An individualized, sensitive frequency range for early detection of ototoxicity

Effects of Stimulus Type on 16-kHz Detection Thresholds

OBJECTIVES

Audiometric testing typically does not include frequencies above 8 kHz. However, recent research suggests that extended high-frequency (EHF) sensitivity could affect hearing in natural communication environments. Clinical assessment of hearing often employs pure tones and frequency-modulated (FM) tones interchangeably regardless of frequency. The present study was designed to evaluate how the stimulus chosen to measure EHF thresholds affects estimates of hearing sensitivity.

DESIGN

The first experiment used standard audiometric procedures to measure 8- and 16-kHz thresholds for 5- to 28-year olds with normal hearing in the standard audiometric range (250 to 8000 Hz). Stimuli were steady tones, pulsed tones, and FM tones. The second experiment tested 18- to 28-year olds with normal hearing in the standard audiometric range using psychophysical procedures to evaluate how changes in sensitivity as a function of frequency affect detection of stimuli that differ with respect to bandwidth, including bands of noise. Thresholds were measured using steady tones, pulsed tones, FM tones, narrow bands of noise, and one-third-octave bands of noise at a range of center frequencies in one ear.

RESULTS

In experiment 1, thresholds improved with increasing age at 8 kHz and worsened with increasing age at 16 kHz. Thresholds for individual participants were relatively similar for steady, pulsed, and FM tones at 8 kHz. At 16 kHz, mean thresholds were approximately 5 dB lower for FM tones than for steady or pulsed tones. This stimulus effect did not differ as a function of age. Experiment 2 replicated this greater stimulus effect at 16 kHz than at 8 kHz and showed that the slope of the audibility curve accounted for these effects.

CONCLUSIONS

Contrary to prior expectations, there was no evidence that the choice of stimulus type affected school-age children more than adults. For individual participants, audiometric thresholds at 16 kHz were as much as 20 dB lower for FM tones than for steady tones. Threshold differences across stimuli at 16 kHz were predicted by differences in audibility across frequency, which can vary markedly between listeners. These results highlight the importance of considering spectral width of the stimulus used to evaluate EHF thresholds.

Extended High-Frequency Audiometry for Ototoxicity Monitoring: A Longitudinal Evaluation of Drug-Resistant Tuberculosis Treatment

PURPOSE

The aim of this study was to describe extended high-frequency (EHF) pure-tone audiometry monitoring of ototoxicity in a longitudinal treatment program for drug-resistant tuberculosis (DRTB).

METHOD

This was a retrospective record review of longitudinal conventional (0.25-8 kHz) and EHF (9-16 kHz) audiometry for ototoxicity monitoring of DRTB patients undergoing treatment at community-based clinics between 2013 and 2017. Data from 69 patients with an average age of 37.9 years (SD = 11.2, range: 16.0-63.8 years) were included. Patients were assessed by primary health care audiologists (87%) or community health workers (13%) using portable audiological equipment. The average length of time between initial and exit assessments was 84.6 days (SD = 74.2, range: 2-335 days).

RESULTS

EHF ototoxicity of a mild or greater degree of hearing loss (> 25 dB HL in one or both ears across frequencies) was evident in 85.5% of patients' posttreatment, compared with 47.8% of patients across conventional frequencies. EHF audiometry demonstrated an ototoxic shift (American Speech-Language-Hearing Association criteria) in 56.5% of cases compared with 31.9% when only conventional audiometry was considered. Mean hearing deterioration for patients was significant across EHFs (9-16 kHz) bilaterally (p < .05). Absent EHF thresholds at the initial assessment, owing to maximum output limits, was a limitation that occurred most frequently at 16 kHz (17.4%, 24/138).

CONCLUSIONS

EHF audiometry is most sensitive for the early detection of ototoxicity and should be included in monitoring programs. Clinical ototoxicity monitoring protocols should consider shortened assessment approaches that target frequencies most sensitive to ototoxicity, including EHFs.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21651242.

Ototoxicity prognostic models in adult and pediatric cancer patients: a rapid review

PURPOSE

A cornerstone of treatment for many cancers is the administration of platinum-based chemotherapies and/or ionizing radiation, which can be ototoxic. An accurate ototoxicity risk assessment would be useful for counseling, treatment planning, and survivorship follow-up in patients with cancer.

METHODS

This systematic review evaluated the literature on predictive models for estimating a patient's risk for chemotherapy-related auditory injury to accelerate development of computational approaches for the clinical management of ototoxicity in cancer patients. Of the 1195 articles identified in a PubMed search from 2010 forward, 15 studies met inclusion for the review.

CONCLUSIONS

All but 1 study used an abstraction of the audiogram as a modeled outcome; however, specific outcome measures varied. Consistently used predictors were age, baseline hearing, cumulative cisplatin dose, and radiation dose to the cochlea. Just 5 studies were judged to have an overall low risk of bias. Future studies should attempt to minimize bias by following statistical best practices including not selecting multivariate predictors based on univariate analysis, validation in independent cohorts, and clearly reporting the management of missing and censored data. Future modeling efforts should adopt a transdisciplinary approach to define a unified set of clinical, treatment, and/or genetic risk factors. Creating a flexible model that uses a common set of predictors to forecast the full post-treatment audiogram may accelerate work in this area. Such a model could be adapted for use in counseling, treatment planning, and follow-up by audiologists and oncologists and could be incorporated into ototoxicity genetic association studies as well as clinical trials investigating otoprotective agents.

IMPLICATIONS FOR CANCER SURVIVORS

Improvements in the ability to model post-treatment hearing loss can help to improve patient quality of life following cancer care. The improvements advocated for in this review should allow for the acceleration of advancements in modeling the auditory impact of these treatments to support treatment planning and patient counseling during and after care.

Audiological evaluation (128-20,000Hz) in women with autoimmune thyroiditis: The role of antibodies vs. l-thyroxine deficiency

BACKGROUND AND AIM

Although sensorineural hearing loss may have different aetiologies, we focused on autoimmune hearing loss since it may be reversible with corticosteroid therapy; this entity is sometimes associated with systemic autoimmune diseases. Hashimoto's thyroiditis or chronic autoimmune thyroiditis shows antibodies and may be harmful to hearing thresholds regardless of hypothyroidism effect. To date this effect has not been sufficiently studied and never with extended high frequencies. The aim of this work is to study by age groups whether hearing thresholds in the human auditory range (128-20,000Hz) are affected in Hashimoto's disease.

MATERIALS AND METHODS

Two groups of 128 patients affected by Hashimoto's thyroiditis were included. First group: patients with pathological antithyroid antibodies who do not need L-thyroxine treatment. Second group: patients controlled with L-thyroxine substitutive treatment. Audiometric threshold study comparing between the groups of patients and a group of 209 controls was performed. All patients underwent complete otorhinolaryngological examination, antithyroid antibodies, TSH, T3 and T4 blood levels, tympanometry, conventional pure-tone audiometry, and extended-high-frequency audiometry.

RESULTS

All patients were women. Both groups showed worst audiometric thresholds than the control group; both study groups showed worse hearing than controls, this difference was statistically significant in all frequencies. In the 8-20kHz frequency range, this difference was more than 10dB, and in the 9-16kHz and 20kHz range this difference was more than 20dB. When separated by age groups, in younger subjects (20-29 years) these differences were found in all frequencies, except for conversational frequencies (500-4,000Hz); between 30 and 49 years the difference is statistically significant in all frequencies; and from 50 to 69 years differences are found, especially in the conversational frequencies.

CONCLUSIONS

This first work studying the human auditory range in the chronic autoimmune thyroiditis or Hashimoto's thyroiditis confirms that hearing loss related to the autoimmune disorder predominates at extended-high-frequencies initially. But ends up involving all frequencies in pure-tone conventional audiometry, then it may be detected in routine clinical tests. These results support the role of extended-high-frequencies audiometry to diagnose subclinical hearing loss in patients affected by Hashimoto's thyroiditis.

