Electrocochleographic frequency-following responses as a potential marker of age-related cochlear neural degeneration

Auditory nerve (AN) fibers that innervate inner hair cells in the cochlea degenerate with advancing age. It has been proposed that age-related reductions in brainstem frequency-following responses (FFR) to the carrier of low-frequency, high-intensity pure tones may partially reflect this neural loss in the cochlea (Märcher-Rørsted et al., 2022). If the loss of AN fibers is the primary factor contributing to age-related changes in the brainstem FFR, then the FFR could serve as an indicator of cochlear neural degeneration. In this study, we employed electrocochleography (ECochG) to investigate the effects of age on frequency-following neurophonic potentials, i.e., neural responses phase-locked to the carrier frequency of the tone stimulus. We compared these findings to the brainstem-generated FFRs obtained simultaneously using the same stimulation. We conducted recordings in young and older individuals with normal hearing. Responses to pure tones (250 ms, 516 and 1086 Hz, 85 dB SPL) and clicks were recorded using both ECochG at the tympanic membrane and traditional scalp electroencephalographic (EEG) recordings of the FFR. Distortion product otoacoustic emissions (DPOAE) were also collected. In the ECochG recordings, sustained AN neurophonic (ANN) responses to tonal stimulation, as well as the click-evoked compound action potential (CAP) of the AN, were significantly reduced in the older listeners compared to young controls, despite normal audiometric thresholds. In the EEG recordings, brainstem FFRs to the same tone stimulation were also diminished in the older participants. Unlike the reduced AN CAP response, the transient-evoked wave-V remained unaffected. These findings could indicate that a decreased number of AN fibers contributes to the response in the older participants. The results suggest that the scalp-recorded FFR, as opposed to the clinical standard wave-V of the auditory brainstem response, may serve as a more reliable indicator of age-related cochlear neural degeneration.

Cochlear Implantation in Sporadic Intralabyrinthine Schwannomas with Single-Sided Deafness: Implications for Binaural Hearing

BACKGROUND AND OBJECTIVE

Intralabyrinthine schwannomas (ILSs) may have detrimental effects on ipsilateral hearing, commonly leading to single-sided deafness (SSD). Cochlear implantation in patients with ILSs is an option to partly restore ipsilateral hearing; however, the available literature fails to account for the binaural hearing benefits of a cochlear implant (CI) for ILSs.

METHODS

We prospectively evaluated SSD patients with sporadic ILS undergoing cochlear implantation with simultaneous tumor resection (n = 10) or with tumor observation (n = 1). Patients completed the Speech, Spatial and Qualities Questionnaire (SSQ12) and the Nijmegen Cochlear Implant Questionnaire (NCIQ) pre- and postoperatively, as well as the Bern Benefit in Single-Sided Deafness (BBSSD) questionnaire postoperatively. Patients were also tested postoperatively with and without their CI to measure the effect on localization ability and binaural summation, squelch, and head shadow.

RESULTS

Evaluation was completed for nine and six patients (subjective and objective data, respectively). The CI significantly improved the speech reception threshold (SRT) in the head shadow condition where the target signal was presented to the CI side and the noise to the front (SCIN0). On the other hand, the SRTs in the colocated condition (S0N0) and the condition where the target signal was presented to the front and the noise to the CI side (S0NCI) were unaffected by the CI. The mean localization error decreased significantly from 102° to 61° (p = 0.0031) with the addition of a CI. The scores from SSQ12 demonstrated nonsignificant changes. For NCIQ, the self-esteem and the social interaction domains increased significantly but insignificantly for the remaining domains. The BBSSD responses ranged from +0.5 to +3.5 points.

CONCLUSION

After implantation, patients achieved significantly better scores across some of the patient-reported and objective parameters. In addition to reporting on a number of ILS cases where implantation was performed, the study is the first of its kind to document patient-reported and objective binaural hearing improvement after cochlear implantation in patients with ILS and, thereby, lends support to the active management of ILS.

Enlarged Vestibular Aqueduct and Associated Inner Ear Malformations: Hearing Loss Prognostic Factors and Data Modeling from an International Cohort

ACKGROUND

There is a need to operationalize existing clinical data to support precision medicine in progressive hearing loss (HL). By utilizing enlarged vestibular aqueduct (EVA) and its associated inner ear abnormalities as an exemplar, we model data from a large international cohort, confirm prognostic factors for HL, and explore the potential to generate a prediction model to optimize current management paradigms.

METHODS

An international retrospective cohort study. Regression analyses were utilized to model frequency-specific HL and identify prognostic factors for baseline average HL severity and progression. Elastic-net regression and machine learning (ML) techniques were utilized to predict future average HL progression based upon routinely measurable clinical, genetic, and radiological data.

RESULTS

Higher frequencies of hearing were lost more severely. Prognostic factors for HL were the presence of incomplete partition type 2 (coefficient 12.95 dB, P=.011, 95% CI 3.0-22 dB) and presence of sac signal heterogeneity (P=.009, 95% CI 0.062-0.429) on magnetic resonance imaging. Elastic-net regression outperformed the ML algorithms (R2 0.32, mean absolute error 11.05 dB) with coefficients for baseline average hearing level and the presence of sac heterogeneity contributing the most to prediction outcomes.

CONCLUSION

Incomplete partition type 2 and endolymphatic sac signal heterogeneity phenotypes should be monitored closely for hearing deterioration and need for early audiological rehabilitation/cochlear implant. Preliminary prediction models have been generated using routinely collected health data in EVA. This study showcases how international collaborative research can use exemplar techniques to improve precision medicine in relatively rare disease entities.

Tinnitus suppression in a prospective cohort of 45 cochlear implant recipients: occurrence, degree and correlates

OBJECTIVE

To determine tinnitus prevalence and severity in a cohort of unselected first-time cochlear implant (CI) recipients whose primary motive for CI was sensorineural hearing loss (SNHL), and to evaluate the effect of CI on tinnitus after cochlear implantation.

