Physiological Basis of Noise-Induced Hearing Loss in a Tympanal Ear

Acoustic overexposure, such as listening to loud music too often, results in noise-induced hearing loss. The pathologies of this prevalent sensory disorder begin within the ear at synapses of the primary auditory receptors, their postsynaptic partners and their supporting cells. The extent of noise-induced damage, however, is determined by overstimulation of primary auditory receptors, upstream of where the pathologies manifest. A systematic characterization of the electrophysiological function of the upstream primary auditory receptors is warranted to understand how noise exposure impacts on downstream targets, where the pathologies of hearing loss begin. Here, we used the experimentally-accessible locust ear (male, Schistocerca gregaria) to characterize a decrease in the auditory receptor's ability to respond to sound after noise exposure. Surprisingly, after noise exposure, the electrophysiological properties of the auditory receptors remain unchanged, despite a decrease in the ability to transduce sound. This auditory deficit stems from changes in a specialized receptor lymph that bathes the auditory receptors, revealing striking parallels with the mammalian auditory system.SIGNIFICANCE STATEMENT Noise exposure is the largest preventable cause of hearing loss. It is the auditory receptors that bear the initial brunt of excessive acoustic stimulation, because they must convert excessive sound-induced movements into electrical signals, but remain functional afterward. Here we use the accessible ear of an invertebrate to, for the first time in any animal, characterize changes in auditory receptors after noise overexposure. We find that their decreased ability to transduce sound into electrical signals is, most probably, due to changes in supporting (scolopale) cells that maintain the ionic composition of the ear. An emerging doctrine in hearing research is that vertebrate primary auditory receptors are surprisingly robust, something that we show rings true for invertebrate ears too.

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.

Pars tensa and tympanicomalleal joint: proposal for a new anatomic classification

PURPOSE

The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification.

METHODS

This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection.

RESULTS

The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint".

CONCLUSIONS

It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.

A comparative study to evaluate the efficacy of EGF, FGF-2, and 0.3% (w/v) ofloxacin drops on eardrum regeneration

BACKGROUND

Traumatic tympanic membrane perforations (TMPs) tend to spontaneous healing, however, large TMPs usually fail to healing. Clinical and experimental studies had demonstrated that growth factors accelerated the healing of large TMPs. The aim of this study was to compare the effects of growth factors and 0.3% (w/v) ofloxacin drops n the healing of human large TMPs.

METHODS

A total of 184 human large traumatic TMPs were randomly assigned to receive epidermal growth factor (EGF) treatment, fibroblast growth factor-2 (FGF-2) treatment, 0.3% (w/v) ofloxacin drops treatment, and conservative observation (only).

RESULTS

A total of 180 patients were analyzed in this study at the 6-month follow-up. The closure rates of the perforations in the EGF, FGF-2, 0.3% (w/v) ofloxacin drops, and conservative observation groups were 91.11%, 93.18%, 95.65%, and 82.22%, respectively, the closure rates did not significantly differ among the groups (P = .165). Similarly, pairwise comparisons did not reveal any significant between-group differences (P > .0083). However, the difference of the mean closure time was significant among the 4 groups (P < .001), pairwise comparisons showed that closure time was significantly longer in the observational group than in the other 3 groups (P < .001). Nevertheless, no significant difference in mean closure time was evident between any 2 treated groups (P > .0083). The mean hearing gain after 6 months was 11.49 ± 5.88 dB for the EGF group, 10.89 ± 5.16 dB for the FGF-2 group, 10.54 ± 5.56 dB for the ofloxacin group, and 9.29 ± 5.36 dB for the observation group. Differences in hearing improvement rates among the 4 groups were not statistically significant (P = .283).

CONCLUSION

Epidermal growth factor, FGF-2, and 0.3% (w/v) ofloxacin drops accelerated the closure of large TMPs compared with conservative treatment. Surprisingly, neither the closure rate nor closure time differed significantly among the 3 treated groups. Further experimental studies to demonstrate whether 0.3% (w/v) ofloxacin per se accelerates the healing of TMPs will be interesting in the future.