Audiological Risk Factors, Referral Rates and Dropouts: 9 Years of Universal Newborn Hearing Screening in North Sardinia

Background: Objectives of the present work were to analyze the prevalence of hearing loss in our population of screened newborns during the first 9 years of the universal newborn hearing screening (UNHS) program at University Hospital Sassari (Italy) (AOU Sassari), to analyze the risk factors involved, and to analyze our effectiveness in terms of referral rates and dropout rates. Methods: Monocentric retrospective study whose target population included all the newborns born or referred to our hospital between 2011 and 2019. Results: From 2011 to 2019, a total of 11,688 babies were enrolled in our screening program. In total, 3.9‱ of wellborn babies and 3.58% of neonatal intensive care unit (NICU) babies had some degree of hearing loss. The most frequently observed risk factors among non-NICU babies were family history of hearing loss (3.34%) and craniofacial anomalies (0.16%), among NICU babies were low birth weight (54.91%) and prematurity (24.33%). In the multivariate analysis, family history of hearing loss (p < 0.001), NICU (p < 0.001), craniofacial anomalies (p < 0.001), low birth weight (<1500 g) (p = 0.04) and HIV (p = 0.03) were confirmed as risk factors. Conclusions: Our data are largely consistent with the literature and most results were expected, one relevant exception being the possible role of NICU as a confounding factor and the limited number of risk factors confirmed in the multivariate analysis.

The audiogram: Detection of pure-tone stimuli in ototoxicity monitoring and assessments of investigational medicines for the inner ear

Pure-tone thresholds have long served as a gold standard for evaluating hearing sensitivity and documenting hearing changes related to medical treatments, toxic or otherwise hazardous exposures, ear disease, genetic disorders involving the ear, and deficits that develop during aging. Although the use of pure-tone audiometry is basic and standard, interpretation of thresholds obtained at multiple frequencies in both ears over multiple visits can be complex. Significant additional complexity is introduced when audiometric tests are performed within ototoxicity monitoring programs to determine if hearing loss occurs as an adverse reaction to an investigational medication and during the design and conduct of clinical trials for new otoprotective agents for noise and drug-induced hearing loss. Clinical trials using gene therapy or stem cell therapy approaches are emerging as well with audiometric outcome selection further complicated by safety issues associated with biological therapies. This review addresses factors that must be considered, including test-retest variability, significant threshold change definitions, use of ototoxicity grading scales, interpretation of early warning signals, measurement of notching in noise-induced hearing loss, and application of age-based normative data to interpretation of pure-tone thresholds. Specific guidance for clinical trial protocols that will assure rigorous methodological approaches and interpretable audiometric data are provided.

Cisplatin-associated ototoxicity: perspectives from a single institution cervical cancer cohort and implications for developing a locally responsive monitoring programme in a public healthcare setting

Background

Ototoxicity monitoring is uncommon in South Africa, despite the increased use of ototoxic medication to manage the burden of disease in the country. The successful implementation of such a protocol requires cognisance of contextual realities and multiple dimensions for consideration from both patients and service providers. As part of an ongoing cohort study on cisplatin-associated ototoxicity and efforts to better inform the implementation of such programmes, the perspectives of cervical cancer patients and healthcare workers towards ototoxicity monitoring were assessed.

Methods

This concurrent-triangulation mixed-methods study was conducted at a tertiary hospital in South Africa. Self-reported questionnaires from patients (n = 80) and healthcare personnel comprising clinicians, oncology nurses, pharmacists, and radiotherapists (n = 32), results of audiological evaluations, researcher field notes, and estimated patient and service provider costs contributed to data for this study. Data analysis included descriptive statistics, comparison of test characteristics and deductive thematic analysis.

Results

The ototoxicity monitoring programme was positively received by the participants, with 90.6% of healthcare personnel and 89% of patients reporting it to be beneficial. The clinicians (76.6%) were identified as the main providers of information on the effects of chemotherapy medication and made the necessary referrals for audiological evaluation. The approximate cost of setting up such a programme included purchase of equipment (US56 700) and the appointment of an audiologist (US 26 250). The approximate costs to patients included transport costs (US$ 38) and the loss of income for the day (US 60), calculated at the minimum wage per hour, if employed. Creative appointment scheduling, easy facility access and detailed locally comprehensible couselling improved patient compliance to the programme. Whilst the sequential use of American Speech-Language-Hearing Association (ASHA) and National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) criteria aided in an evidence-informed approach to aural rehabilitation, DPOAEs and speech discrimination displayed low sensitivity (range 1.45% – 22.39%) but high specificity (range 77.78% – 100%) when identifying ototoxic change.

Conclusion

This novel study, through a ‘real-world’ experience, has revealed that an ototoxicity monitoring programme is feasible in South Africa, through meaningful engagements with- and considerations from- patients and service providers regarding planning, delineation of responsibilities and cost implications. The findings can potentially serve as a roadmap for other limited resource environments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08099-8.

ASK1 is a novel molecular target for preventing aminoglycoside-induced hair cell death

Aminoglycoside antibiotics are lifesaving medicines, crucial for the treatment of chronic or drug resistant infections. However, aminoglycosides are toxic to the sensory hair cells in the inner ear. As a result, aminoglycoside-treated individuals can develop permanent hearing loss and vestibular impairment. There is considerable evidence that reactive oxygen species (ROS) production and the subsequent phosphorylation of c-Jun N-terminal kinase (JNK) and P38 mitogen-activated protein kinase (P38) drives apoptosis in aminoglycoside-treated hair cells. However, treatment strategies that directly inhibit ROS, JNK, or P38 are limited by the importance of these molecules for normal cellular function. Alternatively, the upstream regulator apoptosis signal-regulating kinase 1 (ASK1/MAP3K5) is a key mediator of ROS-induced JNK and P38 activation under pathologic but not homeostatic conditions. We investigated ASK1 as a mediator of drug-induced hair cell death using cochlear explants from Ask1 knockout mice, demonstrating that Ask1 deficiency attenuates neomycin-induced hair cell death. We then evaluated pharmacological inhibition of ASK1 with GS-444217 as a potential otoprotective therapy. GS-444217 significantly attenuated hair cell death in neomycin-treated explants but did not impact aminoglycoside efficacy against P. aeruginosa in the broth dilution test. Overall, we provide significant pre-clinical evidence that ASK1 inhibition represents a novel strategy for preventing aminoglycoside ototoxicity. KEY MESSAGES: • ASK1 is an upstream, redox-sensitive regulator of P38 and JNK, which are known mediators of hair cell death. • Ask1 knockout does not affect hair cell development in vivo, but significantly reduces aminoglycoside-induced hair cell death in vitro. • A small-molecule inhibitor of ASK1 attenuates neomycin-induced hair cell death, and does not impact antibiotic efficacy in vitro. • ASK1 may be a novel molecular target for preventing aminoglycoside-induced hearing loss.

Extended high-frequency audiometry in research and clinical practice

Audiometric testing in research and in clinical settings rarely considers frequencies above 8 kHz. However, the sensitivity of young healthy ears extends to 20 kHz, and there is increasing evidence that testing in the extended high-frequency (EHF) region, above 8 kHz, might provide valuable additional information. Basal (EHF) cochlear regions are especially sensitive to the effects of aging, disease, ototoxic drugs, and possibly noise exposure. Hence, EHF loss may be an early warning of damage, useful for diagnosis and for monitoring hearing health. In certain environments, speech perception may rely on EHF information, and there is evidence for an association between EHF loss and speech perception difficulties, although this may not be causal: EHF loss may instead be a marker for sub-clinical damage at lower frequencies. If there is a causal relation, then amplification in the EHF range may be beneficial if the technical difficulties can be overcome. EHF audiometry in the clinic presents with no particular difficulty, the biggest obstacle being lack of specialist equipment. Currently, EHF audiometry has limited but increasing clinical application. With the development of international guidelines and standards, it is likely that EHF testing will become widespread in future.

