Finite element analysis of eustachian tube function in cleft palate infants based on histological reconstructions

The mechanism of balloon Eustachian tuboplasty: a biomechanical study

Obstructive Eustachian tube dysfunction (OETD) is a common condition resulting from inadequate opening of the Eustachian tube (ET). A new surgical treatment involves high-pressure inflation of a balloon within the ET, with the aim of dilating the soft tissue structure. However, the mechanical effects of this intervention have not been established, nor the impact of changing device size or other technical parameters. A novel experimental technique allowed quantification of plastic and elastic tissue deformation in model materials and then human cadaver ETs during balloon dilation, based on the measured balloon inflation pressure-volume relationship. Plastic tissue deformation was found to be greater using larger balloons and deeper device insertion, but increasing the inflation pressure had a more limited effect, with most deformation occurring well below the clinically used pressures. Histological assessment of ET tissue suggested that mucosal tearing and cartilage cracking were in part responsible for the mechanical changes. Balloon dilation of the ET has huge potential if found to be clinically effective, but currently there is a need to understand and develop the technique further. The novel methods employed in this study will be valuable in future laboratory and in vivo studies of ET balloon dilation. Pressures are reported in Bar as this unit is used for medical balloon dilation procedures in clinical practice. 1 Bar = 100,000 Pa.

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Behavioral Signs of (Central) Auditory Processing Disorder in Children with Nonsyndromic Cleft Lip and/or Palate: A Parental Questionnaire Approach

Objective

Children with nonsyndromic cleft lip and/or palate often have a high prevalence of middle ear dysfunction. However, there are also indications that they may have a higher prevalence of (central) auditory processing disorder. This study used Fisher's Auditory Problems Checklist for caregivers to determine whether children with nonsyndromic cleft lip and/or palate have potentially more auditory processing difficulties compared with craniofacially normal children.

Methods

Caregivers of 147 school-aged children with nonsyndromic cleft lip and/or palate were recruited for the study. This group was divided into three subgroups: cleft lip, cleft palate, and cleft lip and palate. Caregivers of 60 craniofacially normal children were recruited as a control group. Hearing health tests were conducted to evaluate peripheral hearing. Caregivers of children who passed this assessment battery completed Fisher's Auditory Problems Checklist, which contains 25 questions related to behaviors linked to (central) auditory processing disorder.

Result

Children with cleft palate showed the lowest scores on the Fisher's Auditory Problems Checklist questionnaire, consistent with a higher index of suspicion for (central) auditory processing disorder. There was a significant difference in the manifestation of (central) auditory processing disorder-linked behaviors between the cleft palate and the control groups. The most common behaviors reported in the nonsyndromic cleft lip and/or palate group were short attention span and reduced learning motivation, along with hearing difficulties in noise.

Conclusion

A higher occurrence of (central) auditory processing disorder-linked behaviors were found in children with nonsyndromic cleft lip and/or palate, particularly cleft palate. Auditory processing abilities should not be ignored in children with nonsyndromic cleft lip and/or palate, and it is necessary to consider assessment tests for (central) auditory processing disorder when an auditory diagnosis is made for this population.

Quantification of nasal airflow resistance in English bulldogs using computed tomography and computational fluid dynamics

Stenotic nares, edematous intranasal turbinates, mucosal swelling, and an elongated, thickened soft palate are common sources of airflow resistance for dogs with brachycephalic airway syndrome. Surgery has focused on enlarging the nasal apertures and reducing tissue of the soft palate. However, objective measures of surgical efficacy are lacking. Twenty-one English bulldogs without previous surgery were recruited for this prospective, pilot study. Computed tomography was performed using conscious sedation and without endotracheal intubation using a 128 multidetector computed tomography scanner. Raw multidetector computed tomography data were rendered to create a three-dimensional surface mesh model by automatic segmentation of the air-filled nasal passage from the nares to the caudal soft palate. Three-dimensional surface models were used to construct computational fluid dynamics models of nasal airflow resistance from the nares to the caudal aspect of the soft palate. The computational fluid dynamics models were used to simulate airflow in each dog and airway resistance varied widely with a median 36.46 (Pa/mm)/(l/s) and an interquartile range of 19.84 to 90.74 (Pa/mm)/(/s). In 19/21 dogs, the rostral third of the nasal passage exhibited a larger airflow resistance than the caudal and middle regions of the nasal passage. In addition, computational fluid dynamics data indicated that overall measures of airflow resistance may significantly underestimate the maximum local resistance. We conclude that computational fluid dynamics models derived from nasal multidetector computed tomography can quantify airway resistance in brachycephalic dogs. This methodology represents a novel approach to noninvasively quantify airflow resistance and may have utility for objectively studying effects of surgical interventions in canine brachycephalic airway syndrome.

