Bacterial cytolysin perturbs round window membrane permeability barrier in vivo: possible cause of sensorineural hearing loss in acute otitis media

Does Mucosal Chronic Otitis Media Leads to Sensorineural Hearing Loss

Sensori-neural hearing loss (SNHL) results from inner ear damage or injury to the neural pathways that relay signals from the inner ear to the brain. A serious sequelae of COM is damage to the inner ear. This study aimed at finding the occurrence of SNHL in unilateral mucosal COM. One Hundred patients who had unilateral mucosal COM were enrolled in the study and underwent pure tone audiometry using Audio 4002 system in acoustically treated room. Bone conduction (BC) threshold less than 20 dB was taken as normal. Significant SNHL of 23% was seen in mucosal COM. Unilateral mucosal COM leads to significant impact on BC thresholds. The risk of SNHL increases with larger perforation size and increasing duration and active stage of disease.

Extended high frequency hearing loss in tinnitus-positive chronic suppurative otitis media patient

OBJECTIVES

To determine the association between extended high frequency hearing loss and tinnitus in normal cochlear function based on a conventional audiometry chronic suppurative otitis media (CSOM) patient.

DESIGN AND METHODS

A cross-sectional study was conducted on 220 ears diagnosed as having CSOM with an equal number of tinnitus and without tinnitus groups. Only those with normal cochlear function based on conventional pure tone audiometry (250 Hz to 8 kHz) were included. They were further tested for hearing at extended high frequencies of up to 16 kHz. The severity of tinnitus was tested using a tinnitus questionnaire.

RESULTS

The prevalence of extended high frequency hearing loss in the normal cochlear function CSOM patients with tinnitus was 81.8% (95% CI 74.5%, 89.1%), whereas the prevalence in the tinnitus negative group was 30.0% (95% CI 21.3%, 38.7%). There was a significant association between extended high frequency hearing loss and tinnitus in CSOM patients (P < .001). The average thresholds were significantly higher in the tinnitus group at all extended high frequencies tested with an increasing trend of significance toward the higher frequencies. However, this study did not observe any association between the severity of tinnitus and extended high frequency hearing loss.

CONCLUSION

The development of tinnitus among normal cochlear function CSOM patients indicates that the damage has occurred at a higher frequency level. However, the severity of tinnitus does not predict the degree of higher frequency hearing loss. Therefore, the presence of tinnitus warrants more aggressive monitoring and treatment to prevent sensorineural hearing loss from developing into the speech frequencies.

LEVEL OF EVIDENCE

4.

Extended high frequency hearing and speech perception implications in adults and children

Extended high frequencies (EHF), above 8 kHz, represent a region of the human hearing spectrum that is generally ignored by clinicians and researchers alike. This article is a compilation of contributions that, together, make the case for an essential role of EHF in both normal hearing and auditory dysfunction. We start with the fundamentals of biological and acoustic determinism - humans have EHF hearing for a purpose, for example, the detection of prey, predators, and mates. EHF hearing may also provide a boost to speech perception in challenging conditions and its loss, conversely, might help explain difficulty with the same task. However, it could be that EHF are a marker for damage in the conventional frequency region that is more related to speech perception difficulties. Measurement of EHF hearing in concert with otoacoustic emissions could provide an early warning of age-related hearing loss. In early life, when EHF hearing sensitivity is optimal, we can use it for enhanced phonetic identification during language learning, but we are also susceptible to diseases that can prematurely damage it. EHF audiometry techniques and standardization are reviewed, providing evidence that they are reliable to measure and provide important information for early detection, monitoring and possible prevention of hearing loss in populations at-risk. To better understand the full contribution of EHF to human hearing, clinicians and researchers can contribute by including its measurement, along with measures of speech in noise and self-report of hearing difficulties and tinnitus in clinical evaluations and studies.

Chronic Otitis Media and its Correlation with Unilateral Sensorineural Hearing Loss in a Tertiary Care Centre of North India

Relation between chronic otitis media and sensorineural hearing loss is controversial. Otitis media can cause threshold shift in high frequency range. Also this correlation with patient's age, disease duration and normal ear is of importance for early prevention of hearing loss. The aim of this study was to evaluate relationship between sensorineural hearing loss and chronic otitis media. We also studied association of bone conduction between diseased ear and contralateral normal ear. In this study, 840 patients of unilateral COM were included. Audiometry was done and data analyzed. Majority of patients showing SNHL had COM for over a period of 5 years. Squamosal disease showed early progression to SNHL than mucosal disease. Higher frequencies were found to be more affected and maximum bone gap was seen at 4000 Hz. There was significant difference in mean bone conduction threshold between diseased ear and normal ear at all frequencies (p value < 0.001). Contradicting studies have emerged about association of SNHL with COM. Studies suggest that SNHL does not change with age but with duration. Bone conduction threshold tends to increase with increasing frequency. Few authors also pointed that this may be due to Carhart's effect and not due to disease damaging inner ear.

