Hearing Loss Group Research Articles

Hearing preservation up to 3 years after gamma knife radiosurgery for Gardner-Robertson class I patients with vestibular Schwannomas.

Vestibular schwannoma patients with Gardner-Robertson (GR) class I hearing seek to maintain high-level hearing whenever possible. To evaluate hearing outcomes at 2 to 3 years in GR class I patients who underwent Gamma Knife radiosurgery (GKRS). Sixty-eight patients with GR class I hearing were identified between 2006 and 2009. Twenty-five patients had no subjective hearing loss (group A) and 43 patients reported subjective hearing loss (group B) before GKRS. The median tumor volume (1 cm) and tumor margin dose (12.5 Gy) were the same in both groups. Serviceable hearing retention rates (GR grade I or II) were 100% for group A compared with 81% at 1 year, 60% at 2 years, and 57% at 3 years after GKRS for group B patients. Group A patients had significantly higher rates of hearing preservation in either GR class I (P < .001) or GR class II (P < .001). Patients with a pure tone average (PTA) <15 dB before GKRS had significantly higher rates of preservation of GR class I or II hearing. At 2 to 3 years after GKRS, patients without subjective hearing loss or a PTA <15 dB had higher rates of grade I or II hearing preservation. Modification of the GR hearing classification into 2 groups of grade I hearing (group A, those with no subjective hearing loss and a PTA <15 dB; and group B, those with subjective hearing loss and a PTA >15 dB) may be useful to help predict hearing preservation rates at 2 to 3 years after GKRS.

Auditory Development Assessment with LittlEARS® Auditory Questionnaire in Children with and without Hearing Loss

The purpose of this study was to evaluate the validity and reliability of the Korean version of LittlEARS® Auditory Questionnaire (LEAQ-K) in normal hearing (NH) children aged 0 through 24 months, and in children with hearing loss (HL) using hearing aids or cochlear implant for 0 through 24 months after identification of their hearing loss before 24 month of age. Data collection was carried out with onehundred eight NH and thirty one HL children filling out a LEAQ-K. There sults with NH group showed that the total score of LEAQ-K was highly correlated with the chronological age (r = .904), and that age accounted for 82.3% of the total variance of the LEAQ-K score, which indicated LEAQ-K homogeneously measured the age-dependent auditory behavior. The Korean norm curve was highly correlated (r = .995) to the data from the overall sample from Coninx et al.(2009), which implied very good comparability of Koran language specific norm data with the overall sample data. Internal consistency (Cronbach’s alpha = .96) and reliability (Spearman’s split-half coefficient = .93) were very good. The results were true for the HL group using hearing aids or cochlear implant. The rate of auditory development in the HL group was faster than the NH group, especially between 6 through 15 months after exposure to sounds through their hearing assistive devices. The hearing age of the HL group was the only factor that accounted for 73.0% of the total variance of the LEAQ-K total score. The results suggest that LEAQ-K is a reliable and valid tool for assessing auditory skills of young children with and without hearing loss.

Episodic Dizziness with Unilateral Hearing Loss: Clinical Characteristics According to Hearing Loss Pattern

