Understanding drug ototoxicity: molecular insights for prevention and clinical management

An NIR-emitting cyanine dye with pyridinium groups: the impact of regio-bond connection on the photophysical properties

Two ESIPT-based isomeric cyanines were synthesized with significant bathochromic shift in the optical absorption λabs and emission λem, along with a very large Stokes shift. Probe 2 exhibited a longer conjugation and better photostability. Both compounds exhibited good selectivity for labeling the plasma membrane of prokaryotic cells and the hair cells of zebrafish.

Adenovirus-mediated effects of Wnt and Notch signalling pathways on hair cell regeneration in mice

Some genes are delivered to cochleae by adenoviruses to restore partial hearing function. This provides promising prospects for gene therapies for hearing loss from hair cell damage. To study the adenovirus (AD)-mediated effect of the Wnt and Notch signalling pathways on hair cell regeneration in the mouse cochlea, we constructed a β-catenin-adenovirus (β-catenin-AD) to increase the activity of the Wnt signalling pathway and a NICD (intracellular domain of Notch1)-RNAi-adenovirus to decrease the activity of the Notch signalling pathway (NICD-RNAi-AD). Our study indicated that approximately 40% of supporting cells in the cochleae damaged by gentamicin were infected with the adenoviruses. Following the β-catenin-AD-mediated increase in Wnt signalling pathway activity, mitotic regeneration was increased, while direct transdifferentiation was increased after the NICD-RNAi-AD-mediated decrease in Notch signalling pathway activity. The expected synergistic interaction on hair cell regeneration was not obtained after coinfection of β-catenin-AD and NICD-RNAi-AD into the damaged cochleae, which might be due to the low cotransfection efficiency to supporting cells. Our study indicated that it may be possible to develop AD mediated gene therapies for hearing loss that act by regulating the Wnt and Notch signalling pathways.

[Hearing loss following the use of topical otitis therapeutics in dogs]

OBJECTIVE

Hearing loss occurring in temporal association with the topical application of otic medications is regularly reported to the Federal Office of Consumer Protection and Food Safety (Bundesamt für Verbraucherschutz und Lebensmittelsicherheit - BVL) in the form of adverse event (AE) reports. Although deafness or impaired hearing are listed as possible adverse reactions in the Summary of Product Characteristics of the otic medications approved in Germany little information about the underlying causes is available to date.

MATERIAL AND METHODS

A search for cases reporting impaired hearing following the use of otic medication was conducted in the national AE database. Subsequently, descriptive analysis was performed. Due to their small number, cases involving cats were excluded. Possible risk factors and causes of hearing loss were considered against the background of current literature.

RESULTS

While dogs of all age groups were affected, the majority of reports referred to dogs older than 10 years of age. Besides crossbreds, dogs of the breeds West Highland White Terrier, Dalmatian, Miniature Poodle and French Bulldog were most frequently involved. The analysis of the available data does not point to specific products or active substances that could be associated with a more frequent occurrence of hearing loss.

CONCLUSION AND CLINICAL RELEVANCE

In addition to possible ototoxicity of a product, other causes of hearing loss should be considered. These include the underlying otitis itself, age-related hearing loss, previously undetected unilateral congenital deafness, or conductive deafness due to obstruction of the ear canal. Treatment options include discontinuation of potentially ototoxic substances or treatment of conductive deafness, e. g. by removal of drug residues and exudate or treatment of otitis media. In the case of hearing loss subsequent to the use of otic medication, the BVL should be notified of this event in as much detail as possible in order to further improve the data situation concerning this topic.

Ototoxicity in childhood: Recommendations of the CODEPEH (Commission for the Early Detection of Childhood Hearing Loss) for prevention and early diagnosis

Ototoxicity is defined as the damage, reversible or irreversible, produced in the inner ear by various substances that are called ototoxic and that can cause hearing loss and/or an alteration of the vestibular system. Permanent hearing loss significantly affects quality of life and is especially important in children. The lack or delay in its detection is frequent, since it often progresses in an inconspicuous manner until it affects communication and overall development. This impact can be minimized by following a strategy of audiological monitoring of ototoxicity, which allows for its early detection and treatment. This document recommends that children who are going to be treated with cisplatin or aminoglycosides be monitored. This CODEPEH review and recommendation document focuses on the early detection, prophylaxis, otoprotection, monitoring and treatment of ototoxicity caused by aminoglycosides and platinum-based antineoplastics in the paediatric population.

Safety considerations with new antibacterial approaches for chronic bacterial prostatitis

Introduction: Chronic bacterial prostatitis (CBP) is a difficult-to-eradicate infection. Antibacterial therapy with currently licensed agents is hindered due to the increasing emergence of pathogen resistance worldwide and to frequent infection relapse. With limited treatment options, physicians are investigating new agents, which, however, may raise safety concerns.Areas covered: Antibacterial agents currently licensed for CBP were not considered. Available reports about the safety and efficacy of antibacterial agents that have been clinically tested or tentatively used to treat CBP in single cases were evaluated. This review also focused on agents targeting Gram-positive pathogens, whose prevalence as causative agents of CBP is increasing.Expert opinion: (i) Most antibacterial agents considered in this review have been administered off-label in the interest of patients, and their use requires particular caution. (ii) Reports describing the usage of many of the drugs reviewed here are still scant, and readers should be warned of the limited published evidence supporting therapy for CBP with these agents. (iii) As treatment must extend over several weeks, medium-term adverse events may occur and therapy should be individualized, taking into account the dosage and the potential toxicity of each specific antibiotic. Regarding dangerous drug-drug interactions, particular attention should be paid to the risk of ECG-QT-interval elongation.

