Evoked Brainstem Responses Research Articles

Universal Neonatal Hearing Screening - a Necessity and not a Choice

INTRODUCTION
 Congenital deafness in a child is often missed. Several distraction tests have evolved over time to diagnose congenital deafness. These are of limited value in the era of Evoked response audiometry. Evoked responses, such as Oto-acoustic emission (OAE) and Brainstem Evoked Response Audiometry (BERA) have played a significant role in early diagnosis of congenital hearing impairment. The study was conducted to compare the result of neonatal hearing screening in high risk and non high risk neonates.
 
 MATERIALS AND METHODS
 A study was conducted over a time period of three months at a tertiary care institute to screen all live neonates for congenital hearing impairment using OAE and BERA.
 
 RESULT
 1182 neonates were screened for hearing impairment. 336 were in High risk group and rest in Non high risk group. Nine neonates turned out to have abnormal BERA result (absence of wave V). Six of them were high risk babies and rest 3 were non high risk.
 
 DISCUSSION
 33.33% of congenital deaf population detected by UNHS belong to the Non High Risk group. Studies across the world suggest at least 50% chance of missing out a congenital deaf child if Universal Neonatal Hearing Screening is not practiced.
 
 CONCLUSION
 In order to ensure that early detection and effective intervention are made on all newborns with hearing impairment, UNHS should be performed. Three stage UNHS protocol using TEOAEs and BERA showed that the implementation of UNHS for congenital childhood hearing loss among all newborns in India feasible and effective.

Evaluation of duration of antibiotic therapy in neonatal bacterial meningitis: a randomized controlled trial.

To compare the effect of 10 days versus 14 days of antibiotic therapy in neonatal meningitis on treatment failure rate. The study was a randomized controlled trial conducted at a referral neonatal unit. The participants were 70 neonates with meningitis randomized to receive 10 days (study group) or 14 days (control group) of antibiotics. The primary outcome measure studied was treatment failure in each group within 28 days of enrolment. None of the neonates among either of the groups had occurrence of meningitis during follow-up. Occurrence of sepsis was observed after discharge in three neonates in the control group and none in the study group. Brainstem-evoked response audiometry was abnormal in one neonate in the study group. Adverse effects of drugs and neurological deficits were not observed in the study population. Short course of antibiotic therapy (10 days) is effective, with potential benefits of shorter hospital stay.

A presedation fluid bolus does not decrease the incidence of propofol-induced hypotension in pediatric patients.

Propofol is commonly used in pediatric sedation, which may cause hypotension during induction. Our goal was to determine the effect of a preinduction 20-mL/kg isotonic fluid bolus on propofol-induced hypotension, assess clinical signs of hypoperfusion during hypotension, and evaluate for age-related propofol dosing differences. This prospective, randomized, controlled, nonblinded study was conducted at Children's Hospital of Illinois. Patients were children 6 to 60 months of age who needed sedation for MRI or auditory brainstem-evoked response testing. The treatment group received a preinduction 20-mL/kg isotonic saline bolus before procedure initiation. Patients were continuously monitored via cardiorespiratory monitor with pulse oximetry and end-tidal carbon dioxide measurements. Cardiovascular indices and clinical signs of hypoperfusion were compared between groups, and propofol dosing differences were compared between age groups. One hundred twenty-six patients were randomly assigned to treatment (n=52) or control (n=74) conditions. Twelve patients in the treatment group and 14 patients in the control group experienced postinduction hypotension, as defined by the Pediatric Advanced Life Support guidelines. One patient in each group was given volume resuscitation when blood pressure did not improve after a reduction in the propofol infusion rate. No hypotensive patients had physical signs of hypoperfusion, and patients≤1 year of age needed significantly more propofol. A 20-mL/kg preinduction isotonic saline bolus does not prevent propofol-induced hypotension. No clinical signs of hypoperfusion were noted with induced hypotension, and infants≤12 months old need significantly more propofol per kilogram for procedures.

