Middle Ear Pressure Regulation-Complementary Active Actions of the Mastoid and the Eustachian Tube

Imaging of Pulsatile Tinnitus

Tinnitus is a common complaint that approximately three-fourths of adults will experience at some point in their life. While for many it is a mild nuisance, for some it can be debilitating, affecting cognition and quality of life, increasing stress, and leading to anxiety, depression, and in severe circumstances even suicide. Pulsatile tinnitus refers to the perception of a heartbeat-like sound without external stimulus. Although less common than nonpulsatile tinnitus, pulsatile tinnitus raises concern for underlying disease that can have a high risk of causing the patient harm if undiagnosed, and most of these patients will have positive findings at imaging. While these findings are often subtle, identifying them can have a meaningful impact on the patient's quality of life. The literature on pulsatile tinnitus is changing rapidly with improved imaging techniques and novel minimally invasive treatment options. A careful history and physical examination together with appropriate imaging are therefore critical in identifying the underlying cause. With emerging surgical, endovascular, and supportive technologies, the vast majority of patients with bothersome pulsatile tinnitus can be cured or have their symptoms ameliorated. The objective of this narrative review is to present a comprehensive analysis of the currently available literature on pulsatile tinnitus, with a focus on understanding its pathophysiologic mechanisms, diagnostic pathways, imaging findings, and the spectrum of available management strategies and ultimately to propose a structured framework that aids radiologists as well as clinicians in identifying an underlying diagnosis and guiding management of these patients. ©RSNA, 2024 Supplemental material is available for this article.

Cholesteatoma Severity Determines the Risk of Recurrent Paediatric Cholesteatoma More Than the Surgical Approach

OBJECTIVE

To evaluate factors that influence the rate of cholesteatoma recurrence (growth of new retraction cholesteatoma) in children.

METHODS

Review of children with primary acquired or congenital cholesteatoma. Severity was classified by extent and EAONO-JOS stage, and surgery by SAMEO-ATO. Primary outcome measure was 5-year recurrence rate using Kaplan-Meier or Cox regression analysis.

RESULTS

Median age was 10.7 years for 408 cholesteatomas from which 64 recurred. Median follow up was 4.6 years (0-13.5 years) with 5-year recurrence rate of 16% and 10-year of 29%. Congenital cholesteatoma (n = 51) had 15% 5-year recurrence. Of 216 pars tensa cholesteatomas, 5-year recurrence was similar at 14%, whereas recurrence from 100 pars flaccida cholesteatomas was more common at 23% (log-rank, p = 0.001). Sub-division of EAONO-JOS Stage 2 showed more recurrence in those with than without mastoid cholesteatoma (22.1% versus 10%), with more in Stage 3 (31.9%; p = 0.0003). Surgery without mastoidectomy, including totally endoscopic ear surgery, had 11% 5-year recurrence. Canal wall-up tympanomastoidectomy (CWU) and canal wall-down/mastoid obliteration both had 23% 5-year recurrence. Multivariate analysis showed increased recurrence for EAONO-JOS Stage 3 (HR 5.1; CI: 1.4-18.5) at risk syndromes (HR 2.88; 1.1-7.5) and age < 7 years (HR 1.9; 1.1-3.3), but not for surgical category or other factors.

CONCLUSION

Young age and more extensive cholesteatoma increase the risk of recurrent cholesteatoma in children. When controlling for these factors, surgical approach does not have a significant effect on this outcome. Other objectives, such as lower post-operative morbidity and better hearing outcome, may prove to be more appropriate parameters for selecting optimal surgical approach in children.

Bio-Compatible Sensor for Middle Ear Pressure Monitoring on a Bio-Degradable Substrate

Hypotension in the middle ear can cause serious diseases and hearing disorders. Until now, pressure in the middle ear is measured indirectly by using the impedance of the tympanic membrane (tympanometry). Direct methods are just described in scientific studies and would be harmful in clinical routine. Here, we demonstrate a bio-compatible pressure sensor, which can resolve pressure changes in the range of −7.5 kPa up to +7.5 kPa, and due to its compact design (area of 2 × 4 mm2), can be directly implanted in the human middle ear. Furthermore, the read-out of the pressure sensor can be conveniently done using wireless data communication technologies employing a plate capacitor with an elastic dielectric for pressure monitoring and a planar coil. Thus, our sensor allows for direct pressure measurements in the middle ear, avoiding additional surgeries after device implantation.

Are the hearing and eustachian tube functions of the hot air balloon pilots disturbed?

OBJECTIVE

To evaluate the hearing and Eustachian tube functions (ETF) of hot air balloon (HAB) pilots, who are exposed to high altitude occupationally.

MATERIALS AND METHODS

The study was designed as a cross-sectional controlled study. Thirty HAB pilots and 30 healthy volunteers were included. Pure tone audiometry and speech discrimination scores (SDS) were used to assess the hearing function. Pure tone average (PTA) was calculated using the hearing thresholds (HT) at the frequencies 500, 1000, 2000, and 4000 Hz. Tympanometry and automatic Williams test (ETF1) were conducted to assess the ETF of the participants. Eustachian Tube Dysfunction (ETD) was defined as the change of tympanometric peak pressure (TPP) at rest (P1) less than in 10 decapascals (daPa) with Valsalva (P2) and Toynbee (P3) maneuvers. Eustachian Tube Dysfunction Questionnaire-7 (ETDQ-7) was also administrated.

RESULTS

Mean ages of the participants were 32.03±8.12 and 32.33±9.47 years in the HAB and control groups, respectively (p = 0.865). HTs, PTAs, SDSs, P1, P2, P2-P1 and P1-P3 values were similar in the groups (p > 0.05). P3 values ​​in both ears were significantly higher in the HAB group compared to the control group (p = 0.018, p = 0.002). Positive correlations were detected between the duration of the experience of HAB pilots and their HTs at 4 kHz and 8 kHz (p < 0.05) The prevalence of ETD in at least one ear was 83.7% and in both ears was 43.3% in the HAB group, both of which were significantly higher than the control group (p = 0.001, p = 0.049). The ETDQ-7 scores were also higher in the HAB group compared to the control group (p < 0.001).

