Mucosal folds in human eustachian tube: a hypothesis regarding functional localization in the tube

Functional aspects of the Eustachian tube by means of 3D-modeling

The extent of dysfunction of the Eustachian tube (ET) is relevant in understanding the pathogenesis of secondary otological diseases such as acute or chronic otitis media. The underlying mechanism of ET dysfunction remains poorly understood except for an apparent genesis such as a nasopharyngeal tumor or cleft palate. To better describe the ET, its functional anatomy, and the biomechanical valve mechanism and subsequent development of diagnostic and interventional tools, a three-dimensional model based on thin-layer histology was created from an ET in this study. Blackface sheep was chosen as a donor. The 3-D model was generated by the coherent alignment of the sections. It was then compared with the cone-beam computed tomography dataset of the complete embedded specimen taken before slicing. The model shows the topographic relation of the individual components, such as the bone and cartilage, the muscles and connective tissue, as well as the lining epithelium with the lumen. It indicates a limited spiraling rotation of the cartilaginous tube over its length and relevant positional relationships of the tensor and levator veli palatine muscles.

Otitis media in coronavirus disease 2019: a case series

Background

Manifestations of the coronavirus disease 2019 in ENT include sore throat, rhinorrhoea, anosmia and dysgeusia. Whether coronavirus disease 2019 causes otitis media is not known.

Objective

To assess the presence of otitis media in a series of patients with confirmed coronavirus disease 2019 and ENT symptoms.

Methods

The study included patients with coronavirus disease 2019, confirmed on polymerase chain reaction assay, who had otological (e.g. otalgia, otorrhoea, hearing loss) or other ENT (e.g. anosmia, dysgeusia) manifestations of coronavirus disease 2019, in two tertiary referral hospitals in Iran. Patients were excluded if they had a background of otological problems including previous acute otitis media, chronic otitis media, otological surgery, and trauma or radiotherapy to the head and neck.

Results

Otitis media was found in eight patients with coronavirus disease 2019 and no background of otological problems. Six patients had middle-ear effusion, three had typical signs of acute otitis media, and one had a tympanic membrane perforation. Most patients had hearing loss; conductive hearing loss and mild sensorineural hearing loss at high frequencies were the underlying mechanisms.

Conclusion

Otitis media should be considered a manifestation or associated symptom of coronavirus disease 2019 during the current pandemic.

Establishment of a Large Animal Model for Eustachian Tube Functional Study in Miniature Pigs

This study was performed to investigate whether miniature pigs are a suitable animal model for studies of the Eustachian tube (ET). Sixteen Chinese experimental miniature pigs were used in this investigation. Ten animals were used for anatomical and morphometric analyses to obtain qualitative and quantitative information regarding the ET. Three animals were used for histological analysis to determine the fine structure of ET cross-sections. Three animals were used to investigate the feasibility of balloon dilation of the Eustachian tube (BDET). The anatomical study indicated that the pharyngeal orifice and tympanic orifice of the miniature pig ET are located at the posterior end of the nasal lateral wall and anterior wall of the middle ear cavity, respectively. The cartilaginous tube was seen to pass through the whole length of the ET, the length of the cartilaginous part of the ET and the diameter of the isthmus were similar between humans and miniature pigs. The inclination of the ET in miniature pigs was larger than that in humans. The gross histology seemed to be slightly different between miniature pig and human, but the fine structures were essentially the same in both species. BDET experiments verified that the miniature pig model is suitable as a model for clinical operations. The miniature pig ET corresponds very well to that of humans. In addition, the miniature pig ET is suitable as a model for clinical operations. Therefore, the miniature pig is a valid animal model for ET study. Anat Rec, 302:1024-1038, 2019. © 2019 Wiley Periodicals, Inc.

Do mucosal folds in the eustachian tube function as microturbinates?

OBJECTIVES/HYPOTHESIS

Mucosal folds in the eustachian tube (ET) may function as microturbinates and provide protection and clearance.

