In vivo demonstration of the absorptive function of the middle ear epithelium

Assessing the Efficacy of Tragal Pumping in a Novel Tympanostomy Tube-Rat Model

Objective

Tragal pumping (TP) is a practice of pushing on the tragus to raise pressure within the external auditory canal and is a commonly recommended adjunctive maneuver believed to facilitate the introduction of ototopical medications into the middle ear cavity via a tympanostomy tube. To investigate the efficacy of TP in the penetration of eardrops into the middle ear cavity via tympanostomy tube, we established the novel tympanostomy tube-rat model. We investigated the histology of the middle ear to determine the efficacy in moving fluid into the middle ear.

Study Design

Prospective controlled animal study.

Setting

Animal laboratory in a university hospital.

Methods

Ten rats were recruited, and a tympanostomy tube insertion and green dye eardrops into outer ears were performed on bilateral ears. TP was performed only on 1 ear and was not applied on the other ear in each rat. Green dye in a middle ear cavity in hematoxylin and eosin-stained temporal bone sections was evaluated by blinded experts in microscopic anatomy (staining grade) and by using Image J software (staining level). The results of these 2 methods were statistically validated.

Results

The staining grade (P < .001) and the staining level (P < .001) were significantly higher in the ears which we applied TP than in the control ears. The results of 2 methods were significantly and positively correlated (r = .898, P < .001).

Conclusion

Our results showed that the TP accelerate the penetration of eardrops into the middle ear cavity in the tympanostomy tube-rat model.

[Application of allogenous dural membrane (brefotissue DM) in surgical treatment of retraction pockets of the tympanic membrane]

INTRODUCTION

The tactics of treating patients with retraction pockets of the tympanic membrane is still debatable. When choosing surgical treatment, preference is given to the removal of the retraction pocket with simultaneous reconstruction of the posterior-upper wall of the external auditory canal (retraction area) with a cartilage or fascial flap, autologous bone, or a combination of the above tissues. Considering the well-known negative aspects of the use of all the mentioned grafts, there is a need to find new types of tissues to strengthen the retraction pocket. For example, dura mater brefotissue has good plastic properties, resistance to infection, is easy to prepare, store, and is cheaper than many allografts.

AIM

Evaluation of the possibility of using dura mater brefotissue in the surgical treatment of patients with retraction pockets of the tympanic membrane.

MATERIALS AND METHODS

The study included 52 patients who underwent surgery to eliminate the retraction pocket. All of them were divided into 2 groups. In the first - the main (n=25) cartilage of the auricle was used to seal the relaxed part of the tympanic membrane, in the second - the control (n=27) applied tissue of the dura mater. After 1, 3, 6 and 12 months, to assess the result of the intervention, all patients underwent otomicroscopy, audiometry with the calculation of the average sound conduction index for speech frequencies.

RESEARCH RESULTS

Fewer cases (4 patients out of 27) had difficulty in graft placement with the use of dura mater compared to the group where cartilage was used (9 patients out of 25). The average duration of graft placement was 8±0.5 minutes in the control group and 2±0.3 minutes in the main group. A stable morphological result was obtained in the group with the use of brefotissue in 26 patients (96%) and only in 20 patients (80%) with the use of cartilage. It is important to note that in the group with the use of brefotissue, in the early postoperative period, there was an increase in the air-bone interval, and 1 month after the operation, the average values increased by 10±0.5 dB. 12 months after the operation, the above parameters returned to preoperative.

CONCLUSION

The conducted study indicates that the dura mater brefotissue, having sufficient strength, the convenience of forming a given shape and placing it in the desired position, can be successfully used in the surgical treatment of patients with retraction pockets of the tympanic membrane.