Received July 8, 2014 Revised August 12, 2014 Accepted August 26, 2014 Address for correspondence Jae Yun Jung, MD Department of OtolaryngologyHead & Neck Surgery, Dankook University College of Medicine, 201 Manghyang-ro, Dongnam-gu, Cheonan 330-715, Korea Tel +82-41-550-3973 Fax +82-41-556-1090 E-mail jjkingy2k@gmail.com Background and ObjectivesZZLow frequency hearing loss is known to be the most common hearing loss form in Meniere’s disease (MD) and episodic dizziness with low frequency sensorineural hearing loss is considered a very crucial symptom for the diagnosis of MD. However, flat or high frequency hearing loss is also commonly encountered in the Ear, Nose and Throat clinic. The aim of this study is to investigate the differences in clinical manifestation between episodic dizzy patients with low frequency hearing loss (LFHL) group and non-low frequency hearing loss (non-LFHL) group. Subjects and MethodZZWe reviewed medical records of 78 patients (36 of LFHL group and 42 of non-LFHL group) who had episodic dizziness with unilateral hearing loss and analyzed clinical characteristics according to hearing loss pattern. ResultsZZThe clinical features of LFHL include a predominance of female sufferers, high incidence of tinnitus and short duration of dizziness. There was no significant difference in frequency, nature of dizziness, and results of vestibular function test. Although the proportion of patients diagnosed with definite MD was higher in LFHL group at initial and final diagnosis, there were no statistically significant differences between two groups. ConclusionZZTherefore, when episodic dizziness is accompanied with unilateral hearing loss, not only low frequency but flat or high frequency hearing loss could be considered as a critical sign for possible progression to Meniere’s disease and careful observation should be taken. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(3):173-6

Radial Maze Test in a Mouse Model of Noise-Induced Hearing Loss

Received December 19, 2014 Revised March 13, 2015 Accepted March 16, 2015 Address for correspondence Shi Nae Park, MD, PhD Department of OtorhinolaryngologyHead and Neck Surgery, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Korea Tel +82-2-2258-6215 Fax +82-2-595-1354 E-mail snparkmd@catholic.ac.kr Background and ObjectivesZZHearing loss has been hypothesized to contribute to cognitive decline in the elderly. However, earlier studies yielded conflicting results, and the causal relationship has not been elucidated to date. In the present study, the authors set up a radial maze apparatus for assessment of cognition in mice, and investigated the relationship between cognition and hearing loss that occur immediately after noise exposure. Materials and MethodZZSpatial learning and memory were assessed in male C57BL/6 mice with or without hearing loss using an unconfined, partially-baited, 8-arm radial maze with different arm length (25 or 50 cm). The performance indicators included total trial time, latency, reference memory error, working memory error, and correct entry ratio. Mice in the hearing loss group were exposed to 60 min of 110 dB white noise for 14 days, and then auditory brainstem response thresholds were measured. ResultsZZMice showed better performances in a 25 cm-arm radial maze than in a 50 cm-arm maze. The control and the hearing loss groups exhibited similar performance curves, except for the working memory curve in 25 cm-arm radial maze. Hearing-impaired mice were better at working memory tasks than the control mice, probably due to an early cognitive compensatory mechanism. ConclusionZZA radial maze with 25 cm arm is appropriate for the test of learning and memory in mice. Acute hearing loss after noise exposure was not associated with decreased cognition. Further follow-up research has been planned to find the effect of long-term hearing loss on cognition and the mechanism by which these two domains are connected. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(6):395-401

Comparison of Speech Audiometry Using KS Word List and Hahm's List in Hearing Impaired Adults

Received July 1, 2014 Revised August 11, 2014 Accepted August 19, 2014 Address for correspondence Hyung-Jong Kim, MD, PhD Department of Otolaryngology, Hallym University Sacred Heart Hospital, 22 Gwanpyeong-ro 170beon-gil, Dongan-gu, Anyang 431-796, Korea Tel +82-31-380-3842 Fax +82-31-386-3860 E-mail hjk1000@hallym.ac.kr * Both contributed equally on this work. Background and ObjectivesZZThe purpose of this study was to compare speech audiometry test results of the conventional Hahm’s list with those of Korean standard word lists for adults (KS-WL-A) using both live voice and compact disc (CD) speech presentation modes. Subjects and MethodZZEighty patients with sensorineural hearing loss and 23 control subjects with normal hearing participated in the study. Each hearing loss group comprised 20 subjects (mild, moderate, moderately severe, and severe hearing loss groups). Speech audiometry was performed to measure the speech recognition threshold (SRT) and word recognition score. KSWL-A was presented either through a live voice mode or recorded CD materials. Test words from Hahm’s list were presented using the live voice mode only. Pure tone audiometry was also conducted for all subjects. ResultsZZDifferences between the SRT and pure tone average were within 6 dB in all subgroups in all three stimulation methods, indicating high reliability of the SRT in both the conventional and Korean standard methods. The moderate, moderately severe, and severe hearing loss groups showed lower word recognition scores in the CD mode with KS-WL-A than with the two live voice modes. ConclusionZZBoth the live voice mode and CD mode showed reliable speech audiometry test results in normal and hearing-impaired subjects. Although the CD mode is recommended to standardize test methods and reduce test errors, the live voice mode might be more effective for patients with moderate to severe hearing loss. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(2):88-94