Prevalence of minimal hearing loss in South Korea

This study evaluated the prevalence of minimal hearing loss (MHL) in South Korea based on the 2010 to 2012 Korea National Health and Nutrition Examination Survey. A total of 16,630 representative individuals (older than 12 years) who completed ear examinations and structured questionnaires were analyzed. Only participants who had normal tympanic membranes were included. MHL was categorized into the following three groups: 1) unilateral sensorineural hearing loss (USHL, pure-tone average (PTA) ≥ 15 dB in the affected ear), 2) bilateral sensorineural hearing loss (BSHL, 15 dB ≤ PTA < 40 dB in both ears), and 3) high-frequency sensorineural hearing loss (HFSHL, two or more high-frequency thresholds > 25 dB in either ear). To evaluate clinical symptoms, subjective hearing status, tinnitus, and quality of life of each MHL group were compared to those of normal-hearing listeners. The use of hearing aids (HAs) was also investigated in the MHL population. The prevalence of normal hearing and MHL were 58.4% and 37.4%, respectively. In univariate analyses, the prevalence of MHL increased with age. It was significantly increased in males. Regarding clinical symptoms, 13.0% and 92.1% of participants with MHL reported difficulties with hearing and annoying tinnitus, respectively. In multivariate analyses, these proportions were significantly higher in the MHL groups than in normal-hearing listeners. Participants with MHL also showed significantly lower Euro Qol-5D index scores than did normal-hearing listeners. Regarding hearing rehabilitation, among minimally hearing impaired participants with subjective hearing loss, only 0.47% of individuals used HAs. Our results reveal that MHL is common in South Korea. It is associated with significant subjective hearing loss, tinnitus, and poor quality of life. Therefore, clinicians need to pay attention to this special group and provide proper counselling and rehabilitative management.

Retrospective air bone gap evaluation of patients with tympanic membrane central perforation

PURPOSE

The purpose of this study was to evaluate hearing recovery and air-bone gap (ABG) before and after tympanoplasty surgery in patients with tympanic membrane central perforation.

METHODS

Histories and audiological assessments of 160 cases (total of 26 ears from 22 patients; 11 men and 11 women) from patients who had undergone tympanoplasty surgery and hearing reconstruction due to tympanic membrane central perforation were evaluated. Pre-postoperative audiograms and the pure tone, air-bone hearing thresholds and ABG gains were evaluated.

RESULTS

The mean age of the patients was 38.6 years (± 16.04). The mean postoperative follow-up period was 13.4 months (± 15.5). The mean preoperative ABG was 25.36 dB (± 9.9) and postoperative ABG was 17.36 dB (± 11.68) (p = 0.001). When four groups were compared before surgery and after surgery period as 0-6 months, 6-12 months, 1-2 years and 2 years in terms of pre- and postoperative ABG values, no statistically significant difference was observed (p>0.05). All patients were divided into three groups: < 20 years of age; between the ages of 21-40; and, >41 years of age, and no statistically significant difference were found between the groups (p> 0.05). Surgeries of the patients 21-40 years of age were more successful (ABG gain) than other age groups. No statistically significant gender differences were found in ABG averages (p = 0.33), but clinical results were significantly better in women as compared with men.

CONCLUSION

In patients with central tympanic membrane perforation, tympanoplasty surgery with temporal fascia is beneficial in terms of hearing recovery.

Motion of tympanic membrane in guinea pig otitis media model measured by scanning laser Doppler vibrometry

Otitis media (OM) is an inflammatory or infectious disease of the middle ear. Acute otitis media (AOM) and otitis media with effusion (OME) are the two major types of OM. However, the tympanic membrane (TM) motion differences induced by AOM and OME have not been quantified in animal models in the literature. In this study, the guinea pig AOM and OME models were created by transbullar injection of Streptococcus pneumoniae type 3 and lipopolysaccharide, respectively. To explore the effects of OM on the entire TM vibration, the measurements of full-field TM motions were performed in the AOM, OME and untreated control ears by using scanning laser Doppler vibrometry (SLDV). The results showed that both AOM and OME generally reduced the displacement peak and produced the traveling-wave-like motions at relatively low frequencies. Compared with the normal ear, OME resulted in a significant change of the TM displacement mainly in the inferior portion of the TM, and AOM significantly affected the surface motion across four quadrants. The SLDV measurements provide more insight into sound-induced TM vibration in diseased ears.