The Physiologic Role of Corticosteroids in Menière's Disease: An Update on Glucocorticoid-mediated Pathophysiology and Corticosteroid Inner Ear Distribution

: There are multiple treatment options for Ménière's disease (MD), including dietary modifications, aminoglycoside therapy, and surgery. All have limitations, ranging from limited effectiveness to permanent hearing loss. Corticosteroids have long been used to manage MD due to their relative efficacy and tolerability, but the exact mechanism for disease alleviation is uncertain. Until recently, the precise distribution and role that glucocorticoid receptors play in inner ear diseases have remained largely uninvestigated. Several studies propose they influence mechanisms of fluid regulation through ion and water homeostasis. This review will provide an update on the basic science literature describing the activity of endogenous glucocorticoids and exogenous corticosteroids in the inner ear and the relevance to MD, as well as early clinical trial data pertaining to the application of novel technologies for more effective administration of corticosteroids for the treatment of MD.

Further Research Needed to Understand Relationship Between Tubarial Glands and Eustachian Tube Dysfunction

The pathophysiology of eustachian tube dysfunction (ETD) remains poorly characterized, and it may result in significant patient morbidity. A recent study has identified a collection of previously unidentified salivary glands in the nasopharynx that overlay the torus tubarius. While salivary gland tissue has been described in the nasopharynx, the newly discovered salivary gland tissue has been denoted tubarial glands (TGs) and theorized to be a distinct organ. The TGs have been suggested to aid in lubrication of the oropharynx and nasopharynx. However, the exact clinical significance of TGs is unknown. Given the proximity of the TG to the eustachian tube, it is possible that the TGs may be related to the development of ETD. Future studies of the TGs and related pathophysiology may improve approaches to developing future ETD treatments.

Effect of delivery mode on neonate auditory brainstem responses to air- and bone-conducted stimuli

OBJECTIVES

The object of this study was to examine if caesarean section delivered neonates have different middle ear function relative to neonates with vaginal delivery.

METHODS

Auditory brainstem responses (ABRs) were examined in caesarean section delivered (n = 23) and vaginally delivered (n = 29) neonates. ABRs were also evoked with air- and bone-conducted stimuli (i.e., clicks and CE-Chirps) and presented at a screening intensity level (i.e., 30 dB nHL). Wave V latencies and amplitudes were examined as a function of mode of delivery and stimuli.

RESULTS

Statistically significant longer wave V latencies evoked with air-conducted stimuli were seen in caesarean section delivered neonates (p = .042). There was no statistically significant difference in wave V latencies with bone-conducted stimuli among the two groups of neonates (p = .42). There were no significant differences in wave V amplitude between neonates with caesarean section and vaginal delivery for air-conducted (p = .42) stimuli. Wave V amplitudes were not significantly different as a function of mode of delivery with CE-Chirp stimulus (p = .41). Wave V amplitudes were significantly larger for the caesarean section delivered neonates with the bone-conducted click stimulus (p = .036).

CONCLUSIONS

The ABR wave V latency disparity with air- and bone-conducted stimuli support the notion that differences in middle ear function exist between the two groups of newborns. It was speculated that delayed fluid resorption in the middle ear exists in neonates with caesarean section delivery compared to those with vaginal delivery.

Communication pathways to and from the inner ear and their contributions to drug delivery

The environment of the inner ear is highly regulated in a manner that some solutes are permitted to enter while others are excluded or transported out. Drug therapies targeting the sensory and supporting cells of the auditory and vestibular systems require the agent to gain entry to the fluid spaces of the inner ear, perilymph or endolymph, which surround the sensory organs. Access to the inner ear fluids from the vasculature is limited by the blood-labyrinth barriers, which include the blood-perilymph and blood-strial barriers. Intratympanic applications provide an alternative approach in which drugs are applied locally. Drug from the applied solution enters perilymph through the round window membrane, through the stapes, and under some circumstances, through thin bone in the otic capsule. The amount of drug applied to the middle ear is always substantially more than the amount entering perilymph. As a result, significant amounts of the applied drug can pass to the digestive system, to the vasculature, and to the brain. Drugs in perilymph pass to the vasculature and to cerebrospinal fluid via the cochlear aqueduct. Conversely, drugs applied to cerebrospinal fluid, including those given intrathecally, can enter perilymph through the cochlear aqueduct. Other possible routes in or out of the ear include passage by neuronal pathways, passage via endolymph and the endolymphatic sac, and possibly via lymphatic pathways. A better understanding of the pathways for drug movements in and out of the ear will enable better intervention strategies.