Multi-scale finite element modeling of Eustachian tube function: influence of mucosal adhesion

The inability to open the collapsible Eustachian tube (ET) leads to the development of chronic Otitis Media (OM). Although mucosal inflammation during OM leads to increased mucin gene expression and elevated adhesion forces within the ET lumen, it is not known how changes in mucosal adhesion alter the biomechanical mechanisms of ET function. In this study, we developed a novel multi-scale finite element model of ET function in adults that utilizes adhesion spring elements to simulate changes in mucosal adhesion. Models were created for six adult subjects, and dynamic patterns in muscle contraction were used to simulate the wave-like opening of the ET that occurs during swallowing. Results indicate that ET opening is highly sensitive to the level of mucosal adhesion and that exceeding a critical value of adhesion leads to rapid ET dysfunction. Parameter variation studies and sensitivity analysis indicate that increased mucosal adhesion alters the relative importance of several tissue biomechanical properties. For example, increases in mucosal adhesion reduced the sensitivity of ET function to tensor veli palatini muscle forces but did not alter the insensitivity of ET function to levator veli palatini muscle forces. Interestingly, although changes in cartilage stiffness did not significantly influence ET opening under low adhesion conditions, ET opening was highly sensitive to changes in cartilage stiffness under high adhesion conditions. Therefore, our multi-scale computational models indicate that changes in mucosal adhesion as would occur during inflammatory OM alter the biomechanical mechanisms of ET function. Copyright © 2016 John Wiley & Sons, Ltd.

Imaging of the Eustachian tube and its function: a systematic review

Introduction

The Eustachian tube is a complex and inaccessible structure, which maintains middle ear ventilation to facilitate transmission of sound from the tympanic membrane to the cochlea. A renewed interest in treatments for eustachian tube dysfunction has led to a demand for methods of imaging the Eustachian tube, and assessing tube opening non-invasively. This review aims to summarise the use of imaging in the anatomical assessment of the Eustachian tube, and to explore how radiological techniques can be used to assess tube function.

Methods

A systematic review of the literature was performed with narrative data analysis.

Results

With high-resolution images, the soft and bony anatomy of the Eustachian tube can be assessed in detail. CT and MRI are best suited to identifying features associated with obstructive or patulous Eustachian tube dysfunction, though true assessments of function have only been achieved with contrast enhanced radiographs and scintigraphy. A single modality has yet to provide a complete assessment. No test has entered routine clinical use, but further development and research is underway.

Conclusion

Significant information can be gained from imaging the Eustachian tube, and as faster acquisition techniques are developed, it is possible that dynamic imaging of tubal opening could play an important role in the assessment of patients with ET dysfunction.

Behavioral assessment of auditory processing disorder in children with non-syndromic cleft lip and/or palate

OBJECTIVE

Peripheral hearing disorders have been frequently described in children with non-syndromic cleft lip and/or palate (NSCL/P). However, auditory processing problems are rarely considered for children with NSCL/P despite their poor academic performance in general compared to their craniofacially normal peers. This study aimed to compare auditory processing skills, using behavioral assessment techniques, in school age children with and without NSCL/P.

METHODS

One hundred and forty one Mandarin-speaking children with NSCL/P aged from 6.00 to 15.67 years, and 60 age-matched, craniofacially normal children, were recruited. Standard hearing health tests were conducted to evaluate peripheral hearing. Behavioral auditory processing assessment included adaptive tests of temporal resolution (ATTR), and the Mandarin pediatric lexical tone and disyllabic-word picture identification test in noise (MAPPID-N).