Acoustic effects of the reconstructed lateral epitympanic wall in a temporal bone and clinical study

OBJECTIVE

Acoustic evaluation of reconstruction of the lateral epitympanic wall with bone or cartilage in a temporal bone study, and evaluation of audiometric data of patients who underwent cholesteatoma surgery with reconstruction of the lateral epitympanic wall with horseshoe-shaped cartilage.

STUDY DESIGN

Temporal bone study and retrospective chart review.

METHODS

Preparation of temporal bones included reconstruction of the epitympanic wall with fixated and loose cartilage and bone. The volume velocities of the stapes footplate were measured from the inner-ear side of the footplate by laser scanning doppler vibrometry following sound stimulation in the outer ear canal. Additionally, the audiometric data of 13 consecutive patients who underwent epitympanic cholesteatoma surgery, with an intact ossicular chain and reconstruction of the scutum with a horseshoe-shaped cartilage in contact with the malleus' neck, were evaluated retrospectively.

RESULTS

The experimental results showed similar volume velocities at the stapes footplate for the fixated and unfixated cartilage as well as for the unfixated bone. However, the fixated bone yielded significantly reduced volume velocities. Clinical data confirmed that the cartilaginous horseshoe- technique allowed for a stable reconstruction of the scutum with satisfying audiometric outcome.

CONCLUSION

In case of cholesteatoma surgery and the need for the reconstruction of the scutum, no adverse effects on hearing outcome are to be expected by using the malleus' neck as an anchoring point for cartilaginous scutum reconstruction.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:1427-1434, 2017.

Audiologic changes after pinna augmentation

No studies to date have objectively assessed whether pinna morphology affects sound intensity detected within the external auditory canal (EAC). Commonly performed procedures on the EAC are carried out for acquired and congenital pathology, together with correction of ear deformities. Our aim was to use an experimental model to identify whether a relationship exists between pinna shape and its subsequent effect on the hearing subject. An anatomically accurate and life-size model made of rubber composite was used for this study. Serial sections (small wedge, defect open; small wedge, defect closed; large wedge, defect open; large wedge, defect closed [equivalent to a protruding ear]; and pinnectomy) were undertaken, and the sound intensity changes assessed at the junction between the EAC and middle ear (tympanic membrane position) using an AURICAL Plus (Otometrics; Taastrup, Denmark) sound processor. A statistically significant loss was demonstrated for wedge-excised models, which was greatest at 180° azimuth. This loss was significantly reduced when the wedge defects were closed. A statistically significant improvement was demonstrated in the protruding ("bat") ear model compared with the normal ear at 0° azimuth. In this model, gain in sound intensity is adversely affected by pinna wedge resection. Because this change may be increased in those with protruding ears, this factor is important to consider for all cosmetic and noncosmetic operations to the pinna, and it supports the notion that the pinna is not a simple funnel.

Wideband reflectance in Down syndrome

OBJECTIVE

Children with Down syndrome (DS) have a high incidence of middle ear disorders and congenital abnormalities of the external, middle and inner ear. Energy reflectance (ER), a wideband acoustic immittance (WAI) measurement parameter, can measure the sound energy reflected or absorbed in the ear canal over a wider range of frequencies more efficiently and faster than conventional single-tone 226 Hz tympanometry. The aim of the present study was to compare the WAI measurements of children with DS with those of typically developing, normal-hearing children according to their tympanometric findings.

METHODS

Four groups of children with Down syndrome (age range: 2 years and 4 months to 16 years and 3 months; mean age: 8.5 yr) with normal tympanograms (19 ears), flat tympanograms (13 ears), mild negative pressure tympanograms (6 ears between -100 and -199 daPa at the admittance peak) and severe negative pressure tympanograms (4 ears at -200 daPa or lower at the admittance peak) were assessed. All findings were compared with data obtained from 21 ears of a healthy control group (age range: 3 years and 1 month to 13 years and 11 months; mean age: 7.9 yr). The subjects underwent tympanometry with a 226-Hz probe tone frequency and ER measurements along the 200-6,000 Hz range with a chirp stimulus using the Middle-Ear Power Analyzer (MEPA3 - HearID) by Mimosa Acoustics (Champaign, IL), software, version 3.3 [38].