CONCLUSION

Both the subjective and objective measures of ETF indicate that ETD is common among the HAB pilots. However, the hearing functions of those seem to be unaffected.

A Novel Instrument for Endoscopic Ear Surgery With a Steerable Flexible Tip: A Pediatric Anatomical Validation Study

HYPOTHESIS

This study compares the reaching ability of two classes of transcanal endoscopic ear surgery (TEES) instruments when operating on difficult to access anatomical targets; two novel instruments with steerable flexible tips (SFT-A and SFT-B) and suction capability are compared with standard commercially available tools.

BACKGROUND

TEES surgeons identified the need for a new surgical instrument that can enable accessibility of all areas visualized by the endoscope. This motivated the development of the two instrument prototypes.

METHODS

Six temporal bone models were 3D printed based on CT data from five cholesteatoma patients. Four anatomical targets were marked on each model. Using these targets, the reaching ability while using four standard TEES instruments were compared with the SFT-A and SFT-B prototypes by five surgeon participants. Results were analysed to compare success rates of contacting each target using each tool by fitting four Firth's logistic regression models. This calculated the statistically significant differences (p < 0.05) in tool success rate.

RESULTS

Using SFT-A to contact the sinus tympani (100%) was significantly more successful than the Panetti suction dissector for atticus (PAT) (77%) and to contact the sinodural angle (0%) was less successful than the PAT (10%) and SFT-B (93%). Using SFT-B to contact the lateral semicircular canal (90%) was significantly more successful than all current tools and to contact the sinodural angle (93%) was significantly more successful than all tools.

CONCLUSION

Using SFT-B enables enhanced accessibility of anatomical structures during TEES which may lead to less extensive bone removal to facilitate minimally invasive TEES.

Correlation between tympanometry volume and three-dimensional computed tomography mastoid volumetry in tympanoplasty candidates

OBJECTIVE

Ventilation of the middle ear and mastoid air cells is believed to play an important role in the pathogenesis of chronic ear disease. Traditionally, ventilation is assessed by computed tomography. However, this exposes patients to cumulative radiation injury. In cases with a perforation in the tympanic membrane, tympanometry potentially presents a non-invasive alternative to measure the ventilated middle-ear and mastoid air cell volume. This study hypothesised that total tympanometry volume correlates with ventilated middle-ear and mastoid air cell volume.

METHOD

Total tympanometry volume was compared with ventilated middle-ear and mastoid air cell volume on computed tomography scans in 20 tympanic membrane perforations.

RESULTS

There was a high correlation between tympanometry and computed tomography volumes (r = 0.78; p < 0.001). A tympanometry volume more than 2 ml predicted good ventilation on computed tomography.

CONCLUSION

These results may help reduce the need for pre-operative computed tomography in uncomplicated cases with tympanic membrane perforations.

"Benefits of the pedicled osteoplastic flap as a surgical approach of mastoidectomy in cochlear implant surgery"

OBJECTIVE

To evaluate the esthetic and functional results of an osteoplastic flap for mastoid cavity closure in cochlear implant surgery.

STUDY DESIGN

Double-blind, prospective, randomized clinical trial.

SETTING

tertiary referral center.

INTERVENTION(S)

On hundred and twenty-six patients were randomized in 2 groups for cochlear implant surgery. Cases (n: 63) underwent simple mastoidectomy using an anteriorly pedicled osteoplastic flap for mastoid closure. In controls (n: 63), a traditional periosteal flap was used. Evaluation with the POSAS questionnaire was performed 1 year after surgery to assess surgical wound esthetics. Sixteen patients from each group had postoperative CT-scans and wideband tympanometry to assess mastoid aeration and middle ear absorbance. Gender and time after surgery were correlated.

MAIN OUTCOME MEASURE(S)

Evaluation of the quality of the surgical wound with the application of a questionnaire validated in the medical literature and translated into Portuguese language called POSAS, considering the perception of the blinded patient and doctor regarding the surgical technique proceeded. A lower POSAS score suggests better esthetics of the surgical wound. Secondary outcomes are volumetric measurement of aeration inside mastoid cavity using 3D computer tomography exam, which aims to analyze the influence of fibrocicatricial retraction in the surgical wound into the mastoid and the interference of its aeration volume in the absorption of sound in the middle ear, using the wideband tympanometry exam.

RESULTS

The POSAS questionnaire in the Case group showed a lower level of local pain and itchiness, a skin color and thickness more similar to the surrounding skin and less irregularity and stiffness, with no influence from time after surgery and gender compared to the Control group. The median tomographic volume was 6.37 cc in the cases and 4.60 cc in controls. Wideband tympanometry showed general smaller sound absorbance in the Case group results, specially, at 1000 Hz frequency. No intraoperative or postoperative complications were observed with the osteoplastic flap.

CONCLUSIONS

This technique is an effective and safe alternative to alleviate common problems of mastoid surgery for cochlear implantation. In addition to esthetic benefits, it has less interference in middle ear physiology of sound absorbance and less fibrous tissue into the mastoid cavity during the follow-up of more than 1 year.

Tubomanometry Measurement Success Rate in Clinical Practice

OBJECTIVES

Tubomanometry (TMM) is an objective method for investigating Eustachian tube (ET) function, but difficulties in technique and interpretation may reduce its usability. The objective of our study was to investigate common difficulties with TMM in different ET dysfunction (ETD) patient groups and at different pressures (30, 40, and 50 mbars) when first introducing TMM to otologic practice. Furthermore, we wanted to investigate whether it would be possible to perform TMM at only one pressure and obtain a representative result.