STUDY DESIGN

Descriptive study.

METHODS

Nineteen whole-mount temporal bone ET specimens (nine pediatric and 10 adult) were evaluated in the present study. Five specific localizations for each case were selected. The cartilaginous segment of the ET was divided vertically and the length of mucosal surfaces and the number of mucosal folds of anterior and posterior walls on the histological sections were analyzed with MetaMorph 7.5.2.0 software.

RESULTS

The length of the mucosal surface of the posterior wall of the ET was longer than the anterior wall (P < .05). In pediatric specimens, the posterior wall had more mucosal folds than adult specimens (P < .05).

CONCLUSIONS

Microturbinates in the posterior wall of the ET may provide important protection and clearance functions for children and play a role in the pathogenesis of eustachian tube dysfunction

Chinchilla as a robust, reproducible and polymicrobial model of otitis media and its prevention

There is compelling evidence that many infectious diseases of humans are caused by more than one microorganism. Multiple diverse in vitro systems have been used to study these complex diseases, and although the data generated have contributed greatly to our understanding of diseases of mixed microbial etiology, having rigorous, reproducible and relevant animal models of human diseases are essential for the development of novel methods to treat or prevent them. All animal models have inherent limitations; however, they also have important advantages over in vitro methods, including the presence of organized organ systems and an intact immune system, which promote our ability to characterize the pathogenesis of, and the immune response to, sequential or coinfecting microorganisms. For the highly prevalent pediatric disease otitis media, or middle-ear infection, the chinchilla (Chinchilla lanigera) has served as a gold-standard rodent host system in which to study this multifactorial and polymicrobial disease.

Prevalence of OME Is Reduced in Young Children Using Chewing Gum

OBJECTIVE

The present study investigates a possible relationship between use of chewing gum and otitis media with effusion (OME) in children. Chewing obviously activates jaw movements, increases salivary flow, and, by the way, the rate of swallowing and the rate of activations of peritubal muscles and tubal openings. Chewing also requires nasal respiration, thus preventing mouth breathing.

DESIGN

Cross-sectional study: 1756 children (2 to 6 yr of age), apparently in good health and visiting different Dutch child health centers in the region of Utrecht were examined between September 1999 and April 2002. OME was diagnosed by combined tympanometry and otoscopy. The criterion for OME was unilateral or bilateral type B tympanogram, according to Jerger. The parents had to fill out a questionnaire with a question pertaining to the chewing habits of their child.

RESULTS

Logistic regression points out that age and season as well as chewing gum-consuming habits significantly influence the prevalence of OME. The strongest effects are age (OME becomes less frequent with age) and season (OME occurs less when climate is more favorable), but -- ceteris paribus -- a child consuming daily or at least weekly chewing gum shows significantly less chance for OME than a child who seldom consumes or consumes no chewing gum (p = 0.023).

CONCLUSIONS

In the case of regular use of chewing gum, the probability of having OME in children is reduced by 40%. It seems plausible that children with immature oral motorics do not like chewing gum.

Functional tubal therapy for persistent otitis media with effusion in children: myth or evidence?

Otitis media with effusion (OME), a form of inflammatory middle ear disease, is a common reason for young children to visit their family doctor and to have surgery. Tubal dysfunction plays a major role in the pathogenesis. In case of persistent OME, there seems to be a logical rationale for a favourable effect on the tubal dysfunction of a functional active motoric approach combined with behavioral changes (hygiene), and as a consequence for a therapeutic effect on the middle ear disease. The basic principles of this functional treatment are: active ventilation of the middle ear, correction of immature and undesirable deviant mouth habits, increasing swallowing frequency, activating jaw and palate movements, and encouraging the use of chewing gum. The bases for this functional therapy are critically analysed, and it may be concluded that all of these principles rely upon evidence based physiological mechanisms. However, the limited available clinical data from the literature are reviewed, and appear as methodologically weak. The results of an own prospective randomized pilot study comparing functional treatment with watchful waiting may be considered encouraging, since a borderline significance level was reached with a small amount of subjects.