Relationships among hearing loss, cognition and balance ability in community-dwelling older adults.

[Purpose] The purpose of this study was to determine the relationships among hearing loss, cognition, and balance ability in elderly individuals. [Subjects and Methods] In total, 46 elderly individuals over 65 years of age who were attending senior welfare centers participated in this study. Through a hearing test, the speech frequency pure tone average in the better ear was checked. We set a criterion of hearing loss if the better ear hearing level (BEHL) value was 25 dB or more. Cognition ability was evaluated using the Korean mini-mental state examination (K-MMSE). Dynamic balance ability was evaluated by the timed up and go (TUG) test, and static balance ability was tested using a one-leg stance test (OLST). [Results] The ages of the subjects were all related to BEHL, TUG, K-MMSE, and OLST. BEHL had a negative correlation with OLST, whereas it had no correlation with K-MMSE or TUG. The hearing loss group had a significantly shorter OLST time than the normal hearing group. [Conclusion] As elderly individuals get older, their hearing and cognition, as well as their balance abilities deteriorate. The results of this study indicate there is a significant correlation between hearing loss and static balance.

Contrast perilymphatic MRI findings of inner ear in sudden hearing loss with vertigo

Objective To explore the contrast perilymphatic MRI characteristics of inner ears with sudden hearing loss with vertigo. Methods Forty three patients with sudden hearing loss with vertigo and 35 patients with unilateral tinnitus diagnosed by the department of Otolaryngology-Head and Neck Surgery were retrospectively included. Forty eight ears (38 ears with unilateral sudden hearing loss and 10 ears in 5 cases with bilateral sudden hearing loss) were regarded as sudden hearing loss group, 35 asymptomatic ears (the opposite ears of the unilateral tinnitus ears) as control group. Thirty eight opposite ears of the 38 unilateral sudden hearing loss ears and 35 ears of the control group showed normal in the pure tone audiometry exam. One hundred and twenty one ears (48 hearing loss ears, 38 opposite ears of the 38 unilateral sudden hearing loss ears and the 35 control group's ears) underwent contrast perilymphatic MR exams, 0.4 to 0.5 ml gadolinium hydrate diluted with saline was injected through the tympanic membrane, twenty four hours later, three-dimensional fluid attenuated inversion recovery (3D-FLAIR) sequence was performed using a 3.0 T MRI scanner. After the contrast perilymphatic MR exam, success in the exam was judged through the raw image. The signal intensity ratio (SIR) of cochlea basal turn and homolateral brain stem was quantitatively calculated. The SIR difference of 48 ears with sudden hearing loss and 35 asymptomatic ears in control group was analyzed by t test. The SIR difference of the 38 unilateral sudden hearing loss ears and the contralateral asymptomatic ears was also analyzed. The presence of endolymphatic hydrops was judged. Results The contrast perilymphatic MRI of 121 inner ears with intratympanic gadolinium injection were all successful. Endolymphatic hydrops were observed in 12 sudden hearing loss ears with the occurrence rate of 25%(12/48). The SIR of basal turn and homolateral brain stem of the sudden hearing loss ears (2.062±0.907) were lower than the SIR of the control groups' asymptomatic ears (2.703± 0.640) with significant difference between them (t=3.619,P=0.001), the SIR of basal turn and homolateral brain stem of the unilateral sudden hearing loss ears (1.941±0.860) were also lower than the SIR of the contralateral asymptomatic ears (2.411±0.670) with statistical difference between them (t =3.270,P=0.002). Conclusions Endolymphatic hydrops were observed in sudden hearing loss with vertigo. The SIR of the cochlea in sudden hearing loss ears were lower than that of the asymptomatic ears, indicating the abnormal permeability of the round window membrane. Key words: Hearing loss; Sudden; Magnetic resonance imaging