RESULTS

Age effects were found in children with cleft disorder but not in the control group for gap detection thresholds with ATTR narrow band noise in the across-channel stimuli condition, with a significant difference in test performance between the 6 to 8 year group and 12 to 15 year group of children with NSCL/P. For MAPPID-N, the bilateral cleft lip and palate subgroup showed significantly poorer SNR-50% scores than the control group in the condition where speech was spatially separated from noise. Also, the cleft palate participants showed a significantly smaller spatial separation advantage for speech recognition in noise compared to the control group children.

CONCLUSION

ATTR gap detection test results indicated that maturation for temporal resolution abilities was not achieved in children with NSCL/P until approximately 8 years of age compared to approximately 6 years for craniofacially normal children. For speech recognition in noisy environments, poorer abilities to use timing and intensity cues were found in children with cleft palate and children with bilateral cleft lip and palate compared to craniofacially normal children. Consequently, it is worthwhile to consider the potential for auditory processing disorder in when assessing the auditory status of children with NSCL/P.

Computational analysis of microbubble flows in bifurcating airways: role of gravity, inertia, and surface tension

Although mechanical ventilation is a life-saving therapy for patients with severe lung disorders, the microbubble flows generated during ventilation generate hydrodynamic stresses, including pressure and shear stress gradients, which damage the pulmonary epithelium. In this study, we used computational fluid dynamics to investigate how gravity, inertia, and surface tension influence both microbubble flow patterns in bifurcating airways and the magnitude/distribution of hydrodynamic stresses on the airway wall. Direct interface tracking and finite element techniques were used to simulate bubble propagation in a two-dimensional (2D) liquid-filled bifurcating airway. Computational solutions of the full incompressible Navier-Stokes equation were used to investigate how inertia, gravity, and surface tension forces as characterized by the Reynolds (Re), Bond (Bo), and Capillary (Ca) numbers influence pressure and shear stress gradients at the airway wall. Gravity had a significant impact on flow patterns and hydrodynamic stress magnitudes where Bo > 1 led to dramatic changes in bubble shape and increased pressure and shear stress gradients in the upper daughter airway. Interestingly, increased pressure gradients near the bifurcation point (i.e., carina) were only elevated during asymmetric bubble splitting. Although changes in pressure gradient magnitudes were generally more sensitive to Ca, under large Re conditions, both Re and Ca significantly altered the pressure gradient magnitude. We conclude that inertia, gravity, and surface tension can all have a significant impact on microbubble flow patterns and hydrodynamic stresses in bifurcating airways.

Panel 2

Objective

This report reviews the literature to identify the advances in our understanding of the middle ear (ME)–Eustachian tube (ET) system during the past 4 years and, on that basis, to determine whether the short-term goals elaborated in the last report were achieved and propose updated goals to guide future otitis media (OM) research.

Data Sources

Databases searched included PubMed, Web of Science (1945-present), Medline (1950 to present), Biosis Previews (1969-present), and the Zoological Record (1978 to present). The initial literature search covered the time interval from January 2007 to June 2011, with a supplementary search completed in February 2012.

Review Methods

The panel topic was subdivided; each contributor performed a literature search and provided a preliminary report. Those reports were consolidated and discussed when the panel met on June 9, 2011. At that meeting, the progress was evaluated and new short-term goals proposed.

Conclusions

Progress was made on 16 of the 19 short-term goals proposed in 2007. Significant advances were made in the characterization of ME gas exchange pathways, modeling ET function, and preliminary testing of treatments for ET dysfunction.

Implications for Practice

In the future, imaging technologies should be developed to noninvasively assess ME/ET structure and physiology with respect to their role in OM pathogenesis. The new data derived from form/function experiments should be integrated into the finite element models and used to develop specific hypotheses concerning OM pathogenesis and persistence. Finally, rigorous studies of treatments, medical or surgical, of ET dysfunction should be undertaken.