Kurt Stephan

Congenital Deafness and Sinoatrial Node Dysfunction in Mice Lacking Class D L-Type Ca2+ Channels

Voltage-gated L-type Ca2+ channels (LTCCs) containing a pore-forming alpha1D subunit (D-LTCCs) are expressed in neurons and neuroendocrine cells. Their relative contribution to total L-type Ca2+ currents and their physiological role and significance as a drug target remain unknown. Therefore, we generated D-LTCC deficient mice (alpha1D-/-) that were viable with no major disturbances of glucose metabolism. alpha1D-/-mice were deaf due to the complete absence of L-type currents in cochlear inner hair cells and degeneration of outer and inner hair cells. In wild-type controls, D-LTCC-mediated currents showed low activation thresholds and slow inactivation kinetics. Electrocardiogram recordings revealed sinoatrial node dysfunction (bradycardia and arrhythmia) in alpha1D-/- mice. We conclude that alpha1D can form LTCCs with negative activation thresholds essential for normal auditory function and control of cardiac pacemaker activity.

Acute Otitis Externa: Efficacy and Tolerability of N-Chlorotaurine, a Novel Endogenous Antiseptic Agent†

Objective: The studys objective was to test the tolerability and efficacy of the endogenous antiseptic N‐chlorotaurine (NCT) in comparison with a standard clinical treatment according to a phase IIb clinical trial protocol.

Post-operative Stapedius Reflex Tests with Simultaneous Loudness Scaling in Patients Supplied with Cochlear Implants

The estimation of the maximum comfort loudness levels (MCL) by measurements of the electrically elicited stapedius reflex was examined in six experienced cochlear implant users supplied with the COMBI 40 implant system. The stapedius reflex was tested and loudness scaling was performed simultaneously using an up/down stimulation protocol close to the reflex threshold with automated recording of both test procedures. The electrical stapedius reflex threshold (ESRT) and loudness scaling were evaluated separately. Scaling at the reflex threshold ranged between normal and loud. The range of stimulus intensities corresponding to ESRT is much smaller than that at a particular loudness category. The overall correlation between ESRT and MCL was high (r=0.92), with a similar dependence of ESRT and MCL on the channel stimulated. Thus, when the stapedius reflex can be detected post-op-eratively, the ESRT can be applied successfully for the fitting procedure of the speech processor. Simultaneous loudness scaling during the entire reflex test showed that overstimulation via the implant can be avoided effectively.

Stapedius Reflex Threshold in Cochlear Implant Patients

The contralateral stapedius reflex elicited by sinusoidal electrostimulation via cochlear implant was investigated in 12 patients. Contraction of the middle ear muscle was monitored by time-resolved synchronized digital sampling of the impedance change in the contralateral ear. The reflex was detected in all patients in whom the uncomfortable loudness level (UCLL) could be reached and who had intact middle ear function. Generally, the reflex threshold is located in the upper part of the dynamic range between the most comfortable loudness (MCL) and the UCLL. The demonstrated method may provide suitable assistance in speech processor adjustment in difficult-to-test patients.

Optimierung des Hörscreenings mittels Transient evozierter otoakustischer Emissionen (TEOAE) bei Neugeborenen

ZusammenfassungDie Akzeptanz otoakustischer Emissionen (OAE) als flächendeckendes Hörscreening bei Neugeborenen wird mit einem möglichst geringen Prozentsatz von nicht bestandenen Hörtests steigen. Ziel der vorliegenden Untersuchung war es deshalb, Ergebnisse der Messung von OAE in Hinblick auf ein praktikables Screening zu analysieren, den Test zu modifizieren und die Praktikabilität der Modifikation zu überprüfen. Die Optimierung wurde erzielt durch 1. Bewertung des Tests als bestanden sobald OAE auf einem Ohr nachweisbar sind, 2. Messung erst ab dem 2. Tag post partum und 3. Wiederholung des Tests bereits innerhalb von 1–2 Tagen, wenn auf keiner Seite OAE nachweisbar waren.3690 gesunde Neugeborene und 243 intensivpflichtige Neugeborene wurden dem Siebtest mit dem System ILO88 im Modus Quick-check zugeführt, an insgesamt 3820 Kindern wurde der Test vollständig, d.h. unter Berücksichtigung von Punkt 3 durchgeführt.Bei den gesunden Neugeborenen konnte unter Berücksichtigung dieser 3 Modifikationen der Prozentsatz mit bestandenen Hörtests von 79,5% auf über 99% erhöht werden. Somit mußten nur 0,7% der gesunden Neugeborenen einer weiteren Abklärung zugeführt werden; bei den intensivpflichtigen Neugeborenen waren 3,8% weiter abklärungsbedürftig.Die Ergebnisse zeigen, daß die von uns vorgeschlagenen Modifikationen zu einer Erhöhung der Spezifität des Hörscreenings mittels OAE und damit zu einer Verringerung der Anzahl der Kinder, die einer Abklärung zugeführt werden müssen, beitragen.SummaryOne of the major drawbacks using transient evoked otoacoustic emissions (TEOAEs) for hearing screening in newborn infants is the high fail rate in normal-hearing children. The purpose of the present study was to improve the overall performance of the test procedure and reduce of the fail rate. Improvement was obtained by 3 modifications: (1) change of the pass criterion in healthy newborns by requiring TEOAEs in at least one ear and nor both ears, (2) performing the test only after the second post-partum day, and (3) using a second-stage screening prior to hospital discharge in new-borns who failed the initial test. In all, 3980 newborns from 2 well-baby clinics and 243 new-borns from a neonatal intensive care unit (NICU) were screened using an system ILO-88 system program mode quick-check test was completed in 3820 infants. Considering these modifications, the pass rate of healthy new-borns was improved from 79.5% to >99%, and only 0.7% of the false-negative (healthy) new-borns required further audiological evaluation. Babies from the NICU failed in 3.8% of the screening tests. Overall, the number of new-borns who failed the ILO-88 screening test was significantly reduced and the fail rate minimize when compared to previously published experiences with TEOAEs in new-born hearing screening.