A high-fat diet delays age-related hearing loss progression in C57BL/6J mice.

ObjectiveAge-related hearing loss (AHL), or presbycusis, is the most common sensory disorder among the elderly. We used C57BL/6J mice as an AHL model to determine a possible association between AHL and a high-fat diet (HFD).MethodsForty C57BL/6J mice were randomly assigned to a control or HFD group. Each group was divided into the following subgroups: 1-, 3-, 5- and 12-month groups (HFD, n = 5/subgroup; control, n = 5/subgroup). Nine CBA/N-slc mice were also used as a 12-month control (n = 5) or 12-month HFD (n = 4) group. The mice were fed a HFD or normal (control) diet throughout this study. Hearing function was evaluated at 1, 3, 5 and 12 months using auditory evoked brainstem responses (ABRs). Spiral ganglion cells (SGCs) were also counted.ResultsThe elevation of ABR thresholds (at 4 and 32 kHz) at 3 and 5 months was significantly suppressed in the HFD group compared with the control groups for C57BL/6J mice. After 12 months, the elevation of ABR thresholds was significantly suppressed in the HFD group at all frequencies for C57BL/6J mice. In contrast, CBA/N-slc mice displayed opposite outcomes, as ABR thresholds at all frequencies at 12 months were significantly elevated in the HFD group compared with the control group. For the C57BL/6J mice at 12 months, SGC numbers significantly decreased in all parts of the cochleae in the control group compared with the HFD groups. In contrast, for the CBA/N-slc mice, SGC numbers significantly decreased, particularly in the upper parts of the cochleae in the HFD group compared with the control groups.ConclusionsThe elevation in ABR thresholds and SGC loss associated with aging in the HFD-fed C57BL/6J mice were significantly suppressed compared with those in the normal diet-fed mice. These results suggest that HFD delays AHL progression in the C57B/6J mice.

Development of electrically evoked auditory brainstem response modules of REZ-I domestic cochlear implant device

To develop electrically evoked auditory brainstem response(EABR) modules of REZ-I domestic cochlear implant device, and testify the reliability and validity of the modules. Postoperative EABR were recorded in guinea pigs by using the self-designed EABR module. EABR waves were recorded in all 15 ears of 9 guinea pigs with normal hearing. The threshold was (159.00 ± 50.21) current level (CL) and eIII wave latency was (2.36 ± 0.46) ms of 100 µs pulse width stimulation; for 150 µs pulse width stimulation, the threshold was (131.44 ± 49.25) CL and eIII wave latency was (2.59 ± 0.46)ms; for 200 µs pulse width stimulation, the threshold was (119.63 ± 52.56) CL and e III wave latency was (2.62 ± 0.44)ms. According the preliminary results of the study, the reliability and stability of the EABR modules of domestic cochlear implant device can meet the demands of EABR recording.

Delayed auditory pathway maturation and prematurity.

Hearing loss is the most common sensory disorder in developed countries and leads to a severe reduction in quality of life. In this uncontrolled case series, we evaluated the auditory development in patients suffering from congenital nonsyndromic hearing impairment related to preterm birth. Six patients delivered preterm (25th-35th gestational weeks) suffering from mild to profound congenital nonsyndromic hearing impairment, descending from healthy, nonconsanguineous parents and were evaluated by otoacoustic emissions, tympanometry, brainstem-evoked response audiometry, and genetic testing. All patients were treated with hearing aids, and one patient required cochlear implantation. One preterm infant (32nd gestational week) initially presented with a 70 dB hearing loss, accompanied by negative otoacoustic emissions and normal tympanometric findings. The patient was treated with hearing aids and displayed a gradual improvement in bilateral hearing that completely normalized by 14 months of age accompanied by the development of otoacoustic emission responses. Conclusions We present here for the first time a fully documented preterm patient with delayed auditory pathway maturation and normalization of hearing within 14 months of birth. Although rare, postpartum development of the auditory system should, therefore, be considered in the initial stages for treating preterm hearing impaired patients.