METHODS

Prospective longitudinal study of 45 adult CI recipients with moderate to profound SNHL. Patients completed the Danish version of the Tinnitus Handicap Inventory (THI) and a visual analogue scale (VAS) for tinnitus burden before implantation, 4 months after implantation and 14 months after implantation.

RESULTS

The study included 45 patients, of which 29 (64%) had pre-implant tinnitus. Median THI score (IQR) significantly decreased from 20 (34) to 12 (24) at first follow-up (p < 0.05) and to 6 points (17) at second follow-up (p < 0.001). Median VAS (IQR) for tinnitus burden decreased from 33 (62) to 17 (40; p = 0.228) and 12 (27, p < 0.05) at the first and second follow-ups, respectively. Tinnitus was totally suppressed in 19% of patients, improved in 48%, remained unchanged in 19% and worsened in 6%. 2 patients reported new tinnitus. At the second follow-up, 74% of patients had slight or no tinnitus handicap, 16% had mild handicaps, 6% had moderate handicaps, and 3% had severe handicaps. High pre-implant THI and VAS scores correlated with greater decrease in THI scores over time.

CONCLUSION

64% of the patients with SNHL had pre-implant tinnitus, which was decreased 4 and 14 months after implantation. Overall, 68% of patients with tinnitus improved their tinnitus handicap after CI. Patients with higher THI and VAS scores had a larger decline and the highest benefits in terms of tinnitus handicap improvement. The study findings demonstrate that the majority of patients with moderate to profound SNHL eligible for cochlear implantation benefit from complete or partial tinnitus suppression and improved quality of life after implantation.

Objective Vestibular Test Battery and Patient Reported Outcomes in Cochlear Implant Recipients

OBJECTIVE

Cochlear implantation (CI) may have undesired effects on the vestibular apparatus. However, the literature holds no consensus on vestibular affection and the testing tools applied to test for vestibular dysfunction after cochlear implantation are inconsistent. We aimed to investigate the impact of CI on vestibular function by an extensive test battery including patient-reported outcomes.

STUDY DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENTS

Forty adult unilateral first-time CI recipients.

INTERVENTION

Vestibular function was evaluated pre- and post-implantation with the video head impulse test (VHIT), the caloric test and cervical vestibular evoked myogenic potentials (cVEMPs), and the patient-reported dizziness handicap inventory (DHI).

RESULTS

Mean VHIT gain decreased from preoperative 0.92 to 0.84 postoperative (p = 0.018); mean caloric unilateral weakness increased from 20.5% preoperative to 42.9% postoperative (p < 0.0001); cVEMP responses were present on 10 operated ears preoperative and five ears postoperative, and compared with non-implanted ears, cVEMP responses on implanted ears were impaired (p = 0.023). 50% of patients reported early postoperative dizziness, but the mean DHI score remained unchanged (p = 0.94). The DHI scores correlated poorly with the objective outcomes (rs = 0.19 and rs = -0.22).

CONCLUSION

Vestibular function is significantly affected after cochlear implantation, but vestibular hypofunction varies with the test used. Although early dizziness after implantation is common, later DHI scores are not significantly higher than before the implantation, indicating that central compensation plays a major role for these patients.

[Auditory brainstem implantation]

In this review, we discuss the auditory brainstem implant (ABI), which is a neuroprosthetic device being an advanced hearing aid in cases of bilateral, profound or complete hearing impairment due to a non-functional or absent cochlear nerve, or an inner ear malformation precluding cochlear implantation. Originally indicated in patients with bilateral vestibular schwannomas caused by neurofibromatosis type 2, the ABI has in recent years seen an increase in the aural rehabilitation of congenitally deaf children. Outcomes for patients are mixed, but generally the device leads to a reasonable improvement in speech perception.

[Cochlear implantation for adults]

A cochlear implant is an electrode, which is implanted in the inner ear to establish or re-establish hearing. Based on estimates on the prevalence of undertreated bilateral profound hearing loss, the number of adult people receiving a cochlear implant is low. In addition, many people with residual acoustic hearing or people with single-sided deafness could benefit from a cochlear implant. Due to the recent expansions in the indications for cochlear implantation and the unmet need for hearing improvement among the adult population, more focus on referring these patients to audiological cochlear implantation workup is recommended, as argued in this review.

Nordic results of cochlear implantation in adults: speech perception and patient reported outcomes

BACKGROUND

Although cochlear implantation (CI) is widely performed in postlingually hearing-impaired adults in the Nordic countries, the literature on hearing outcomes remains scarce. Aims/objectives: To evaluate and correlate hearing outcomes after implantation.

METHODS

Prospective evaluation of 40 adult first-implantation recipients pre- and post-implantation with Dantale, the Danish Hearing in Noise Test (HINT), the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Speech, Spatial and Qualities of Hearing Scale (SSQ12).

RESULTS

Dantale_mean increased from 50% (95% CI [41.7,58.4])) to 73% (95% CI [66.6,80.1]) and 19% (95% CI [13.3,25.1]) to 40%(95% CI [32.1,46.7]) (quiet/noise). HINT_words increased from 71% (95% CI [58.8,83.8]) to 83% (95% CI [69.8,95.4]) and 59% (95% CI [46.2,70.6]) to 73% (95% CI [63.3,82.8]) (quiet/noise). NCIQ_mean changed from 277 (95% CI [252.4,301.6]) to 396 (95% CI [366.7,424.7]) and SSQ12_mean from 27 (95% CI [21.3,31.8]) to 48 (95% CI [39.4,55.6]). Correlations coefficients were r _s = 0.39-0.74 (p < .01) between Dantale/HINT, rs = 0.78 (p < .0001) between NCIQ/SSQ12, r _s = 0.41-0.59 (p < .01) between NCIQ/SSQ12 and Dantale and r _s = 0.24-0.41 (ns) between NCIQ/SSQ12 and HINT.

