A Proof-of-Concept Computer Vision Approach for Measurement of Tympanic Membrane Perforations

OBJECTIVE

Size, an important characteristic of a tympanic membrane perforation (TMP), is commonly assessed with gross estimation via visual inspection, a practice which is prone to inaccuracy. Herein, we demonstrate feasibility of a proof-of-concept computer vision model for estimating TMP size in a small set of perforations.

METHODS

An open-source deep learning architecture was used to train a model to segment and calculate the area of a perforation and the visualized tympanic membrane (TM) in a set of endoscopic images of mostly anterior and relatively small TMPs. The model then computed relative TMP size by calculating the ratio of perforation area to TM area. Model performance on the test dataset was compared to ground-truth manual annotations. In a validation survey, otolaryngologists were tasked with estimating the size of TMPs from the test dataset. The primary outcome was the average absolute error of model size predictions and clinician estimates compared to sizes determined by ground-truth manual annotations.

RESULTS

The model's average absolute error for size predictions was a 0.8% overestimation for all test perforations. Conversely, among the 38 survey respondents, the average clinician error was a 11.0% overestimation (95% CI, 5.2-16.7%, p = 0.003).

CONCLUSIONS

In a small sample of TMPs, we demonstrated a computer vision approach for estimating TMP size is feasible. Further validation studies must be done with significantly larger and more heterogenous datasets.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:2906-2911, 2024.

Tympanic membrane perforations cannot be reliably detected using computed tomography based on 15 cadaver dogs

The integrity of the tympanic membrane is an important factor when deciding treatment and therapeutic recommendations for dogs with ear disease; however, otoscopic examination may be difficult to perform due to features of external ear canal disease or patient compliance. CT is useful for the evaluation of middle ear disease, including cases in which middle ear disease is detected incidentally. The tympanic membrane is detectable using CT, but anecdotally, apparent focal defects or discontinuities of the tympanic membrane are often seen in patients with and without ear disease. The purpose of this prospective, observer agreement study was to determine if perforations of the tympanic membrane are reliably detectable on CT. Fifteen cadaver dogs underwent CT and video otoscopy to verify the integrity of each tympanic membrane. Cadavers were randomly assigned to have the tympanic membranes left intact or to undergo a myringotomy on either the left, the right, or both sides. CT was performed immediately following the myringotomies. Four blinded evaluators evaluated the pre- and post-myringotomy scans for a total of 30 scans (60 tympanic membranes). Average accuracy was low (44%), and interobserver agreement for all four evaluators was fair. Although the tympanic membrane is visible on CT, perforations of the tympanic membrane are unlikely to be accurately detected or excluded. The appearance of an intact tympanic membrane or defect in the membrane on CT should not be used as criteria to guide clinical treatment recommendations based on this cadaver model.

Tracking cell layer contribution during repair of the tympanic membrane

The tympanic membrane (i.e. eardrum) sits at the interface between the middle and external ear. The tympanic membrane is composed of three layers: an outer ectoderm-derived layer, a middle neural crest-derived fibroblast layer with contribution from the mesoderm-derived vasculature, and an inner endoderm-derived mucosal layer. These layers form a thin sandwich that is often perforated following trauma, pressure changes or middle ear inflammation. During healing, cells need to bridge the perforation in the absence of an initial scaffold. Here, we assessed the contribution, timing and interaction of the different layers during membrane repair by using markers and reporter mice. We showed that the ectodermal layer is retracted after perforation, before proliferating away from the wound edge, with keratin 5 basal cells migrating over the hole to bridge the gap. The mesenchymal and mucosal layers then used this scaffold to complete the repair, followed by advancement of the vasculature. Finally, differentiation of the epithelium led to formation of a scab. Our results reveal the dynamics and interconnections between the embryonic germ layers during repair and highlight how defects might occur.

[The technique and application of individualized tympanic membrane flap in the repair of tympanic membrane under endoscopy ear surgery]

Objective:To investigate the technique of personalized flap making under otoscopy and its clinical application. Methods:The clinical data of patients who underwent 301 Military Hospital myringoplasty in the Department of otoendoscopic surgery, Department of Otorhinolaryngology, head and neck surgery, Department of Otorhinolaryngology, from October 2022 to 2023 August were analyzed retrospectively, all enrolled patients were performed independently by the same skilled otoendoscopic surgeon. The patients' general condition, medical history, tympanic membrane perforation scope, perforation size, need for tympanic cavity exploration, thickness of skin flap, tympanic cavity lesion scope, skin flap making method and postoperative rehabilitation were collected. Results:Many factors such as the location of tympanic membrane perforation, the thickness of the skin flap, the degree of curvature or stricture of the ear canal and the extent of the lesion in the tympanic cavity should be considered in the manufacture of the individualized tympanic membrane skin flap, the way of skin flap making does not affect the long-term postoperative rehabilitation, but it can effectively avoid unnecessary ear canal skin flap injury and improve the operation efficiency. Conclusion:Scientific flap fabrication is important for improving surgical efficiency and enhancing surgical confidence.