A Case of Pheochromocytoma as a Subsequent Neoplasm in a Survivor of Childhood Embryonal Rhabdomyosarcoma

Childhood cancer survivors are at risk for subsequent neoplasms. We describe the clinical presentation and genetic testing of a 29-year-old woman diagnosed with a pheochromocytoma 22 years post-treatment for childhood embryonal rhabdomyosarcoma of the bladder. Genetic testing for cancer predisposition revealed a pathogenic variant in BRCA2 and a variant of uncertain significance in MSH2. Pathogenic variants associated with deafness were also identified in GJB2. This article reports a novel subsequent neoplasm following childhood embryonal rhabdomyosarcoma, and discusses the potential contribution of genetic cancer predisposition to this case as well as the clinical implications of genetic testing.

Community-Based Ototoxicity Monitoring for Drug-Resistant Tuberculosis in South Africa: An Evaluation Study

In response to the drug-resistant tuberculosis (DRTB) ototoxicity burden in South Africa, ototoxicity monitoring has been decentralised, with community health workers (CHWs) acting as facilitators. This study describes a community-based ototoxicity monitoring programme (OMP) for patients with DRTB. Findings are compared to the recommended guidelines for ototoxicity monitoring, the OMP protocol and published studies. This was a retrospective study of longitudinal ototoxicity monitoring of 831 patients with DRTB, using data collected at community-based clinics in the City of Cape Town between 2013 and 2017. Approximately half (46.8%) of the patients had an initial assessment conducted in accordance with the OMP protocol recommendations, and follow-up rates (79.5%) were higher than those of a similar DRTB programme. However, patients in this study were not monitored within the timeframes or with the regularity recommended by the guidelines or the OMP protocol. Extended high-frequency pure-tone audiometry (27.5%) was underutilised by testers and data recording was inconsistent (e.g., 37.7% of patient gender was not recorded by testers). Community-based OMP using CHWs to facilitate monitoring showed improvement over previous hospital-based reports, with more accessible services and higher follow-up rates. However, to improve OMP outcomes, OMP managers should reassess current protocols and data recording practices.

A Randomized Controlled Trial Using Automated Technology for Improving Ototoxicity Monitoring in VA Oncology Patients

Purpose Determine the efficacy of ototoxicity monitoring (OM) administered as automated protocols with the Oto-ID mobile audiometer (automated ototoxicity monitoring [A-OM]), compared with usual care (UC) OM in cancer patients receiving cisplatin. Method Participants were patients (n = 46, mean age 64.7 years; range: 30-78 years) receiving cisplatin-based chemotherapy at the Department of Veterans Affairs Portland Health Care System. A randomized controlled trial contrasted A-OM and UC at up to three program evaluations (PEs) conducted by the study audiologist who was blinded to arm through PE1. PE1 occurred before randomization or oncology treatment; PE2 and PE3 occurred during and/or after treatment at 35 and 365 days postrandomization. The A-OM group (n = 24) used Oto-ID to screen their hearing before each cisplatin dose. Oto-ID results were sent to the study audiologist for interpretation, follow-up, and care coordination. The UC group (n = 22) received a consult for OM services through the audiology clinic. Outcomes included hearing shift near each patient's high-frequency hearing limit, revised hearing-handicap inventory score, and survival time from the start of treatment. Adherence to OM protocols, patients' use of aural rehabilitation services, and oncologists' treatment decisions were also examined. Results Ototoxicity was identified at a high overall rate (46% and 76% at 35 and 365 days, respectively, postrandomization). Adherence to monitoring prior to each cisplatin dose was 83.3% for those randomized to A-OM compared with 4.5% for UC. Randomization to A-OM was not associated with reduced ototoxic hearing shifts or self-reported hearing handicap relative to UC; neither did it compromise participants' survival. Half of participants in each arm accessed aural rehabilitation services. One in each arm had a documented ototoxicity-related cisplatin dose reduction. Conclusions Auditory impairment was an actionable concern for the participants and their oncology providers. A dedicated surveillance program using the Oto-ID's automated protocols improved adherence to OM recommendations over a traditional UC service delivery model. Supplemental Material https://doi.org/10.23641/asha.16649602.

Functional Impacts of Aminoglycoside Treatment on Speech Perception and Extended High-Frequency Hearing Loss in a Pediatric Cystic Fibrosis Cohort

Purpose The purpose of this study is to better understand the prevalence of ototoxicity-related hearing loss and its functional impact on communication in a pediatric and young adult cohort with cystic fibrosis (CF) and individuals without CF (controls). Method We did an observational, cross-sectional investigation of hearing function in children, teens, and young adults with CF (n = 57, M = 15.0 years) who received intravenous aminoglycoside antibiotics and age- and gender-matched controls (n = 61, M = 14.6 years). Participants completed standard and extended high-frequency audiometry, middle ear measures, speech perception tests, and a hearing and balance questionnaire. Results Individuals with CF were 3-4 times more likely to report issues with hearing, balance, and tinnitus and performed significantly poorer on speech perception tasks compared to controls. A higher prevalence of hearing loss was observed in individuals with CF (57%) compared to controls (37%). CF and control groups had similar proportions of slight and mild hearing losses; however, individuals with CF were 7.6 times more likely to have moderate and greater degrees of hearing loss. Older participants displayed higher average extended high-frequency thresholds, with no effect of age on average standard frequency thresholds. Although middle ear dysfunction has not previously been reported to be more prevalent in CF, this study showed that 16% had conductive or mixed hearing loss and higher rates of previous otitis media and pressure equalization tube surgeries compared to controls. Conclusions Individuals with CF have a higher prevalence of conductive, mixed, and sensorineural hearing loss; poorer speech-in-noise performance; and higher rates of multiple symptoms associated with otologic disorders (tinnitus, hearing difficulty, dizziness, imbalance, and otitis media) compared to controls. Accordingly, children with CF should be asked about these symptoms and receive baseline hearing assessment(s) prior to treatment with potentially ototoxic medications and at regular intervals thereafter in order to provide otologic and audiologic treatment for hearing- and ear-related problems to improve communication functioning.

Hearing Impairment in Infants with Hypoxic Ischemic Encephalopathy Treated with Hypothermia

Therapeutic hypothermia acts as the standard of care for infants with moderate to severe hypoxic ischemic encephalopathy (HIE). A proportion of neonates who undergo hypothermia due to HIE have shown to develop various degrees of hearing impairment. Analyzing and identifying infants at high risk of developing hearing difficulties is fundamental for early intervention of such auditory complications. The aim was to assess clinical factors in the development of hearing impairment following therapeutic hypothermia in HIE infants. A retrospective analysis was performed on infants hospitalized in our neonatology department in Poznan University of Medical Sciences, Poland. All infants experienced moderate to severe HIE, and were treated with therapeutic hypothermia. Risk factors for hearing impairment were identified in all infants included in the study. Clinical data during hospital stay and follow-up hearing status were analyzed. A total of 87 HIE infants were included in the study. Seventy-six infants (40 male and 36 female) had otoacoustic emission (OAE) examination following birth, of which 14 (18.4%) demonstrated abnormal (positive) results. Infants with abnormal OAE results had significantly lower blood pH (6.86 ± 0.16, p = 0.001) and base excess (BE) (-22.46 ± 2.59, p = 0.006). Of the 49 infants who returned for follow-up assessment, 4 (8.2%) were diagnosed with sensorineural bilateral hearing impairment (1 infant, mild [<40 dB], 2 moderate [41-70 dB], and 1 profound [>90 dB]). The biochemical analysis following birth revealed significantly lower umbilical BE levels (-23.90 ± 4.99, p = 0.041) and higher lactate levels (160.67 ± 4.93, p = 0.019) in the infants with eventual sensorineural hearing deficit. Infants with moderate or severe HIE are at risk of delayed onset hearing loss. Diligent efforts to monitor auditory status are required, even if early screening results for hearing are insignificant. Exploring biochemical parameters, such as lactate, BE, and blood pH, can prove beneficial in identifying HIE infants at risk of developing a hearing impairment.