CONCLUSION

The study documents a high auditory performance and patient-perceived improvement after implantation and advocate broader awareness of implantation as treatment option in the growing population of severe-to-profound hearing-impaired adults. Correlations between hearing measures may influence future evaluation practices.

Association of SLC26A4 mutations, morphology, and hearing in pendred syndrome and NSEVA

OBJECTIVE

To investigate the relations of monoallelic (M1), biallelic (M2), or the absence of mutations (M0) in SLC26A4 to inner ear morphology and hearing levels in individuals with Pendred syndrome (PS) or nonsyndromic enlarged vestibular aqueduct (NSEVA) associated with hearing loss.

METHODS

In a cohort of 139 PS/NSEVA individuals, 115 persons from 95 unrelated families had full genetic sequencing of SLC26A4, and 113 had retrievable images for re-assessment of inner ear morphology. The association between the number of mutant alleles in SLC26A4, inner ear morphology (including endolymphatic sac size and protein content on magnetic resonance imaging), and hearing level (pure tone average) was explored.

RESULTS

Biallelic SLC26A4 mutations (M2) occurred in three-quarters of the cohort and was invariably associated with poor hearing; in 87%, it was associated with incomplete partition type II of the cochlea as well as enlarged endolymphatic sac and vestibular aqueduct. M1 or M0 individuals exhibited a greater variability in inner ear morphology. Endolymphatic sac size and presence of "high-protein" sac contents were significantly higher in M2 individuals compared to M1 and M0 individuals.

CONCLUSION

The number of SLC26A4 mutations is associated with severity and variability of inner ear morphology and hearing level in individuals with PS or NSEVA. M2 individuals have poorer hearing and present largely incomplete partition type II of the cochleas with enlarged endolymphatic sacs, whereas individuals with M1 and no detectable SLC26A4 mutations have less severe hearing loss and more diverse inner ear morphology.

LEVEL OF EVIDENCE

4. Laryngoscope, 129:2574-2579, 2019.

Otoacoustic Emissions for Outcome Prediction in Postanoxic Brain Injury

Background: Non-invasive, easy-to-use bedside tools to estimate prognosis in unresponsive patients with postanoxic brain injury are needed. We assessed the usefulness of otoacoustic emissions as outcome markers after cardiac arrest. Methods: Distortion product otoacoustic emissions (DPOAE) and transient evoked otoacoustic emissions (TEOAE) were measured in cardiac arrest patients whose prognosis was deemed to be poor following standard neurological assessment (n = 10). Ten patients with myocardial infarction without prior loss of consciousness served as controls. Results: Compared to controls with myocardial infarction, cardiac arrest patients with poor neurological prognosis had significantly less often preserved DPOAE (9.2 vs. 40.8% positive measurements; OR 0.15 (CI 0.07-0.30); p < 0.0001). Partially preserved DPOAE were noted in 4 cardiac arrest patients. TEOAE were not statistically different between the two groups. Conclusions: Despite their convenience, otoacoustic emissions cannot be used as reliable prognostic markers in cardiac arrest survivors. This is because we identified 4 cases with partially preserved otoacoustic emissions in a sample of 10 unresponsive post-cardiac arrest patients whose neurological condition was so poor that active treatment was withdrawn. However, we suggest that future research should address if decaying outer hair cell function over time may serve as a proxy for evolving ischemic brain damage.

[Cochlear implantation in children]

Children with severe hearing impairment or deafness are preferably recognised and treated with a cochlear implant (CI) before the age of one year, as early stimulation of the auditory sense is essential for the development of spoken language. Today, children with deafness are offered a bilateral CI, as it allows for improved speech perception in noise and sound localisation. However, the indications for cochlear implantation have been extended to include children with asymmetric hearing loss, in order to avoid the development of aural preference syndrome, which may limit the effect of a CI later.

Correction to: The CAPOS mutation in ATP1A3 alters Na/K-ATPase function and results in auditory neuropathy which has implications for management

The following information was inadvertently omitted in the original publication.

Cochlear implantation in Pendred syndrome and non-syndromic enlarged vestibular aqueduct - clinical challenges, surgical results, and complications

OBJECTIVE

To explore specific clinical issues, surgical results, and complications of 80 cochlear implantations (CI) in 55 patients with Pendred syndrome (PS) or non-syndromic enlarged vestibular aqueduct (NSEVA).

BACKGROUND

Previous studies have focused either on unselected case series or on populations with mixed cochlear malformations. PS/NSEVA accounts for up to 10% of congenital SNHL, rendering this a large group of cochlear implant candidates. The abnormal inner ear anatomy of these patients may be associated with a lower surgical success rate and a higher rate of complications.

STUDY DESIGN

Retrospective review of patients' medical records and CT/MRI.

SETTING

Tertiary referral center.

MATERIALS AND METHODS

The medical records and CT/MRI images of 55 PS/NSEVA patients receiving 80 cochlear implantations from 1982-2014 were reviewed. Demographic data, surgical results, intra-operative incidents, and post-operative complications were retrieved.

RESULTS

Complications occurred in 36% of implantations; 5% hereof major complications. Gushing/oozing from the cochleostoma occurred in 10% of implantations and was related to transient, but not prolonged post-operative vertigo.

CONCLUSION

Intra-operative risks of gushing/oozing and post-operative vertigo are the primary clinical issues in PS/NSEVA patients regarding CI. Nonetheless, the surgical success rate is high and the major complication rate is low; similar to studies of unselected series of CI recipients.

