Short-time cold atmospheric pressure plasma exposure can kill all life stages of the poultry red mite, Dermanyssus gallinae, under laboratory conditions.

In the present study, the acaricidal effects of cold atmospheric pressure plasma treatment on poultry red mites of different developmental stages have been investigated under laboratory conditions using a dielectric barrier discharge system. A total of 1890 poultry red mites and 90 mite eggs, respectively, were exposed to the plasma under various parameter settings with a single plasma pulse generated using the gas mixture of the ambient air at atmospheric pressure. The results showed that all developmental stages of the poultry red mite could be killed by cold atmospheric pressure plasma treatment. Plasma exposure to mite eggs resulted in a complete 100% hatch inhibition regardless of the parameter settings. Post-exposure mortality rates of larvae, nymphs and adults showed significant differences after utilization of plasma at 10 W for 1.0 s. In addition, the mortality rate increased with progressing time after plasma exposure. An average mortality rate of 99.7% was observed after 12 h in all mites exposed to plasma, regardless of the selected plasma parameter, developmental stage, and nutritional status of the mites. Cold atmospheric pressure plasma has an acaricidal effect on all developmental stages of Dermanyssus gallinae, suggesting that it could be developed to an effective method for the control of poultry red mites in laying hen husbandry.

Identification of risk factors for residual cholesteatoma in children and adults: a retrospective study on 110 cases of revision surgery / Identificação de fatores de risco para colesteatoma residual em crianças e adultos: um estudo retrospectivo de 110 casos de cirurgia revisionais

Abstract Introduction: Residual disease after cholesteatoma removal is still a challenge for the otorhinolaryngologist. Scheduled "second-look" surgery and, more recently, radiological screenings are used to identify residual cholesteatoma as early as possible. However, these procedures are cost-intensive and are accompanied by discomfort and risks for the patient. Objective: To identify anamnestic, clinical, and surgery-related risk factors for residual cholesteatoma. Methods: The charts of 108 patients, including children as well as adults, having undergone a second-look or revision surgery after initial cholesteatoma removal at a tertiary referral hospital, were analyzed retrospectively. Results: Gender, age, mastoid pneumatization, prior ventilation tube insertion, congenital cholesteatoma, erosion of ossicles, atticotomy, resection of chorda tympani, different reconstruction materials, and postoperative otorrhea did not emerge as statistically significant risk factors for residual disease. However, prior adenoid removal, cholesteatoma growth to the sinus tympani and to the antrum and mastoid, canal-wall-up 2 ways approach, and postoperative retraction and perforation were associated with a statistically higher rate of residual disease. A type A tympanogram as well as canal-wall-down plus reconstruction 2 ways approach for extended epitympanic and for extended epitympanic and mesotympanic cholesteatomas were associated with statistically lower rates of residual disease. A score including the postoperative retraction or perforation of the tympanic membrane, the quality of the postoperative tympanogram and the intraoperative extension of the cholesteatoma to the sinus tympani and/or the antrum was elaborated and proved to be suitable for predicting residual cholesteatoma with acceptable sensitivity and high specificity. Conclusion: Cholesteatoma extension to the sinus tympani, antrum and mastoid makes a residual disease more likely. The canal-wall-down plus reconstruction 2 ways approach seems safe with similar rates of residual cholesteatoma and without the known disadvantages of canal-wall-down surgery. The described score can be useful for identifying patients who need a postoperative radiological control and a second-look surgery.