Changes in Cochlear Blood Flow Due to Endotoxin-Induced Otitis Media

The purpose of this study was to elucidate the influence of otitis media on blood flow in the lateral wall of the cochlea by means of a model of endotoxin-induced otitis media. The cochlear blood flow (CBF) following lipopolysaccharide inoculation into the middle ear cavities of rats was measured by laser-Doppler flowmetry and compared with that of untreated ears. After this evaluation, the influence on CBF of concomitant use of a nitric oxide synthase inhibitor was also investigated. The first day after inoculation, the CBF of treated ears decreased significantly. This decrease recovered gradually between the 7th and 14th days. With concomitant use of a nitric oxide synthase inhibitor, the decrease in CBF was prevented to some extent. The results showed a functional influence upon CBF by endotoxin-induced otitis media. The significance of prophylactic use of the drug is also discussed in regard to the effect on CBF following otitis media.

Effect of intratympanic steroid administration on sensorineural hearing loss associated with acute otitis media

OBJECTIVE

To evaluate a small cohort of patients who presented with symptoms and signs consistent with acute infective sensorineural hearing loss who were treated with intratympanic steroids.

METHOD

Seven patients received a 7-day course of oral antibiotics and oral prednisolone followed by 3 intratympanic injections of methylprednisolone and 1 week of topical dexamethasone drops.

RESULTS

Hearing improved in 57 per cent of patients (four out of seven). The mean improvement in this group was 24 dB (range, 10-52 dB). The magnitude of the sensorineural hearing loss at presentation was less in those who responded to intratympanic steroid therapy than in non-responders (mean pure tone average of 30 dB versus 65 dB pre-intratympanic steroids, and 14 dB versus 83 dB post-intratympanic steroids, respectively).

CONCLUSION

The results of our study suggest that intratympanic steroids provide a valuable contribution to the treatment of acute infective sensorineural hearing loss and may provide additional benefit by virtue of a concentrated local steroid effect in patients who do not respond to antibiotics.

BDNF as otoprotectant in toxin-induced hearing loss

CONCLUSION

Brain-derived neurotrophic factor (BDNF) can prevent auditory brainstem response (ABR) threshold shift changes caused by Pseudomonas aeruginosa exotoxin A (PaExoA).

OBJECTIVE

Peptides of the neurotrophin family are known to prevent neuronal death during embryonic development by interacting with specific membrane receptors. The purpose of this study was to investigate whether a single dose of BDNF is an effective protectant against toxic effects of PaExoA-induced ABR threshold shifts.

MATERIALS AND METHODS

Eight groups of Sprague-Dawley rats were used. There were five control groups (n = 20) as follows. Group A (n = 4) received NaCl solution; group B (n = 3) received 4 µg BDNF; group C (n = 4) received 1 μg/20 μl PaExoA; group D (n = 4) received 2 μg/20 μl PaExoA; group E (n = 5) received 10 µg/20 µl PaExoA injected into the round window niche. Three treatment groups (n = 13) received a single dose of PaExoA and 4 µg of BDNF simultaneously. Group 1 (n = 3) received 1 μg/20 μl PaExoA + 4 µg of BDNF; group 2 (n = 5) received 2 μg/20 μl PaExoA + 4 µg BDNF; group 3 (n = 5) received 10 μg/20 μl PaExoA + 4 µg BDNF. ABR was used to measure efficacy by analyzing threshold shifts before and after injections.

RESULTS

A single dose of BDNF prevented changes in ABR thresholds following exposure to increasing concentrations of PaExoA injected into the middle ear.

Predisposing factors for inner ear hearing loss association with chronic otitis media

The aim of the present study was to investigate the consequences of chronic otitis media on inner ear function. Retrospective analysis of conventional pure-tone audiometry tests was carried out on 344 patients who were scheduled for surgical treatment of unilateral chronic otitis media without other risk factors for sensorineural hearing loss. Bone conduction thresholds of diseased ears were compared with those of contralateral, non-diseased ears. Selected clinical features were assessed among diseased ears to examine possible influences on inner ear function. Mean bone conduction threshold differences varied from 0.6 dB at 0.5 kHz to 3.7 dB at 4 kHz. These differences augmented with increasing duration of middle ear disease. Impaired hearing by bone conduction thresholds of diseased ears correlated with increased age at every frequency and with an interruption of the ossicular chain only at higher frequencies. The severity of sensorineural hearing loss correlated with longer duration of middle ear disease. Thus, surgical treatment of dry and apparently stable tympanic membrane perforation is warranted.