RESULTS

Statistically significant differences were observed in the ER curves for some comparisons between the studied groups. There was also a negative correlation between the static acoustic admittance at the tympanic membrane level and ER measured with a chirp stimulus at 500 and 1,000 Hz. The discriminant analysis technique, which used a chirp stimulus at 1,000 and 1,600 Hz to classify the participants' data based on ER values, achieved a correct classification rate of 59.52% for participants with DS.

CONCLUSION

While groups with abnormal middle ear status, as indicated by tympanometry, showed higher ER values compared to the DS tymp A group and the control group, similar reflectance curves were observed between control group and the DS tymp A group. WAI shows promise as a clinical diagnostic tool in investigating the impact of middle ear disorders in DS group. However, further research is required to investigate this issue in narrower age range group and a larger sample size.

Diagnosis of Middle Ear Disease using Tympanograms and Digital Imaging

OBJECTIVE: The study investigates the ability of physicians with different levels of training to accurately identify middle ear (ME) pathology using tympanograms and tympanic membrane (TM) digital photographs.

STUDY DESIGN AND SETTING: Groups of medical students, internal medicine residents, and attending and resident otolaryngologists were presented with a set of 50 matched tympanograms and photographs of TMs. The physicians were asked to differentiate between a normal and an abnormal-appearing TM. The sensitivity and specificity of diagnosis of ME pathology by physicians were compared with the gold standard, examining the ME cavity for pathology during myringotomy.

RESULTS: The sensitivity did not vary among physicians with different levels of training; however, specificity improved with an increase in physician experience.

CONCLUSIONS AND SIGNIFICANCE: This study establishes a baseline for accuracy of diagnosis of ME pathology using tympanograms and photographs of TMs as compared with binocular otomicroscopy and the gold standard, myringotomy. EBM rating: B-2.

Pressed scar tissue for tympanic membrane grafting in revision tympanoplasty

OBJECTIVE

Compare the efficacy of pressed scar tissue grafts to standard fascia and areolar tissue grafts for use in tympanoplasty.

STUDY DESIGN

A retrospective review of a prospective computerized database of tympanoplasty and mastoid surgeries at an academic, tertiary care practice was performed. Search parameters were set to find all patients who underwent tympanoplasty with or without mastoidectomy with use of various grafting materials for repair of tympanic membrane perforation from 1996 to 2002. All ages were included. Patients with cholesteatoma at the time of surgery were excluded. The short-term graft take rate was evaluated at 30 to 90 days to identify any differences in results using the standard fascia and areolar grafts vs. pressed scar tissue grafts. Other parameters that may have an influence on outcome were analyzed including mastoidectomy, infection, perforation size, perforation location, age of patient, primary vs. revision surgery, number of previous surgeries, postauricular vs. transcanal approaches, and medial vs. lateral grafting techniques. Hearing results were analyzed to see whether the use of scar tissue grafts resulted in equivalent outcomes compared to standard graft materials.

RESULTS:

There were no statistically significant differences in short-term tympanic membrane closure rates in subjects undergoing surgery using standard fascia/areolar tissue grafts and pressed scar tissue grafts. Hearing results were also statistically equivalent regardless of graft material used. The only parameter that was somewhat associated with successful closure of tympanic perforation was use of the postauricular approach compared to the transcanal approach.

CONCLUSIONS

Pressed scar tissue grafts are as efficacious as standard fascia and areolar tissue grafts when used to repair tympanic membrane perforations. Pressed scar tissue graft can be used successfully in cases such as revision tympanoplasty when standard tissue grafts are not available or difficult to obtain. EBM rating: B-3.