Psychometric properties of a revised Danish translation of the international outcome inventory for hearing aids (IOI-HA)

Objective

The original Danish translation of the international outcome inventory for hearing aids (IOI-HA) proved problematic as the wording of item 5 was not semantically clear, rendering the questionnaire internally inconsistent. The objective of this study was to examine data collected with a revised Danish translation of the IOI-HA in order to: (1) evaluate the effect of the revision, and (2) to examine if the psychometric properties of the revised translation of the IOI-HA are equivalent to those of previously validated translations.

Design

Psychometric properties were evaluated performing inter-item correlation analysis, principal component analysis, and item-total correlation.

Study sample

Three hundred forty-one adult hearing-impaired participants—all of whom were voluntary hearing aid testers attached to the Global Audiology Group in GN ReSound A/S on a non-payment basis — were mailed a revised Danish IOI-HA questionnaire.

Results

Statistical analysis revealed good internal consistency along with a clear division of items into two distinct factors.

Conclusions

The revised Danish translation of the IOI-HA proves internally consistent. Furthermore, it possesses psychometric properties equivalent to those reported in several corresponding studies of other translations. Data obtained from it can therefore validly be considered comparable to data obtained from previously validated translations of the IOI-HA.

Experience with cochlear implants in Greenlanders with profound hearing loss living in Greenland

OBJECTIVE

Cochlear implant (CI) treatment was introduced to the world in the 1980s and has become a routine treatment for congenital or acquired severe-to-profound hearing loss. CI treatment requires access to a highly skilled team of ear, nose and throat specialists, audiologists and speech-language pathologists for evaluation, surgery and rehabilitation. In particular, children treated with CI are in need of long-term post-operative auditory training and other follow-up support.

DESIGN

The study is retrospective with updated information on present performance.

RESULTS

Since 2001, a total of 11 Greenlandic patients living in Greenland have been treated with CI, 7 children and 4 adults. Of these children, 4 use oral communication only and are full-time CI-users, 2 with full-time use of CI are still in progress with use of oral communication, and 1 has not acquired oral language yet, but has started auditory and speech training. Six children attend mainstream public school while one child is in kindergarten. Of the adults, only 1 has achieved good speech perception with full-time use of CI while 3 do not use the CI.

DISCUSSION

From an epidemiological point of view, approximately 1-3 children below 6 years are in need of a CI every second year in Greenland often due to sequelae from meningitis, which may cause postinfectious deafness. Screening of new-borns for hearing has been started in Greenland establishing the basis for early diagnosis of congenital hearing impairment and subsequent intervention. The logistics and lack of availability of speech therapists in Greenland hampers possibilities for optimal language and speech therapy of CI patients in Greenland. This study aims at describing the results of CI treatment in Greenlanders and the outcome of the CI operations along with the auditory and speech/language outcomes. Finally, we present a suggestion for the future CI treatment and recommendations for an increased effort in the treatment and rehabilitation of implanted patients in Greenland.

Significant regional differences in Denmark in outcome after cochlear implants in children

INTRODUCTION

The objectives of the present study were to study regional differences in outcome for a paediatric cochlear implant (CI) population after the introduction of universal neonatal hearing screening (UNHS) and bilateral implantation in Denmark.

MATERIAL AND METHODS

Data relate to 94 subjects. A test battery consisting of eight different tests/assessments was performed in order to report the level of audition, speech, language and self-esteem. For data analyses of any associations between the regions, Fisher's exact test was used. Potential rater variability within either of the centres was assessed using logistic regression models.

RESULTS

The levels of audition were comparable between the group from West Denmark (West) and the group from East Denmark (East). In contrast, all tests of speech and language revealed a statistically significant difference between East and West. In all tests, West subjects scored significantly lower than East subjects. West children received more hours of speech therapy, more learning support assistance, and more parents used signing. Furthermore, the parents from West were significantly less involved in the auditory rehabilitation of their children than parents from East.

CONCLUSION

The results were remarkable and call for a thorough evaluation of both the quality and organization of the paediatric CI population with particular concern for the paediatric CI population of West Denmark.

FUNDING

The Oticon foundation financially supported this study. Trial registration was not relevant as the study is designed as a prospective case series.

TRIAL REGISTRATION

not relevant.

Phenotype in 18 Danish subjects with genetically verified CHARGE syndrome

CHARGE (coloboma of the eye, heart defects, choanal atresia, retarded growth and development, genital hypoplasia and ear anomalies and/or hearing loss) syndrome is a rare genetic, multiple-malformation syndrome. About 80% of patients with a clinical diagnose, have a mutation or a deletion in the gene encoding chromodomain helicase DNA-binding protein 7 (CHD7). Genotype-phenotype correlation is only partly known. In this nationwide study, phenotypic characteristics of 18 Danish CHD7 mutation positive CHARGE individuals (N = 18) are presented. We studied patient records, clinical photographs, computed tomography, and magnetic resonance imaging (MRI). Information was not available for all traits in all subjects. Therefore, the results are presented as fractions. The following prevalence of cardinal symptoms were found: coloboma, 16/17; heart defects, 14/18; choanal atresia, 7/17; retarded growth and development, 11/13; genital abnormalities, 5/18; ear anomalies, 15/17 and sensorineural hearing loss, 14/15. Vestibular dysfunction (10/13) and swallowing problems (12/15) were other frequent cranial nerve dysfunctions. Three-dimensional reconstructions of MRI scans showed temporal bone abnormalities in >85%. CHARGE syndrome present a broad phenotypic spectrum, although some clinical features are more frequently occurring than others. Here, we suggest that genetic testing for CHD7 mutation should be considered in neonates with a specific combination of several clinical symptoms.