Confirmation of Transiently Evoked Otoacoustic Emissions Based on User-Independent Criteria

Transiently evoked otoacoustic emissions (TEOAEs) were recorded from 525 ears (children, 3-11 years). Based on visual evaluation, the recordings were classified as TEOAEs present, absent or uncertain. Within each group the distribution of response level and reproducibility as well as of four derived parameters were calculated. The latter comprised: (1) corrected response level (difference between response level and approximated noise), (2) weighted response level (product of response level and correlation), (3) weighted sound pressure of the response (product of sound pressure and correlation) and (4) level of the weighted sound pressure of the response (weighted sound pressure of the response transformed to decibels). Based on these distributions, criteria to separate recordings with TEOAEs from recordings without TEOAEs were established. In this study the cutoff point is the parameter value where the amount of incorrectly identified recordings with TEOAEs is equal to the amount of correctly identified recordings without TEOAEs. The corresponding limiting values are: (a) response level 7.3 dB with 7.6% incorrect identifications for each group, (b) reproducibility 56% with 4.2% incorrect identifications, (c) corrected response level 2.4 dB with 5% incorrect identifications, (d) weighted response level 3.7 dB with 3.2% of incorrect identifications, (e) sound pressure of the response 0.027 mPa with 2% incorrect identifications and (f) level of the weighted sound pressure of the response 1.22 dB with 2% incorrect identifications.

The fetus and noise

From 23 weeks of gestation some and from 28 weeks all healthy fetuses are capable of reacting to sound stimulation. The intrauterine acoustic environment is dominated by maternal sounds--heartbeat, breathing, the mothers voice, borborygmi and sounds caused by body movements. Background noise is never below 28 dB and can rise to 84 dB when the mother is singing. Noises that are meant to reach the fetus must be louder than the background noise and must be of low frequency as high frequency sounds are damped by maternal tissue. Vibroacoustic stimulation tests (VAST) have become popular in pregnancy surveillance over the last 20 years, mostly using an artificial larynx. Advantages and problems of the various VAST protocols in fetal monitoring are discussed in the light of animal experiments and clinical studies. Health legislation laws in most countries forbid pregnant women to work in surroundings with a high noise level (80 dB continuous noise and/or rapid impulse noise changes of 40 dB). Whereas regulations for pregnant women are easy to enforce in industry, pregnant women employed in discos or performing as musicians spend most of their working day exposed to noise impact higher than the recommended limit.

Stapedius reflex growth function in cochlear implant patients

The growth function of the contralateral stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 9 patients and compared to reflex functions obtained for acoustic stimulation in 3 normal-hearing subjects. Sinusoidal signal bursts with the same time pattern were used for the two stimulation modes, the contraction of the middle ear muscle was monitored by sampling the compliance change in the contralateral ear. The reflex amplitudes were found to increase with increasing stimulus intensity in all individuals except in 1 with electrical stimulation. The slope of the intensity function for electrostimulation ranged between 5 and 85%/dB and in the acoustical mode between 2 and 4%/dB. In case of electrostimulation a frequency effect was observed.

Quality standards for bone conduction implants

Abstract Conclusion: Bone conduction implants are useful in patients with conductive and mixed hearing loss for whom conventional surgery or hearing aids are no longer an option. They may also be used in patients affected by single-sided deafness. Objectives: To establish a consensus on the quality standards required for centers willing to create a bone conduction implant program. Method: To ensure a consistently high level of service and to provide patients with the best possible solution the members of the HEARRING network have established a set of quality standards for bone conduction implants. These standards constitute a realistic minimum attainable by all implant clinics and should be employed alongside current best practice guidelines. Results: Fifteen items are thoroughly analyzed. They include team structure, accommodation and clinical facilities, selection criteria, evaluation process, complete preoperative and surgical information, postoperative fitting and assessment, follow-up, device failure, clinical management, transfer of care and patient complaints.

Hearing preservation cochlear implantation in children: The HEARRING Group consensus and practice guide

Objectives: To provide multidisciplinary cochlear implant teams with a current consensus statement to support hearing preservation cochlear implantation (HPCI) in children, including those children with symptomatic partial deafness (PD) where the intention is to use electric-acoustic stimulation (EAS). The main objectives are to provide guidelines on who is a candidate, how to assess these children and when to implant if Med-El Flex electrode arrays are chosen for implantation. Methods: The HEARRING group reviewed the current evidence and practice regarding the management of children to be considered for HPCI surgery emphasizing the assessment needed prior to implantation in order to demonstrate the benefits in these children over time. The consensus statement addresses following three key questions: (1) Should these children be treated? (2) How to identify these children? (3) How to manage these children? Summary: The HEARRING group concludes that irrespective of the degree of residual hearing present, the concepts of hearing and structure preservation should be applied in every child undergoing cochlear implantation and that HPCI is a safe and reliable treatment option. Early detection and multidisciplinary assessment are key to the identification of children with symptomatic PD, these children should undergo HPCI as early as possible.