Resumo Introdução: A doença residual após a remoção do colesteatoma ainda é um desafio para o otorrinolaringologista. A cirurgia revisional programada e, mais recentemente, exames radiológicos são usados para identificar o colesteatoma residual o mais precocemente possível. Entretanto, esses procedimentos são dispendiosos e acompanhados de desconforto e riscos para o paciente. Objetivo: Identificar fatores de risco anamnésicos, clínicos e relacionados à cirurgia para o colesteatoma residual. Método: Foram analisados retrospectivamente os prontuários de 108 pacientes, crianças e adultos, que passaram por revisão cirúrgica após a remoção inicial do colesteatoma em um hospital terciário de referência. Resultados: Sexo, idade, pneumatização da mastoide, inserção anterior de tubo de ventilação, colesteatoma congênito, erosão dos ossículos, aticotomia, ressecção da corda do tímpano, diferentes materiais de reconstrução e otorreia pós-operatória não se mostraram fatores de risco estatisticamente significantes para a ocorrência de doença residual. Entretanto, remoção prévia da adenoide, crescimento do colesteatoma para o interior do seio timpânico e para o antro e a mastoide, abordagem de duas vias com canal wall-up e retração e perfuração pós-operatórias foram associados a uma taxa estatisticamente maior de doença residual. Um timpanograma tipo A, assim como a reconstrução de duas vias com a abordagem canal wall-down para colesteatomas com extensão para o recesso epitimpânico e/ou extensão epitimpânica e mesotimpânica, foram associados com taxas estatisticamente menores da doença residual. Um escore, que incluiu a retração ou perfuração pós-operatória da membrana timpânica, a qualidade do timpanograma pós-operatório e a extensão intraoperatória do colesteatoma para o seio timpânico e/ou antro, foi elaborado e se mostrou adequado para predizer colesteatoma residual com sensibilidade aceitável e alta especificidade. Conclusão: A extensão do colesteatoma para o seio timpânico, antro e mastoide torna a doença residual mais provável. A abordagem do tipo canal wall-down mais a reconstrução de 2 vias parecem seguras com taxas semelhantes de colesteatoma residual e sem as desvantagens conhecidas da cirurgia do tipo canal wall-down. O escore descrito pode ser útil para identificar pacientes que necessitam de controle radiológico pós-operatório e cirurgia revisional.

Identification of risk factors for residual cholesteatoma in children and adults: a retrospective study on 110 cases of revision surgery.

INTRODUCTION: Residual disease after cholesteatoma removal is still a challenge for the otorhinolaryngologist. Scheduled "second-look" surgery and, more recently, radiological screenings are used to identify residual cholesteatoma as early as possible. However, these procedures are cost-intensive and are accompanied by discomfort and risks for the patient. OBJECTIVE: To identify anamnestic, clinical, and surgery-related risk factors for residual cholesteatoma. METHODS: The charts of 108 patients, including children as well as adults, having undergone a second-look or revision surgery after initial cholesteatoma removal at a tertiary referral hospital, were analyzed retrospectively. RESULTS: Gender, age, mastoid pneumatization, prior ventilation tube insertion, congenital cholesteatoma, erosion of ossicles, atticotomy, resection of chorda tympani, different reconstruction materials, and postoperative otorrhea did not emerge as statistically significant risk factors for residual disease. However, prior adenoid removal, cholesteatoma growth to the sinus tympani and to the antrum and mastoid, canal-wall-up 2 ways approach, and postoperative retraction and perforation were associated with a statistically higher rate of residual disease. A type A tympanogram as well as canal-wall-down plus reconstruction 2 ways approach for extended epitympanic and for extended epitympanic and mesotympanic cholesteatomas were associated with statistically lower rates of residual disease. A score including the postoperative retraction or perforation of the tympanic membrane, the quality of the postoperative tympanogram and the intraoperative extension of the cholesteatoma to the sinus tympani and/or the antrum was elaborated and proved to be suitable for predicting residual cholesteatoma with acceptable sensitivity and high specificity. CONCLUSION: Cholesteatoma extension to the sinus tympani, antrum and mastoid makes a residual disease more likely. The canal-wall-down plus reconstruction 2 ways approach seems safe with similar rates of residual cholesteatoma and without the known disadvantages of canal-wall-down surgery. The described score can be useful for identifying patients who need a postoperative radiological control and a second-look surgery.

Influence of Cochlear Implantation on Postural Control and Risk of Falls.