Expectations about hearing aids: demographic and audiological predictors: Expectativas acerca de los auxiliares auditivos: predictores demográficos y audiológicos

The Expected Consequences of Hearing Aid Ownership inventory (ECHO) is a 14-item questionnaire for measuring expectations about hearing aids. The objectives of this study were to evaluate the ECHO questionnaire used in the Danish National Hearing Health Service in terms of reliability and validity; to use the inventory to assess the patients' pre-fitting expectations in different domains, to gain information on possible predictors for the magnitude of expectations, and to evaluate whether first-time users had realistic expectations. The questionnaire was administered to 805 consecutive patients, and responses were received from 47.7%, representative for the population examined in the department. The median age was 74.1 years, with an even distribution of males and females, and a median better-ear pure-tone average (0.5-4 kHz) of 41.3 dB HL. The results showed that the questionnaire had acceptable reliability and validity when the original subscales were rearranged. The pre-fitting expectations with regard to the positive effect of amplification and different aspects related to the hearing aid and service were, overall, very high. Age and hearing status were predictors of the magnitude of expectations related to the hearing aid and the service. In first-time users, unrealistic positive expectations were found with regard to potentially negative features of hearing aids.

GRM7 variants confer susceptibility to age-related hearing impairment

Age-related hearing impairment (ARHI), or presbycusis, is the most prevalent sensory impairment in the elderly. ARHI is a complex disease caused by an interaction between environmental and genetic factors. Here we describe the results of the first whole genome association study for ARHI. The study was performed using 846 cases and 846 controls selected from 3434 individuals collected by eight centers in six European countries. DNA pools for cases and controls were allelotyped on the Affymetrix 500K GeneChip for each center separately. The 252 top-ranked single nucleotide polymorphisms (SNPs) identified in a non-Finnish European sample group (1332 samples) and the 177 top-ranked SNPs from a Finnish sample group (360 samples) were confirmed using individual genotyping. Subsequently, the 23 most interesting SNPs were individually genotyped in an independent European replication group (138 samples). This resulted in the identification of a highly significant and replicated SNP located in GRM7, the gene encoding metabotropic glutamate receptor type 7. Also in the Finnish sample group, two GRM7 SNPs were significant, albeit in a different region of the gene. As the Finnish are genetically distinct from the rest of the European population, this may be due to allelic heterogeneity. We performed histochemical studies in human and mouse and showed that mGluR7 is expressed in hair cells and in spiral ganglion cells of the inner ear. Together these data indicate that common alleles of GRM7 contribute to an individual's risk of developing ARHI, possibly through a mechanism of altered susceptibility to glutamate excitotoxicity.

Genome-wide SNP-based linkage scan identifies a locus on 8q24 for an age-related hearing impairment trait

Age-related hearing impairment (ARHI), or presbycusis, is a very common multifactorial disorder. Despite the knowledge that genetics play an important role in the etiology of human ARHI as revealed by heritability studies, to date, its precise genetic determinants remain elusive. Here we report the results of a cross-sectional family-based genetic study employing audiometric data. By using principal component analysis, we were able to reduce the dimensionality of this multivariate phenotype while capturing most of the variation and retaining biologically important features of the audiograms. We conducted a genome-wide association as well as a linkage scan with high-density SNP microarrays. Because of the presence of genetic population substructure, association testing was stratified after which evidence was combined by meta-analysis. No association signals reaching genome-wide significance were detected. Linkage analysis identified a linkage peak on 8q24.13-q24.22 for a trait correlated to audiogram shape. The signal reached genome-wide significance, as assessed by simulations. This finding represents the first locus for an ARHI trait.

Occupational noise, smoking, and a high body mass index are risk factors for age-related hearing impairment and moderate alcohol consumption is protective: a European population-based multicenter study

A multicenter study was set up to elucidate the environmental and medical risk factors contributing to age-related hearing impairment (ARHI). Nine subsamples, collected by nine audiological centers across Europe, added up to a total of 4,083 subjects between 53 and 67 years. Audiometric data (pure-tone average [PTA]) were collected and the participants filled out a questionnaire on environmental risk factors and medical history. People with a history of disease that could affect hearing were excluded. PTAs were adjusted for age and sex and tested for association with exposure to risk factors. Noise exposure was associated with a significant loss of hearing at high sound frequencies (>1 kHz). Smoking significantly increased high-frequency hearing loss, and the effect was dose-dependent. The effect of smoking remained significant when accounting for cardiovascular disease events. Taller people had better hearing on average with a more pronounced effect at low sound frequencies (<2 kHz). A high body mass index (BMI) correlated with hearing loss across the frequency range tested. Moderate alcohol consumption was inversely correlated with hearing loss. Significant associations were found in the high as well as in the low frequencies. The results suggest that a healthy lifestyle can protect against age-related hearing impairment.

The contribution of GJB2 (Connexin 26) 35delG to age-related hearing impairment and noise-induced hearing loss

HYPOTHESIS

The common GJB2 (Connexin 26) 35delG mutation might contribute to the development of age-related hearing impairment (ARHI) and noise-induced hearing loss (NIHL).

BACKGROUND

GJB2, a gene encoding a gap junction protein expressed in the inner ear, has been suggested to be involved in the potassium recycling pathway in the cochlea. GJB2 mutations account for a large number of individuals with nonsyndromic recessive hearing loss, with 35delG being the most frequent mutation in populations of European origin. Other genes involved in potassium homeostasis have been suggested to be associated with ARHI and NIHL, and distortion product otoacoustic emission distortions indicative of hearing loss alterations have been found in 35delG carriers.

METHOD

We genotyped 35delG in two distinct sample sets: an ARHI sample set, composed of 2,311 Caucasian samples from nine different centers originating from seven different countries with an age range between 53 and 67 years, and an NIHL sample set consisting of 702 samples from the two extremes of a noise-exposed Polish sample.

RESULTS

After statistical analysis, we were unable to detect an association between 35delG and ARHI, nor between 35delG and NIHL.