Prophylactic antibiotics has no benefit for outcome in clean myringoplasty-A register-based cohort study from SwedEar

OBJECTIVES

To investigate if prophylactic antibiotics (PA) in conjunction with myringoplasty of clean and uninfected ears entails a reduction of postoperative infections within 6 weeks after surgery, and whether it affects the healing rate of the tympanic membrane (TM) at follow-up, 6-24 months after surgery.

DESIGN

A retrospective cohort study of prospectively collected data.

SETTING

Data extracted from The Swedish Quality Register for Ear Surgery (SwedEar), the years 2013-2019.

PARTICIPANTS

All patients in SwedEar with a registered clean conventional myringoplasty (tympanoplasty type I) including a follow-up visit.

MAIN OUTCOME MEASURES

The effect of PA use on TM healing rate at follow-up and postoperative infection within 6 weeks of surgery.

RESULTS

In the study group (n = 1665) 86.2% had a healed TM at follow-up. There was no significant difference between the groups that had PA administered (87.2%) or not (86.1%). A total of 8.0% had a postoperative infection within 6 weeks. Postoperative infection occurred in 10.2% of the group that received PA (n = 187) compared with 7.7% of the group that did not receive PA. However, this difference was not statistically significant. Postoperative infection within 6 weeks significantly lowered the frequency of healed TMs.

CONCLUSION

PA administered during clean conventional myringoplasty does not improve the chance of having a healed TM at follow up, nor decrease the risk of having a postoperative infection within 6 weeks after surgery.

Necessities, opportunities, and challenges for tympanic membrane perforation scaffolding-based bioengineering

Tympanic membrane (TM) perforation is a global clinical dilemma. It occurs as a consequence of object penetration, blast trauma, barotrauma, and middle ear diseases. TM perforation may lead to otitis media, retraction pockets, cholesteatoma, and conductive deafness. Molecular therapies may not be suitable to treat perforation because there is no underlying tissue matrix to support epithelium bridging. Chronic perforations are usually reconstructed with autologous grafts via surgical myringoplasty. Surgical treatment is uncomfortable for the patients. The grafting materials are not perfect because they produce an opaque membrane, fail in up to 20% of cases, and are suboptimal to restore acoustic function. Millions of patients from developing parts of the world have not got access to surgical grafting due to operational complexities, lack of surgical resources, and high cost. These shortcomings emphasize bioengineering to improve placement options, healing rate, hearing outcomes, and minimize surgical procedures. This review highlights cellular, structural, pathophysiological, and perforation specific determinants that affect healing, acoustic and surgical outcomes; and integrates necessities relevant to bioengineered scaffolds. This study further summarizes scaffolding components, progress in scaffolding strategies and design, and engenders limitations and challenges for optimal bioengineering of chronic perforation.

Computer simulation study of the penetration of pulsed 30, 60 and 90 GHz radiation into the human ear

There is increasing interest in applications which use the 30 to 90 GHz frequency range, including automotive radar, 5 G cellular networks and wireless local area links. This study investigated pulsed 30-90 GHz radiation penetration into the human ear canal and tympanic membrane using computational phantoms. Modelling involved 100 ps and 20 ps pulsed excitation at three angles: direct (orthogonal), 30° anterior, and 45° superior to the ear canal. The incident power flux density (PD) estimation was normalised to the International Commission on Non-Ionizing Radiation Protection (1998) standard for general population exposure of 10 Wm-2 and occupational exposure of 50 Wm-2. The PD, specific absorption rate (SAR) and temperature rise within the tympanic membrane was highly dependent on the incident angle of the radiation and frequency. Using a 30 GHz pulse directed orthogonally into the ear canal, the PD in the tympanic membrane was 0.2% of the original maximal signal intensity. The corresponding PD at 90 GHz was 13.8%. A temperature rise of 0.032° C (+20%, -50%) was noted within the tympanic membrane using the equivalent of an occupational standard exposure at 90 GHz. The central area of the tympanic membrane is exposed in a preferential way and local effects on small regions cannot be excluded. The authors strongly advocate further research into the effects of radiation above 60 GHz on the structures of the ear to assist the process of setting standards.