BACKGROUND: Cochlear implantation is an important method of hearing rehabilitation. Earlier studies have shown the influence of implantation on the vestibular system. However, until now, the effect of hearing rehabilitation with cochlear implants (CI) on postural control and body stability has not been sufficiently studied. OBJECTIVE: To analyse the effect of hearing rehabilitation with activated CI and different sound inputs (music, speech text, and white noise) on postural control and risk of falls after implantation. METHODS: This was a prospective clinical trial that included 33 adult patients with at least 6 months' use of a CI (mean time after implantation = 23 months). All patients underwent a standard or geriatric (for patients >60 years) balancing deficit test protocol with a mobile posturography system (VertiGuard®) in different situations (CI deactivated/activated and different sound inputs). As the main outcome measure, the risk of falls (%) after each protocol was calculated by evaluating body sway both forward to backward and side to side (°/s). RESULTS: With the CI deactivated, the mean risk of falls was 45.5%. After activation of the CI, there was a small decrease in the mean risk of falls, but it was statistically significant. With an additional sound input (music or speech text) this decrease was more pronounced: 42.0 and 42.4%, respectively. This effect seems to be more pronounced in older patients. Regarding the individual patients, 72% had an improvement in the risk of falls with an activated CI, and 28% had a slight deterioration. An activated CI accompanied by sound input (music) further improved the individual risk of falls. CONCLUSIONS: Compared with prior research, this study found that the risk of falls after implantation decreased over a longer time period. Furthermore, the use of a CI and different sound inputs had a positive effect on postural control. These findings support the need for optimal hearing rehabilitation, especially in elderly patients. Although this effect is relatively small, it is important to consider for further studies that rehabilitation with CI may reduce the risk of falls. While the auditory system supposedly contributes to postural control only to a small degree and the mechanism is still poorly understood, further studies with bigger samples are warranted to clarify these effects.

Cochlear Implant Surgery and the Risk of Falls in an Adult Population.

OBJECTIVE: To determine the effect of cochlear implant surgery on the balance and risk of falls in an adult patient population using a mobile posturograph. DESIGN: Prospective clinical pilot study. SETTING: Cochlear implant center at a tertiary referral hospital. SUBJECTS AND METHODS: Twenty adult patients undergoing cochlear implant surgery were tested using a mobile posturograph (VertiGuard). The standard balancing deficit test, or the geriatric standard balancing deficit test protocol (for patients older than 60 yr), was performed both 1 day before and 3 to 5 days after surgery. OUTCOME MEASURES: The risk of falls (%) was calculated from the body sway both forward-to-backward and side-to-side in degrees per second. RESULTS: The mean preoperative risk of falls in the whole study population was 51% (24-max. 86%) and was thus already higher than that in a normal healthy population (norm 0-40%). Comparison of the postoperative risk of falls to the preoperative risk for all 20 patients revealed a mean increased risk of falls of 1.25% after CI surgery. This is not a statistically significant increase. There was also no statistically significant increase when comparing the fall risk calculated using either the standard balancing deficit test protocol or the geriatric standard balancing deficit test protocol alone. CONCLUSION: Postural control in cochlear implant candidates is already decreased before surgery compared with a healthy population. However Comparison of pre- and postoperative body sway measurements did not reveal a significant increase in fall risk as a result of cochlea implant surgery. Therefore in this study population, cochlear implant surgery did not influence balance and risk of falls. Further testing with a larger study population would be necessary to determine the development of falls risk over time after cochlear implant surgery.

Laser-assisted fixation of a nitinol stapes prosthesis.

BACKGROUND AND OBJECTIVE: Otosclerosis is an inner ear bone disease characterized by fixation of the stapes and consequently progressive hearing loss. One treatment option is the surgical replacement of the stapes by a prosthesis. When so called "smart materials" like nitinol are used, prosthesis fixation can be performed using a laser without manual crimping on the incus. However, specific laser-prosthesis interactions have not been described yet. The aim of the present study was to elucidate the thermo-mechanical properties of the NiTiBOND® prosthesis as a basis for handling instructions for laser-assisted prosthesis fixation. STUDY DESIGN AND MATERIALS AND METHODS: Closure of the NiTiBOND® prosthesis was induced ex vivo by either a diode laser emitting at λ = 940 nm or a CO2 laser (λ = 10,600 nm). Total energy for closure was determined. Suitable laser parameters (pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis) were assessed. Specific laser-prosthesis interactions were recorded. RESULTS: Especially the diode laser was found to be an appropriate energy source. A total energy deposit of 60 mJ by pulses in near contact application was found to be sufficient for prosthesis closure ex vivo. Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter. Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account. CONCLUSION: NiTiBOND® stapes prosthesis can be closed by very little energy when appropriate energy sources like diode lasers are used, suggesting a relatively safe application in vivo. Lasers Surg. Med. 50:153-157, 2018. © 2017 Wiley Periodicals, Inc.