Hearing function in patients living with HIV/AIDS.

During the earlier years of the HIV/AIDS epidemic, initial reports described sensorineural hearing loss in up to 49% of individuals with HIV/AIDS. During those years, patients commonly progressed to advanced stages of HIV disease and frequently had neurological complications. However, the abnormalities on pure-tone audiometry and brainstem-evoked responses outlined in small studies were not always consistently correlated with advanced stages of HIV/AIDS. Moreover, these studies could not exclude the confounding effect of concurrent opportunistic infections and syphilis. Additional reports also have indicated that some antiretroviral medications may be ototoxic; thus, it has been difficult to make conclusions regarding the cause of changes in hearing function in HIV-infected patients. More recently, accelerated aging has been suggested as a potential explanation for the disproportionate increase in complications of aging described in many HIV-infected patients; hence, accelerated aging-associated hearing loss may also be playing a role in these patients. We conducted a large cross-sectional analysis of hearing function in over 300 patients with HIV-1 infection and in 137 HIV-uninfected controls. HIV-infected participants and HIV-uninfected controls underwent a 2-hr battery of hearing tests including the Hearing Handicap Inventory, standard audiometric pure-tone air and bone conduction testing, tympanometric testing, and speech reception and discrimination testing. Three-way analysis of variance (ANOVA) and logistic regression analysis of 278 eligible HIV-infected subjects stratified by disease stage in early HIV disease (n = 127) and late HIV disease (n = 148) and 120 eligible HIV-uninfected controls revealed no statistically significant differences among the three study groups in either overall 4-frequency pure-tone average (4-PTA) or hearing loss prevalence in either ear. Three-way ANOVA showed significant differences in word recognition scores in the right ear among groups, a significant group effect on tympanogram static admittance in both ears and a significant group effect on tympanic gradient in the right ear. There was significantly larger admittance and gradient in controls as compared to the HIV-infected group at late stage of disease. Hearing loss in the HIV-infected groups was associated with increased age and was similar to that described in the literature for the general population. Three-way ANOVA analysis also indicated significantly greater pure-tone thresholds (worse hearing) at low frequencies in HIV patients in the late stage of disease compared with HIV-uninfected controls. This difference was also found by semi-parametric mixed effects models. Despite reports of "premature" or "accelerated" aging in HIV-infected subjects, we found no evidence of hearing loss occurring at an earlier age in HIV-infected patients compared to HIV-uninfected controls. Similar to what is described in the general population, the probability of hearing loss increased with age in the HIV-infected subjects and was more common in patients over 60 years of age. Interestingly, HIV-infected subjects had worse hearing at lower frequencies and have significant differences in tympanometry compared to HIV-uninfected controls; these findings deserve further study.

Prevalence of Hearing Loss among Preterm Very‐Low‐Birth‐Weight Babies

Objectives: Determine the prevalence of hearing impairment and auditory neuropathy among preterm very-low-birth-weight (VLBW) babies at 1 year corrected age. Methods: Twenty babies were recruited. The subjects underwent transient evoked otoacoustic emission (TEOAE) and automated auditory brainstem response (AABR) at 34 to 36 weeks while they were still in the neonatal intensive care unit. The subjects were followed up with brainstem evoked response (BSER) at 3 months and 1 year of corrected age. A patient was considered to have hearing impairment if either 1 or both ears failed the test. The risk factors for hearing impairment are noted. Results: Thirty-five percent (14 out of 40 ears) failed TEOAE and 12.5% (5 out of 40 ears) failed AABR screen. Two babies defaulted BSER appointment. BSER at 3 months corrected age showed 5.5% (1 out of 18) with bilateral profound sensorineural hearing loss, 16.7% (3 out of 18) bilateral mild conductive hearing loss, and 77.8% (14 out of 18) with normal hearing. At 1 year of corrected age 5.5% (1 out of 18) had profound sensorineural hearing loss, 5.5% (1 out of 18) mild conductive hearing loss, and 89% (16 out of 18) had normal hearing. There was no prevalence of auditory neuropathy or progressive hearing loss in this study. Conclusions: Those VLBW babies achieved maturity of hearing at 3 months corrected age, therefore no repeat BSER is required at 1 year.