CONCLUSION

Our findings indicate that there is no increased susceptibility in 35delG carriers for the development of ARHI or NIHL.

The grainyhead like 2 gene (GRHL2), alias TFCP2L3, is associated with age-related hearing impairment

Age-related hearing impairment (ARHI) is the most prevalent sensory impairment in the elderly. ARHI is a complex disease caused by an interaction between environmental and genetic factors. The contribution of various environmental factors has been relatively extensively studied. In contrast, investigations to identify the genetic risk factors have only recently been initiated. In this paper we describe the results of an association study performed on 2418 ARHI samples derived from nine centers from seven European countries. In 70 candidate genes, a total of 768 tag single nucleotide polymorphisms (SNPs) were selected based on HAPMAP data. These genes were chosen among the monogenic hearing loss genes identified in mice and men in addition to several strong functional candidates. After genotyping and data polishing, statistical analysis of all samples combined resulted in a P-value that survived correction for multiple testing for one SNP in the GRHL2 gene. Other SNPs in this gene were also associated, albeit to a lesser degree. Subsequently, an analysis of the most significant GRHL2 SNP was performed separately for each center. The direction of the association was identical in all nine centers. Two centers showed significant associations and a third center showed a trend towards significance. Subsequent fine mapping of this locus demonstrated that the majority of the associated SNPs reside in intron 1. We hypothesize that the causative variant may change the expression levels of a GRHL2 isoform.

Contribution of the N-acetyltransferase 2 polymorphism NAT2*6A to age-related hearing impairment

BACKGROUND

Age-related hearing impairment (ARHI) is the most common sensory impairment in older people, affecting 50% of those aged 80 years. The proportion of older people is increasing in the general population, and as a consequence, the number of people affected with ARHI is growing. ARHI is a complex disorder, with both environmental and genetic factors contributing to the disease. The first studies to elucidate these genetic factors were recently performed, resulting in the identification of the first two susceptibility genes for ARHI, NAT2 and KCNQ4.

METHODS

In the present study, the association between ARHI and polymorphisms in genes that contribute to the defence against reactive oxygen species, including GSTT1, GSTM1 and NAT2, was tested. Samples originated from seven different countries and were combined into two test population samples, the general European population and the Finnish population. Two distinct phenotypes for ARHI were studied, Z(low) and Z(high), representing hearing in the low and high frequencies, respectively. Statistical analysis was performed for single polymorphisms (GSTM1, GSTT1, NAT2*5A, NAT2*6A, and NAT2*7A), haplotypes, and gene-environment and gene-gene interactions.

RESULTS

We found an association between ARHI and GSTT1 and GSTM1 in the Finnish population sample, and with NAT2*6A in the general European population sample. The latter finding replicates previously published data.

CONCLUSION

As replication is considered the ultimate proof of true associations in the study of complex disorders, this study provides further support for the involvement of NAT2*6A in ARHI.

Familial aggregation of tinnitus: a European multicentre study

INTRODUCTION AND AIM

Tinnitus is a common condition affecting approximately 20% of the older population. There is increasing evidence that changes in the central auditory system following cochlear malfunctioning are responsible for tinnitus. To date, few investigators have studied the influence of genetic factors on tinnitus. The present report investigates the presence of a familial effect in tinnitus subjects.

METHODS

In a European multicentre study, 198 families were recruited in seven European countries. Each family had at least 3 siblings. Subjects were screened for causes of hearing loss other than presbyacusis by clinical examination and a questionnaire. The presence of tinnitus was evaluated with the question "Nowadays, do you ever get noises in your head or ear (tinnitus) which usually last longer than five minutes". Familial aggregation was tested using three methods: a mixed model approach, calculating familial correlations, and estimating the risk of a subject having tinnitus if the disorder is present in another family member.

RESULTS

All methods demonstrated a significant familial effect for tinnitus. The effect persisted after correction for the effect of other risk factors such as hearing loss, gender and age. The size of the familial effect is smaller than that for age-related hearing impairment, with a familial correlation of 0.15.

CONCLUSION

The presence of a familial effect for tinnitus opens the door to specific studies that can determine whether this effect is due to a shared familial environment or the involvement of genetic factors. Subsequent association studies may result in the identification of the factors responsible. In addition, more emphasis should be placed on the effect of role models in the treatment of tinnitus.

Autosomal dominant optic atrophy associated with hearing impairment and impaired glucose regulation caused by a missense mutation in the WFS1 gene

Autosomal dominant optic atrophy (ADOA) is genetically heterogeneous, with OPA1 on 3q28 being the most prevalently mutated gene. Additional loci are OPA3, OPA4, and OPA5, located at 19q13.2, 18q12.2, and 22q12.1-q13.1, respectively. Mutations in the WFS1 gene, at 4p16.3, are associated with either optic atrophy (OA) as part of the autosomal recessive Wolfram syndrome or with autosomal dominant progressive low frequency sensorineural hearing loss (LFSNHL) without any ophthalmological abnormalities. Linkage and sequence mutation analyses of the ADOA candidate genes OPA1, OPA3, OPA4, and OPA5, including the genes WFS1, GJB2, and GJB6 associated with recessive inherited OA or dominant LFSNHL, were performed. We identified one novel WFS1 missense mutation E864K, c.2590G-->A in exon 8 that co-segregates with ADOA combined with hearing impairment and impaired glucose regulation. This is the first example of autosomal dominant optic atrophy and hearing loss associated with a WFS1 mutation, supporting the notion that mutations in WFS1 as well as in OPA1 may lead to ADOA combined with impaired hearing.