Effect of Repeated Exposures on Word Learning in Quiet and Noise

This study examines the impact of repeated exposures on word learning of preschool children with and without hearing loss (HL) in quiet and noise conditions. Participants were 19 children with HL and 17 peers with normal hearing (NH). Children were introduced to 16 words: 8 in quiet and 8 in noise conditions. Production and identification scores were collected after single exposures to words and following three exposures through individual training sessions. A significant main effect for Exposure was found for identification with significant Hearing Status × Exposure interaction, with children in the NH outperforming the HL group when only one exposure to the target words was provided. Repeated exposures to target words provide benefits to both groups of preschool children, but offer additional benefits to children with HL, particularly younger children. This provides additional support for speech–language pathologists to preview and review vocabulary introduced in classroom settings.

Mutations in the mitochondrial 12S rRNA gene in elderly Chinese people

Conclusion: Our data indicate that the mitochondrial 12S rRNA gene, and particularly the A827G mutation, may be associated with susceptibility to age-related hearing loss. Objective: Hearing loss associated with aging is common among elderly persons. In all genetic backgrounds, mitochondrial DNA (mtDNA) mutations may be one of the most important factors contributing to aging and age-related hearing loss. The mitochondrial 12S rRNA is a hot spot for deafness-associated mutations in Chinese populations. The purpose of the present study was to elucidate the relationship of 12S rRNA gene polymorphisms and age-related hearing loss. Methods: The 12S rRNA gene polymorphisms were detected by direct sequencing. Statistical analyses were performed to assess the associations between age-related hearing loss and 12S rRNA gene variants. Results: We report here a systematic mutational screening of the mitochondrial 12S rRNA gene in 662 elderly subjects from the general population with various hearing threshold levels (211 controls and 451 age-related hearing loss subjects). Mutational screening of the mitochondrial 12S rRNA gene identified 55 nucleotide changes, including 4 mutations localized at highly conserved sites and 51 known variants. Of the known deafness-associated mutations in the mitochondrial 12S rRNA gene, the incidence of the A1555G mutation was 0.15%, A827G was 4.38%, T1095C was 0.45%, and T1005C was 3.78%. The incidence of the other known variants was 0.15–99.85%. We found statistically significant differences in the proportions of subjects with the A827G mutation among the various age-related hearing loss groups and normal controls.

Hearing loss and type 2 diabetes: is there a link?

AbstractRecent meta‐analysis has confirmed an association between hearing loss and diabetes. The cause remains uncertain and open to academic debate.This five‐year retrospective study examined the outcomes of patients referred for audiological investigations from a large primary care diabetes clinic. Audiological assessment included pure‐tone audiometry, and the presence of neuropathy was identified by foot examination and risk stratification.Referral rates of patients with diabetes were nearly twice those seen in the non‐diabetic population (7.5% [107/1428] vs 4% [499/12422]). Hearing loss was identified in 77 patients. The majority (84.1%) had high‐frequency sensorineural hearing loss. Loss of protective sensation on the 10 g monofilament test (OR 3.2, CI 1.6–6.5) and vibration sense (OR 2.6, CI 1.2–5.6) was significantly higher in the hearing loss group when compared with a group with type 2 diabetes and normal hearing (n = 219). The hearing loss group had almost twice the rate of at‐risk feet (37.7% vs 20.1%); (OR 2.4, CI 1.4–4.2). Pre‐existing cardiovascular disease was the only pre‐morbid condition that was associated with hearing loss (OR 1.8, 95% CI 1.1–3.2). There were no differences in HbA1c and lipids.This is the first study from primary care to show that hearing loss is prevalent and has a strong association with peripheral neuropathy.There are no effective strategies yet identified that can prevent or reverse diabetes‐related hearing loss. Clinicians should recognise the association between diabetes and hearing loss, and engage in preventative health education and hearing conservation strategies. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Relationship between conductive hearing loss and maxillary constriction.