METHODS

A retrospective chart review of a 2-year cohort of 114 patients with a history of ETD treated at a tertiary referral center. Primary outcome was the success rate of TMM, secondary the reasons for unsuccessful measurements. Tertiary outcome was the correlation of TMM results at adjacent pressures.

RESULTS

TMM success rate was 91%, varying 81 to 94% in different ETD patient groups and 87 to 94% at different pressures. Unsuccessful measurements resulted from air-leaks from the external ear canal, abnormal ear canal pressure curves (R < 0) and at 50 mbar, difficulties in reaching sufficient nasopharyngeal pressure. TMM results were similar in 88% of cases at 30 and 40 mbars and in 86% of cases at 40 and 50 mbars.

CONCLUSIONS

TMM success rate seems sufficiently high for clinical diagnostics, and most difficulties may be overcome with proper interpretation during the TMM measurement session, and thus repeating the measurements when necessary. Considering the diagnostic information that would be lost if using only a single, predefined pressure, we suggest using all three pressures.

Eustachian Tube Function in Patients with Symptoms on Baro-Challenge

OBJECTIVES

To explore the relationship between aural symptoms during baro-challenge and the underlying measured Eustachian tube (ET) function. Two key questions were addressed. (1) In patients who have features of obstructive ET dysfunction, is there a measurable underlying difference in ET function between those who experience severe symptoms on baro-challenge and those that do not? (2) What is the diagnostic value of ET function tests in the identification of patients with severe symptoms on baro-challenge?

METHODS

Patients with symptoms of obstructive ET dysfunction were recruited, with the presence of aural symptoms on baro-challenge established via the clinical history and analysis of the Cambridge ET Dysfunction Assessment, a patient-reported outcome measure (PROM). ET function tests were assessed in each patient: 9 objective and semi-objective measures of ET opening, and 2 symptom-based PROMs. The tests' results were grouped by type of ET opening assessed, generating passive and active dysfunction scores. Individual test results were assessed for diagnostic accuracy in reference to features in the history or PROM-based evidence of symptoms on baro-challenge.

RESULTS

Both passive and active opening of the ET was significantly reduced in ears with a history of pain on baro-challenge. Some patients had apparent severe obstructive ET dysfunction without symptoms on baro-challenge, whilst others had symptoms but normal test results. No individual test of ET opening was of diagnostic value in predicting those ears likely to experience pain or exacerbated symptoms on baro-challenge.

CONCLUSION

The relationship between aural pain during baro-challenge and ET function appears more complex than had been assumed, with pain possibly related to factors other than just ET function.

The outcomes of endoscopic myringoplasty: packing with gelatin sponge versus packing with nothing

Background: Packing with gelatin sponge has long been widely used in myringoplasty. However, there is no research on packing with nothing.Aims/objectives: To analyse the differences between packing with gelatin sponge and packing with nothing.Material and methods: Patients with tympanic membrane perforation were randomly divided into a packing with gelatin sponge group and a packing with nothing group. Differences between the groups were compared.Results: The operation time of group A (34.00 ± 1.05 min) was significantly shorter than that of group B (42.20 ± 1.40 min; p < .00); 1 patient (2.86%) in group A and 35 patients (100%) in group B had a dry ear time of longer than 1 week (p < .001). Ten patients (28.57%) in group A and 24 patients (68.57%) in group B had aural fullness after the operation (p < .001). The air-bone gap (ABG) in group A was smaller than that in group B at 1 week, 1 month, 2 months and 3 months after the operation (p < .05).Conclusion and significance: Group A achieved the same good results, but it had a short operation time, an early dry ear time, a low incidence of aural fullness and early recovery of hearing.

The Effects of Hypoxia on Middle Ear Pressure Regulation

Background: Middle ear (ME) pressure regulation has been suggested as a physiological mechanism that maintains pressure equilibrium between the ME and the ambient environment. This mechanism would be based on a complex sensorineural reflex loop composed of mechanoreceptors, an integrative center, and efferent neural pathways. Our aim was to demonstrate that hypoxic conditions, which would inhibit mechanoreceptors in general, similarly participate in the inhibition of the opening of the Eustachian tube (ET), and thus, to suggest that such receptors are involved in the overall regulation of ME pressure. Materials and Methods: Among 14 healthy volunteers, tubomanometry was performed in normoxia followed by hypoxia, and 3 parameters were evaluated for each ear under each condition, allowing the evaluation of the reactivity of the system: ET opening latency index (R), the Index of Velum Contraction (IVC), and the latency of pressure instauration (C2-C1). Results: Hypoxia induced a significant increase in the opening latency index of ET opening, without deleterious effects on the quality (IVC) and latency (C2-C1) of soft palate contraction. Conclusions: Our study supports the theory of a sensorineural reflex loop and provides evidence for the existence of mechanoreceptors, whose function is modified by changes in oxygen partial pressure, able to collect information on pressure variations between the ME and the external environment.

On the functional compartmentalization of the normal middle ear. Morpho-histological modelling parameters of its mucosa

BACKGROUND

Middle ear physiology includes both sound pressure transmission and homeostasis of its static air pressure. Pressure gradients are continuously created by gas exchange over the middle ear mucosa as well as by ambient pressure variations. Gas exchange models require actual values for regional mucosa thickness, blood vessel density, and diffusion distance. Such quantitative data have been scarce and limited to few histological samples from the tympanic cavity (TC) and the antrum. However, a detailed regional description of the morphological differences of the TC and mastoid air cell system (MACS) mucosa has not been available. The aim of the present study was to provide such parameters.

METHODS

The study included sets of three histological H&E-slides from 15 archived healthy temporal bones. We performed a comparison of the mucosa morphology among the following regions: (1) anterior TC; (2) inferior TC; (3) posterior TC; (4) superior TC; (5) MACS antrum; (6) superior MACS; (7) central MACS; (8) inferior MACS.

