Variations in genetic assessment and recurrence risks quoted for childhood deafness: a survey of clinical geneticists.

We report here the results of a questionnaire survey of consultant clinical geneticists in the United Kingdom to which we had an 81% response rate. In this questionnaire we asked about: (1) the nature of services currently offered to families with hearing impaired children, (2) what recurrence risks they quoted in isolated non-syndromic cases, and (3) what they might suggest for improving the range of genetic services available at present. We noted great variation both in these services and in the recurrence risks quoted in isolated cases.

Combined cochleo-saccular and neuroepithelial abnormalities in the Varitint-waddler-J (VaJ) mouse.

Hearing loss in Varitint-waddler-J (VaJ) mice is of mixed origin with both cochleo-saccular and neuroepithelial components. Both VaJ/VaJ and VaJ/+ mutants show impaired cochlear function, but the homozygotes are more severely affected than heterozygotes. Neither group have any detectable compound action potential.

A study of the acoustic reflex using fast-rate otoacoustic emissions.

Fast-rate otoacoustic emissions (OAEs) were used to determine the inward and outward transmission change produced by the stapedial muscle reflex. The subjects were otologically normal adult volunteers. Satisfactory recordings were obtained from a total of 16 ears.

Dichotic pitches as illusions of binaural unmasking. II. The Fourcin pitch and the dichotic repetition pitch.

The predictions of three models are compared with respect to existing experimental data on the perception of the Fourcin pitch (FP) and the dichotic repetition pitch (DRP). Each model generates a central spectrum (CS), which is examined for peaks at frequencies consistent with the perceived pitches. A modified equalization-cancellation (mE-C) model of binaural unmasking [Culling and Summerfield, J.

Dichotic pitches as illusions of binaural unmasking. I. Huggins' pitch and the "binaural edge pitch".

The two most salient dichotic pitches, the Huggins pitch (HP) and the binaural edge pitch (BEP), are produced by applying interaural phase transitions of 360 and 180 degrees, respectively, to a broadband noise. This paper examines accounts of these pitches, concentrating on a "central activity pattern" (CAP) model and a "modified equalization-cancellation" (mE-C) model. The CAP model proposes that a dichotic pitch is heard at frequency f when an individual across-frequency scan in an interaural cross-correlation matrix contains a sharp peak at f.

Maximum length sequences and Volterra series in the analysis of transient evoked otoacoustic emissions.

Previous work from this group (IHR, Southampton) has shown the feasibility of using maximum length sequence (MLS) stimulation to obtain evoked otoacoustic emissions (OAE). Because an MLS is one of a set of inputs that enables the Volterra series to be computed, we investigated its use with OAE. We wanted to see if the Volterra series could model the system and if we could extract the higher order kernels.

Epidemiology of permanent childhood hearing impairment in Trent Region, 1985-1993.

This retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in children born between 1985 and 1993 and resident in Trent Health Region, achieved an ascertainment of 92.9% of that expected from previous studies and 100% for the subset of children born between 1985 and 1990. The prevalence rate of all permanent hearing impairment > or = 40 dB HL for the birth cohort 1985-90 is 133 (95% confidence interval, (ci) 122-145) per 100,000 live births (1 in 750).

Neonatal otoacoustic emissions recorded using maximum length sequence stimuli.

Objective: Maximum length sequence (MLS) stimulation allows transient evoked otoacoustic emissions (TEOAEs) to be recorded at very high stimulation rates. Previous work has focused on recording from normally hearing adult subjects; the aim of this study was to obtain information about emissions recorded using this technique from newborns and to compare these results with those obtained from adults. The feasibility of recording from newborns on the postnatal wards also was addressed.

Shaker-1 mutations reveal roles for myosin VIIA in both development and function of cochlear hair cells.

The mouse shaker-1 locus, Myo7a, encodes myosin VIIA and mutations in the orthologous gene in humans cause Usher syndrome type 1B or non-syndromic deafness. Myo7a is expressed very early in sensory hair cell development in the inner ear. We describe the effects of three mutations on cochlear hair cell development and function.

Mapping of the alpha-tectorin gene (TECTA) to mouse chromosome 9 and human chromosome 11: a candidate for human autosomal dominant nonsyndromic deafness.

alpha-Tectorin is one of the major noncollagenous components of the mammalian tectorial membrane in the inner ear. We have mapped the gene encoding alpha-tectorin to mouse chromosome 9 and human chromosome 11 in a known region of conserved synteny. Human YAC clones containing alpha-tectorin have been identified, demonstrating physical linkage to the anonymous marker D11S925.