A Comparison of Distortion Product Otoacoustic Emission Properties in Ménière's Disease Patients and Normal-Hearing Participants.

OBJECTIVES: Postmortem examination of temporal bones of Ménière's disease patients consistently show dilated endolymphatic spaces of the inner ear, for which the term endolymphatic hydrops has been coined. During the past decade, magnetic resonance imaging techniques for the inner ear appeared, advancing the diagnosis of Ménière's disease. They require, however, a field-strength of at least 3 T, are costly and not universally available. Alternative, noninvasive, cost-effective tests with high sensitivity and specifity for endolymphatic hydrops are desirable. In this study, we test the suitability of distortion product otoacoustic emissions (DPOAEs) for endolymphatic hydrops detection. Previous measurements of the commonly recorded cubic DPOAEs mainly register cochlear hearing loss and are not specific for Ménière's disease. Simultaneous recordings of cubic and quadratic DPOAEs might be more suitable to detect endolymphatic hydrops, because both DPOAE orders react differently to changes of the cochlear operating point as they might occur in Ménière's disease patients. DESIGN: Cubic and quadratic DPOAEs were recorded in normal-hearing participants (N = 45) and in the affected and unaffected ears of patients with a diagnosis of definite Ménière's disease (N = 32). First, to assess the integrity of DPOAE-generating mechanisms, cubic DPOAE-grams were obtained with primary tone frequencies f2 between 1 and 8 kHz with primary tone levels l1 = 60 dB SPL and l2 = 50 dB SPL, and a fixed primary tone frequency ratio of 1.22. Then, cubic and quadratic DPOAEs were simultaneously recorded with primary tone levels l1 = l2 = 65 dB SPL and at primary tone frequencies f2 = 4 and 5 kHz, where f1 was successively varied such that the ratio f2/f1 ranged between 1.1 and 1.6 in 0.04 steps while quadratic and cubic DPOAE levels were extracted from the same recording. RESULTS: Cubic DPOAEs were significantly reduced in the affected ears of Ménière's disease patients, and slightly reduced in the unaffected ears of Ménière's disease patients, relative to the ears of normal-hearing participants. In contrast, no significant changes could be seen in quadratic DPOAEs across the ears of normal-hearing participants and Ménière's disease patients. CONCLUSIONS: We could identify a relatively good preservation of quadratic DPOAE levels in relation to a reduction of cubic DPOAE levels as a potential noninvasive diagnostic approach in the early stage of suspected Ménière's disease. Future studies validating the differential diagnostic power of this parameter in control groups with nonhydropic forms of hearing loss are warranted.

Patient benefit from Cochlear implantation in single-sided deafness: a 1-year follow-up.

The objective of the study was to evaluate the quality of life and benefit in patients with single-side deafness before and 1 year after cochlear implantation. In a prospective observational study design, ten adult patients with single-sided deafness undergoing cochlear implantation were included. All patients had on the implantation side no speech discrimination with normal hearing aids. The contralateral side was normal or marginal hearing loss. For determining the subject benefit from cochlear implantation, each patient answered standardized questionnaires directly before implantation and 1 year after. Regarding the questionnaire Speech, Spatial and Qualities of Hearing (SSQ), the tests yielded a significant difference in the subdomains "speech intelligibility" and "spatial hearing". The Nijmegen Cochlear Implant Questionnaire (NCIQ) showed a significant difference in the subdomain "basic sound perception", but not in the total score. The Glasgow Hearing Aid Benefit Profile (GHABP) showed on average moderate satisfaction in the subdomains "hearing aid benefit" and "residual disability". In general quality of life, no significant difference was found measured by the questionnaire EQ-5D-3L. One year after cochlear implantation, most patients with single-sided deafness showed benefits in hearing as measured by validated questionnaires However, not all patients reported a significant improvement in general quality of life. Therefore, it is important to inform patients adequately and offer alternative treatments before implantation.