The muscular compliance of the auditory tube: a model-based survey

OBJECTIVES

The role of the paratubal muscles, especially the medial pterygoid muscle, still is unclear. The aim of this study was to define the function of the medial pterygoid muscle concerning the muscular compliance of the auditory tube.

METHODS

High-resolution cross-sectional T1 magnetic resonance imaging data of one of the authors' paratubal structures were used, a new functional 3-D model of the auditory tube and its related structures visualized by the Hamburg VOXEL-MAN digital image system.

RESULTS

Functional 3-D reconstructions of the paratubal structures reveal that the medial pterygoid muscle is acting as a movable hypomochlion of the tensor veli palatini muscle. Contraction of the medial pterygoid muscle increases and relaxation decreases the force of the tensor veli palatini muscle on the distal part of the auditory tube. Hence, the opening pressure of the auditory tube is moderated by the action of the medial pterygoid muscle.

CONCLUSION

The influence of the medial pterygoid muscle on the opening pressure of the auditory tube may have an impact on the diagnosis and therapy in patients with patent auditory tube as well as the middle ear pathology in patients with cleft palate.

The eustachian tube. Update on anatomy, development, and function

Central to many pathologic conditions affecting the middle ear is the failure of the ET to perform its functions of regulation of middle ear pressure, clearance of middle ear secretions, and protection of the middle ear space. Recent advances in radiologic imaging and fiberoptic endoscopes have allowed a more detailed description of the structure and function of this area. Hopefully, with the knowledge gained from advances in this area, more effective medical treatment options for common otologic problems, such as otitis media, will become available.

Mucosa-associated lymphoid tissue in middle ear and eustachian tube

The presence of mucosa-associated lymphoid tissue (MALT) was investigated histopathologically in every 20th section from 99 vertically cut, celloidin-embedded temporal bone-eustachian tube (ET) specimens. Among specimens from infants and children between 1 month and 7 years of age, MALT was found in 22 of 44 (50%). However, in 26 adults over 18 years of age, MALT was found in only 2 specimens (7.7%), a significantly lower incidence than that in infants and children. Moreover, MALT did not appear in any of the 21 neonates under the age of 1 month. All 99 specimens were classified into 2 groups: 41 specimens with otitis media (OM) and 58 specimens without OM. The presence of MALT was significantly higher in specimens with OM (43.9%) than in specimens without OM (13.8%). Mucosa-associated lymphoid tissue was found in the ET, middle ear, and mastoid process in 18 specimens (43.9%). 5 specimens (12.2%), and 1 specimen (2.4%) with OM, respectively, and in 8 (13.8%), 0, and 0 specimens without OM. In regard to the distribution of MALT, it occurred more frequently in the pharyngeal half of the cartilaginous portion of the ET than in the rest of the ET, middle ear, and mastoid; the presence was significantly greater in the inferior half of the cartilaginous portion of the ET than in the superior half. Inflammatory cell infiltration in the cartilaginous and bony portions of the ET was significantly greater in specimens with OM than in specimens without OM with no MALT. However, even in some specimens without OM, inflammatory cells were found in the ET, particularly in the pharyngeal half of the cartilaginous portion of the ET. These findings suggest that MALT has a close relationship to OM and that it may be a local response to repeated infection.