Hearing and age-related changes in the gray mouse lemur.

In order to examine auditory thresholds and hearing sensitivity during aging in the gray mouse lemur (Microcebus murinus), suggested to represent a model for early primate evolution and Alzheimer research, we applied brainstem-evoked response audiometry (BERA), traditionally used for screening hearing sensitivity in human babies. To assess the effect of age, we determined auditory thresholds in two age groups of adult mouse lemurs (young adults, 1-5years; old adults, ≥7years) using clicks and tone pips. Auditory thresholds indicated frequency sensitivity from 800Hz to almost 50kHz, covering the species tonal communication range with fundamentals from about 8 to 40kHz. The frequency of best hearing at 7.9kHz was slightly lower than that and coincided with the dominant frequencies of communication signals of a predator. Aging shifted auditory thresholds in the range between 2 and 50.4kHz significantly by 12-27dB. This mild presbyacusis, expressed in a drop of amplitudes of BERA signals, but not discernible in latencies of responses, suggests a metabolic age-related decrease potentially combined with an accompanying degeneration of the cochlear nerve. Our findings on hearing range of this species support the hypothesis that predation was a driving factor for the evolution of hearing in small ancestral primates. Likewise, results provide the empirical basis for future approaches trying to differentiate peripheral from central factors when studying Alzheimer's disease-like pathologies in the aging brain.

Neonatal brainstem dysfunction after preterm birth predicts behavioral inhibition

Behavioral inhibition (BI), the tendency to withdraw or exhibit negative affect when experiencing stressful situations, is a major risk factor for the development of social anxiety. However, neonatal biologic origins of this progression are still unknown. Click here to enter text.This study aimed to extend frameworks of behavioral inhibition by exploring empirically the central role of neonatal brainstem electrophysiologic functions in the development of social disengagement and BI. Sixty-six preterm neonates (means ±SD: gestation age = 33.1 ± 1.22 weeks, birth weight = 1775 + 346.7 g; 51% female) participated in a prospective longitudinal study. The infants were tested within the first 2 weeks of postnatal life using an auditory brainstem-evoked response test. Based on the typicality of the major ABR wave latencies, waves I, III and V, neonates were divided into two groups (compromised, CBSF- with at least one component ≥1.5 SDs from the mean for the respective gestation age; normal, NBSF, with all components within 1.5 SD around the mean), and were enrolled in a prospective longitudinal follow-up study. This report extends previous work from 4 m by testing responses to socioemotional challenges during the Separation-Reunion paradigm at 12 m. Results show that infants with neonatal CBSF were more susceptible to be classified as BI at 12 m (age corrected for prematurity) than infants with NBSF (66% vs. 40%, respectively). The most striking symptom in the CBSF group was a disability to initiate self-regulatory activities in response to a socioemotional challenge, resulting in frequent passivity/dependency (p < .001). Statistical regression analysis revealed that face-to-face gaze engagement at 4 m moderates the risk related to neonatal CBSF for the emergence of BI at 12 m, but did not overturn the emergence of BI. Results support the hypothesis that neonatal brainstem dysfunction canalizes behavioral inhibition. These findings highlight, for the first time, the role of the early developing brainstem in later development of BI and in abilities to initiate self-regulatory behavior.