To evaluate the relationship between conductive hearing loss and maxillary constriction. A total of 120 people, aged from 7 to 40 years, who were referred to an audiologist when taking out health insurance or for school pre-registration check-up, were selected for this study. A total of 60 participants who had hearing threshold levels greater than 15dB in both ears were chosen as the conductive hearing loss group. The remaining 60, with normal hearing thresholds of less than 15dB, were used as the control group. All participants were referred to an orthodontic clinic. Participants who had a posterior crossbite and high palatal vault were considered to suffer from maxillary constriction. There were no significant differences between the sex ratios and mean ages of the groups. However, participants with conductive hearing loss were 3.5 times more likely than controls to suffer from maxillary constriction. Patients who suffer from conductive hearing loss are likely to show a maxillary abnormality when examined by an orthodontist.

Effects of substance P during the recovery of hearing function after noise-induced hearing loss

Substance P (SP) is a widely distributed neurotransmitter in living tissues and is involved in various repair processes. We investigated the possibility that SP may ameliorate cochlear hair cell damage produced by noise exposure. The present study examined the effect of SP in protecting the cochlea from noise damage in guinea pigs exposed to noise after an infusion of SP into the inner ear. Changes in the hearing threshold (auditory brain response, ABR), number of synaptic ribbons, and the appearance of the outer hair cells after noise exposure were analyzed at 2 severity levels of noise-induced hearing loss. The moderate noise-induced hearing loss (110dB, 3h) group showed recovery in the ABR threshold over time, finally reaching a level slightly above pre-exposure levels, with only slight injury to the synaptic ribbons and minimal changes in the appearance of the outer hair cells. Our results indicated that in moderate hearing loss, SP exhibited a protective effect on the inner ear, both functionally and structurally. While the final magnitude of ABR threshold elevation was greater in severe noise-induced hearing loss, the synaptic ribbons and outer hair cells showed signs of severe damage.

Effect of isoflurane anesthesia on noise-induced hearing loss in guinea pigs

Objective To evaluate the effect of isoflurane anesthesia on noise-induced hearing loss in guinea pigs.Methods Forty-eight healthy adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 4 groups (n =12 each) using a random number table:control group (C group),isoflurane group (I group),noise-induced hearing loss group (N group),and isoflurane + noise-induced hearing loss group (I + N group).Isoflurane was inhaled for 140 min at a concentration of 1％ in I and I + N groups.N and I + N groups were exposed to the noise of 4 kHz center frequency and 118-122 dB sound pressure level for 120 min starting from 20 min after administration.Mean arterial pressure (MAP) was recorded at 10,40,70,100 and 120 min of exposure to noise and cochlear blood flow (CoBF) was recorded before administration and at 10,40,70,100 and 120 min of exposure to noise.Auditory brainstem response (ABR) threshold was recorded before administration and at 1 h,72 h,and 10 days after the end of exposure to noise.Arterial blood samples were obtained and the plasma noradrenaline (NE) concentration was detected by HPLC before exposure to noise and immediately after the end of exposure to noise.Results Compared with group C,MAP and the change rate of CoBF were significantly decreased,and the plasma NE concentration was increased immediately after the end of exposure to noise in I group,and MAP was increased,the change rate of CoBF was decreased,and the plasma NE concentration immediately after the end of exposure,and ABR threshold after the end of exposure were increased in N and I + N groups.Compared with N group,MAP was significantly decreased,the change rate of CoBF was increased,the plasma NE concentration immediately after the end of exposure,and ABR threshold at 1 and 72 h after the end of exposure were increased,and no significant was found in ABR threshold at 10 days after the end of exposure in I + N group.Conclusion Isoflurane anesthesia exerts temporary but not permanent protective effects against noise-induced hearing loss in guinea pigs and partial inhibition of activation of sympathetic nerve and increased CoBF may be involved in the mechanism. Key words: Isoflurane; Anesthesia,inhalation; Hearing loss, noise-induced