Effect of Spatial Orientation of the Horizontal Semicircular Canal on the Vestibulo-Ocular Reflex.

OBJECTIVE: To determine if an alignment of the horizontal semi-circular canal (hSCC) with the plane of rotation would enhance the vestibular-ocular reflex (VOR) gain result as it has been previously suggested. STUDY DESIGN: Comparative study of a physiological vestibular function test in healthy subjects. SETTING: Tertiary referral center for otology and neurotology. PATIENTS: Twenty two healthy volunteers were recruited for this study. Their mean age was 25.6 years and the sex distribution was 14:8 (M:F). None of the subjects had a history of audiovestibular disorders. INTERVENTION: The video Head Impulse Test (v-HIT) was performed with the hSCC in the conventional position (head upright, horizontal gaze) and also with the hSCC in-line with the earth horizontal. MAIN OUTCOME MEASURES: depending on the alignment of the hSCC with the plane of head rotation. RESULTS: There was no significant difference between the results, either for the VOR gain at 60 ms, or the regression slope gain, when the two alternative head positions were compared. CONCLUSIONS: The data acquired in this study show that the VOR as measured by the v-HIT is not enhanced by aligning the plane of the hSCC with the plane of rotation during the testing procedure. Hence, we recommend that the positioning of the patient, with the head upright and a horizontal gaze direction should be routinely used in the clinical evaluation of the angular VOR by v-HIT.

Aftereffects of Intense Low-Frequency Sound on Spontaneous Otoacoustic Emissions: Effect of Frequency and Level.

The presentation of intense, low-frequency (LF) sound to the human ear can cause very slow, sinusoidal oscillations of cochlear sensitivity after LF sound offset, coined the "Bounce" phenomenon. Changes in level and frequency of spontaneous otoacoustic emissions (SOAEs) are a sensitive measure of the Bounce. Here, we investigated the effect of LF sound level and frequency on the Bounce. Specifically, the level of SOAEs was tracked for minutes before and after a 90-s LF sound exposure. Trials were carried out with several LF sound levels (93 to 108 dB SPL corresponding to 47 to 75 phons at a fixed frequency of 30 Hz) and different LF sound frequencies (30, 60, 120, 240 and 480 Hz at a fixed loudness level of 80 phons). At an LF sound frequency of 30 Hz, a minimal sound level of 102 dB SPL (64 phons) was sufficient to elicit a significant Bounce. In some subjects, however, 93 dB SPL (47 phons), the lowest level used, was sufficient to elicit the Bounce phenomenon and actual thresholds could have been even lower. Measurements with different LF sound frequencies showed a mild reduction of the Bounce phenomenon with increasing LF sound frequency. This indicates that the strength of the Bounce not only is a simple function of the spectral separation between SOAE and LF sound frequency but also depends on absolute LF sound frequency, possibly related to the magnitude of the AC component of the outer hair cell receptor potential.

Residual Hearing Outcomes After Cochlear Implant Surgery Using Ultra-flexible 28-mm Electrodes.

OBJECTIVE: To evaluate the preservation of low frequency residual hearing after cochlear implant surgery using an electrode for atraumatic implantation and complete cochlear stimulation. STUDY DESIGN: Retrospective clinical record study. SETTING: Tertiary referral center. PATIENTS: Fifty-six patients with functional deafness who had undergone cochlear implant surgery and received a Flex electrode (MED-EL GmbH, Innsbruck, Austria) between 2011 and 2014. INTERVENTION: Audiometric testing was performed before surgery and at the time of initial fitting. MAIN OUTCOME MEASURE: Change in low frequency residual hearing measured by pure tone audiometry. RESULTS: Preoperative hearing was relatively poor. After surgery low frequency residual hearing was partially preserved in most cases, however there was a significant hearing loss at all frequencies compared with the preoperative state. In only 23% of all cases complete hearing preservation was observed. CONCLUSION: Despite the use of a flexible electrode, complete preservation of low frequency residual hearing can only be achieved in a minority of patients. The use of a full insertion electrode of 28 mm in patients with poor preoperative thresholds does not allow for usable additional hearing at present.