Pharmaco-Audiology Vigilance in the Treatment of Adult Patients with HIV/Aids: Ototoxicity Monitoring Protocol Recommendation

South Africa is considered the epicenter of HIV/AIDS with a high rate of TB infection as well. Links have been established between treatments of these conditions to ototoxicity. However, no standardized and systematic ototoxicity monitoring exists within the clinical sites where these conditions are treated, with very minimal and adhoc involvement of audiologists as part of the treatment team. With 3.4 million HIV-infected South Africans being reported to have been on antiretroviral drugs by the end of March 2016; with universal coverage being the target, it is important that ototoxicity monitoring becomes part of the treatment plan. The objective of the current paper is to propose an ototoxicity monitoring protocol that can be implemented within this population to ensure that systematic data are collated in order for evidence-based protocols to be adopted within the South African context. Such a protocol will also allow for early identification and intervention of ototoxic hearing loss within this population. Enough evidence exists to support implementation of standardized protocols that will allow for proper, accurate, efficient, and reliable comparisons of data within and between patients; as well as between and within treatment sites - both locally and internationally. It is hoped that implementation of such a monitoring protocol will also have significant implications for the expanded role of the audiologist in the drug development process, affording evidence-based benefit-risk assessments of drugs in the market for this population.

Prospective cohort study of ototoxicity in persons with cystic fibrosis following a single course of intravenous tobramycin

INTRODUCTION

Aminoglycoside (AG) antibiotics, such as tobramycin, are known to be ototoxic but important clinically due to their bactericidal efficacy. Persons with cystic fibrosis (CF) are at risk for AG-induced ototoxicity due to the repeated use of intravenous (IV) tobramycin for the treatment of pulmonary exacerbations. While it is well-established that ototoxic hearing loss is highly prevalent in this clinical population, the progression of hearing loss over time remains unclear. Cumulative IV-AG dosing has been associated with a higher risk of ototoxic hearing loss, yet some individuals lose substantial hearing after a single IV-AG treatment, while others never seem to lose hearing.

METHODS

31 persons with CF (18 on IV tobramycin, 13 controls) were enrolled in an observational study. Pure-tone hearing thresholds (0.25-16 kHz) were measured at baseline (pre-treatment) and at follow-up for each subject. A hearing shift was determined using various metrics, and outcomes were compared to characterize changes in hearing bilaterally for both study groups.

RESULTS

Comparison of pure-tone threshold shifts between baseline and follow-up audiograms following either a course of IV tobramycin (n = 18) or no intervening therapy (n = 13) demonstrated significant (p < 0.05) threshold shifts in all continuous metrics tested.

CONCLUSION

A single course of IV tobramycin causes ototoxic hearing loss in some people with CF, which supports the need for routine ototoxicity monitoring and management in this clinical population. These findings also suggest that people with CF are a suitable population for clinical trials examining ototherapeutics in single IV-tobramycin treatment episodes.

A quick and reliable estimate of extended high-frequency hearing

OBJECTIVE

To encourage researchers to perform high-frequency threshold estimation using a technique outlined by Rieke and colleagues, described as fixed-level frequency threshold estimation. Their method used a Bekesy-style roving tone to estimate the highest audible frequency of a listener. The tone was fixed in its intensity (SPL) and changed in frequency as the participant indicated whether they could perceive the tone, or not. This was developed specifically for ototoxicity monitoring in the extended high-frequency region. Rieke and colleagues established that this approach to measuring hearing thresholds is both fast and reliable.

DESIGN

The current article extends this approach to using a simple PC-soundcard-transducer setup and the method of limits to rapidly establish the highest audible frequency of a listener.Study sample: 24 listeners performed standard and fixed-level audiometry in the extended high-frequency range.

RESULTS

The method described is rapid and reliable and a single summary metric is obtained for each listener.

CONCLUSIONS

The advantage of the described approach over standard pure-tone audiometry in the extended high-frequency range is the time taken, the ability to avoid missing data points and the risk of distortions or electrical noise when close to maximal system output.

Ebselen attenuates tobramycin-induced ototoxicity in mice

BACKGROUND

Cystic fibrosis patients are often adminstered tobramycin to treat pulmonary infections. Unfortunately, a common side effect is hearing loss, which can fluctuate. Ebselen has known anti-inflammatory properties and could reduce the incidence and severity of tobramycin-induced hearing loss.

METHODS

In vitro: neonatal cochlear cultures were treated with tobramycin or cotreated with tobramycin and ebselen for 3 days. In vivo: adult mice were injected with tobramycin or tobramycin and ebselen for 14 days. ABRs were collected in a repeated measures design until 56 days after treatments. ABR threshold shifts were analyzed and a novel cochleotoxic criteria applied to determine the incidence of ototoxicity. Cochlear immunohistology was analyzed for IHC and OHC loss.

RESULTS

Tobramycin leads to significant IHC and OHC loss in cochlear explant cultures. Ebselen co-treatment at 1:20 concentrations resulted in significant otoprotection. Tobramycin leads to significant ABR threshold shifts that are ameliorated by ebselen co-treatment. Hearing loss did not correlate with significant IHC or OHC loss.

CONCLUSIONS

This mouse model of tobramycin-induced ototoxicity is clinically relevant in that it results in an incidence and severity of hearing loss recently documented in clinic. The in vitro experiments show that tobramycin kills hair cells and that ebselen co-treatment can attenuate this ototoxicity. The in vivo model shows tobramycin-induced hearing loss is ameliorated by ebselen co-treatment, but this is not explained by concomitant hair cell loss. These preclinical data support the testing of ebselen in CF patients receiving tobramycin treatment.

Looking beyond the audiogram in ototoxicity associated with platinum-based chemotherapy

Introduction

Ototoxicity associated with platinum-based chemotherapy is highly prevalent and can cause detrimental consequences among cancer survivors.

Discussion

In this article, we highlight important aspects of the evaluation of ototoxicity with the aim to increase awareness of Oncologists in this regard. Standard pure tone audiometry alone is inadequate for this context. Comprehensive and consistent hearing tests should be implemented in a monitoring and surveillance program. High-frequency audiometry (10–16 kHz) is a sensitive tool in the detection of ototoxic hearing loss at onset. In addition to threshold audiometry, measures of speech comprehension (both in quiet and in noise) can add useful information in the evaluation of hearing in real-life situations. Not only hearing loss, but also tinnitus and imbalance are common in patients who receive platinum-based chemotherapy, and can cause debilitating effects upon quality of life in this population. Moreover, self-report measures associated with cochlear and vestibular handicaps can provide valuable information regarding the impact of ototoxicity.

Conclusions

It is vital to build awareness about the variety and impact of the symptoms of ototoxicity. Comprehensive evaluation of hearing status along with self-reported impact of the cochlear and vestibular handicap should be implemented in a monitoring and surveillance program for appropriate investigation and management.

Hearing loss in police K9 handlers and non-K9 handlers

Objective: The objective of this study was to assess and compare the hearing of police K9 handlers and non-K9 handlers.Design: Cross-sectional design.Study sample: Hearing was assessed on 30 police officers, 12 K9 handlers and 18 non-K9 handlers, from Northeast Ohio.Results: There were no significant differences in audiologic test results between police K9 handlers and non-K9 handlers. Audiometric results revealed that 66.7% of K9 handlers and 83.3% of non-K9 handlers presented with hearing loss. Noise notches, consistent with noise-induced hearing loss (NIHL), and asymmetric hearing losses were observed for both groups. Subjective questionnaires indicated low awareness regarding the risks and identification of NIHL in this population.Conclusions: This study represents one of the few studies that focus on hearing assessments in police K9 handlers and non-K9 handlers in the United States and internationally. Significant differences between these two groups were not found, suggesting that K9 handlers do not present a higher risk for NIHL than non-K9 handlers. Nonetheless, the high prevalence of hearing loss identified for both groups in this study suggests the need for increased conservation efforts to raise awareness regarding hearing loss prevention and the need for routine audiologic monitoring for this underserved population.