Relationship of Hearing Loss and Dementia

To determine whether baseline hearing loss increases cognitive decline and risk for all-cause dementia in a population of elderly individuals. Longitudinal cohort study. Community-based, outpatient. Men and women aged 65 years or older without dementia at baseline. All subjects completed the Modified Mini-Mental Status Exam (3MS-R) at baseline and over 3 triennial follow-up visits. Hearing loss (HL) at baseline was based on observation of hearing difficulties during testing or interview. Incident dementia was determined by clinical assessment and expert consensus. Dementia and 3MS-R score. At baseline, 4,463 subjects were without dementia, 836 of whom had HL. Of those with HL, 16.3% developed dementia, compared with 12.1% of those without HL (p < 0.001). Mean time to dementia was 10.3 years in the HL group versus 11.9 years for non-HL (log rank test p < 0.001). In Cox regression analyses controlling for sex, presence of APOE- [Latin Small Letter Open E]4 allele, education, and baseline age, and cardiovascular risk factors, HL was an independent predictor of developing dementia (hazard ratio = 1.27, p = 0.026 [95% CI, 1.03-1.56]). Linear mixed models controlling for similar covariates showed HL was associated with faster decline on the 3MS-R, at a rate of 0.26 points/year worse than those without HL. Elderly individuals with HL have an increased rate of developing dementia and more rapid decline on 3MS-R scores than their nonhearing impaired counterparts. These findings suggest that hearing impairment may be a marker for cognitive dysfunction in adults age 65 years and older.

Cognitive workload and visual behavior in elderly drivers with hearing loss

To examine eye tracking data and compare visual behavior in individuals with normal hearing (NH) and with moderate hearing loss (HL) during two types of driving conditions: normal driving and driving while performing a secondary task. 24 participants with HL and 24 with NH were exposed to normal driving and to driving with a secondary task (observation and recall of 4 visually displayed letters). Eye movement behavior was assessed during normal driving by the following performance indicators: number of glances away from the road; mean duration of glances away from the road; maximum duration of glances away from the road; and percentage of time looking at the road. During driving with the secondary task, eye movement data were assessed in terms of number of glances to the secondary task display, mean duration of glances to the secondary task display, and maximum duration of glances to the secondary task display. The secondary task performance was assessed as well, counting the number of correct letters, the number of skipped letters, and the number of correct letters ignoring order. While driving with the secondary task, drivers with HL looked twice as often in the rear-view mirror than during normal driving and twice as often as drivers with NH regardless of condition. During secondary task, the HL group looked away from the road more frequently but for shorter durations than the NH group. Drivers with HL had fewer correct letters and more skipped letters than drivers with NH. Differences in visual behavior between drivers with NH and with HL are bound to the driving condition. Driving with a secondary task, drivers with HL spend as much time looking away from the road as drivers with NH, however with more frequent and shorter glances away. Secondary task performance is lower for the HL group, suggesting this group is less willing to perform this task. The results also indicate that drivers with HL use fewer but more focused glances away than drivers with NH, they also perform a visual scan of the surrounding traffic environment before looking away towards the secondary task display.