Repair of subtotal tympanic membrane perforations: A temporal bone study of several tympanoplasty materials

The aim of this project was to investigate the effects of different types of graft material, and different remaining segments of the native TM on its motion. In twelve human temporal bones, controlled TM perforations were made to simulate three different conditions. (1) Central perforation leaving both annular and umbo rims of native TM. (2) Central perforation leaving only a malleal rim of native TM. (3) Central perforation leaving only an annular rim of native TM. Five different graft materials (1) perichondrium (2) silastic (3) thin cartilage (4) thick cartilage (5) Lotriderm^® cream were used to reconstruct each perforation condition. Umbo and stapes vibrations to acoustic stimuli from 250 to 6349 Hz were measured using a scanning laser Doppler vibrometer. Results showed that at low frequencies: in the Two Rims condition, all grafting materials except thick cartilage and Lotriderm cream showed no significant difference in umbo velocity from the Normal TM, while only Lotriderm cream showed a significant decrease in stapes velocity; in the Malleal Rim condition, all materials showed a significant decrease in both umbo and stapes velocities; in the Annular Rim condition, all grafting materials except Lotriderm and perichondrium showed no significant difference from the Normal TM in stapes velocity. Umbo data might not be reliable in some conditions because of coverage by the graft. At middle and high frequencies: all materials showed a significant difference from the Normal TM in both umbo and stapes velocities for all perforation conditions except in the Annular Rim condition, in which silastic and perichondrium showed no significant difference from the Normal TM at umbo velocity in the middle frequencies. In the low frequencies, the choice of repair material does not seem to have a large effect on sound transfer. Our data also suggests that the annular rim could be important for low frequency sound transfer.

Effects of an enrofloxacin-silver sulfadiazine emulsion in the ears of rabbits with perforated tympanic membranes

OBJECTIVE

To determine whether an enrofloxacin-silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy.

ANIMALS

6 healthy adult New Zealand White rabbits.

PROCEDURES

Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination.

RESULTS

Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution-treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent.

CONCLUSIONS AND CLINICAL RELEVANCE

Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.

Retrospective Analysis of 24 Cases of Forensic Medical Identification on Traumatic Tympanic Membrane Perforations

OBJECTIVES

To study the case characteristics of forensic medical identification of traumatic tympanic membrane perforations, and to discuss the key points of forensic medical identification and evaluations methods for tympanic membrane perforations.

METHODS

Twenty-four cases of traumatic tympanic membrane perforations accepted by the Academy of Forensic Science during 2017 were retrospectively analysed. The data of perforation size, form, predilection site, healing time and healing mode were evaluated.

RESULTS

For the traumatic tympanic membrane perforations, the study showed that the small size of perforation （<1/2 quadrant） with irregular shape was common. The location of perforations was almost on the anterior and inferior quadrant, and centripetal migration healing was common. The healing rate within 6 weeks was up to 90%.

CONCLUSIONS

In the identification cases of traumatic tympanic membrane perforations, the key is to determine whether it is traumatic and whether it will heal spontaneously within 6 weeks. It is suggested to check the tympanic membrane weekly by an otic endoscope combined with acoustic impedance measurement at the sixth week, which can improve the accuracy, objectivity and scientificity of the identification.

Incidence of middle ear barotrauma in staged versus linear chamber compression during hyperbaric oxygen therapy: a double blinded, randomized controlled trial

CONTEXT

Middle ear barotrauma (MEB) is common during chamber compression in hyperbaric oxygen therapy. However, little evidence exists on an optimal compression protocol to minimize the incidence and severity of MEB.

OBJECTIVE

To compare the incidence of MEB during hyperbaric oxygen therapy using two different chamber compression protocols.

DESIGN

Double-blinded, randomized controlled trial.

SETTING

Hyperbaric Medicine Unit, The Townsville Hospital, Queensland, Australia, September 2012 to December 2014.

PATIENTS

100 participants undergoing their first hyperbaric oxygen therapy session.

INTERVENTION

Random assignment to a staged (n=50) or a linear (n=50) compression protocols. Photographs of tympanic membranes were taken pre- and post-treatment and then graded. Middle ear barotrauma was defined as an increase of at least one grade on a modified TEED scale.