Chronic Conductive Hearing Loss Leads to Cochlear Degeneration

Synapses between cochlear nerve terminals and hair cells are the most vulnerable elements in the inner ear in both noise-induced and age-related hearing loss, and this neuropathy is exacerbated in the absence of efferent feedback from the olivocochlear bundle. If age-related loss is dominated by a lifetime of exposure to environmental sounds, reduction of acoustic drive to the inner ear might improve cochlear preservation throughout life. To test this, we removed the tympanic membrane unilaterally in one group of young adult mice, removed the olivocochlear bundle in another group and compared their cochlear function and innervation to age-matched controls one year later. Results showed that tympanic membrane removal, and the associated threshold elevation, was counterproductive: cochlear efferent innervation was dramatically reduced, especially the lateral olivocochlear terminals to the inner hair cell area, and there was a corresponding reduction in the number of cochlear nerve synapses. This loss led to a decrease in the amplitude of the suprathreshold cochlear neural responses. Similar results were seen in two cases with conductive hearing loss due to chronic otitis media. Outer hair cell death was increased only in ears lacking medial olivocochlear innervation following olivocochlear bundle cuts. Results suggest the novel ideas that 1) the olivocochlear efferent pathway has a dramatic use-dependent plasticity even in the adult ear and 2) a component of the lingering auditory processing disorder seen in humans after persistent middle-ear infections is cochlear in origin.

Pressure chamber tests of eustachian tube function document lower efficiency in adults with colds when compared to without colds

CONCLUSIONS

Fractional gradient equilibrated (FGE) for ears with applied positive but not negative middle ear (ME)-ambient pressure gradients is highly sensitive to a cold-like illness (CLI).

OBJECTIVE

The sequential development of eustachian tube (ET) dysfunction, ME under-pressure, and otitis media (OM) characterizes many children during a CLI. If linked, OM burden would be lessened by interventions that promote/preserve good ET function during a CLI. Evaluating this requires a quantitative ET function test for MEs with an intact tympanic membrane responsive to a CLI.

METHODS

Pressure chamber testing of ET function was performed at +200 and -200 daPa in 3 groups of adults: group I, 21 subjects with an extant CLI and groups II and III, 14 and 57 adults, respectively, without a CLI. ME-chamber pressure gradient was recorded by tympanometry before and after the subject swallowed twice. ET functional efficiency was quantified as the FGE, which was then compared among groups using a Mann-Whitney U test.

RESULTS

At chamber pressures of 200 daPa, the ME-chamber pressure gradient was negative, and FGE was low and not different among groups. At chamber pressures of -200 daPa that gradient was positive, and FGE was significantly higher in groups II and III when compared with group I.

Factors affecting loss of tympanic membrane mobility in acute otitis media model of chinchilla

Recently we reported that middle ear pressure (MEP), middle ear effusion (MEE), and ossicular changes each contribute to the loss of tympanic membrane (TM) mobility in a guinea pig model of acute otitis media (AOM) induced by Streptococcus pneumoniae (Guan and Gan, 2013). However, it is not clear how those factors vary along the course of the disease and whether those effects are reproducible in different species. In this study, a chinchilla AOM model was produced by transbullar injection of Haemophilus influenzae. Mobility of the TM at the umbo was measured by laser vibrometry in two treatment groups: 4 days (4D) and 8 days (8D) post inoculation. These time points represent relatively early and later phases of AOM. In each group, the vibration of the umbo was measured at three experimental stages: unopened, pressure-released, and effusion-removed ears. The effects of MEP and MEE and middle ear structural changes were quantified in each group by comparing the TM mobility at one stage with that of the previous stage. Our findings show that the factors affecting TM mobility do change with the disease time course. The MEP was the dominant contributor to reduction of TM mobility in 4D AOM ears, but showed little effect in 8D ears when MEE filled the tympanic cavity. MEE was the primary factor affecting TM mobility loss in 8D ears, but affected the 4D ears only at high frequencies. After the release of MEP and removal of MEE, residual loss of TM mobility was seen mainly at low frequencies in both 4D and 8D ears, and was associated with middle ear structural changes. Our findings establish that the factors contributing to TM mobility loss in the chinchilla ear were similar to those we reported previously for the guinea pig ears with AOM. Outcomes did not appear to differ between the two major bacterial species causing AOM in these animal models.