Lipreading in School-Age Children: The Roles of Age, Hearing Status, and Cognitive Ability

PURPOSE The study addressed three research questions: Does lipreading improve between the ages of 7 and 14 years? Does hearing loss affect the development of lipreading? How do individual differences in lipreading relate to other abilities? METHOD Forty children with normal hearing (NH) and 24 with hearing loss (HL) were tested using 4 lipreading instruments plus measures of perceptual, cognitive, and linguistic abilities. RESULTS For both groups, lipreading performance improved with age on all 4 measures of lipreading, with the HL group performing better than the NH group. Scores from the 4 measures loaded strongly on a single principal component. Only age, hearing status, and visuospatial working memory were significant predictors of lipreading performance. CONCLUSIONS Results showed that children's lipreading ability is not fixed but rather improves between 7 and 14 years of age. The finding that children with HL lipread better than those with NH suggests experience plays an important role in the development of this ability. In addition to age and hearing status, visuospatial working memory predicts lipreading performance in children, just as it does in adults. Future research on the developmental time-course of lipreading could permit interventions and pedagogies to be targeted at periods in which improvement is most likely to occur.

A Comparison of Auditory Brain Stem Responses Elicited by Click and Chirp Stimuli in Adults With Normal Hearing and Sensory Hearing Loss

The aim of this study was to compare the human auditory brain stem response (ABR) elicited by clicks and chirps with overall behavioral hearing thresholds in participants with normal hearing and with sensory hearing loss. The authors hypothesized that ABRs to chirps would be more robust and that thresholds would be more similar to overall behavioral hearing thresholds compared with ABRs to clicks. Twenty-five adults with normal hearing and 25 adults with sensory hearing loss were recruited. Subjects were without middle ear or neurological pathologies at the time of testing. Subjects with sensory hearing loss were separated into mild to moderate hearing loss and mild to severe hearing loss groups. Behavioral hearing thresholds for pure tones were obtained at nine octave and interoctave frequencies ranging from 250 to 8000 Hz; an average of these nine frequencies was calculated for each participant. Evoked potential thresholds were measured by ABRs to click and chirp stimuli. Analyses included wave V absolute latencies and wave V peak-to-peak amplitudes. Thresholds for ABRs to clicks and chirps were compared with each other and with overall behavioral hearing thresholds. ABR thresholds to chirp and click stimuli did not differ significantly for either the normal-hearing or the hearing loss groups. Wave V peak-to-peak amplitude was higher for chirps than clicks, particularly at lower intensities, for all groups. ABR thresholds to chirps were closer to overall behavioral thresholds than clicks in all groups. Moreover, ABR thresholds to chirps did not differ significantly from behavioral thresholds in the two hearing loss groups. ABRs obtained with chirp stimuli provide an efficient method for estimating hearing thresholds in individuals with normal hearing and sensory hearing loss where broadband signals are selected for testing. ABRs to chirps display higher peak-to-peak amplitudes than those obtained with clicks and may provide responses closer to behavioral thresholds. This information could result in improved accuracy in identifying hearing loss and estimating hearing sensitivity for broadband signals in infants, children, and difficult-to-test older populations.

Cross-Modal Re-Organization in Adults with Early Stage Hearing Loss

Cortical cross-modal re-organization, or recruitment of auditory cortical areas for visual processing, has been well-documented in deafness. However, the degree of sensory deprivation necessary to induce such cortical plasticity remains unclear. We recorded visual evoked potentials (VEP) using high-density electroencephalography in nine persons with adult-onset mild-moderate hearing loss and eight normal hearing control subjects. Behavioral auditory performance was quantified using a clinical measure of speech perception-in-noise. Relative to normal hearing controls, adults with hearing loss showed significantly larger P1, N1, and P2 VEP amplitudes, decreased N1 latency, and a novel positive component (P2’) following the P2 VEP. Current source density reconstruction of VEPs revealed a shift toward ventral stream processing including activation of auditory temporal cortex in hearing-impaired adults. The hearing loss group showed worse than normal speech perception performance in noise, which was strongly correlated with a decrease in the N1 VEP latency. Overall, our findings provide the first evidence that visual cross-modal re-organization not only begins in the early stages of hearing impairment, but may also be an important factor in determining behavioral outcomes for listeners with hearing loss, a finding which demands further investigation.