RESULTS

Regions (1)-(3), situated below the inter-attico-tympanic diaphragm, had the largest proportion of high respiratory epithelium, cilia and loose lamina propria within the mucosa, as well as the thickest mucosa and the largest diffusion distance. Regions (6)-(8), situated above the diaphragm, had the thinnest mucosa, the shortest distance to the blood vessels, together with the largest proportion of flat epithelium and very few cilia. Regions (4)-(5), still supradiaphragmatic, had intermediary values for these parameters, but generally closer to regions (6)-(8). The blood vessel density and the proportion of active mucosa were not significantly different among the regions.

CONCLUSION

Mucosa of regions (1), (2) and (3) represented a predominantly clearance-specific morphology, whereas in regions (4)-(8) it seemed adapted to gas exchange. However, the lack of statistically significant differences in blood vessel density and proportion of active mucosa indicated that all regions could be involved in gas exchange with the highest adaptation in the superior MACS. This pattern divides the middle ear functionally along the inter-attico-tympanic diaphragm rather than the anatomical division into TC and MACS.

A new theory interprets the development of a retraction pocket as a natural self-healing process

PURPOSE

The thesis that cholesteatoma evolves from a retraction pocket is widely accepted today. Yet, its prime etiology, the question of what triggers the invagination of healthy skin, still remains unclear despite centuries of investigations into the origin of cholesteatoma. A new idea interprets the horizontal migration of skin into the middle ear cavities as a self-healing process, curing an underlying inflammation in the tympanic cavity, through the overgrowth and contact with immunologically active tissue.

METHODS

A retrospective analysis of the interrelation of retraction pockets and underlying granulation tissue was conducted in 209 second-look cholesteatoma surgeries over the last decade.

RESULTS

A stable tympanic membrane over aerated, healthy middle ear mucosa was found in 71.3% of cases. In 11%, small retractions with air in other parts of the middle ear cleft (epitympanic, sinus or anterior mesotympanum) were described. In 6.2%, granulations under a retraction were found. Only 3.8% of the reports revealed air behind a retraction or did not provide enough information on the mucosa situation behind the drum membrane.

CONCLUSIONS

A new hypothesis interprets the origin of a retraction pocket-the precursor of a cholesteatoma-as a natural attempt by the body to cure an underlying inflammation in a cavity. Analogous phenomena exist, e.g. the migration of the omentum towards a local inflammation in the abdomen. This idea, which is supported by the findings in our 209 second-look surgeries, is the first explanation of the origin of retraction pockets that is compatible with the various characteristics of original or recurrent cholesteatoma. A prophylaxis against a recurrent cholesteatoma might be attained by securing free drainage of the mucosa into the tubal orifice with the use of thin silicone foils in an attempt to prevent any granulation in the middle ear cleft, similar to the principles of modern rhinosinusoidal surgery with its emphasis on unblocked mucosa clearance. This allows gas production in the healed middle ear mucosa to recover, reducing the risk of a recurrent retraction.

On the median pharyngeal valve of the American alligator (Alligator mississippiensis)

The middle ear cavities of crocodilians have complex connections with the pharyngeal lumen, including lateral and median components which both open into a single chamber located on the dorsal midline of the pharynx. This chamber and the surrounding soft-tissue is herein termed the median pharyngeal valve. In the American alligator (Alligator mississippiensis) this valve opens, for a duration of 0.3 s, approximately every 120 s; the patency of the median pharyngeal valve was not influenced by either auditory stimuli or by submersing the alligator underwater. The median pharyngeal valve has an outer capsule of dense connective tissue and fibrocartilage and an inner "plug" of loose connective tissue. These opposing surfaces are lined by respiratory epithelium and separated by a cavity that is continuous with the middle ear cavities and the pharyngeal lumen (through a central opening in the capsule termed the pore). The inner plug of the median pharyngeal valve is contacted by skeletal muscles positioned to serve as both elevators/retractors (which would open the valve) and elevators/protractors (which, in conjunction with gravity, would close the valve). Unlike other vertebrate valve systems, the median pharyngeal valve appears to function as a deformable ball check valve.

Radiological differences between HIV-positive and HIV-negative children with cholesteatoma

INTRODUCTION

HIV-positive children are possibly more prone to developing cholesteatoma. Chronic inflammation of the middle ear cleft may be more common in patients with HIV and this may predispose HIV-positive children to developing cholesteatoma. There are no studies that describe the radiological morphology of the middle ear cleft in HIV-positive compared to HIV-negative children with cholesteatoma.

OBJECTIVES

Compare the radiological differences of the middle ear cleft in HIV-positive and HIV-negative children with cholesteatoma.

METHODS

A retrospective, cross-sectional, observational analytical review of patients with cholesteatoma at our institute over a 6 year period.

RESULTS

Forty patients were included in the study, 11 of whom had bilateral cholesteatoma and therefore 51 ears were eligible for our evaluation. HIV-positive patients had smaller (p=0.02) mastoid air cell systems (MACS). Forty percent of HIV-positive patients had sclerotic mastoids, whereas the rate was 3% in HIV-negative ears (p<0.02). Eighty-two percent of the HIV-positive patients had bilateral cholesteatoma compared to 7% of the control group (p<0.02). There was no difference between the 2 groups with regards to opacification of the middle ear cleft, bony erosion of middle ear structures, Eustachian tube obstruction or soft tissue occlusion of the post-nasal space.

CONCLUSION

HIV-positive paediatric patients with cholesteatoma are more likely to have smaller, sclerotic mastoids compared to HIV-negative patients. They are significantly more likely to have bilateral cholesteatoma. This may have implications in terms of surveillance of HIV-positive children, as well as, an approach to management, recurrence and follow-up. HIV infection should be flagged as a risk factor for developing cholesteatoma.

Should Nasal Function be Considered Prior to Tympanoplasty?