Safety of transtympanic application of 4 % manuka honey in a chinchilla animal model

The antimicrobial and anti-biofilm properties of manuka honey (MH) are currently being explored in the treatment of chronic recalcitrant rhinosinusitis. Due to similarities between chronic rhinosinusitis and chronic otitis, manuka honey may find applications in the management of challenging cases of chronic otitis media implicating biofilms. The goal of this study was to investigate the safety of topical application of 4 % MH in the middle ear. Eleven adult female chinchillas had one of their ears randomly assigned to receive transtympanic 4 % MH, while the contralateral ear served as control. Auditory brainstem-evoked response (ABR) was performed before and after MH application. The facial nerve function and vestibular system were assessed clinically. The animals were euthanized one month following the last application, and the cochleae samples were processed for light and scanning electron microscopy. There was no statistically significant differences between ABR thresholds in both control and experimental ears before and after the application of MH. No morphological differences were seen in both groups of cochleae. The outer hair cell counts for both groups were comparable. Our results suggest that 4 % MH appears not toxic to the cells of the cochlea after 4 weeks of application. The long-term effects of prolonged contact on the structure and function of the cochlea however need further investigations.

Prevalence of hearing loss in patients with late-onset Pompe disease: Audiological and otological consequences

Objective: The metabolic disorder Pompe disease mainly affects the skeletal muscle in adults. The hearing impairment due to stapedius muscle involvement in adult patients is not known. Design: The frequency, severity, and type of hearing impairment was characterized prospectively using pure-tone audiometry, tympanometry, stapedial reflexes, otoacoustic emissions, and brainstem-evoked response audiometry in adult patients on enzyme replacement therapy for genetically confirmed Pompe disease. Study sample: 11 adult patients (median age: 47 years, range: 22–71). Results: Four patients complained about subjective hearing disturbances. Using World Health Organization definition of hearing impairment, abnormal hearing thresholds resulting in mild hearing loss were found in 36% of patients. Compared to normative data (ISO 7029), the hearing threshold was below the median in all but three ears. Stapedial reflexes could not be elicited ipsilateral in 18% and contralateral in 36%. Auditory brainstem responses showed no retrocochlear pathology. Conclusions: The prevalence of hearing loss slightly exceeded the normative data of the general population. Consistent with previous studies the hearing impairment was usually mild. The percentage of pathological stapedial reflexes exceeded that of matched control subjects and suggests a selective involvement of the stapedius muscle, potentially as a sequela of Pompe disease.

Tumor Necrosis Factor-alpha-mutant Mice Exhibit High Frequency Hearing Loss

Exogenous tumor necrosis factor-alpha (TNF-α) plays a role in auditory hair cell death by altering the expression of apoptosis-related genes in response to noxious stimuli. Little is known, however, about the function of TNF-α in normal hair cell physiology. We, therefore, investigated the cochlear morphology and auditory function of TNF-α-deficient mice. Auditory evoked brainstem response showed significantly higher thresholds, especially at higher frequencies, in 1-month-old TNF-α(-/-) mice as compared to TNF-α(+/-) and wild type (WT); hearing loss did not progress further from 1 to 4 months of age. There was no difference in the gross morphology of the organ of Corti, lateral wall, and spiral ganglion cells in TNF-α(-/-) mice compared to WT mice at 4 months of age, nor were there differences in the anatomy of the auditory ossicles. Outer hair cells were completely intact in surface preparations of the organ of Corti of TNF-α(-/-) mice, and synaptic ribbon counts of TNF-α(-/-) and WT mice at 4 months of age were similar. Reduced amplitudes of distortion product otoacoustic emissions, however, indicated dysfunction of outer hair cells in TNF-α(-/-) mice. Scanning electron microscopy revealed that stereocilia were sporadically absent in the basal turn and distorted in the middle turn. In summary, our results demonstrate that TNF-α-mutant mice exhibit early hearing loss, especially at higher frequencies, and that loss or malformation of the stereocilia of outer hair cells appears to be a contributing factor.

