluded that ultrasonography may offer a means of investigating canine laryngeal abnormalities.