[Tympanometry in the premature infants of different gestational age during the primary audiological examination]

The objective of the present work was to study specific approaches of tympanometry in the premature infants of different gestational age. A total of 122 typmanograms (243 ears) were available for the analysis. Peculiarities of recording tympanograms and their characteristics in the premature infants of different gestational age (including static compliance, intratympanic pressure, and tympanogram width) have been demonstrated. The optimal frequency of tympanometry in the premature infants of different gestational age was determined.

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.

Conductive hearing loss induced by experimental middle-ear effusion in a chinchilla model reveals impaired tympanic membrane-coupled ossicular chain movement

Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30-40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the chinchilla as an animal model, umbo velocity (V U) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz-12 kHz) before and after filling the middle ear with different volumes (0.5-2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20-40-dB increases in CM thresholds and 15-35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.

Otitis media

Acute otitis media (AOM) is diagnosed based on visualization of a full or bulging tympanic membrane with middle ear effusion. The distribution of bacteria causing AOM in North America under the influence of pneumococcal conjugate vaccination and antibiotic selection pressure has resulted in a predominance of β-lactamase-producing Haemophilus influenzae followed by penicillin-resistant Streptococcus pneumoniae. Although guidelines continue to endorse amoxicillin as the preferred treatment, amoxicillin/clavulanate in high dosage would be the preferred treatment based on the otopathogen mix currently. Antibiotic prophylaxis has fallen into disfavor as a preventative strategy for AOM recurrences.

[Clinical analysis of abnormal acoustic admittance in preschool children with nasal and nasopharyngeal disorders]

OBJECTIVE

To investigate the risk factors of related disorders, which could lead to potential otitis media by observing the abnormal configuration of drum and abnormal acoustic immittance without symptoms in preschool children.

METHODS

Eighty-one cases (162 ears) received flexible pharyngorhinoscopy, skin prick test, CT examination of sinus, and were diagnosed as allergic rhinitis, chronic sinusitis, adenoid hypertrophy. They had no complaints of ear related symptoms, but were observed to have abnormality in ear drum by physical examined. Acoustic immittance measurement were performed, so as to estimate whether they were accompany with potential otitis media. The changes of examination and tests were analyzed before and after the treatment.

RESULTS

There were 15 cases (29 ears) with abnormal acoustic admittance among 81 cases (162 ears) who had no ear related symptoms but had different degree abnormality in ear drum. The morbidity rate of these 15 patients was 13.6% (6/44 ears) in allergic rhinitis patients, 18.2% (12/66 ears) in chronic sinusitis patients, and 21.2% (11/52 ears) in adenoid hypertrophy patients, respectively. The differences among the three diseases had statistical significance (χ² = 63.02,P < 0.05). Among 29 ears, 28 ears whose type of tympanic pressure curve were transferred from type C to type A two weeks after treatment. One ear whose type of tympanic pressure curve transferred from type B to type C four weeks after treatment. All cases had been followed up with no recurrent cases.

CONCLUSIONS

Some preschool children with nasal and nasopharyngeal disorders had abnormal configuration of drum and abnormal acoustic immittance, and had potential risk for otitis media. Among the disorders, adenoid hypertrophy impact more on middle ear function. The early intervention of related diseases could prevent the developing trend of otitis media.

Non-invasive methods of estimating intracranial pressure

Non-invasive measurement of intracranial pressure can be invaluable in the management of critically ill patients. We performed a comprehensive review of the literature to evaluate the different methods of measuring intracranial pressure. Several methods have been employed to estimate intracranial pressure, including computed tomography, magnetic resonance imaging, transcranial Doppler sonography, near-infrared spectroscopy, and visual-evoked potentials. In addition, multiple techniques of measuring the optic nerve and the optic nerve sheath diameter have been studied. Ultrasound measurements of the optic nerve sheath diameter and Doppler flow are especially promising and may be useful in selected settings.