Effectiveness of instillation of triamcinolone acetonide into the middle ear for eosinophilic otitis media associated with bronchial asthma

BACKGROUND

Eosinophilic otitis media (EOM) is a newly recognized middle ear disease found in asthmatic patients. EOM is characterized by a highly viscous middle ear effusion that contains many eosinophils and is extremely unresponsive to conventional treatments for common otitis media. To our knowledge, no systemic study regarding the efficacy of treatments for EOM has been performed.

OBJECTIVE

To determine the effectiveness of instillation of triamcinolone acetonide, which is a suspension of steroids, into the mesotympanum and eustachian tube as a treatment for patients with EOM.

METHODS

We studied the efficacy of the instillation of triamcinolone acetonide in 43 ears of 24 patients with EOM. Efficacy was evaluated according to the length of the period without middle ear effusion or otorrhea. We also determined the otomicroscopic findings and the hearing levels before and after therapy. For controls, 27 ears of 14 patients treated by topical administration of betamethasone were similarly evaluated.

RESULTS

The middle ear effusion or otorrhea was controlled for more than 3 weeks after 1 instillation of triamcinolone acetonide in 35 ears, and the efficacy rate (81%) was significantly higher than that in the controls (7 ears, 26%). In the triamcinolone acetonide group, the average air conduction hearing level at the speech frequency range was significantly improved, and deterioration of the bone conduction hearing threshold was rarely found during therapy.

CONCLUSION

The instillation of triamcinolone acetonide into the mesotympanum and eustachian tube is an effective treatment for patients with EOM.

[Cochlear involvement in acute otitis media]

OBJECTIVE

An experimental design with mice has been realized to understand the origin of sensorial hearing loss related to infectious processes in the middle ear. Our aim is to study if the cilliated cells in the Corti organ's are lost after one or more acute otitis media.

MATERIAL AND METHODS

For that, thirty Sprague-Dawley mice have been divided in two groups. In the first one, we have induced one acute otitis media, in the second group we have induced two infections of this kind.

RESULTS

The statistic study shows that the loss of the cilliated cells is greater in the basal turn of the mice is cochlea, in the first group (alpha=0,020) and also in the second (alpha=0,038). We've noticed in the first group the near absence of injury in the middle turn, but in all samples of the second group we found that injury (alpha=0,002).

CONCLUSIONS

In acute otitis media, the loss of ciIliated cells are mainly in the basal turn of the mice is cochlea, and affects the middle turn when the infection is repeated.

A comparative study of intratympanic steroid and NO synthase inhibitor for treatment of cochlear lateral wall damage due to acute otitis media

We studied the damage to the cochlear lateral wall induced by otitis media and the therapeutic effects of intratympanic administration of steroid and nitric oxide (NO) synthase inhibitor. In Sprague-Dawley rats, right middle ear cavities were inoculated with lipopolysaccharide, followed after 30 min by intratympanic administration of dexamethasone, NOS-inhibitor or PBS. Twenty-four hours after lipopolysaccharide inoculation, cochlear blood flow was measured by laser-Doppler flowmetry. Prostaglandin E(1) was topically applied to the round window membrane of the right ear and changes in cochlear blood flow were calculated. Changes of cochlear blood flow were significantly different among the three groups. Increases in cochlear blood flow following PGE(1) application were higher in the group that received NOS-inhibitor. Electron microscopic examination revealed that changes in the stria vascularis were less severe in rats treated with dexamethasone or NOS-inhibitor. Our results show the effectiveness of intratympanic dexamethasone or NOS-inhibitor in treating cochlear lateral wall damage caused by otitis media.

Adenoviral vector gene delivery via the round window membrane in guinea pigs

We have found that damage from a local anesthetic solution containing phenol permitted beta-galactosidase (beta-gal) gene delivery to the guinea pig inner ear via the round window membrane (RWM). RWM damage was evident as degeneration of the outer epithelium. After adenovirus lacZ vector was applied to the damaged RWM, immunohistochemistry showed strong beta-gal expression in the RWM, mesothelial cells, organ of Corti, spiral limbus, spiral ligament and spiral ganglion. In the vestibular labyrinth, expression was seen in the sensory and supporting cells, transitional cells, and the dark-cell area. Thus, adenovirus can transfect a variety of inner ear cells in the guinea pig through a damaged RWM.