Divergent expression of α-ENaC in middle ear mucosa in the course of otitis media with effusion induced by barotrauma

CONCLUSION

Gene transcription and protein expression of α-ENaC showed a divergent expression in association with the development of OME induced by barotrauma.

OBJECTIVES

ENaC was identified to mediate the fluid absorption through epithelia of the middle ear. This study was designed to investigate the involvement of ENaC in otitis media with effusion (OME) induced by barotrauma.

METHODS

A rat model of otitis media with effusion was established using a pressure cabin. The dynamic expression of α-ENaC was detected by Real time-PCR and western blot in the course of otitis media.

RESULTS

Compared with the control, the volume of α-ENaC mRNA and protein increased significantly by 3.18-fold and 2.8-fold on the 3(rd) day, respectively, while decreased by 0.54-fold and 0.32-fold on the 7(th) day, respectively.

Control of middle ear inflammatory and ion homeostasis genes by transtympanic glucocorticoid and mineralocorticoid treatments

HYPOTHESIS

Transtympanic steroid treatment will induce changes in ion homeostasis and inflammatory gene expression to decrease middle ear inflammation due to bacterial inoculation.

BACKGROUND

Otitis media is common, but treatment options are limited to systemic antibiotic therapy or surgical intervention. Systemic glucocorticoid treatment of mice decreases inflammation and improves fluid clearance. However, transtympanic delivery of glucocorticoids or mineralocorticoid has not been explored to determine if direct steroid application is beneficial.

METHODS

Balb/c mice received transtympanic inoculation of heat-killed Haemophilus influenzae (H flu), followed by transtympanic treatment with either prednisolone or aldosterone. Mice given PBS instead of steroid and untreated mice were used as controls. Four hours after steroid treatment, middle ears were harvested for mRNA extraction and 24 hours after inoculation middle ears were harvested and examined for measures of inflammation.

RESULTS

H flu inoculation caused the increased expression of nearly all inflammatory cytokine genes and induced changes in expression of several genes related to cellular junctions and transport channels. Both steroids generally reversed the expression of inflammatory genes and caused ion and water regulatory genes to return to normal or near normal levels. Histologic evaluation of middle ears showed improved fluid and inflammatory cell clearance.

CONCLUSION

Improvement in middle ear inflammation was noted with both the glucocorticoid prednisolone and the mineralocorticoid aldosterone. This was due to reversal of inflammation-induced changes in middle ear cytokine genes, as well as those involved in ion and water homeostasis. Because glucocorticoids bind to the mineralocorticoid receptor, but not the reverse, it is concluded that much of the reduction of fluid and other inflammation measures was due to these steroids impact on ion and water transport channels. Further research is necessary to determine if this alternative mineralocorticoid treatment for otitis media will be clinically effective with fewer side effects than glucocorticoids.

Inner ear tissue remodeling and ion homeostasis gene alteration in murine chronic otitis media

HYPOTHESIS

Studies were designed to ascertain the impact of chronic middle ear infection on the numerous ion and water channels, transporters, and tissue remodeling genes in the inner and middle ear.

BACKGROUND

Permanent sensorineural hearing loss is a significant problem resulting from chronic middle ear disease, although the inner ear processes involved are poorly defined. Maintaining a balanced ionic composition of endolymph in the inner ear is crucial for hearing; thus, it was hypothesized that this may be at risk with inflammation.

METHODS

Inner and middle ear RNA collected separately from 6-month-old C3H/HeJ mice with prolonged middle ear disease were subjected to qRT-PCR for 8 common inflammatory cytokine genes, 24 genes for channels controlling ion (sodium, potassium, and chloride) and water (aquaporin) transport, tight junction claudins, and gap junction connexins, and 32 tissue remodeling genes. Uninfected Balb/c mice were used as controls.

RESULTS

Significant increase in inner ear inflammatory and ion homeostasis (claudin, aquaporin, and gap junction) gene expression, and both upregulation and downregulation of tissue remodeling gene expression occurred. Alteration in middle ear ion homeostasis and tissue remodeling gene expression was noted in the setting of uniform upregulation of cytokine genes.