Acquired Hearing Loss, Anger, and Emotional Distress: The Mediating Role of Perceived Disability

The aim of the study was to test whether acquired hearing loss (AHL)-related perceived disability mediates the association between AHL and psychological outcomes, including anger. Two-hundred ninety-seven consecutive outpatients with AHL assessed by pure tone average (PTA) loss completed the following: Hearing Handicap Inventory for Adults (HHIA), State-Trait Anger Expression Inventory-2 (STAXI-2), Brief Symptom Inventory (BSI), Diagnostic Criteria for Use in Psychosomatic Research (DCPR), and Social Functioning Questionnaire. In the sample, composed of 44.5% males with a mean age of 53.8 and a mean PTA of 30.7, AHL was associated to perceived hearing handicap, also correlating to all psychological measures except DCPR demoralization. Associations were stronger between the HHIA-Emotional Subscale, STAXI-2 State Anger and Feeling Angry, and BSI-Somatization, Interpersonal Sensitivity, Depression, and Psychoticism. Perceived disability predicted the presence of almost all psychosocial outcomes and confirms to be the most significant target of clinical action.

Chirp-Evoked Otoacoustic Emissions and Middle Ear Absorbance for Monitoring Ototoxicity in Cystic Fibrosis Patients

OBJECTIVES

The goal of this study was to investigate the use of transient-evoked otoacoustic emissions (TEOAEs) and middle ear absorbance measurements to monitor auditory function in patients with cystic fibrosis (CF) receiving ototoxic medications. TEOAEs were elicited with a chirp stimulus using an extended bandwidth (0.71 to 8 kHz) to measure cochlear function at higher frequencies than traditional TEOAEs. Absorbance over a wide bandwidth (0.25 to 8 kHz) provides information on middle ear function. The combination of these time-efficient measurements has the potential to identify early signs of ototoxic hearing loss.

DESIGN

A longitudinal study design was used to monitor the hearing of 91 patients with CF (median age = 25 years; age range = 15 to 63 years) who received known ototoxic medications (e.g., tobramycin) to prevent or treat bacterial lung infections. Results were compared to 37 normally hearing young adults (median age = 32.5 years; age range = 18 to 65 years) without a history of CF or similar treatments. Clinical testing included 226-Hz tympanometry, pure-tone air-conduction threshold testing from 0.25 to 16 kHz and bone conduction from 0.25 to 4 kHz. Experimental testing included wideband absorbance at ambient and tympanometric peak pressure and TEOAEs in three stimulus conditions: at ambient pressure and at tympanometric peak pressure using a chirp stimulus with constant incident pressure level across frequency and at ambient pressure using a chirp stimulus with constant absorbed sound power across frequency.

RESULTS

At the initial visit, behavioral audiometric results indicated that 76 of the 157 ears (48%) from patients with CF had normal hearing, whereas 81 of these ears (52%) had sensorineural hearing loss for at least one frequency. Seven ears from four patients had a confirmed behavioral change in hearing threshold for ≥3 visits during study participation. Receiver operating characteristic curve analyses demonstrated that all three TEOAE conditions were useful for distinguishing CF ears with normal hearing from ears with sensorineural hearing loss, with an area under the receiver operating characteristic curve values ranging from 0.78 to 0.92 across methods for frequency bands from 2.8 to 8 kHz. Case studies are presented to illustrate the relationship between changes in audiometric thresholds, TEOAEs, and absorbance across study visits. Absorbance measures permitted identification of potential middle ear dysfunction at 5.7 kHz in an ear that exhibited a temporary hearing loss.

CONCLUSIONS

The joint use of TEOAEs and absorbance has the potential to explain fluctuations in audiometric thresholds due to changes in cochlear function, middle ear function, or both. These findings are encouraging for the joint use of TEOAE and wideband absorbance objective tests for monitoring ototoxicity, particularly, in patients who may be too ill for behavioral hearing tests. Additional longitudinal studies are needed in a larger number of CF patients receiving ototoxic drugs to further evaluate the clinical utility of these measures in an ototoxic monitoring program.

The Inner Ear Heat Shock Transcriptional Signature Identifies Compounds That Protect Against Aminoglycoside Ototoxicity

Mechanosensory hair cells of the inner ear transduce auditory and vestibular sensory input. Hair cells are susceptible to death from a variety of stressors, including treatment with therapeutic drugs that have ototoxic side effects. There is a need for co-therapies to mitigate drug-induced ototoxicity, and we showed previously that induction of heat shock proteins (HSPs) protects against hair cell death and hearing loss caused by aminoglycoside antibiotics in mouse. Here, we utilized the library of integrated cellular signatures (LINCS) to identify perturbagens that induce transcriptional profiles similar to that of heat shock. Massively parallel sequencing of RNA (RNA-Seq) of heat shocked and control mouse utricles provided a heat shock gene expression signature that was used in conjunction with LINCS to identify candidate perturbagens, several of which were known to protect the inner ear. Our data indicate that LINCS is a useful tool to screen for compounds that generate specific gene expression signatures in the inner ear. Forty-two LINCS-identified perturbagens were tested for otoprotection in zebrafish, and three of these were protective. These compounds also induced the heat shock gene expression signature in mouse utricles, and one compound protected against aminoglycoside-induced hair cell death in whole organ cultures of utricles from adult mice.

Drug-Induced Ototoxicity: Diagnosis and Monitoring

Ototoxicity diagnosis and management has historically been approached using a variety of methods. However, in recent years a consensus on useful and practical approaches has been developed through clinical guidelines of the American Speech Language Hearing Association, the American Academy of Audiology, and multiple clinical trials published in peer-reviewed literature. Some of the guidelines and approaches are used to detect and monitor ototoxicity, while others are used to grade adverse events. Some of the audiologic measures are primary, while others are adjunct measures and may be tailored to the specific needs of the patient or clinical trial. For some types of monitoring, such as drug-induced tinnitus or dizziness, validated paper survey instruments can be both sensitive and easy for fragile patients. This review addresses the characteristics of some of the most common clinical ototoxins and the most common methods for detecting and monitoring ototoxicity in clinical practice and clinical trials.

Applying U.S. national guidelines for ototoxicity monitoring in adult patients: perspectives on patient populations, service gaps, barriers and solutions

OBJECTIVES

To promote establishment of effective ototoxicity monitoring programs (OMPs), this report reviews the U.S. national audiology guidelines in relation to "real world" OMP application. Background is provided on the mechanisms, risks and clinical presentation of hearing loss associated with major classes of ototoxic medications.

DESIGN

This is a non-systematic review using PubMed, national and international agency websites, personal communications between ototoxicity experts, and results of unpublished research. Examples are provided of OMPs in various healthcare settings within the U.S. civilian sector, Department of Defense (DoD), and Department of Veterans Affairs (VA).

STUDY SAMPLE

The five OMPs compared in this report represent a convenience sample of the programs with which the authors are affiliated. Their opinions were elicited via two semi-structured teleconferences on barriers and facilitators of OMP, followed by a self-administered questionnaire on OMP characteristics and practices, with responses synthesized herein. Preliminary results are provided from an ongoing VA clinical trial at one of these OMP sites. Participants were 40 VA patients who received cisplatin chemotherapy in 2014-2017. The study arms contrast access to care for OMP delivered on the treatment unit versus usual care as provided in the audiology clinic.

RESULTS

Protocols of the OMPs examined varied, reflecting their diverse settings. Service delivery concerns included baseline tests missed or completed after the initial treatment, and monitoring tests done infrequently or only after cessation of treatment. Perceived barriers involved logistics related to accessing and testing patients, such as a lack of processes to help patients enter programs, patients' time and scheduling constraints, and inconvenient audiology clinic locations. Use of abbreviated or screening methods facilitated monitoring.