Cellular distribution of mucosa-associated lymphoid tissue with otitis media in children

This study examined mucosa-associated lymphoid tissue (MALT) in the eustachian tube (ET), middle ear (ME), and mastoid antrum (MA) in 163 celloidin-embedded temporal bones from children with or without otitis media. Otitis media was defined by the presence of histopathologically identified inflammatory cell infiltration in the mucosa or cavity of the ME. We found MALT in the ET in 30 cases (46.2%), in the ME in 19 cases (29.2%), and in the MA in 4 cases (6.2%) out of 65 cases of otitis media, and in the ET in 7 (7.1%), in the ME in 0, and in the MA in 0 out of 98 specimens without otitis media. No MALT appeared in any children under the age of 1 month. Immunohistochemical methods were used to investigate MALT in 12 horizontally cut temporal bones with OM. The follicular area contained OPD4-positive (helper-inducer T) cells and a few CD8-positive (cytotoxic and suppressor T) cells, whereas the parafollicular area contained OPD4-positive and CD8-positive T cells. CD57-positive (natural killer) cells were confined to the germinal center. CD30-positive (activated T and B) cells were observed throughout the follicles. A few CD15-positive (granulocyte, monocyte) cells were found in the follicles. Histopathologic and immunohistochemical findings were indistinguishable for MALT in the ET, ME, and MA. Our results suggest that MALT may be a mechanism for producing a rapid and massive local immune reaction to repeated bacterial infections via the ET.

The eustachian tube caliber and craniofacial skeleton in guinea pigs

The temporal bone and eustachian tube (ET) keep developing up to adulthood in conjunction with facial growth, and the researchers considered that insufficient tubal function in childhood might be related to size, shape and position of the ET. In this study, we performed correlation and stepwise regression analyses between craniofacial skeletal parameters and diameter of the cartilaginous ET in 90 guinea pigs. Data showed that, not the potency of the lumen at the superior part of the cartilaginous ET, but the configuration of the cartilage surrounding the superior part of the ET, and position of the lateral lamina appeared to be significantly associated with the balance of the growth potentials between the naso-premaxillary unit, maxillo-zygomatic unit and the anterior cranial base. Therefore, we may hypothesize that the balance between these subunits of the developing craniofacial skeleton has determinative effect on tensor veli palatini muscle (TVPM).

Anatomic relationships between Ostmann's fatty tissue and eustachian tube

To examine anatomic relationships between Ostmann's fatty tissue (OF) and the eustachian tube (ET), we evaluated serial histologic sections of 32 normal temporal bone-ET specimens and made a quantitative analysis of several measurements (height, width, and volume). We compared results in specimens from individuals in whom the ET was still developing (those 19 years and younger) to results in specimens from individuals with adult ETs (those older than 19). We found that 1) the main body of OF is located at the inferolateral aspect of the ET and 2) postnatally, OF grows in volume, mainly by an increase in height, so that OF maintains the same vertical relationship to the growing ET and does not increase in width. The former finding indicates that OF might exert static pressure on the ET not to open widely. The latter finding indicates that the relatively thicker mass of OF may narrow the ET in those with immature ETs. These results indicate a possible role for OF in ET function, which in turn has been implicated in otitis media with effusion.

Mucosal folds of eustachian tube in young children

Differences in the extent of mucosal folding in the superior versus the inferior half of the human Eustachian tube (ET) were studied in young children by measuring the length of the mucosal margin and counting the number of mucosal folds, as they appeared in histological cross-sections, in the pharyngeal, midcartilaginous, isthmus, and osseous portions of each half of the ET in 12 normal ET/temporal bone specimens from 12 individuals aged 1 day to 2 years. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in the pharyngeal, midcartilaginous, and isthmus portions (paired t-test, pharyngeal portion: t[11] = 3.71, p < 0.01; midcartilaginous portion: t[11] = 4.52, p < 0.01; isthmus portion: t[11] = 3.40, p < 0.01). However, there was no significant difference between in the inferior half and in the superior half at the osseous portion. Also there were significantly more mucosal folds in the inferior half than in the superior half in all four portions (paired t-test, pharyngeal portion: t[11] = 3.46, p < 0.01; midcartilaginous portion: t[11] = 7.40, p < 0.01; isthmus portion: t[11] = 5.03, p < 0.01; osseous portion: t[11] = 4.49, p < 0.01). These results indicate that the surface area of the mucosa in the inferior half of the ET is larger than that of the superior half.(ABSTRACT TRUNCATED AT 250 WORDS)