Atmospheric Pressure and Onset of Episodes of Menière's Disease - A Repeated Measures Study.

BACKGROUND: External changes of air pressure are transmitted to the middle and inner ear and may be used therapeutically in Menière's disease, one of the most common vertigo disorders. We analyzed the possible relationship of atmospheric pressure and other meteorological parameters with the onset of MD vertigo episodes in order to determine whether atmospheric pressure changes play a role in the occurrence of MD episodes. METHODS: Patients of a tertiary outpatient dizziness clinic diagnosed with MD were asked to keep a daily vertigo diary to document MD episodes (2004-2009). Local air pressure, absolute temperature and dew point temperature were acquired on an hourly basis. Change in meteorological parameters was conceptualized as the maximum difference in a 24 hour time frame preceding each day. Effects were estimated using additive mixed models with a random participant effect. We included lagged air parameters, age, sex, weekday and season in the model. RESULTS: A total of 56 persons (59% female) with mean age 54 years were included. Mean follow-up time was 267 days. Persons experienced on average 10.3 episodes during the observation period (median 8). Age and change in air pressure were significantly associated with vertigo onset risk (Odds Ratio = 0.979 and 1.010). We could not show an effect of sex, weekday, season, air temperature, and dew point temperature. CONCLUSIONS: Change in air pressure was significantly associated with onset of MD episodes, suggesting a potential triggering mechanism in the inner ear. MD patients may possibly use air pressure changes as an early warning system for vertigo attacks in the future.

Responses of the Human Inner Ear to Low-Frequency Sound.

The perceptual insensitivity to low frequency (LF) sound in humans has led to an underestimation of the physiological impact of LF exposure on the inner ear. It is known, however, that intense, LF sound causes cyclic changes of indicators of inner ear function after LF stimulus offset, for which the term "Bounce" phenomenon has been coined.Here, we show that the mechanical amplification of hair cells (OHCs) is significantly affected after the presentation of LF sound. First, we show the Bounce phenomenon in slow level changes of quadratic, but not cubic, distortion product otoacoustic emissions (DPOAEs). Second, Bouncing in response to LF sound is seen in slow, oscillating frequency and correlated level changes of spontaneous otoacoustic emissions (SOAEs). Surprisingly, LF sound can induce new SOAEs which can persist for tens of seconds. Further, we show that the Bounce persists under free-field conditions, i.e. without an in-ear probe occluding the auditory meatus. Finally, we show that the Bounce is affected by contralateral acoustic stimulation synchronised to the ipsilateral LF sound. These findings clearly demonstrate that the origin of the Bounce lies in the modulation of cochlear amplifier gain. We conclude that activity changes of OHCs are the source of the Bounce, most likely caused by a temporary disturbance of OHC calcium homeostasis. In the light of these findings, the effects of long-duration, anthropogenic LF sound on the human inner ear require further research.

Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Ménière's Disease Patients.

Tinnitus is one of the three classical symptoms of Ménière's disease (MD), an inner ear disease that is often accompanied by endolymphatic hydrops. Previous studies indicate that tinnitus in MD patients is dominated by low frequencies, whereas tinnitus in non-hydropic pathologies is typically higher in frequency. Tinnitus of rather low-frequency (LF) quality was also reported to occur for about 90 s in normal-hearing participants after presentation of intense, LF sound (120 dB SPL, 30 Hz, 90 s). LF sound has been demonstrated to also cause temporary endolymphatic hydrops in animal models. Here, we quantify tinnitus in two study groups with chronic (MD patients) and presumably transient endolymphatic hydrops (normal-hearing participants after LF exposure) with a psychophysical procedure. Participants matched their tinnitus either with a pure tone of adjustable frequency and level or with a noise of adjustable spectral shape and level. Sensation levels of matching stimuli were lower for MD patients (mean: 8 dB SL) than for normal-hearing participants (mean: 15 dB SL). Transient tinnitus after LF-exposure occurred in all normal-hearing participants (N = 28). About half of the normal-hearing participants matched noise to their tinnitus, the other half chose a pure tone with frequencies below 2 kHz. MD patients matched their tinnitus with either high-frequency pure tones, mainly above 3 kHz, or with a noise. Despite a significant proportion of MD patients matching low-pass (roaring) noises to their tinnitus, the range of matched stimuli was more heterogeneous than previous data suggested. We propose that in those participants with noise-like tinnitus, the percept is probably generated by increased spontaneous activity of auditory nerve fibers with a broad range of characteristic frequencies, due to an impaired ion balance in the cochlea. For tonal tinnitus, additional mechanisms are conceivable: focal hair cell loss can result in decreased auditory nerve firing and a central auditory overcompensation. Also, normal-hearing participants after LF-exposure experience alterations in spontaneous otoacoustic emissions, which may contribute to a transient tonal tinnitus.