RESULTS

The observed MEB incidence under the staged protocol was 48% compared to 62% using the linear protocol (P=0.12, exact one-sided binomial test), and thus the staged protocol did not show a significant improvement in MEB. However, the staged protocol resulted in significantly less severe deteriorations in MEB grades when compared to the linear protocol (P=0.028, exact one-sided Mann-Whitney type test).

CONCLUSION

The use of the assessed staged compression protocol for the first hyperbaric oxygen treatment showed no significant effect on the overall incidence of MEB when compared to the gold standard linear protocol but resulted in a significant improvement in the severity of the experienced MEBs. Further studies are needed to elucidate an optimal compression protocol to minimize middle ear barotrauma.

Hearing Loss in Young Adults Who Had Ventilation Tube Insertion in Childhood

It is known that insertion of ventilation tubes can cause damage to the tympanic membrane and hearing deterioration in the long term. To investigate long-term effects of recurrent otitis media and of ventilation tube insertion, we used a study group (n = 358 subjects), with or without a history of otitis media and/or ventilation tube insertion, derived from a birth cohort that had been followed for 16 years. At 18 years of age, a standardized audiometric and otoscopic examination was performed. We found that ventilation tube insertion in childhood was associated with a mean persistent hearing loss in young adults of about 5 to 10 dB at the group level with a sensorineural component of 3 to 4 dB. This hearing loss could not be explained by the disease load of otitis media in childhood. Repeated insertions of ventilation tubes caused a greater deterioration of hearing than did a single insertion. Structural changes of the tympanic membrane were a mediating factor in the causal relationship between ventilation tube insertion and hearing loss. We conclude that ventilation tube insertion in childhood may induce hearing deterioration in the long term.

Tympanic membrane bleeding complications during hyperbaric oxygen treatment in patients with or without antiplatelet and anticoagulant drug treatment

INTRODUCTION

Middle ear barotrauma (MEBt) is a frequently occurring complication of hyperbaric oxygen treatment (HBOT). High-grade MEBt may involve tympanic membrane (TM) haemorrhaging. Although many patients undergoing HBOT use antiplatelet or anticoagulant drugs, it is unknown whether these drugs increase the risk of MEBt and particularly TM bleeding complications.

METHODS

This multicentre, prospective cohort study investigates the prevalence of MEBt and TM bleeding during HBOT in patients using antiplatelet/anticoagulant drugs, compared with control patients not on such medications. MEBt was assessed by video otoscopy of the TM pre and post HBOT and scored according to the modified Teed score. Any complications from previous HBOT sessions were retrospectively documented.

RESULTS

Of 73 patients receiving HBOT, 34 used antiplatelet/anticoagulant drugs. Mild MEBt (Teed score 1 or 2) occurred in 23 of these 34 patients and in 31 of the 39 controls. Teed score 3 MEBt occurred in only two of the control-group patients and none of the patients using antiplatelet/anticoagulant drugs. Two patients using anticoagulant drugs reported epistaxis during a previous HBOT session, epistaxis was not reported by any control patients.

CONCLUSION

Low-grade MEBt is common during HBOT, however, high-grade barotrauma is rare with current chamber operating procedures. Patients using antiplatelet/anticoagulant drugs potentially may be prone to MEBt-associated haemorrhagic complications, but we did not observe any such increase in this cohort. Only mild epistaxis occurred in patients using anticoagulant drugs.

[Comparative study of the clinical observation on traumatic perforation of tympanic membrane]

OBJECTIVE

To explore the clinical treatment effects of sea buckthorn oil for in different size traumatic perforation of tympanic membrane in different size.

METHOD

Prospective, randomized study of 199 outpatients with traumatic perforation of tympanic membrane who were enrolled between December 2012 and December 2014 after informed consent. The patients were divided into treatment group (101 cases) and control group (98 cases). According to the size of the perforations, patients in each group were divided into large perforation group, middle perforation groups and small perforation group. The cases in large perforation group, middle perforation groups and small perforation group were 36, 34, 31 in treatment group and 35, 33, 30 in control group. The patients in treatment group were treated with sea buckthorn oil once a week, while the patient in control group were self-healing and checked once a week. All the patients were followed-up in two months. The healing rate of two groups was applied for the evaluation indicator of clinical effect. We compared the healing rate, average healing time and phological change of tympanic membrane of patients at the first and second month.