CONCLUSIONS

The most effective OMPs integrated audiological management into care pathways of the clinical specialties that prescribe ototoxic medications. More OMP guidance is needed to inform evaluation schedules, outcome reporting, and determination of actionable ototoxic changes. Guidance is also lacking on the use of hearing conservation approaches suitable for the mass testing needed to support large-scale OMP efforts. Guideline adherence might improve with formal endorsement from organizations governing the medical specialty stakeholders in OMP such as oncologists, pulmonologists, infectious disease specialists, ototolaryngologists and pharmacists.

Progressive Hearing Loss among Patients with Cystic Fibrosis and Parenteral Aminoglycoside Treatment

OBJECTIVE

Hearing loss is a significant and growing problem as patients with cystic fibrosis (CF) live longer and experience frequent courses of intravenous aminoglycoside antibiotics (hereafter, "IVs"). This study seeks to document that risk in a large adult population with CF, accounting for age and aminoglycoside exposure.

STUDY DESIGN

Retrospective case review of patients with CF who had multiple audiograms over years.

SETTING

Tertiary care cystic fibrosis setting.

SUBJECT AND METHODS

The first and last audiograms recorded over a 10-year period were compared for 165 adult patients with CF. Patients were divided into 3 study groups: 34 patients with no intervening aminoglycoside IVs (0 IVs), 103 patients with 1 to 9 IVs, and 28 patients with ≥10 IVs. Threshold shift (TS) between the audiograms were examined for the 3 groups before and after age/sex adjustments. Two new hearing loss metrics were tested.

RESULTS

At first examination, 48% of patients (average age, 30.0 years) already had hearing loss. At last examination (average, 4.4 years later), 64% of the patients had hearing loss even with age/sex adjustment. Use of the age/sex hearing threshold adjustment eliminated the TS in the 0 IVs group. Two new metrics calculated for each patient demonstrated that 48% of patients who had 1 to 9 IVs had ototoxic scores, while almost 80% of the ≥10 IV group had ototoxic scores.

CONCLUSION

The majority of adult patients with CF are (often repeatedly) exposed to parenteral aminoglycosides and lose hearing at a rate that far exceeds that predicted from aging alone.

Ototoxicity: A Challenge in Diagnosis and Treatment

Ototoxicity is the pharmacological adverse reaction affecting the inner ear or auditory nerve, characterized by cochlear or vestibular dysfunction. The panorama of drug-induced hearing loss has widened over last few decades. Although ototoxic medications play an imperative role in modern medicine, they have the capacity to cause harm and lead to significant morbidity. Evidence has shown early detection of toxicity through prospective ototoxicity monitoring allows for consideration of treatment modifications to minimize or prevent permanent hearing loss and balance impairment. Although many ototoxicity monitoring protocols exist, their practicality is questionable due to several factors. Even though the existing protocols have proven to be effective, certain lacunae in practice have been encountered due to discrepancies among recommended protocols. Implementation of these protocols is mostly held back due to the incapacitated status of the patient. The choice of early ototoxicity identification techniques is still debatable due to variables such as high degree of sensitivity, specificity and reliability, less time consumption and less labour-intensive to the patient. Hence, the diagnosis and effective treatment of ototoxicity is challenging, even today. A stringent protocol with more practicality encompassing all elements aimed at profiling the effects of ototoxicity is greatly needed. This review describes an efficient application of ototoxicity monitoring and treatment protocol as an attempt to reduce the challenges in diagnosis and management of ototoxicity.

A Store-and-Forward Tele-Audiology Solution to Promote Efficient Screenings for Ototoxicity during Cisplatin Cancer Treatment

BACKGROUND

Tele-audiology improves access, controls cost, and improves efficiency of many aspects within health care. We have developed and validated a device, the ototoxicity identification device (OtoID), which enables remote hearing monitoring by a patient during chemotherapy treatment. Aspects of the design such as patient self-testing and texting of results to the audiology clinic are important features of this device.

PURPOSE

The purpose of this article is to present the efficacy and effectiveness of the OtoID hearing screener.

RESEARCH DESIGN

A repeated measures design was used in this study.

STUDY SAMPLE

Twenty-one veterans undergoing cisplatin chemotherapy were recruited in this study.

DATA COLLECTION AND ANALYSIS

Participants were tested using the OtoID at each cisplatin treatment by an audiologist using the manual mode of test and the participant using the automated mode of test. Test sensitivity and specificity were developed from the detection (yes/no) of an American Speech-Language-Hearing Association (ASHA) change in hearing.

RESULTS

The OtoID had a test sensitivity of 80.6% and specificity of 85.3%. A logistic regression model analysis of the probability of an ASHA shift identified by the automated OtoID was conducted. Separate models were fit to establish effects of age, average baseline thresholds in the sensitive range for ototoxicity (SRO), and dose of cisplatin on the probability of a positive hearing change result. Interactions were also included to evaluate these effects on the sensitivity and false-positive rates of the automated test. Results indicated no statistically significant effects of age, of baseline hearing in the SRO frequencies, or of cisplatin dose.

CONCLUSIONS

The OtoID automated test can be recommended for use. The automated test provides significant personnel efficiencies. The modem with simple text messaging function recently added to the device improves on these efficiencies.

Hearing impairment in premature newborns-Analysis based on the national hearing screening database in Poland

Objectives

The incidence of sensorineural hearing loss is between 1 and 3 per 1000 in healthy neonates and 2–4 per 100 in high-risk infants. The national universal neonatal hearing screening carried out in Poland since 2002 enables selection of infants with suspicion and/or risk factors of hearing loss. In this study, we assessed the incidence and risk factors of hearing impairment in infants ≤33 weeks’ gestational age (wga).

Methods

We analyzed the database of the Polish Universal Newborns Hearing Screening Program from 2010 to 2013. The study group involved 11438 infants born before 33 wga, the control group—1487730 infants. Screening was performed by means of transient evoked otoacoustic emissions. The risk factors of hearing loss were recorded. Infants who failed the screening test and/or had risk factors were referred for further audiological evaluation.

Results

Hearing deficit was diagnosed in 11% of infants ≤25 wga, 5% at 26–27 wga, 3.46% at 28 wga and 2–3% at 29–32 wga. In the control group the incidence of hearing deficit was 0.2% (2.87% with risk factors). The most important risk factors were craniofacial malformations, very low birth weight, low Apgar score and mechanical ventilation. Hearing screening was positive in 22.42% newborns ≤28 wga and 10% at 29–32 wga and in the control group.

Conclusions

Hearing impairment is a severe consequence of prematurity. Its prevalence is inversely related to the maturity of the baby. Premature infants have many concomitant risk factors which influence the occurrence of hearing deficit.

Universal newborn hearing screening: methods and results, obstacles, and benefits

The incidence of sensorineural hearing loss ranges from 1 to 3 per 1,000 live births in term healthy neonates, and 2-4 per 100 in high-risk infants, a 10-fold increase. Early identification and intervention with hearing augmentation within 6 mo yields optimal effect. If undetected and without treatment, significant hearing impairment may negatively impact speech development and lead to disorders in psychological and mental behaviors. Hearing screening programs in newborns enable detection of hearing impairment in the first days after birth. Programs to identify hearing deficit have significantly improved over the two decades, and their implementation continues to grow throughout the world. Initially based on risk factors, these programs identified only 50-75% of infants with hearing loss. Current recommendations are to conduct universal hearing screening in all infants. Techniques used primarily include automated auditory brainstem responses and otoacoustic emissions that provide noninvasive recordings of physiologic auditory activity and are easily performed in neonates and infants. The aim of this review is to present the objectives, benefits, and results of newborn hearing screening programs including the pros and cons of universal vs. selective screening. A brief history and the anticipated future development of these programs will also be discussed.