Two families with phenotypically different hereditary low frequency hearing impairment: longitudinal data and linkage analysis

Two families with low frequency hearing impairment have been described previously. Family A (Danish) presented a sensorineural hearing impairment most pronounced for frequencies below 2 kHz and a pedigree typical for an autosomal dominant trait with complete penetrance (Königsmark type). Family B, originating from the Faroe Islands, showed conflicting audiological test results, making a valid classification impossible. The pedigree suggested autosomal dominant inheritance with incomplete penetrance. The objectives of the present study are to acquire longitudinal audiometric data, to clarify the mode of transmission, and to localize the mutant gene by reevaluation of the two families. The methods used are evaluation of the family history, audiological examination and linkage analysis. In family A, update of the pedigree fitted the assumption of an autosomal dominant mode of transmission. In six examined subjects audiological data were available from the previous study. The median progression over a 13-21-year period was 13.8 dB HL for the thresholds, averaged across 0.5, 1, 2 and 4 kHz and 17.5 dB HL for the thresholds, averaged across 2 and 4kHz. In family B, the probable mode of transmission is autosomal dominant with reduced penetrance. In this family no progression of the hearing impairment was found. Linkage analysis of family A showed a lod score of 3.53, indicating significant linkage to the loci DFNA6 and DFNA14 on chromosome 4, previously found to be involved in low frequency hearing impairment. Family B was not linked to the region on chromosome 4, further adding to the genetic heterogeneity in low frequency sensorineural hearing impairment.

Cystic hygroma of the head and neck--a long-term follow-up of 44 cases

Cystic hygroma of the neck is a relatively rare congenital malformation usually diagnosed during the first years of infancy. Complete surgical extirpation may be impossible without sacrificing important neurovascular structures. This paper reports the long-term outcome of surgical treatment during a 35-year period. A follow-up examination of 44 patients (24 males and 20 females) treated in our departments during the last 35 years was performed. Median age at first operation was 1.5 years (0-28 years) The observation period ranged between 1 and 36 years, median 16.2 years. Indications for operation were space occupying lesion, haemorrhage, dysphagia, difficulties in pronunciation or breathing and infection or nerve lesions. Fifty percent of the patients revealed residual or recurrent hygroma at the time of follow-up. Forty-four percent suffered from impaired speech, food intake, breathing or swallowing. Thirty-six percent were cosmetically bothered, and only 11% reported reduced quality of life. A significant correlation was noted between the extension of the lesion and (i) the number of operations performed and (ii) the rate of recurrent or residual hygroma. The rate of residual or recurrent hygroma was statistically higher for the suprahyoid lesions compared with the infrahyoid lesions. The localization and extent of the lesion is related to the surgical outcome. Surgical intervention should be centralized and should be considered carefully. Neurovascular structures should not be damaged in an attempt to effect complete removal. The above-mentioned results lead to a search for a new therapeutic modality, and the authors have recently taken up the Japanese way of treating hygromas by intralesional injection of OK-432. The first two patients treated by this technique had total regression of the lesion, and the method seems to be promising as an alternative to surgery.

Clinical study of a digital vs an analogue hearing aid

Digital signal processing in hearing instruments has brought new perspectives to the compensation of hearing impairment and may result in alleviation of the adverse effects of hearing problems. This study compares a commercially available digital signal processing hearing aid (HA) (Senso) with a modern analogue HA with programmable fitting (Logo). The HAs tested are identical in appearance and, in spite of a different mode of operation, the study design ensured blinding of the test subjects. Outcome parameters were: improvements in speech recognition score in noise (deltaSRSN) with the HAs; overall preference for HA; overall satisfaction; and various measures of HA performance evaluated by a self-assessment questionnaire. A total of 28 experienced HA users with sensorineural hearing impairment were included and 25 completed the trial. No significant differences were found in deltaSRSN between the two HAs. Eleven subjects indicated an overall preference for the digital HA, 10 preferred the analogue HA and 4 had no preference. Concerning overall satisfaction, 8 subjects rated the digital HA superior to the analogue one, whereas 7 indicated a superior rating for the analogue HA and 10 rated the HAs equal. Acceptability of noise from traffic was the only outcome parameter which gave a significant difference between the HAs in favour of the digital HA. It is concluded that there are no significant differences in outcome between the digital and analogue signal processing HAs tested by these experienced HA-users.

Peritonsillar infiltration with low-dose tenoxicam after tonsillectomy

We have compared the effect of peritonsillar infiltration with tenoxicam 5 mg and placebo on postoperative pain after tonsillectomy. Fifty patients undergoing bilateral elective tonsillectomy under general anaesthesia were allocated randomly to receive peritonsillar infiltration with tenoxicam 5 mg in 8 ml of normal saline (4 ml per tonsil) or normal saline only, before tracheal extubation. Median time to first request for morphine (30 min in each group, P = 0.83), cumulative morphine requirements from 0 to 2 h after surgery (two and one doses, P = 0.50), and from 2 to 24 h after surgery (one dose in each group, P = 0.17) were similar. There were no significant differences between groups in VAS scores at rest or when drinking 100 ml of water at any time. The power of detecting a reduction in VAS scores of 20 mm was 90% at the 5% significance level.

[Bone-anchored auricular prosthesis]

During the period February 1989-September 1991, 15 patients with absent or defective pinna were treated with a bone-anchored auricular prosthesis at the ENT-department, Rigshospitalet, Copenhagen. These patients were followed up from the hospital records and by means of a questionnaire. Altogether 40 titanium implants have been inserted, of which one implant was found not to be integrated at the time of the second-stage surgery. Five patients underwent additional surgery, one patient because of non-integration of a screw, and four patients on account of soft-tissue reactions. From the questionnaire replies it appears that all patients found the cosmetic result and the technique concerning mounting of the prosthesis very satisfactory. Nearly half the patients found that the care of the skin around the abutments caused considerable problems. Three patients had experienced unintended losses of the prosthesis. In conclusion, treatment with a bone anchored auricular prosthesis has considerable advantages compared to treatment with a prosthesis attached by adhesive. Furthermore the use of a bone-anchored prosthesis should be considered a viable alternative to surgical reconstruction because of the outstanding aesthetic result and because the surgical procedure puts less strain on the patient. The disadvantage of the method is the lifelong daily care of the skin and the dependence on the health services.