RESULT

The total healing ratio of patients in treatment group is 62.4% and 79.2% compared with 29.6% and 57.1% in control group at the first and second month (P < 0.05). There is statistical significance between the healing ratios of middle, large perforation groups in treatment group and control group (P < 0.05). There is no statistical significance between the healing ratios of small perforation group in treatment group and control group (P > 0.05). The average healing time of large, middle and small perforation group at the second month are significantly shorter than the control group.

CONCLUSION

It is better to apply observation method and let it self-healed for small traumatic tympanic membrane perforation according to its higher healing ratio. While, it is better to apply sea buckthorn oil method for middle and large traumatic tympanic membrane perforation according to its lower healing ratios. Sea buckthorn oil treatment is benefitial for increasing the ratio of perforation healing, shorten the healing time, resumpting of the middle ear function earlier, helping most of the patients to avoid operation and the reduce medical expense. Therefore, it is valuable to promote the method in clinical treatment.

The O'Neill grading system for evaluation of the tympanic membrane: A practical approach for clinical hyperbaric patients

Eustachian tube dysfunction (ETD) and middle ear barotrauma (MEB) are the two most common complications of clinical hyperbaric oxygen (HBO2) treatment. The current grading system, the Teed's Classification, was first described in 1944 with modifications to this system over the years, but none are specific for the evaluation and treatment of patients undergoing clinical HBO2 therapy. Currently, the standard of care is a baseline otoscopic examination performed prior to starting HBO2 therapy. Repeat otoscopy is required for patients having ETD, pain or other symptoms during the compression and/or decompression phase of the treatment. Results from these examinations are used to determine the proper course of treatment for the ETD or MEB. The Teed's classification was not intended to correlate with the consistency of diagnosis, the clinical approach to relieving symptoms or the treatment of the inflicted trauma. It is not a practical tool for the modern hyperbaric team. We describe a newer grading system, the O'Neill Grading System (OGS), which allows simple, practical and consistent classification of ETD and MEB by all members of the clinical hyperbaric medicine team. Based on the O'Neill Grade assigned, evidence supported suggestions for appropriate actions and medical interventions are offered.

Risk factors affecting human traumatic tympanic membrane perforation regeneration therapy using fibroblast growth factor-2

OBJECTIVE

The use of growth factors to achieve closure of human traumatic tympanic membrane perforations (TMPs) has recently been demonstrated. However, pretreatment factors affecting healing outcomes have seldom been discussed. The objective of this study was to evaluate pretreatment factors contributing to the success or failure of healing of TMPs using fibroblast growth factor-2 (FGF-2).

DESIGN AND PARTICIPANTS

A retrospective cohort study of 99 patients (43 males, 56 females) with traumatic TMPs who were observed for at least 6 months after FGF-2 treatment between March 2011 and December 2012. Eleven factors considered likely to affect the outcome of perforation closure were evaluated statistically using univariate and multivariate logistic regression analysis.

INTERVENTIONS

Each traumatic TMP was treated by direct application of FGF-2.

MAIN OUTCOME MEASURES

Complete closure versus failure to close.

RESULTS

In total, 99 patients were analyzed. The total closure rate was 92/99 (92.9%) at 6 months; the mean closure time was 10.59 ±  6.81 days. The closure rate did not significantly differ between perforations with or without inverted edges (100.0% vs. 91.4%, p = 0.087), among different size groups (p = 0.768), or among different periods of exposure to injury (p = 0.051). However, the closure rate was significantly different between the high- and low-dose FGF-2 groups (85.0% vs. 98.3%, p = 0.010) and between perforations where the umbo or malleus was or was not involved in perforation (85.4% vs. 98.3%, p = 0.012). Additionally, univariate logistic regression analysis tests showed that it was difficult to achieve healing of these perforations with a history of chronic otitis media or residual TM calcification (p = 0.006), the umbo or malleus was involved in perforation (p = 0.038), and with a high dose of FGF-2 (p = 0.035) compared with control groups. Multivariate logistic regression analysis showed that only a history of chronic otitis media and residual TM calcification and perforation close to the umbo or malleus were associated with non-healing of the TM perforation (p = 0.03 and p = 0.017, respectively) with relative risk factors.

CONCLUSIONS

Direct application of FGF-2 can be used in all traumatic TMPs, the size of the perforation and inverted edges did not affect the closure rate, and the most beneficial dose was sufficient to keep the residual eardrum environment moist, but without adding liquid. Additionally, multivariate logistic regression analysis revealed that a large perforation was not a major risk factor for nonhealing of TM perforations. However, a history of chronic otitis media, residual TM calcification and involvement of the umbo or malleus in perforation were significant risk factors.