Mitochondrial DNA mutations associated with aminoglycoside induced ototoxicity

Aminoglycosides (AmAn) are widely used for their great efficiency against gram-negative bacterial infections. However, they can also induce ototoxic hearing loss, which has affected millions of people around the world. As previously reported, individuals bearing mitochondrial DNA mutations in the 12S rRNA gene, such as m.1555A>G and m.1494C>T, are more prone to AmAn-induced ototoxicity. These mutations cause human mitochondrial ribosomes to more closely resemble bacterial ribosomes and enable a stronger aminoglycoside interaction. Consequently, exposure to AmAn can induce or worsen hearing loss in these individuals. Furthermore, a wide range of severity and penetrance of hearing loss was observed among families carrying these mutations. Studies have revealed that these mitochondria mutations are the primary molecular mechanism of genetic susceptibility to AmAn ototoxicity, though nuclear modifier genes and mitochondrial haplotypes are known to modulate the phenotypic manifestation.

Effects of Oxaliplatin, Carboplatin, and Cisplatin Across Treatment on High-Frequency Objective and Subjective Auditory Measures in Adults

Platinum chemotherapies are often ototoxic, initially affecting the basal end of the cochlea. Thus, monitoring high-frequency auditory function is advised to reveal early damage. Objective measures of high-frequency auditory function are repeatable over time, but the sensitivity of these measures for monitoring patients receiving platinum derivatives have not been established. We monitored 13 patients across oxaliplatin, carboplatin, or cisplatin treatment using the highest frequencies with responses for each individual. Behavioral thresholds and distortion product otoacoustic emission (DPOAE) gross frequency (f2=16–2 kHz) and concentrated frequency (1/48 octave steps at the highest frequency with a present DPOAE) sweeps were monitored. DPOAE results indicated changes during treatment within individuals using absolute change criteria, as well as statistically significant differences across trial when analyzing group data. Changes varied depending on the drug administered. Behavioral thresholds changed less often than DPOAE measures and when changes were noted, they initially occurred at the highest frequencies monitored. Often, DPOAE changes occurred at frequencies which conventional equipment could not monitor (>8 kHz). Additionally, some changes were characterized by DPOAE level enhancements at conventional frequencies (<8 kHz), while levels at higher frequencies were reduced. Overall, objective high-frequency measures were sensitive to auditory changes in adults undergoing platinum chemotherapy treatment.

Practical considerations for the application of ear simulators in the calibration of audiometers in the extended high frequency region

OBJECTIVE

Calibration service providers for audiometric equipment often encounter impracticalities in fully implementing the International Electrotechnical Commission (IEC) guidelines for the extended high frequency region. This report evaluates some of the work-around solutions sometimes employed in practice and the implications these have for audiometer calibration results and uncertainties.

DESIGN

The impact of using four different microphone configurations on the ear simulator calibration in the frequency range 125 Hz to 20 kHz, and especially in the extended high frequency range from 10 kHz to 20 kHz, was investigated, at a range of temperatures.

RESULTS

Variations in the response of the ear simulator of up to 6 dB were observed with the different microphone configurations. In addition, using the microphone without its protection grid produced a dip in the high frequency response of approximately 15 dB.

CONCLUSION

While deviation from the practices required in IEC standards is not recommended, replacing the microphone protection grid with a specially fabricated collar (essentially a grid with the top removed) was found to constrain deviations in response to within ±2 dB. It was also concluded that simply removing the microphone protection grid resulted in a wholly unsatisfactory performance.

Frequency and Demographics of Gentamicin Use

OBJECTIVE

To understand how aminoglycosides such as gentamicin are used in a tertiary care setting. To familiarize otologists with the demographics and risk factors associated with gentamicin use at major medical centers to allow the possibility of early intervention.

STUDY DESIGN

Retrospective review of existing clinical data.

SETTING

University of Rochester Medical Center (URMC), including all associated hospitals (Strong Memorial Hospital, Highland Hospital, etc.).

PATIENTS

All hospital inpatients who were prescribed intravenous gentamicin over a 4-year period starting in February 2011.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Major patient populations receiving gentamicin and the associated diagnoses for which gentamicin was prescribed.

RESULTS

A total of 5,257 patients were found to have received gentamicin. Three major populations of patients were found to have received gentamicin: 1) more than half the gentamicin exposures were children and 42% were under 2 years. 2) 18% of the exposures were young adults age 18 to 34 and in this population 88% were woman with most of these hospitalizations pregnancy related. 3) Patients >55 were 19% of the exposures and most of these had serious infections. Disorders associated with patients receiving gentamicin included: perinatal complications (1,564); sepsis (1,399); acute/chronic renal disease (1,287); labor, delivery, or neonatal complications (1,250); diabetes (949); and UTI/pyelonephritis (775).

CONCLUSIONS

Gentamicin is still widely used, and the neonatal population and young adult women are at especially high risk for gentamicin-induced ototoxicity. Further data analysis should focus strategies to protect these populations by avoiding unnecessary exposures and by possible concurrent administration of protective medications such as metformin and aspirin.

Dietary supplement comprised of β-carotene, vitamin C, vitamin E, and magnesium: failure to prevent music-induced temporary threshold shift

This study examined potential prevention of music-induced temporary threshold shift (TTS) in normal-hearing participants. A dietary supplement composed of β-carotene, vitamins C and E, and magnesium was assessed using a randomized, placebo-controlled, double-blind study design. Dosing began 3 days prior to the music exposure with the final dose consumed approximately 30-min pre-exposure. There were no group differences in post-exposure TTS or music-induced decreases in distortion product otoacoustic emission (DPOAE) amplitude. Transient tinnitus was more likely to be reported by the treatment group, but there were no group differences in perceived loudness or bothersomeness. All subjects were monitored until auditory function returned to pre-exposure levels. Taken together, this supplement had no effect on noise-induced changes in hearing. Recommendations for future clinical trials are discussed.

Chloroquine gestational use in systemic lupus erythematosus: assessing the risk of child ototoxicity by pure tone audiometry

The objective of this study was to assess child chloroquine ototoxicity after its use during the gestational period in systemic lupus erythematosus (SLE). Nineteen children over four years old were evaluated: nine were exposed to chloroquine diphosphate (CDP) during gestation and 10 were born from mothers that did not take this drug before conception or anytime during pregnancy (CONTROL). Pure tone audiometry was performed in all children and high and low frequency threshold means were compared to evaluate the hearing status. All nine mothers taking CDP were exposed to this drug at least during the first trimester of pregnancy (56% during the whole gestational period) and the mean time of CDP use was 6.1 + 2.9 months. No significant difference was found in children of CDP and CONTROL groups regarding age (7.6 + 4.4 versus 12.3 + 7.2 years; P 0.10, respectively) and gender (P 0.65). Pure tone high frequency thresholds, which are the first to be affected by ototoxic drugs, presented within normal limits in children exposed or not to CDP (8.5 + 5.0 versus 7.4 + 3.6 dBHL; P 0.55, respectively). Likewise, the mean hearing thresholds at low frequencies were also similar in both groups (11.4 + 4.5 versus 11.9 + 3.0 dBHL; P 0.66). In conclusion, child in utero exposure to chloroquine diphosphate does not seem to induce hearing impairment as measured by pure tone audiometry, reinforcing its safe use during pregnancy of lupus patients.