Prediction of frequency-specific hearing threshold using chirp auditory brainstem response in infants with hearing losses

ObjectivesTo investigate the clinical usefulness of the LS-chirp auditory brainstem response for estimation of behavioral thresholds in young children with mild to severe hearing losses. Methods68 infants (136 ears) aged 6–12 months (mean age=9.2 months) with bilateral mild to severe hearing losses were studied at Children's Hospital of Fudan University. In all cases, the children were referred for LS-chirp ABR and visual reinforcement audiometric (VRA) measurements. The low-frequency band chirp (LF-chirp) thresholds (frequency band=0.1–0.85kHz) were compared to the average VRA thresholds (frequency band=0.25–0.5kHz), whereas the high-frequency band chirp (HF-chirp) thresholds (frequency band=1–10kHz) were compared to the average VRA thresholds (frequency band=1–4kHz) using statistical correlation coefficient values. ResultsThe LS-chirp ABR thresholds are very close to behavioral hearing levels. The mean differences between chirp-ABR and VRA thresholds were within 5dBHL for all measurements. The smallest mean threshold difference (<3dBHL) was obtained for the severe hearing loss group. The correlation coefficient values (r) were 0.97 at low-frequency and high-frequency bands. For each carrier frequency, the best correlations between chirp-ABR thresholds and VRA thresholds were obtained at VRA frequency of 0.25kHz/LF-chirp (r=0.98) and VRA frequency of 1kHz/HF-chirp (r=0.98). ConclusionsThis study demonstrates the effectiveness using chirp-ABR predicted frequency-specific thresholds, especially of low and middle frequencies. LS-chirp ABR thresholds determined behavioral thresholds in patients with severe hearing losses were better than for mild hearing losses. The use of a chirp-ABR testing ensures higher sensitivity and accuracy than that of auditory stead-state evoked response (ASSR) for measuring frequency-specific thresholds in young children.

Effect of propofol on noise-induced hearing loss in guinea pigs

Objective To evaluate the effect of propofol on noise-induced hearing loss in guinea pigs.Methods Forty-eight healthy adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 4 groups (n =12 each) using a random number table:control grotup (C group),propofol group (P group),noise-induced hearing loss group (N group),and propofol + noise-induced hearing loss group (P + N group).A loading dose of propofol 5 mg/kg was infused intravenously over 5 min,followed by infusion at 20 mg· kg-1 · h-1 for 115 min in P and P + N groups,while the equal volume of normal saline was given in N group.N and P+ N groups were exposed to the noise of 4 kHz center frequency and 118-122 dB sound pressure level for 120 min.Distortion product otoacoustic emission (DPOAE) was measured before noise exposure (T1) and at 1 h after the end of noise exposure (T2) and the amplitudes were recorded at the frequencies of 2,4,6 and 8 kHz.After the second measurement of DPOAE,all the animals were sacrificed and organs of Corti were harvested for determination of cochlear 8-isoprostaglandin F(2alpha) (8-iso-PGF2α) content (by ELISA assay) and out hair cell (OHC) count.The rate of OHC lesions was calculated.Results The DPOAE amplitude was significantly lower at frequencies of 4,6 and 8 kHz at T2 than at T1 in N and P + N groups (P ＜ 0.05).Compared with C group,the DPOAE amplitude was significantly decreased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-isoPGF2α content and rate of OHC lesions were increased in N and P + N groups (P ＜ 0.05).Compared with N group,the DPOAE amplitude was significantly increased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-iso-PGF2α content and rate of OHC lesion were decreased in P + N group (P ＜ 0.05).Conclusion Propofol can reduce noise-induced hearing loss in guinea pigs possibility through decreasing oxidative stress response-induced damage to cochlear OHCs. Key words: Propofol ; Hearing loss, noise-induced