A new patch material for tympanic membrane perforation by trauma: the membrane of a hen egg shell

CONCLUSION

The egg shell membrane (ESM) patch may promote tympanic membrane (TM) healing in acute traumatic TM perforation.

OBJECTIVE

To evaluate the use of ESM for treating acute traumatic TM perforation.

METHODS

We reviewed charts of patients with traumatic TM injury from 2008 to 2011. Treatments were an ESM patch or a perforation edge approximation. We divided patients into two groups according to the treatment used. Each patient was matched by treatment onset and perforation size. We compared healing ratio, healing time, and frequency of otorrhea between the perforation edge approximation group and the ESM patch group. Matched t tests were used for analysis.

RESULTS

The healing ratio of the TM showed no significant difference between the two groups, but the time to heal was significantly shorter in the ESM patch group than in the perforation edge approximation group.

[The emergency plastic reconstruction of the tympanic membrane defects of post-traumatic and iatrogenic etiology with the application of the nanostructured bioplastic material]

The objective of the present study was to estimate the effectiveness of the application of the nanostructured bioplastic material for the plastic reconstruction of tympanic defects of post-traumatic and iatrogenic etiology. The authors report the results of the emergency plastic reconstruction of tympanic defects of post-traumatic and iatrogenic nature with the application of the nanostructured bioplastic material (giamatrix). The analysis of the results of the study prfovidd definitive evidence of the effectiveness of plastic reconstruction of tympanic defects with the application of the nanostructured bioplastic material.

Mechanisms of hearing loss after blast injury to the ear

Given the frequent use of improvised explosive devices (IEDs) around the world, the study of traumatic blast injuries is of increasing interest. The ear is the most common organ affected by blast injury because it is the body's most sensitive pressure transducer. We fabricated a blast chamber to re-create blast profiles similar to that of IEDs and used it to develop a reproducible mouse model to study blast-induced hearing loss. The tympanic membrane was perforated in all mice after blast exposure and found to heal spontaneously. Micro-computed tomography demonstrated no evidence for middle ear or otic capsule injuries; however, the healed tympanic membrane was thickened. Auditory brainstem response and distortion product otoacoustic emission threshold shifts were found to be correlated with blast intensity. As well, these threshold shifts were larger than those found in control mice that underwent surgical perforation of their tympanic membranes, indicating cochlear trauma. Histological studies one week and three months after the blast demonstrated no disruption or damage to the intra-cochlear membranes. However, there was loss of outer hair cells (OHCs) within the basal turn of the cochlea and decreased spiral ganglion neurons (SGNs) and afferent nerve synapses. Using our mouse model that recapitulates human IED exposure, our results identify that the mechanisms underlying blast-induced hearing loss does not include gross membranous rupture as is commonly believed. Instead, there is both OHC and SGN loss that produce auditory dysfunction.

Natural evolution of an eardrum bridge in patients with a traumatic eardrum perforation

Although the "eardrum bridge" of traumatic tympanic membrane perforations (TMPs) is very little seen, the underlying natural evolution during the healing process are still unknown.The aim of this retrospective study was to evaluate the natural evolution of the "eardrum bridge" of TMPs. The data for 36 patients with barotrauma-associated traumatic TMPs with an "eardrum bridge" between January 2006 and December 2007 were retrieved. The eardrum bridge was completely liquefied due to infection in one patient. The bridge gradually became necrotic and incorporated into the new eardrum in four patients, and the healed eardrum formed a retraction pocket. In nine patients, epithelial hyperplasia occurred on both sides of the eardrum bridge at the edges, and the bridge became incorporated into the new eardrum, which became very thin over time. However, in 22 patients, the eardrum bridge gradually became necrotic, finally forming a yellow crust-like substance and migrating to the external auditory canal (EAC); it was not incorporated into the new eardrum. The closure of the perforation depended on stratified epithelial migration at the perforation edges near the eardrum bridge, resulting in a normal morphology of the healed eardrum. The present study shows that the eardrum bridge has a different natural evolution during the healing process in patients with a TMP. Most eardrum bridges gradually became necrotic and migrated toward the EAC, and stratified epithelial migration occurred at the perforation edges near the eardrum bridge and closed the perforation. However, a few eardrum bridges gradually became necrotic or developed epithelial hyperplasia, then became incorporated into the new eardrum, resulting in the formation of a retraction pocket and the development of atrophy. Thus, long-term follow-up and histological examination of a larger sample is necessary.