CONCLUSION

Chronic inflammatory middle ear disease can impact inner ear ion and water transport functions and induce tissue remodeling. Recognizing these inner ear mechanisms at risk may identify potential therapeutic targets to maintain hearing during prolonged otitis media.

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.

Mouse middle ear ion homeostasis channels and intercellular junctions

Hypothesis

The middle ear contains homeostatic mechanisms that control the movement of ions and fluids similar to those present in the inner ear, and are altered during inflammation.

Background

The normal middle ear cavity is fluid-free and air-filled to allow for effective sound transmission. Within the inner ear, the regulation of fluid and ion movement is essential for normal auditory and vestibular function. The same ion and fluid channels active in the inner ear may have similar roles with fluid regulation in the middle ear.

Methods

Middle and inner ears from BALB/c mice were processed for immunohistochemistry of 10 specific ion homeostasis factors to determine if similar transport and barrier mechanisms are present in the tympanic cavity. Examination also was made of BALB/c mice middle ears after transtympanic injection with heat-killed Haemophilus influenza to determine if these channels are impacted by inflammation.

Results

The most prominent ion channels in the middle ear included aquaporins 1, 4 and 5, claudin 3, ENaC and Na⁺,K⁺-ATPase. Moderate staining was found for GJB2, KCNJ10 and KCNQ1. The inflamed middle ear epithelium showed increased staining due to expected cellular hypertrophy. Localization of ion channels was preserved within the inflamed middle ear epithelium.

Conclusions

The middle ear epithelium is a dynamic environment with intrinsic mechanisms for the control of ion and water transport to keep the middle ear clear of fluids. Compromise of these processes during middle ear disease may underlie the accumulation of effusions and suggests they may be a therapeutic target for effusion control.

Murine middle ear inflammation and ion homeostasis gene expression

HYPOTHESIS

Ion homeostasis genes are responsible for the movement of ions and water in the epithelium of the middle ear.

BACKGROUND

It is not well known to what extent disruption of ion homeostasis is a factor in the accumulation of middle ear fluid during otitis media.

METHODS

Balb/c mice were transtympanically injected with heat-killed Hemophilus influenza bacteria. Untreated and saline-injected mice were used as controls. Mice were euthanized at 6, 24, and 72 hours and 1 week after injection, the bullae harvested, and total ribonucleic acid isolated from the middle ear tissues. Ion homeostasis genes were analyzed with real-time quantitative reverse transcription-polymerase chain reaction from the following gene families: Na,K-ATPase, claudins, K transport channels, epithelial Na channels, gap junctions, and aquaporins. Inflammatory genes also were analyzed to document inflammation.

RESULTS

All inflammatory genes analyzed were significantly upregulated, more at 6 hours than at 24 hours, with the exception of vascular endothelial growth factor and Mapk8. Most middle ear ion homeostasis genes experienced downregulation because of inflammation. This was most prominent in the aquaporin and Na,K-ATPase genes. Significant upregulation was seen in several genes in response to inflammation and saline independently.

CONCLUSION

The innate immune response to bacteria in the middle ear induces expression of several inflammatory genes. Coinciding with this inflammation is the downregulation of numerous ion homeostasis genes that are involved in ion and water transport and maintenance of tight junctions. This may explain the fluid accumulation within the middle ear seen with both acute and chronic otitis media.

Steroid control of acute middle ear inflammation in a mouse model

OBJECTIVE

To investigate steroids for their potential for therapeutic approaches to control otitis media. Glucocorticoids and mineralocorticoids have differential effects on inflammation and fluid absorption, but little is known of their control of middle and inner ear manifestations of acute otitis media.

DESIGN

Both glucocorticoid (prednisolone and dexamethasone) and mineralocorticoid (aldosterone and fludrocortisone) steroids were investigated for their ability to reduce inflammatory symptoms in a mouse otitis media model.

SETTING

Academic medical center.

SUBJECTS

Acute inflammation was induced by transtympanic injection of heat killed Streptococcus pneumoniae to 100 BALB/c mice.