OBJECTIVE

To evaluate the association between nasal airway function and Eustachian tube (ET) functions and their impact on tympanoplasty in patients with chronic suppurative otitis media (CSOM).

MATERIALS AND METHODS

The study group (CSOM group) consisted of 33 patients scheduled to undergo tympanoplasty for CSOM. Two control groups were formed: a nasal septal deviation (NSD) group of 25 patients scheduled to undergo nasal surgery for NSD, and a control group of 25 healthy individuals with no otologic or rhinologic symptoms. ET functions were assessed tympanometrically with automatic Williams test (ETF1) and modified pressure equalization inflation-deflation test (ETF2) and nasal functions were analyzed using acoustic rhinometry and rhinomanometry. The patients in the CSOM group underwent tympanoplasty, and tests were repeated at the end of the 3rd postoperative month.

RESULTS

Both acoustic rhinometry and rhinomanometry revealed similar nasal function in the CSOM and NSD groups, which was inferior to that of the control group. The CSOM group had the worst ET function. Dysfunctional ETs in the CSOM group improved at 3 months postsurgery, and all groups had a similar outcome regarding ET functions. The outcome of ear surgery was not affected by nasal function, and the graft take rate was 90%.

CONCLUSION

Patients with NSD had generally poor ET function; however, this did not affect the outcomes of tympanoplasty. The preoperative ET function results were inconsistent with the results following tympanoplasty; therefore, they were not predictive of need for septoplasty. Thus, we do not universally recommend surgical correction of NSD prior to ear surgery; however, this decision should be made on an individual basis.

Postoperative Mastoid Aeration Following Canal Wall Up Mastoidectomy according to Preoperative Middle Ear Disease: Analysis of Temporal Bone Computed Tomography Scans

Background and Objectives

The aim of our study was to evaluate postoperative mastoid aeration according to the preoperative middle ear disease and investigate the factors affecting it.

Subjects and Methods

We retrospectively reviewed the high-resolution computed tomography (CT) scans of temporal bones that were taken 1 year after surgery. The postoperative mastoid aeration was evaluated according to the preoperative diagnosis, and classified into three groups: grade 1 (complete mastoid aeration), an air-filled epitympanum and mastoid cavity; grade 2 (partial mastoid aeration), an air-filled epitympanum and partially aerated mastoid cavity; and grade 3 (absence of mastoid aeration), no air space in the mastoid cavity.

Results

The overall mastoid aeration rate was 55.8%, with adhesive otitis media accounting for 21.2%, attic cholesteatoma 53.8%, and chronic otitis media 75.4%. The rates of postoperative mastoid aeration were significantly higher in the chronic otitis media cases and attic cholesteatoma cases than in the adhesive otitis media cases. There were 14 cases requiring revision operations due to the development of a retraction pocket in the tympanic membrane. All of the revised cases had grade 3 postoperative mastoid aeration, and underwent canal wall down mastoidectomies.

Conclusions

The degree of postoperative mastoid aeration is associated with the preoperative middle ear disease. When planning a canal wall up mastoidectomy, the surgeon should contemplate the middle ear disease, because a canal wall down mastoidectomy or mastoid obliteration is recommended if the patient has adhesive otitis media.

A formal description of middle ear pressure-regulation

INTRODUCTION

Middle ear (ME) pressure-regulation (MEPR) is a homeostatic mechanism that maintains the ME-environment pressure-gradient (MEEPG) within a range optimized for "normal" hearing.

OBJECTIVE

Describe MEPR using equations applicable to passive, inter-compartmental gas-exchange and determine if the predictions of that description include the increasing ME pressure observed under certain conditions and interpreted by some as evidencing gas-production by the ME mucosa.

METHODS

MEPR was modeled as the combined effect of passive gas-exchanges between the ME and: perilymph via the round window membrane, the ambient environment via the tympanic membrane, and the local blood via the ME mucosa and of gas flow between the ME and nasopharynx during Eustachian tube openings. The first 3 of these exchanges are described at the species level using the Fick's diffusion equation and the last as a bulk gas transfer governed by Poiseuille's equation. The model structure is a time-iteration of the equation: P^ME_{g(t=(i+1)Δt)} = ∑^s(P^ME_s(t=iΔt)+(1/(β^ME_sV^ME)∑^P(Қ^P_s(P^C_s(t=(iΔt)-P^ME_s(t=(iΔt))). There, P^ME_g(t=iΔt) and P^ME_s(t=iΔt) are the ME total and species-pressures at the indexed times, P^C_s(t=iΔt) is the species-pressure for each exchange-compartment, β^ME_sV^ME is the product of the ME species-capacitance and volume, Қ^P_s is the pathway species-conductance, and ∑^S and ∑^P are operators for summing the expression over all species or exchange pathways.

RESULTS

When calibrated to known values, the model predicts the empirically measured ME species-pressures and the observed time-trajectories for total ME pressure and the MEEPG under a wide variety of physiologic, pathologic and non-physiologic conditions.

CONCLUSIONS

Passive inter-compartmental gas exchange is sole and sufficient to describe MEPR.

Tubotympanic system functioning

The Eustachian (auditory) tube and tympanomastoid cavities form an anatomic and functional whole that cannot easily be divided, and is therefore known as the "tubotympanic system". The system has been the focus of several studies, with complex and sometimes contradictory results, making an overview of its functioning difficult to obtain. The objective of the present article is to review the current state of knowledge, as an indispensable preliminary to understanding tubotympanic system dysfunction, and notably the development of chronic otitis. The system as a whole is covered by mucosa, which provides continuity, although with certain particularities from one area to another, and plays a primordial role. Thus, under physiological conditions, gas diffusion across the tympanomastoid mucosa largely ensures the equilibrium of pressure between the middle ear and outside environment, the tube orifice being very little involved. Under large rapid change in atmospheric pressure, the aeration function of the Eustachian tube comes into play, governed by a reflex mechanism. The system also has other functions that are essential to good middle-ear functioning: protection against nasopharyngeal secretions and pathogens and against certain physiological noises; middle-ear cavity clearance by mucociliary transport of pathogens, partly related to submucosal gland secretion; and immune defense.