Cost-effectiveness considerations in pediatric cochlear implantation.

Objective: To summarizes the results of cost-utility analyses of pediatric cochlear implantation (CI) in the United Kingdom.

Method: Analysis is based on the direct costs of medical and rehabilitative management and also on emerging evidence that implantation leads to a shift in educational placements in favor of mainstreaming with support.

Result: The resulting cost-utility ratio falls on the margin of the range considered acceptable within the British health-care system.

Audiometer calibration: two neglected areas.

British and International Standards for pure tone audiometry require that the static force exerted by the earphone/bone vibrator headband is within certain limits. However, no recommended procedure is given for making force measurements. In addition, standards for audiometers require that linearity of output level is within certain limits.

Localization of the bronx waltzer (bv) deafness gene to mouse chromosome 5.

The bronx waltzer (bv) mutation is an autosomal recessive mutation that is manifested as head tossing and circling in the mouse. The mutation affects the inner hair cells (IHCs) and pillar cells in the organ of Corti of the cochlea and the maculae and cristae of the vestibular part of the inner ear. IHCs begin to degenerate by a controlled mechanism of cell death as early as gestational day 17 (G17) in the basal coil of the cochlea, and few surviving IHCs are seen in the adult.

Are normal hearing thresholds a sufficient condition for click-evoked otoacoustic emissions?

Transiently evolked otoacoustic emissions (TEOAE) have been reported in several studies as absent in a small minority of normal ears. Other studies have reported TEOAEs in all normal ears. Differences between studies may arise directly from criteria for TEOAE identification, criteria for selection of normals, or statistically due to limited sample sizes.

Effect of olivocochlear bundle section on evoked otoacoustic emissions recorded using maximum length sequences.

Presenting clicks according to maximum length sequences (MLS) enables transient evoked otoacoustic emissions (TEOAE) to be recorded at very high stimulation rates. As the click rate is increased from 40 clicks/s up to a maximum rate of 5000 clicks/s there is a reduction in TEOAE amplitude that reaches an approximate asymptote at 1500 clicks/s. One hypothesis put forward to explain this MLS 'rate effect' is that ipsilateral efferent activity is involved.

Unravelling the genetics of deafness.

Hearing-impaired mouse mutants not only are good models for human hereditary deafness, but also are extremely useful for understanding the molecular basis of the cochlear defect. We describe here how we identified the gene responsible for the deafness and vestibular defects in the shaker-1 mouse mutant as a myosin VII gene. Three different mutations, all causing the same phenotype in different lines of mouse, were found, providing good evidence that we had, indeed, found the correct gene.

Transient evoked otoacoustic emissions recorder using maximum length sequences as a function of stimulus rate and level.

Objective: The recently developed technique of recording transient evoked otoacoustic emissions (TEOAEs) using clicks presented according to maximum length sequences (MLSs) enables very high stimulation rates to be used. The aim of this study was to provide normative data on the relationship between TEOAEs recorded conventionally (at 40 clicks/sec) and those recorded using the MLS technique (at 11 maximum rates between 100 and 5000 clicks/sec) to establish a baseline for future clinical studies.

Design: TEOAEs were recorded at 12 rates from 12 normally hearing adult ears at click levels decreasing in 5 dB steps from 68 dB peSPL.

The acoustic reflex in adults with histories of otitis media in childhood.

Objective: To investigate the effects of a history of otitis media (OM) in childhood on the acoustic reflex threshold (ART) in young adults.

Design: Questionnaire responses on childhood ear and hearing problems were obtained from populations of university students. In Study 1, 31 students reporting histories of persistent childhood OM and 34 students with no known OM histories were identified.

A critical review of the role of neonatal hearing screening in the detection of congenital hearing impairment.

Background: This review was commissioned because of the increasing doubt about the ability of existing screening programmes (mainly the health visitor distraction test (HVDT) at 7-8 months) to identify children with congenital hearing impairment, and technological advances which have made neonatal hearing screening an alternative option.

Objectives: To review the available literature on the screening of permanent childhood hearing impairment. To provide commissioners and providers of health care with information about how to deliver a more uniform service, better outcomes, and more cost-effective screening.

Paradigms and paradoxes: mouse (and human) models of genetic deafness.

Mouse models have proved valuable tools in the analysis of human genetic disorders. The identification of the genes mutated in classical mouse mutants and the analysis of the phenotype of mutants following targeted gene disruption have provided some clarification of the development and functioning of the inner ear. A number of these genes also play a role in human deafness.