Low-frequency sound exposure causes reversible long-term changes of cochlear transfer characteristics.

Intense, low-frequency sound presented to the mammalian cochlea induces temporary changes of cochlear sensitivity, for which the term 'Bounce' phenomenon has been coined. Typical manifestations are slow oscillations of hearing thresholds or the level of otoacoustic emissions. It has been suggested that these alterations are caused by changes of the mechano-electrical transducer transfer function of outer hair cells (OHCs). Shape estimates of this transfer function can be derived from low-frequency-biased distortion product otoacoustic emissions (DPOAE). Here, we tracked the transfer function estimates before and after triggering a cochlear Bounce. Specifically, cubic DPOAEs, modulated by a low-frequency biasing tone, were followed over time before and after induction of the cochlear Bounce. Most subjects showed slow, biphasic changes of the transfer function estimates after low-frequency sound exposure relative to the preceding control period. Our data show that the operating point changes biphasically on the transfer function with an initial shift away from the inflection point followed by a shift towards the inflection point before returning to baseline values. Changes in transfer function and operating point lasted for about 180 s. Our results are consistent with the hypothesis that intense, low-frequency sound disturbs regulatory mechanisms in OHCs. The homeostatic readjustment of these mechanisms after low-frequency offset is reflected in slow oscillations of the estimated transfer functions.

Concurrent Acoustic Activation of the Medial Olivocochlear System Modifies the After-Effects of Intense Low-Frequency Sound on the Human Inner Ear.

>Human hearing is rather insensitive for very low frequencies (i.e. below 100 Hz). Despite this insensitivity, low-frequency sound can cause oscillating changes of cochlear gain in inner ear regions processing even much higher frequencies. These alterations outlast the duration of the low-frequency stimulation by several minutes, for which the term 'bounce phenomenon' has been coined. Previously, we have shown that the bounce can be traced by monitoring frequency and level changes of spontaneous otoacoustic emissions (SOAEs) over time. It has been suggested elsewhere that large receptor potentials elicited by low-frequency stimulation produce a net Ca(2+) influx and associated gain decrease in outer hair cells. The bounce presumably reflects an underdamped, homeostatic readjustment of increased Ca(2+) concentrations and related gain changes after low-frequency sound offset. Here, we test this hypothesis by activating the medial olivocochlear efferent system during presentation of the bounce-evoking low-frequency (LF) sound. The efferent system is known to modulate outer hair cell Ca(2+) concentrations and receptor potentials, and therefore, it should modulate the characteristics of the bounce phenomenon. We show that simultaneous presentation of contralateral broadband noise (100 Hz-8 kHz, 65 and 70 dB SPL, 90 s, activating the efferent system) and ipsilateral low-frequency sound (30 Hz, 120 dB SPL, 90 s, inducing the bounce) affects the characteristics of bouncing SOAEs recorded after low-frequency sound offset. Specifically, the decay time constant of the SOAE level changes is shorter, and the transient SOAE suppression is less pronounced. Moreover, the number of new, transient SOAEs as they are seen during the bounce, are reduced. Taken together, activation of the medial olivocochlear system during induction of the bounce phenomenon with low-frequency sound results in changed characteristics of the bounce phenomenon. Thus, our data provide experimental support for the hypothesis that outer hair cell calcium homeostasis is the source of the bounce phenomenon.