Middle ear ventilation status postoperatively after translabyrinthine resection of vestibular schwannoma with mastoid obliteration and Eustachian tube occlusion: is the Eustachian tube enough to ventilate the middle ear without the mastoid air cell system?

BACKGROUND

Gas pressure balance is essential for maintaining normal middle ear function. The mucosal surfaces of the middle ear, the mastoid air cell system (MACS), and the Eustachian tube (ET) play a critical role in this process; however, the extent that each of these factors contributes to overall middle ear ventilation is unknown. The objective of this study was to determine if the ET alone can maintain normal middle ear pressure without the MACS. To do this, we reviewed subjects who had their MACS completely removed with translabyrinthine (TL) surgery for vestibular schwannoma.

METHODS

A retrospective chart review was done to collect pre and postoperative tympanometry data from patients who underwent resection of vestibular schwannoma. Data from the operative side was compared to the non-operative side at 2 years post-op.

RESULTS

Twenty-four patients were included in this study. Of these, 63 % achieved a type A tympanogram at 2 years post-op in the TL resection group, implying an ability to maintain middle ear pressure in the absence of a mastoid cavity. Because some had negative pressures post TL resection, the average change in pre and postoperative pressure was -37.5 daPa for the operative side and 7.8 daPa for the non-operative side. This was significantly different.

DISCUSSION

The difference for change in pre and postoperative pressure and compliance between operative and non-operative side might be expected from the ET plugging during TL resection. However, more interesting are those patients in whom the ET presumably reopens, and in these subjects, despite having no mastoid compartment at all, and the space obliterated with fat, they were still able to maintain normal ventilation of the middle ear space.

CONCLUSION

Our findings imply that the ET alone is adequate to ventilate at least the reduced middle ear space following TL surgery in most subjects, and perhaps in 100 % if the ET hadn't been plugged during surgery. Hence, the mastoid air cell system, even when healthy, is not needed to maintain air in the middle year cleft.

Histological identification of nasopharyngeal mechanoreceptors

The auditory tube plays a fundamental role in regulating middle ear pressure. A "system" sensitive to a pressure gradient between the middle ear and the ambient environment is necessary. The presence of mechanoreceptors in the middle ear and the tympanic membrane has been studied, but the presence of these receptors in the nasopharyngeal region remains unclear. The aim of this study is to confirm the presence of pressure sensitive corpuscles in the nasopharynx. An experimental study was conducted on five fresh and unembalded human cadavers. The pharyngeal ostium of the auditory tube and its periphery was removed in one piece by video-assisted endonasal endoscopy. Samples were fixed in formaldehyde solution, embedded in paraffin, and cut. Slides were analyzed by HES (Hematoxyline Eosine Safran) coloration, by S100 protein and neurofilament protein immunostaining. Encapsulated nerve endings were researched and identified by slides analysis. Eight samples were included in our study. On seven samples, Ruffini corpuscles were identified in the mucosa of the posterior area of the pharyngeal ostium, with a higher concentration in the pharyngeal recess and in the posterior nasopharyngeal wall. Our study identified nasopharyngeal mechanoreceptors that could detect the nasopharyngeal pressure and, by extension, the atmospheric pressure. These findings support the theory of the neuronal reflex arc of isobaric system of the middle ear, based on the existence of a "system" sensitive to a pressure gradient between the middle ear and the ambient environment. Understanding of this system has been helpful in the diagnosis and management of middle ear diseases.

Eustachian Tube Opening Measurement by Sonotubometry Using Perfect Sequences for Healthy Adults

Objectives

The aim of this study was to establish the rate variation of sonotubometric measurements using a specific broadband class of signals, the so-called perfect sequences (PSEQ) among healthy adults and to identify an optimal and technically simple test to provoke Eustachian tube (ET) openings.

Methods

Sonotubometry was performed on 105 healthy adult subjects. Three different consecutive maneuvers were performed for ET opening: dry swallowing, water swallowing (a small [2 mL] and a large [5 mL] water bolus). Values of the amplitude and duration of each measured ET opening were calculated.

Results

A total of 6,300 measurements were performed. Sonotubometric ET openings were detected for all subjects but not for each measurement. In 6,180 of 6,300 measurements (98.1%), objective ET openings were registered. In 11 of 105 subjects (10.5%) at least one sonotubometric ET opening was not detected. The mean ET opening duration time and the mean sound amplitude similar for all performed test and were 270 (SD, ±96) msec, 13.48 (SD, ±6.57) dB.

Conclusion

Sonotubometry based on PSEQ stimuli is a reliable methodology to assess the ET opening function in healthy subjects. Mean ET opening duration time and the mean sound wave amplitude performed similarly in all analysed tests, hence it might be concluded that dry (saliva) and water swallowing are reliable sonotubometric maneuvers and may be used when examining ET opening function. The size of a sip during water swallowing does not affect the sonotubometry result. All maneuvers can be equally used as the optimal test, and water swallow is most comfortable for the subject.