Bonding of enamel-dentin crown fragments after crown fracture. An experimental study using bonding agents

Previous experimental studies into the use of dentin bonding agents for reattachment of enamel-dentin crown fragments have demonstrated fracture strength about 50-60% of that of intact teeth. In the clinic this has been reflected in the frequent need of repeated bonding of the treated incisors due to refracture. Recently newer bonding agents have been developed which can bond equally well with enamel and dentin. Employing the same experimental model, these bonding agents (All-Bond 2, Scotchbond MP) were used to reattach crown fragments to the remaining portion of sheep incisors. Loading of teeth bonded with these agents in an Instron testing machine at a speed of 1 mm/min demonstrated similar fracture strengths as those previously achieved with Gluma, Scotchbond 2 or Tenure. A second study was carried out whereby fragments were bonded with Scotchbond MP and loaded at various speeds. The results demonstrated that the fracture strength decreased exponentially with increased loading speed. By extrapolation, it was concluded that the strength was nil at a loading speed of approximately 2 m/min. It was concluded that the weak link in the bond between tooth fragment and remaining tooth structure is the bonding resin. Theoretically, a resin which is slightly elastic might act as a shock absorber to withstand functional stress. However, studies carried out with resins of varying moduli of elasticity gave disappointing results probably due to their low flexural strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum tryptophan levels in alcoholics

An oral load of L-tryptophan was administered to alcoholics and non-alcoholic control subjects in order to determine whether prolonged ethanol consumption influences serum tryptophan levels. Both samples were taken under fasting conditions and after the load. No differences in fasting serum tryptophan levels were noted. In alcohol addicts and in alcoholics treated with disulfiram (Antabuse) serum tryptophan levels were below normal after the load. No differences were observed in serum tryptophan levels between treated alcoholics not receiving disulfiram and control subjects. The findings suggest that chronic consumption of ethanol-containing beverages can enhance removal of tryptophan from the blood. Explanations to account for this finding are considered.

Traffic accidents involving psychiatric patients. Characteristics of accidents involving drivers who have been admitted to Danish psychiatric departments

A nationwide study of psychiatric in-patients driving motor vehicles and involved in accidents causing bodily injury in the years 1972--74 was undertaken. Compared with drivers in general involved in accidents causing bodily injury, drivers with a psychiatric record were characterized by an over-representation of women. A preponderance of psychiatric drivers in the age group 25--54 was observed. About 3% of drivers with a psychiatric record were involved in two or more accidents during the period studied. A greater proportion of the psychiatrically diseased group drove stolen vehicles, without valid licences, and were found not to have used safety belts at the time of the accident. Occurrence of injury was more frequent among the diseased drivers. They were more frequently alcohol intoxicated and with a higher blood alcohol level. The most commonly encountered diagnostic groups were personality disorder and transitory reactions.

Traffic accidents involving psychiatric patients. Description of the material and general results

The present investigation analyzes the characteristics of traffic accidents involving psychiatric patients and comprises all persons who during the period 1970-74 have been admitted to a psychiatric in-patient institution and who during the period 1972-74 have been involved in a traffic accident causing bodily injury. Accidents with psychiatric patients involved constitute about 5.7% of all traffic accidents reported in Denmark. Compared with the total group of accidents, they are characterized by an over-representation of women and of persons in the age group 25-54 years. Accidents with psychiatric patients are over-represented during the period July-September, and in areas densely built up. The accidents tend to be more complicated, and the psychiatric patients are more likely to get injured and be hopitalized due to the accident. The investigation is based exclusively on routinely collected data. The limitations with which the results are encumbered and the problems concerning methodology and comparison of different studies are discussed.

Psychiatric treatment in a delimited population-with particular reference to outpatients. A demographic study

The present investigation analyses the psychiatric service available to and utilized by a population in a geogrphically delimited area, namely the Randers area with a population of 108.928. During the period 1970-74, the average yearly rate of patients admitted to the three psychiatric institutions covering this area was per 1,000: 7.9 males and 9.1 females. During 1970-71, 1.2 males and 1.8 females per 1,000 were treated as outpatients in a psychiatric clinic affiliated to a psychiatric hospital, and a psychiatric outpatient clinic in a general hospital discharged 4.1 males and 7.7 females per 1,000. It seems probable that despite outpatient treatment the number of admissions increases slightly rather than decreases, and consequently, outpatient treatment cannot replace psychiatric admission.

Incidence of depressive syndromes in a Danish county. The Aarhus County investigation

On the basis of a material from a cumulative registration of the psychiatric morbidity in a geographically delimited population group - the County of Aarhus with approximately 175,000 inhabitants over the age of 15 years - the frequency of depressive syndromes in psychiatric and other medical services was investigated. The material fulfils the following criteria: During the calendar years 1960 to 1964, the patients 1) were residents in the County of Aarhus, 2) had attained the age of 15 years or more, 3) had contacted at least one of the services which systematically sent information to the psychiatric register; and 4) based on an evaluation of all available data, had a main diagnosis of manic-depressive psychosis, psychogenic depression or neurotic depression. An average yearly registration rate of 1.30 per 1,000 men and 3.28 per 1,000 women was found (males: manic-depressive psychosis 0.60, psychogenic depression 0.23 and neurotic depression 0.47; females: manic-depressive psychosis 1.00, psychogenic depression 0.88 and neurotic depression 1.40). The three diagnostic groups show differences in age distribution, geographical pattern and distribution by marital status.