Tolerability of N-chlorotaurine in the guinea pig middle ear: a pilot study using an improved application system

The tissue tolerance of N-chlorotaurine (NCT), a mild endogenous antimicrobial oxidant, has been investigated by application to the guinea pig middle ear. The animals were implanted with a novel cannula system that allows chronic external drug delivery to the round window niche. In the first part of the study, 3 animals each received 100 microL of 0.1% NCT (5.5 mmol/L) and 1% NCT, respectively, in aqueous solution twice daily for 8 days. In the second part, NCT was dissolved in phosphate-buffered saline solution to 300 milliosmolar (isotonic), and 27 microL was injected in 3 additional animals twice daily for 7 days. The guinea pigs injected with 100 microL of NCT developed immediate dizziness and nystagmus and did not thrive. Other reactions included mucosal thickening in the middle ear, rupture of the tympanic membrane, and blood and gelatinous material in the cochlea accompanied by hair cell loss and a 10- to 90-dB elevation of the hearing threshold as determined by auditory brain stem responses. The effects seemed to be dose-dependent, but the rate of variability was high across animals. In contrast, the guinea pigs treated with 27 microL of isotonic NCT showed no signs of discomfort, no or only moderate thickening of the middle ear mucosa, no shift of the hearing threshold, and no hair cell loss. Positive control animals injected with 10% neomycin sulfate developed extensive hair cell loss. Provided that the membranes of the inner ear are intact and that low single-dose volumes are used to avoid increased middle ear pressure, isotonic NCT seems to be well tolerated in the tympanic cavity. The new drug delivery system proved to be advantageous for ototoxicity studies.

Chronic suppurative otitis media and sensorineural hearing loss: Is there a correlation?

Traditionally, it has been accepted that chronic suppurative Otitis media is associated with a breakdown in meekanical conduction of sound leading to conductive hearing loss, On;the contrary, there are two schools of thought when it come, to the issue of cpchlear involvement leading to sensorineural hearing loss (SNIIL) in chronic suppura the Otitis media. The present study was undertaken to find out whether a sensorineural component exists in hearing loss associated with chronic suppurative otitis media, A sample of 100 patients of unilateral chronic suppurative otitis media was selected for the Study and their bone conduction thresholds Mere analyzed in relation to the duration of disease using audiometric data. A 24 per cent incidence of sensoineural hearing loss was found in this series, garticularly involving the higher frequencies. Moreover, the incidence of sensorineural hearing loss progressively increased with the increase in duration of chonic suppurative Ouns meadia.

Local administration of antioxidants to the inner ear. Kinetics and distribution(1)

Round window (r.w.) administration of drugs involves the delivery of medication directly into the inner ear via the r.w. membrane, avoiding a systemic effect of the therapy. Earlier experimental studies suggest that a number of antioxidants and scavengers hold promise for ameliorating the tissue damaging capacity of reactive oxygen species in some acquired cochlear disorders. D-Methionine and thiourea are two small sulfur-containing molecules with an antioxidative and scavenging effect. The passage through the r.w. of radioactive D-methionine and thiourea administered by 1 h infusion to the r.w. was studied in a rat model. Levels of the tracers were measured in scala tympani perilymph (PLT) 17-254 min after r.w. administration. Both tracers pass the r.w. membrane readily. Peak levels were found in the earliest taken samples after the administration. The radioactivity in PLT of the basal turn reached a peak to about 1.5-1.9% of the irrigating medium radioactivity. Following the r.w. administration, the concentration of radioactive D-methionine and thiourea declined with a terminal half-life of 0.57 and 0.77 h, respectively. The distribution of the tracers at the cellular level was analyzed by autoradiography. The most intense expression was found in the lateral wall of the cochlea. It can be postulated that local delivery to the cochlea of D-methionine and thiourea via the r.w. gives high local concentrations of the substances in PLT in the basal turn.

Hearing preservation with labyrinthine ablation in otitis media

OBJECTIVES

Iatrogenic fenestration of the inner ear in the presence of otitis media is commonly associated with permanent hearing loss. Hearing can generally be preserved when the vestibular labyrinth is ablated in a controlled manner in noninflamed ears. The purpose of this study was to examine the feasibility of hearing preservation with violation of the inner ear in the presence of middle ear inflammation.

STUDY DESIGN

Prospective and controlled animal model.

METHODS

Otitis media was induced bilaterally in pigmented guinea pigs with transtympanic injection of Streptococcus pneumoniae, nontypeable Haemophilus influenzae, or formalin-killed nontypeable H influenzae. Two to 4 days after injection, the horizontal canal of one ear was transected and sealed. Hearing was tested before and after labyrinthine ablation.

RESULTS

Otitis media was induced in all ears. Bacterial cultures were positive in 19 of 20 S pneumoniae-injected ears, and in 10 of 16 nontypeable H influenzae-injected ears. One week after surgery, elevation of click thresholds (> 15 dB) was encountered in none of the fenestrated or unfenestrated S pneumoniae-infected ears, in two of six unfenestrated and three of six fenestrated nontypeable H influenzae-infected ears, and in one of five killed-nontypeable H influenzae-injected ears both with and without fenestration.

CONCLUSIONS

These data suggest that ablation of a semicircular canal in the presence of middle ear inflammation or infection does not necessarily lead to profound sensorineural hearing loss. Hearing loss associated with iatrogenic violation of the semicircular canals may be more dependent on factors other than the presence of nonspecific middle ear inflammation.