Clinical Predictors of Streptomycin-Vestibulotoxicity

The Global tuberculosis control is challenged with a growing resistance to antitubercular treatment (ATT) culminating in resistant (MDR/XDR) strains; an important factor being premature withdrawal of streptomycin owing to its morbidity particularly nephrotoxicity and cochleotoxicity as guidelines for their prevention exist. An attempt is made here to address the least recognized and most debilitating vestibular toxic effects of streptomycin and defining a vestibular-protocol for its early detection and progression. Thirty two prospective patients (treatment-failures, relapse and default cases) undergoing ATT (24 shots of IM streptomycin 15-20 mg/kg over 8 weeks) underwent complete vestibular workup including vestibulo-ocular and vestibulo-spinal reflex assessment with an attempt to closely follow them. Four categories (I: No-, II: Occult-, III: Delayed-Manifest- and IV: Manifest-vestibulotoxicity) were defined. The DHI and casual gait abnormality clearly differentiated III/IV from I/II. The occilopsia and head thrust tests significantly differentiated II from I. Rotation and bithermal calorics significantly differentiated I from II and II from III/IV. The Fukuda, Rhomberg, Tandem-Rhomberg and CTSIB were significant in differentiating I from II and II from III/IV. Dix-Hallpike and Positional tests were of no significance in the entire study. The Occilopsia and Head-Thrust tests that showed 100 % positivity for II to IV are more likely to better predict 'manifest' or 'occult' -vestibulotoxicity while DHI and casual gait assessment may be carried out by a paramedic at a peripheral center to suspect vestibulotoxicity. Since we found absolute compliance with our series we feel that vestibulotoxicity may not be a deciding factor for termination of streptomycin provided an in-built mechanism for patient support/counseling be incorporated in management schedule.

d-Methionine reduces tobramycin-induced ototoxicity without antimicrobial interference in animal models

BACKGROUND

Tobramycin is a critical cystic fibrosis treatment however it causes ototoxicity. This study tested d-methionine protection from tobramycin-induced ototoxicity and potential antimicrobial interference.

METHODS

Auditory brainstem responses (ABRs) and outer hair cell (OHC) quantifications measured protection in guinea pigs treated with tobramycin and a range of d-methionine doses. In vitro antimicrobial interference studies tested inhibition and post antibiotic effect assays. In vivo antimicrobial interference studies tested normal and neutropenic Escherichia coli murine survival and intraperitoneal lavage bacterial counts.

RESULTS

d-Methionine conferred significant ABR threshold shift reductions. OHC protection was less robust but significant at 20kHz in the 420mg/kg/day group. In vitro studies did not detect d-methionine-induced antimicrobial interference. In vivo studies did not detect d-methionine-induced interference in normal or neutropenic mice.

CONCLUSIONS

d-Methionine protects from tobramycin-induced ototoxicity without antimicrobial interference. The study results suggest d-met as a potential otoprotectant from clinical tobramycin use in cystic fibrosis patients.

Proposed comprehensive ototoxicity monitoring program for VA healthcare (COMP-VA)

Prevention and rehabilitation of hearing loss and tinnitus, the two most commonly awarded service-connected disabilities, are high priority initiatives in the Department of Veterans Affairs (VA). At least 4,000 Veterans, most with significant hearing loss, will receive cisplatin this year, with more than half sustaining permanent hearing shift and nearly 40% developing new tinnitus. With improved survivability following cancer treatment, Veterans treated with cisplatin are approached with the dual goals of effective treatment and preserved quality of life. This article describes COMP-VA, a comprehensive ototoxicity monitoring program developed for VA patients receiving cisplatin. The program includes an individualized pretreatment prediction model that identifies the likelihood of hearing shift given cisplatin dose and patient factors. It supports both manual and automated hearing testing with a newly developed portable audiometer capable of performing the recommended procedures on the chemotherapy unit during treatment. It also includes objective methods for identifying outer hair cell changes and predicting audiogram changes using distortion-product otoacoustic emissions. We describe this program of evidence-based ototoxicity monitoring protocols using a case example to give the reader an understanding of how this program would be applied, along with a plan for future work to accomplish the final stages of program development.

Temporary threshold shift after impulse-noise during video game play: laboratory data

OBJECTIVE

Prevention of temporary threshold shift (TTS) after laboratory-based exposure to pure-tones, broadband noise, and narrowband noise signals has been achieved, but prevention of TTS under these experimental conditions may not accurately reflect protection against hearing loss following impulse noise. This study used a controlled laboratory-based TTS paradigm that incorporated impulsive stimuli into the exposure protocol; development of this model could provide a novel platform for assessing proposed therapeutics.

DESIGN

Participants played a video game that delivered gunfire-like sound through headphones as part of a target practice game. Effects were measured using audiometric threshold evaluations and distortion product otoacoustic emissions (DPOAEs). The sound level and number of impulses presented were sequentially increased throughout the study.

STUDY SAMPLE

Participants were normal-hearing students at the University of Florida who provided written informed consent prior to participation.

RESULTS

TTS was not reliably induced by any of the exposure conditions assessed here. However, there was significant individual variability, and a subset of subjects showed TTS under some exposure conditions.

CONCLUSIONS

A subset of participants demonstrated reliable threshold shifts under some conditions. Additional experiments are needed to better understand and optimize stimulus parameters that influence TTS after simulated impulse noise.

OtoID: new extended frequency, portable audiometer for ototoxicity monitoring

Portability of equipment is an increasingly important component in the practice of audiology. We report on a new device, the OtoID, that supports evidence-based ototoxicity testing protocols, provides capability for hearing testing on the hospital treatment unit, and can automate patient self-testing. The purpose of this article is to report on the validation and verification of the OtoID portable audiometer in 40 subjects both young and old, with and without hearing impairment. Subjects were evaluated by an audiologist using the manual hearing test program and then self-tested via an automated testing program. Testing was done in a sound booth and on a hospital treatment unit. Therefore, data were collected in four conditions (booth vs hospital unit and automated vs manual testing) and analyzed for testing bias, repeatability, and American Speech-Language-Hearing Association-significant ototoxicity false-positive rate. Repeatable hearing threshold results were obtained on all subjects who performed the test, regardless of hearing status or testing location.

ABR obtained from time-efficient train stimuli for cisplatin ototoxicity monitoring

BACKGROUND

Nonbehavioral methods for identifying cisplatin ototoxicity are important for testing patients with cancer who become too tired or sick to provide a reliable response. The auditory brainstem response (ABR) is a nonbehavioral test that is sensitive to ototoxicity but can be time consuming to implement over a range of frequencies and/or levels. To address this issue, trains of stimuli were developed that offer reliable ABR testing over a range of tone-burst frequencies and levels at a time savings of 77% relative to tone-burst stimuli presented individually. The clinical accuracy of this new method has yet to be determined on a clinical population.

PURPOSE

This project was designed to determine the test performance of a time-effective ABR methodology aimed at identifying hearing shifts from cisplatin among veterans. A secondary goal was to determine whether improved test performance could be achieved by including our previously developed ototoxicity risk assessment model in the ABR prediction algorithm.

RESEARCH DESIGN

A set of discriminant functions were derived using logistic regression to model the risk for cisplatin-induced hearing change. Independent variables were one of several ABR metrics alone and combined with an ototoxicity risk assessment model that includes pre-exposure hearing and cisplatin dose. Receiver operating characteristic curve analysis was used to evaluate the test performance of these discriminant functions.

STUDY SAMPLE

Twenty-two male veterans treated with cisplatin for various cancers provided data from a total of 71 monitoring appointments.

DATA COLLECTION AND ANALYSIS

Data were collected prospectively from one ear of each participant as designated below. Hearing shift was determined for frequencies within an octave of each patient's high-frequency hearing limit, tested in 1/6th-octave steps. ABRs were monitored using a set of two intensity trains from the highest two multiple frequency tone-burst center frequencies (up to 11.3 kHz) that yielded a robust response at baseline. Each intensity train was presented at 65-105 dB peSPL in 10 dB steps. Scorable ABRs were generally limited to the highest two intensities; therefore, analyses concern those levels.

RESULTS

The ABR measurement failure was high, up to 52% for some frequencies and levels. Furthermore, the ABR was not frequently obtained at levels below 85 dB peSPL, consistent with previous studies that suggest a stimulus level of greater than 80 dB peSPL is required to obtain a reliable response to trained stimuli. Using multivariate metrics that included the dose-ototoxicity model, the most accurate scoring function was change in amplitude at lowest half-octave frequency obtained at 105 dB (change in wave V amplitude at frequency 2/105). However, absence of wave V at a monitor patient visit of the ABR response at levels 105 or 95 dB peSPL was deemed the preferred scoring function, because it had lower measurement failure and was within one standard error of the most accurate function.

CONCLUSIONS

Because of the large number of responses that could not be measured at baseline, this technique as implemented holds limited value as an ototoxicity-monitoring method.