Hearing function after intratympanic application of gadolinium-based contrast agent: A long-term evaluation.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate the long-term influence of intratympanic gadolinium-based contrast agent on hearing function in patients with possible Ménière's disease and normal auditory thresholds who were undergoing locally enhanced magnetic resonance imaging scans. STUDY DESIGN: Prospective observational cohort study in a tertiary referral university hospital ear, nose, and throat department. METHODS: Between 2009 and 2012, 17 patients with possible or probable Ménière's disease and a four-tone pure-tone average baseline of <25 dB were recruited for our study. Before undergoing intratympanic injection of gadolinium-based contrast agent, all patients underwent a complete audiological evaluation. The study population was then invited back after at least 6 months postinjection for a follow-up auditory evaluation. This consisted of comprehensive clinical and audiological tests on both sides and were evaluated according to the ototoxicity guidelines. RESULTS: A long-term evaluation of our study group revealed no significant difference in the air-conduction pure-tone average. Furthermore, no statistical difference at individual frequencies compared to baseline was found. There was no evidence of ototoxicity in the injected ear. CONCLUSIONS: Long-term hearing function assessment after intratympanic application of gadolinium-based agent showed no evidence of ototoxicity. The use of intratympanic gadolinium-based agent in the diagnosis of Ménièrés disease is currently a helpful tool, and seems to be a safe method, especially with regard to auditory function. LEVEL OF EVIDENCE: 4.

Influence of insertion depth in cochlear implantation on vertigo symptoms and vestibular function.

OBJECTIVES: The aim of the present study was to investigate the effect of the electrode insertion depth in vestibular function after cochlear implantation. MATERIAL AND METHODS: In a retrospective observational study design, 41 adult patients who had undergone cochlear implantation between 2006 and 2012 at a tertiary referral university hospital were included. The postoperative performed radiograph images of the petrous bone were acquired according to the Stenvers method. These were analyzed to determine electrode insertion depth. Pre- and postoperative subjective vertigo symptoms were assessed by a questionnaire. The function of the horizontal semi-circular canal was evaluated by caloric irrigation and the function of the sacculus was tested by using cervical vestibular evoked myogenic potentials pre- and postoperatively. RESULTS: The average electrode insertion depth was 464°. A certain variability of insertion depth existed among the different electrodes according to their designs. No statistical difference of the insertion depth was found between patients with or without vertigo. There was also no correlation between electrode insertion depth and alterations of the measurable vestibular function. CONCLUSION: In our study the variability of insertion depth didn't have a significant influence on subjective vertigo, horizontal semi-circular canal function or saccular function. Plain radiography is a rapid, simple and cost-effective method to determine electrode insertion depth after implantation. However the scalar position of the electrode cannot be analyzed in plain radiography, so that an interscalar dislocation as a possible influence in vestibular function remains undetected.

Cochlear implantation is safe and effective in patients with MYH9-related disease.

BACKGROUND: MYH9-related disease (MYH9-RD) is a rare syndromic disorder deriving from mutations in MYH9, the gene for the heavy chain of non-muscle myosin IIA. Patients present with congenital thrombocytopenia and giant platelets and have a variable risk of developing sensorineural deafness, kidney damage, presenile cataract, and liver abnormalities. Almost all MYH9-RD patients develop the hearing defect, which, in many individuals, progresses to severe to profound deafness with high impact on quality of life. These patients are potential candidates for cochlear implantation (CI), however, no consistent data are available about the risk to benefit ratio of CI in MYH9-RD. The only reported patient who received CI experienced perisurgery complications that have been attributed to concurrent platelet defects and/or MYH9 protein dysfunction. METHODS: By international co-operative study, we report the clinical outcome of 10 patients with MYH9-RD and severe to profound deafness who received a CI at 8 institutions. RESULTS: Nine patients benefited from CI: in particular, eight of them obtained excellent performances with restoration of a practically normal hearing function and verbal communication abilities. One patient had a slightly worse performance that could be explained by the very long duration of severe deafness before CI. Finally, one patient did not significantly benefit from CI. No adverse events attributable to MYH9-RD syndrome were observed, in particular no perisurgery bleeding complications due to the platelet defects were seen. Patients' perioperative management is described and discussed. CONCLUSIONS: CI is safe and effective in most patients with MYH9-RD and severe to profound deafness and should be offered to these subjects, possibly as soon as they develop the criteria for candidacy.