Prosthetic reconstruction from the tympanic membrane to the stapes head or to the stapes footplate? A laser Doppler study

BACKGROUND

In the absence of the incus, many surgeons believe that reconstruction from the tympanic membrane to the stapes head is more effective than reconstruction to the stapes footplate. This has rarely been tested empirically. Published better clinical results with reconstruction to the stapes head might simply reflect less underlying disease in ears with an intact stapes superstructure.

OBJECTIVE

To compare vibration transmission of these two forms of prosthetic reconstruction.

METHODS

A fresh human cadaveric temporal bone model was used. Round window vibrations in response to sound in the ear canal were measured with a laser Doppler vibrometer. After incus removal, the discontinuity was repaired using a titanium prosthesis. Reconstruction from the tympanic membrane to the stapes head was compared to reconstruction to the stapes footplate.

RESULTS

Reconstruction of both types decreased round window vibrations by 10 to 15 dB between 500 and 3000 Hz compared to the intact middle ear. Reconstruction to the stapes head performed 5 to 10 dB better at lower frequencies (500-2000 Hz), but this was only statistically significant at 1 and 2 kHz.

CONCLUSIONS

There is only a 5 to 10 dB mechanical advantage gained by reconstruction from the tympanic membrane to the stapes head compared to reconstruction to the footplate for frequencies between 1 and 2 kHz.

Effect of type I tympanoplasty on the resonant frequency of the middle ear: comparison between chondrotympanoplasty and temporalis fascia grafting

AIMS

To evaluate the effect of type I chondrotympanoplasty on the resonant frequency (RF) of the middle ear and compare it to the respective outcomes of type I tympanoplasty using temporalis fascia grafting (TFG). Hearing results and respective graft integration rates were also assessed.

MATERIALS AND METHODS

A retrospective comparative study was conducted of patients who had undergone type I tympanoplasty at a tertiary university hospital. Selection criteria included tympanic membrane perforation following chronic otitis media, trauma, or grommet insertion; an intact ossicular chain; a dry ear for at least 3 months; and normal middle ear mucosa. Patients with ossicular discontinuity, ossiculoplasty, cholesteatoma, previous ear surgery, syndromes affecting the middle ear, or younger than 16 years old were excluded.

RESULTS

Sixty-nine patients met the inclusion criteria; chondrotympanoplasty was performed in 39 and TFG in 30. Three patients showed incomplete tympanic membrane closure at follow-up. The graft integration rate was 97.4% in the chondrotympanoplasty group and 93.3% in the TFG group. An air-bone gap closure within 10 dB was achieved in 73.7% of the chondrotympanoplasty patients versus 67.9% of the TFG patients. Hearing gain of 21 to 30 dB in air conduction thresholds was obtained in 65.8% of the chondrotympanoplasty patients and 60.7% of their TFG counterparts. RF was 808 ± 458 Hz in the chondrotympanoplasty group and 628 ± 256 Hz in the TFG group. The RF remained within the normal range in 73.7% of chondrotympanoplasty patients versus 42.9% of TFG patients.

CONCLUSIONS

Chondrotympanoplasty has hearing results comparable to those of TFG myringoplasty. The cartilage can be used without concerns regarding its impact on the middle ear mechanics as the sound-conducive properties of the tympanic membrane remain unchanged.

[The clinical study of tympanic membrane mobility with the use of the autodyne technique]

AIM OF THE STUDY

to estimate the possibility of application of the autodyne method for the detection of nano-displacements of the tympanic membrane and diagnostics of ear diseases.

METHODS

nano-displacements of the tympanic membrane were revealed with the use of the original laser-assisted autodyne technique for the measurement of nano-vibrations. The majority of the measurements were performed in the free auditory field. A total of 182 patients allocated to 7 groups depending on the form of hearing disturbances or their absence were involved in the study.

RESULTS

the values of nano-displacement of the tympanic membrane at different levels of acoustic pressure have been obtained for otologically healthy individuals. The age dependence of this parameter was investigated in the absence of otological pathology. Similar studies were carried out in different groups of patients with the diseases of the middle and internal ears. The mobility of the tympanic membrane was shown to be significantly altered in the presence of adhesive events in the middle ear and pathological changes in the Eustachian tube. The possibilities of the clinical application of the proposed method have been estimated.