Modeling human auditory evoked brainstem responses to speech syllables

Auditory evoked brainstem responses (ABR) are routinely used to assess the neural encoding of sound. Various types of stimuli have been historically considered, and there is a current increasing trend towards the use of syllables, speech and complex (non-speech) sounds. Despite the peripheral origin of ABRs, the nonlinear processing within the cochlea and brainstem makes interpreting responses to these new stimuli a challenge. A recent model was developed [Ro/nne et al. (2012)] to simulate ABRs to transient sounds such as tone pulses, clicks and rising chirps as a function of stimulus level. The present study extends this model to simulate synthetic /ba/, /da/ and /ga/ syllable-evoked ABRs, where the stimuli only differ in their spectral energy of the second formant, f2, within their first 60 ms. The model takes the convolution of the instantaneous discharge rates using a “humanized” nonlinear auditory-nerve model of Zilany et al. (2009) and an empirically derived unitary response function, assumed to reflect contributions from different cell populations within the auditory brainstem. The ABR model was used to explore the physiological basis and spectro-temporal characteristics of key features observed in syllable-evoked ABRs in the literature [Skoe et al. (2011), Hornickel et al. (2009)].

Hearing loss with phosphodiesterase‐5 inhibitors

To assess the effect of tadalafil on auditory functions. Prospective observational study in a tertiary care hospital. Twenty-five tadalafil naïve patients with erectile dysfunction or pulmonary artery hypertension were subjected to pure-tone and brainstem-evoked response audiometry before drug therapy, and 3 and 30 days following drug therapy. Results were compared using analysis of variance for repeated measures with Bonferonni correction. Fifteen patients were taking tadalafil 10 mg for erectile dysfunction, and another 10 patients were on tadalafil 20 mg once daily for pulmonary artery hypertension. No statistically significant difference was found in hearing threshold at baseline and at follow-up (P > .05). However, three patients on tadalafil 20 mg showed a significant increase in hearing threshold at higher frequencies. There was no incidence of sudden sensorineural hearing loss in the study group. This is the first prospective and observational study that evaluated the effect of tadalafil on auditory functions with objective tests. Although there was no statistically significant result to confirm or refute the association between tadalafil and hearing impairment, increased threshold at higher frequencies after taking tadalafil supports the results from previous studies and hints at a possible relationship between the two. Similar large sample studies are warranted to know the exact association of phosphodiesterase-5 inhibitors on auditory functions.

Evaluation of hearing in middle-aged patients with diabetes mellitus type 2

Introduction: Involvement of auditory pathway is one of the examples of central neuropathy in diabetics. The purpose of this study is to compare the auditory function of patients with type 2 diabetes mellitus with healthy subjects. Methodology: 30 diabetic and 30 healthy subjects participated in this study. For all participants conventional pure-tone audiometry (PTA) and Auditory Brainstem Evoked Responses (ABER) study were performed. Results: In PTA Hearing threshold only at 2, 4, 8 KHz frequencies were significantly higher than healthy subjects but were in normal range in patients with diabetes. ABER revealed that absolute latencies of waves I, III, V and inter wave latencies of III-V, I-V, I-III were significantly prolonged in diabetics. Conclusion: In this study, 50% of diabetic patients had hearing defects in ABER test despite normal hearing threshold and good meta-bolic control. Prolonged inter wave latencies of I-III, III-V, I-V explains retrocochlear and brain stem involvement.