INTERVENTIONS

Twenty mice in each experimental group (prednisolone, dexamethasone, aldosterone, and fludrocortisone) were given a steroid in their drinking water the day before inoculation, and these treatments were continued until the mice were killed for histologic examination. Twenty control mice were treated with water only.

MAIN OUTCOME MEASURES

Histologic measure of inflammation: middle ear fluid, inflammatory cell number, and tympanic membrane thickness.

RESULTS

Histologic middle ear morphometrics showed significant steroid effects at both 3 and 5 days in reduction of fluid area, cell number, and tympanic membrane thickness.

CONCLUSIONS

Glucocorticoids were most effective in controlling inflammation. Interestingly, the mineralocorticoids were also effective in reducing the inflammatory response at 5 days, suggesting that their fluid transport function helped clear disease. Thus, steroid control of middle ear disease may be useful in alleviating symptoms faster and reducing the risk to the inner ear.

Control of chronic otitis media and sensorineural hearing loss in C3H/HeJ mice: glucocorticoids vs mineralocorticoids

OBJECTIVE

The impact of glucocorticoids and mineralocorticoids on chronic otitis media (COM) in toll-like receptor 4-deficient C3H/HeJ mice was investigated.

STUDY DESIGN

To evaluate control of COM by steroids with differences in their anti-inflammatory (prednisolone, dexamethasone), and fluid absorption functions (fludrocortisone, aldosterone). A minimum sample size of five animals for each group was required based on power analysis calculations. Sample sizes ranged from 7 to 17 mice per treatment group.

SUBJECTS AND METHODS

Auditory brain stem response (ABR) thresholds were performed at baseline, 2 weeks and 4 weeks. Histopathologic test results were evaluated on all mice ears at the end of the study.

RESULTS

Analysis of variance (ANOVA) of ABR threshold change showed significant treatment effects (P < 0.05) by both steroid types at all time intervals and ABR frequencies except 4 weeks/8 kHz. Histologic assessment showed prednisolone-treated mice (62%) had a higher rate of clearance of middle and inner ear inflammation than control mice (4%).

CONCLUSION

It was concluded that steroid treatments can improve the physiology of chronic middle and inner ear disease seen with COM.

Effect of a large-sized silicone sheet upon recovery of mastoid aeration after mastoidectomy

OBJECTIVE

To evaluate the effect of our large-sized silicone sheet upon postoperative recovery of mastoid aeration in ears after surgery including mastoidectomy and soft-wall reconstruction (SWR).

STUDY DESIGN AND SETTING

Retrospective chart review in a tertiary care center.

SUBJECTS AND METHODS

Recovery of mastoid aeration was assessed by CT 4 to 12 months after surgery on 72 ears (69 patients), in which the silicone sheet covering from the eustachian tube (ET) to the mastoid was placed after SWR procedure with mastoidectomy were done for their chronic otitis media. Results were compared with those with a small silicone sheet.

RESULTS

Recovery of mastoid aeration was significantly better in the large-silicone-sheet group than in the small-silicone-sheet group (chi(2) value = 11.7146, P = 0.0006).

CONCLUSION

This preliminary study suggested that our large-sized silicone sheet may be effective for postoperative recovery of mastoid aeration even in ears operated with SWR procedure.

Mechanism and Rate of Middle Ear Fluid Absorption

Several mechanisms have been suggested to explain the clearance of fluids from the middle ear. These include a pumping action through the eustachian tube, mucociliary beating through the tube, outflow of water to the blood due to osmotic gradients and an active Na(+) transport driving water absorption. In order to assess these mechanisms, the middle ear cavity of paralyzed, ventilated (eustachian tube occluded) guinea pigs was filled with fluids varying in osmotic pressure (hypotonic, isotonic, hypertonic) to which a vertical tube was attached. The change in height of fluid in the tube was taken as a measure of changes in middle ear fluid volume. A greater fluid volume reduction was seen with the hypotonic (1/5 saline) solution. A small volume increase was observed with the hypertonic solution. These results provide evidence that in these experimental conditions, water absorption due to osmotic gradients can contribute to middle ear fluid clearance.