Antifibrotic effect of dexamethasone/alginate-coated silicone sheet in the abraded middle ear mucosa

Silicone sheet is a material which is commonly used in middle ear surgery to prevent the formation of adhesions between the tympanic membrane and the medial bony wall of the middle ear cavity. However, silicone sheet can induce a tight and hard fibrous capsule in the region of the stapes, and this is particularly common in cases of eustachian tube dysfunction. As a result of the fibrous encapsulation around the silicone sheet, postoperative aeration of the stapes can be interrupted causing poor hearing gain. In this study, we performed an in vitro and in vivo evaluation of the antifibrotic effects of a dexamethasone and alginate (Dx/alginate) coating on silicone sheet. The Dx/alginate-coated silicone sheets were fabricated using a plasma-treatment and coating method. The Dx/alginate-coated silicone sheets effectively limited in vitro fibroblast attachment and proliferation due to the controlled release of Dx, which can be modified by manipulation of the alginate coating. For the in-vivo evaluation, guinea pigs (albino, male, weighing 250g) were divided into two groups, with the control group (n=5) implanted with silicone sheet and the test group (n=5) receiving Dx/alginate-coated silicone sheet. Animals were sacrificed 3 weeks after implantation, and histological analysis was performed using hematoxylin and eosin (H&E) and immunohistochemical staining techniques. Dx/alginate-coated silicone sheets showed marked inhibition of fibrosis in both the in vitro and in vivo studies. Silicone sheet that incorporates a Dx/alginate coating can release Dx and inhibit fibrosis in the middle ear. This material could be utilized in middle ear surgery as a means of preserving proper aeration and hearing gain following ossiculoplasty.

Congestion of mastoid mucosa and influence on middle ear pressure - Effect of retroauricular injection of adrenaline

Micro-CT scanning of temporal bones has revealed numerous retroauricular microchannels, which connect the outer bone surface directly to the underlying mastoid air cells. Their structure and dimensions have suggested a separate vascular supply to the mastoid mucosa, which may play a role in middle ear (ME) pressure regulation. This role may be accomplished by changes in the mucosa congestion resulting in volumetric changes, which ultimately affect the pressure of the enclosed ME gas pocket (Boyle's law). Further, such mucosa congestion may be susceptible to α-adrenergic stimulation similar to the mucosa of the nose. The purpose of our study was to investigate these hypotheses by recording the ME pressure in response to adrenergic stimulation administered by retroauricular injections at the surface of the microchannels. In a group of 20 healthy adults we measured the ME pressure by tympanometry initially in the sitting position, and then in the supine position over a 5 min period with 30 s intervals. In each subject, the study included 1) a control reference experiment with no intervention, 2) a control experiment with subcutaneously retroauricular injection of 1 ml isotonic NaCl solution, and 3) a test experiment with subcutaneously retroauricular injection of 1 ml NaCl-adrenaline solution. In both control experiments the ME pressure displayed an immediate increase in response to changing body position; this pressure increase remained stable for the entire period up to five minutes. In the test experiments the ME pressure also showed an initial pressure increase, but it was followed by a distinct significant pressure decrease with a maximum after 90 s. The test group was injected with both a 5 and 10% adrenaline solution, but the responses appeared similar for the two concentrations. Subcutaneous retroauricular injection of adrenaline caused a significant pressure decrease in ME pressure compared with control ears. This may be explained by the microchannels conveying the adrenaline to the underlying mastoid mucosa, where it may result in a vascular constriction and decongestion, ultimately resulting in a ME pressure decrease. These findings suggest that the microchannels contain vascular connections to the mastoid mucosa, and that the mastoid mucosa is susceptible to vasoactive mediators, which may play a role in ME pressure regulation. Further anatomical and physiological experiments should be carried out to confirm these suggestions including pharmacological interactions with the mastoid mucosa.

Update on middle ear barotrauma after hyperbaric oxygen therapy-insights on pathophysiology

Introduction Middle ear barotrauma is the most common side effect of hyperbaric oxygen therapy. Knowledge and understanding of its pathophysiology are crucial for an accurate diagnosis and proper decision making about treatment and prevention.

Objective Describe up-to-date information on pathophysiology of middle ear barotrauma after hyperbaric oxygen therapy considering the physiology of pressure variation of the middle ear.

Data Synthesis Middle ear barotrauma occurs especially during the compression phase of hyperbaric oxygen therapy. The hyperoxic environment in hyperbaric oxygen therapy leads to ventilatory dysfunction of the eustachian tube, especially in monoplace chambers, where the patients are pressurized with 100% O₂, favoring middle ear barotrauma.

Conclusion The eustachian tube, the tympanic cavity, and mastoid work together in a neural controlled feedback system in which various mechanisms concur for middle ear pressure regulation.

MRI findings of otic and sinus barotrauma in patients with carbon monoxide poisoning during hyperbaric oxygen therapy

BACKGROUND AND PURPOSE

To study the MRI findings of otic and sinus barotrauma in patients with carbon monoxide(CO) poisoning during hyperbaric oxygen (HBO) therapy and examine the discrepancies of otic and sinus abnormalities on MRI between barotrauma and acute otitis media with effusion.

MATERIALS AND METHODS

Eighty patients with CO-poisoning diagnosed with otic and sinus barotrauma after HBO therapy were recruited. Brain MRI was performed to predict delayed encephalopathy. Over the same period, 88 patients with acute otitis media with effusion on MRI served as control. The abnormalities of the middle ear and paranasal sinuses on MRI were noted and were compared between groups. Nine patients with barotrauma were followed up by MRI.

RESULTS

In the barotrauma group, 92.5% of patients had bilateral middle ear abnormalities on MRI, and 60% of patients had both middle ear cavity and mastoid cavity abnormalities on MRI in both ears. Both rates were higher than those in the control group (p = 0.000). In the two groups, most abnormalities on MRI were observed in the mastoid cavity. The rate of sinus abnormalities of barotrauma was 66.3%, which was higher than the 50% in the control group (p = 0.033). In the nine patients with barotrauma followed up by MRI, the otic barotrauma and sinus abnormalities had worsened in 2 patients and 5 patients, respectively.

CONCLUSION

MRI is able to depict the abnormalities of otic and sinus barotrauma in patients with CO-poisoning during HBO therapy and to differentiate these from acute otitis media with effusion.

Mastoid surface area-to-volume ratios in adult brazilian individuals

Computed tomography-based measurements of mastoid surface area and volume have not been described for adult Brazilian individuals. These measurements add to the understanding of middle ear physiology, related diseases, and their impact on mastoid pneumatization.