Sepsis otopathy: experimental sepsis leads to significant hearing impairment due to apoptosis and glutamate excitotoxicity in murine cochlea

SUMMARYHearing loss is frequent in intensive care patients and can be due to several causes. However, sepsis has not been examined as a possible cause. The aim of this study is to assess the influence of experimental sepsis on hearing thresholds and to evaluate pathological changes in the cochlea. The cecal ligation puncture technique was used to induce sepsis in 18 mice. Results were compared with those from 13 sham-operated and 13 untreated control mice. The hearing thresholds of the animals were evaluated with auditory evoked brainstem responses prior to the induction of sepsis and again at the peak of the disease. Immediately after the second measurement, the mice were sacrificed and the inner ears harvested and prepared for further evaluation. The cochleae were examined with light microscopy, electron microscopy and immunohistochemistry for Bax, cleaved caspase-3 and Bcl-2. The mice with sepsis showed a significant hearing loss but not the control groups. Induction of apoptosis could be shown in the supporting cells of the organ of Corti. Furthermore, excitotoxicity could be shown at the basal pole of the inner hair cells. In this murine model, sepsis leads to significant hearing impairment. The physiological alteration could be linked to apoptosis in the supporting cells of the organ of Corti and to a disturbance of the synapses of the inner hair cells.

A case of Bickerstaff brainstem encephalitis successfully treated with intravenous immunoglobulin and methylprednisolone after unsuccessful immunoadsorption plasmapheresis

Bickerstaff brainstem encephalitis (BBE) is a rare post-infectious neurological syndrome for which an effective treatment strategy has not been established. Here, we report a case of a 71-year-old male who suffered from an upper respiratory tract infection, and 7 days later, developed numbness of the bilateral upper and lower limbs, unsteady gait and dysarthria. Brain magnetic resonance imaging was normal, nerve conduction study and cerebral spinal fluid analysis were nonspecific. Based on the clinical features, we tentatively diagnosed Guillain-Barré syndrome and started immunoadsorption plasmapheresis. However, consciousness progressively declined to coma level within 10 days. Electroencephalogram showed diffuse slowing, and auditory evoked brainstem response (ABR) demonstrated absence of waves II, III and V. Serum anti-GQ1b IgG autoantibody and anti-GM1b IgG autoantibody were negative. Subsequently, we diagnosed BBE, and clinical symptoms resolved after treatment with intravenous immunoglobulin and methyllprednisolone. On day 62, neurological symptoms were remarkably alleviated with an improvement in ABR. Our observations suggest that immunoadsorption plasmapheresis should be used only when anti-ganglioside antibodies are detected. Combination therapy with intravenous immunoglobulin and methylprednisolone or plasma exchange is recommended as initial therapy.

Erratum to “Development of Brainstem-Evoked Responses in Congenital Auditory Deprivation”

The caption of Figure 1 in the paper at doi:10.1155/2012/182767 has to be corrected as shown here. Also, should be corrected as follows: J. Tillein, S. Heid, E. Lang, R. Hartmann, and A. kral, “Development of brainstem-evoked responses in congenital auditory deprivation,” Neural Plasticity, vol. 2012, Article ID 182767, 11 Pages, 2012. s.a. urn:nbn:de:hebis:30:3-267673

Hypoxia-Inducible Factor and Vascular Endothelial Growth Factor Pathway for the Study of Hypoxia in a New Model of Otitis Media with Effusion

The hypoxia-inducible factor and vascular endothelial growth factor (HIF-VEGF) pathway in hypoxic conditions of the middle ear due to dysfunction of the eustachian tube is still unknown, but it is considered as one pathogenetic mechanism in otitis media. This study was designed to investigate the possible involvement of the HIF-VEFG pathway in otitis media with effusion induced by dysfunction of the eustachian tube. We adopted a soft palate approach to obstruct the orifice of the eustachian tube to establish otitis media in a rat model. Auditory evoked brainstem response and tympanometry were used as hearing function tests, hypoxia-related factors were examined by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of hypoxia-related proteins was detected by Western blot and immunostaining. The model of otitis media with effusion was successfully induced by cauterizing the orifice of the eustachian tube. RT-PCR showed up-regulation of hypoxia-related factors in cauterized ears. Western blot and immunostaining showed that the expression of hypoxia-related proteins in cauterized ears was increased. Hypoxia-induced vascular proliferation and an increase in permeability may be one pathogenetic mechanism of otitis media due to dysfunction of the eustachian tube.