Objective

To check the ratio between mastoid surface area and volume.

Method

This contemporary cross-sectional cohort study included 28 patients submitted to CT imaging of the mastoid. Measurements of surface area and volume were made based on serial CT scans and produced with the aid of software package Image Pro Plus.

Results

Mastoid volumes ranged from 5.5 to 72.4 cm³. Surface areas ranged from 43.9 to 525.2 cm². Surface areas varied linearly with volumes.

Conclusion

Mastoid surface areas and volumes of adult Brazilian subjects followed a linear correlation, as also described in studies carried out in other countries. Mean surface areas and volumes were higher than previously published, unlike surface area-to-volume ratios, which were lower. Further studies with larger populations will provide evidence as to whether Brazilian subjects have larger surface areas and volumes than other populations.

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.

Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning

The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure. In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40-60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40-440 μm) as well as their density at a localized area (average = 75 cm(-2); range = 64-97 cm(-2)). These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hypothesis. Studies on the mastoid mucosa and its blood supply may improve our knowledge of its physiological properties, which may have important implications for our understanding of the pressure regulation of the middle ear. This article is part of a special issue entitled "MEMRO 2012".

Improvement of eustachian tube function by tissue-engineered regeneration of mastoid air cells

Objectives/Hypothesis

Most cases of chronic otitis media (OMC) are associated with poor development of the mastoid air cells (MACs) and poor Eustachian tube (ET) function. We have previously reported that MAC regeneration can effectively eliminate intractable OMC. In this study, we assessed the ability of regenerated MACs to restore normal gas exchange function and contribute to improved ET function.

Study Design

Clinical trial with control.

Setting

General hospitals.

Materials and Methods

Seventy-six patients with OMC, including cholesteatoma and adhesive otitis media, received tympanoplasty and MAC regeneration therapy. At the first-stage of tympanoplasty, artificial pneumatic bones and/or autologous bone fragments were implanted into the opened mastoid cavity. At the 2nd-stage operation, a nitrous oxide (N2O) gas study was performed in 10 patients to measure middle ear pressure (MEP). For the control group, MEP was measured in five patients with good MAC development during cochlear implantation or facial nerve decompression. ET function was measured twice in each patient, once before the 1st operation and 6 months after the second operation.

Results

At the 2nd-stage operation, in all cases with regenerated MACs and in the normal control group, MEP changed after administration of N2O. In contrast, no change in MEP was observed in cases with unregenerated MACs. In 70% (n = 37/53) of the regenerated MAC group, ET function was improved, whereas improvement of ET function was observed in only 13% (n = 3/23) of the unregenerated MAC group.

Conclusions

Tissue-engineered regeneration of MACs improves ET function and gas exchange in the middle ear. Laryngoscope, 2012

Level of Evidence

3b

Mechanical properties of human tympanic membrane in the quasi-static regime from in situ point indentation measurements

The tympanic membrane is a key component of the human auditory apparatus. Good estimates of tympanic membrane mechanical properties are important to obtain realistic models of middle ear mechanics. Current literature values are almost all derived from direct mechanical tests on cut-out strips. For a biomedical specimen like the tympanic membrane, it is not always possible to harvest strips of uniform and manageable geometry and well-defined size suitable for such mechanical tests. In this work, elastic and viscoelastic properties of human tympanic membrane were determined through indentation testing on the tympanic membrane in situ. Indentation experiments were performed on three specimens with a custom-built apparatus that was also used in previously published works. Two types of indentation tests were performed on each specimen: (i) sinusoidal indentation at 0.2 Hz yielding the quasi-static Young's modulus and (ii) step indentation tests yielding viscoelastic properties in the quasi-static regime (0-20 Hz). In the cyclic indentation experiments (type i), the indentation depth and resulting needle force were recorded. The unloaded shape of the tympanic membrane and the membrane thickness were measured and used to create a specimen-specific finite element model of the experiment. The Young's modulus was then found through optimization of the error between model and experimental data; the values that were found for the three different samples are 2.1 MPa, 4.4 MPa and 2.3 MPa. A sensitivity analysis showed that these values are very sensitive to the thickness used in the models. In the step indentation tests (type ii), force relaxation was measured during 120 s and the relaxation curves were fitted with a 5 parameter Maxwell viscoelastic model. The relaxation curves in the time domain were transformed to complex moduli in the frequency domain, yielding viscoelastic properties in the quasi-static regime only.

Three-dimensional finite element analysis of Eustachian tube function under normal and pathological conditions

A primary etiological factor underlying chronic middle ear disease is an inability to open the collapsible Eustachian tube (ET). However, the structure-function relationships responsible for ET dysfunction in patient populations at risk for developing otitis media (OM) are not known. In this study, three-dimensional (3D) finite element (FE) modeling techniques were used to investigate how changes in biomechanical and anatomical properties influence opening phenomena in three populations: normal adults, young children and infants with cleft palate. Histological data was used to create anatomically accurate models and FE techniques were used to simulate tissue deformation and ET opening. Lumen dilation was quantified using a computational fluid dynamic (CFD) technique and a sensitivity analysis was performed to ascertain the relative importance of the different anatomical and tissue mechanical properties. Results for adults suggest that ET function is highly sensitive to tensor veli palatini muscle (TVPM) forces and to periluminal mucosal tissue (PMT) elasticity. Young children and cleft palate subjects exhibited reduced sensitivity to TVPM forces while changes in PMT stiffness continued to have a significant impact on ET function. These results suggest that reducing PMT stiffness might be an effective way to restore ET function in these populations. Varying TVPM force vector relationships via changes in hamulus location had no effect on ET opening in young children and cleft palate subjects but did alter force transmission to the ET lumen during conditions of elevated adhesion. These models have therefore provided important new insights into the biomechanical mechanisms responsible for ET dysfunction.