Detection of unknown ototoxic adverse drug reactions: an electronic healthcare record-based longitudinal nationwide cohort analysis

Ototoxic medications can lead to significant morbidity. Thus, pre-marketing clinical trials have assessed new drugs that have ototoxic potential. Nevertheless, several ototoxic side effects of drugs may remain undetected. Hence, we sought to retrospectively investigate the potential risk of ototoxic adverse drug reactions among commonly used drugs via a longitudinal cohort study. An electronic health records-based data analysis with a propensity-matched comparator group was carried out. This study was conducted using the MetaNurse algorithm for standard nursing statements on electronic healthcare records and the National Sample Cohort obtained from the South Korea National Health Insurance Service. Five target drugs capable of causing ototoxic adverse drug reactions were identified using MetaNurse; two drugs were excluded after database-based analysis because of the absence of bilateral hearing loss events in patients. Survival analysis, log-rank test, and Cox proportional hazards regression models were used to calculate the incidence, survival rate, and hazard ratio of bilateral hearing loss among patients who were prescribed candidate ototoxic drugs. The adjusted hazard ratio of bilateral hearing loss was 1.31 (1.03–1.68), 2.20 (1.05–4.60), and 2.26 (1.18–4.33) in cimetidine, hydroxyzine, and sucralfate users, respectively. Our results indicated that hydroxyzine and sucralfate may cause ototoxic adverse drug reactions in patients. Thus, clinicians should consider avoiding co-administration of these drugs with other well-confirmed ototoxic drugs should be emphasized.

Recording Channelrhodopsin-Evoked Field Potentials and Startle Responses from Larval Zebrafish

Zebrafish are an excellent model organism to study many aspects of vertebrate sensory encoding and behavior. Their escape responses begin with a C-shaped body bend followed by several swimming bouts away from the potentially threatening stimulus. This highly stereotyped motor behavior provides a model for studying startle reflexes and the neural circuitry underlying multisensory encoding and locomotion. Channelrhodopsin (ChR2) can be expressed in the lateral line and ear hair cells of zebrafish and can be excited in vivo to elicit these rapid forms of escape. Here we review our methods for studying transgenic ChR2-expressing zebrafish larvae, including screening for positive expression of ChR2 and recording field potentials and high-speed videos of optically evoked escape responses. We also highlight important features of the acquired data and provide a brief review of other zebrafish research that utilizes or has the potential to benefit from ChR2 and optogenetics.

Ototoxicity in patients with invasive ductal breast cancer who were treated with docetaxel: report of two cases

Docetaxel is an important anti-microtubule agent used to treat a variety of solid tumors, including breast cancer; notably, docetaxel-containing regimens improve outcomes for patients in metastatic, adjuvant, and neoadjuvant settings. However, the effectiveness of docetaxel in clinical practice can be compromised by suboptimal management of side effects. Here, we report two cases of docetaxel-based chemotherapy regimens in patients who exhibited invasive ductal breast cancer and underwent two different clinical treatment approaches. A 58-year-old postmenopausal female received salvage treatment with 8 cycles of docetaxel (67 mg/m²), and a 74-year-old female received 1 cycle of docetaxel (100 mg/m²). The two patients exhibited considerable hearing loss two days later. Of note, both patients had no hearing loss symptoms prior to docetaxel. Thus, ototoxicity may be a side effect of docetaxel that should be considered during treatment.

Suppression of Inflammation Delays Hair Cell Regeneration and Functional Recovery Following Lateral Line Damage in Zebrafish Larvae

Cochlear hair cells in human beings cannot regenerate after loss; however, those in fish and other lower species can. Recently, the role of inflammation in hair cell regeneration has been attracting the attention of scientists. In the present study, we investigated how suppression of inflammatory factors affects hair cell regeneration and the functional recovery of regenerated hair cells in zebrafish. We killed hair cells in the lateral line of zebrafish larvae with CuSO₄ to induce an inflammatory response and coapplied BRS-28, an anti-inflammatory agent to suppress the inflammation. The recovery of the hair cell number and rheotaxis was slower when CuSO₄ and BRS-28 were coapplied than when CuSO₄ was applied alone. The recovery of hair cell count lagged behind that of the calcium imaging signal during the regeneration. The calcium imaging signal in the neuromasts in the inflammation-inhibited group was weaker than that in the noninflammation-inhibited group at the early stage of regeneration, although it returned to normal at the late stage. Our study demonstrates that suppressing inflammation by BRS-28 delays hair cell regeneration and functional recovery when hair cells are damaged. We suspect that BRS-28 inhibits pro-inflammatory factors and thereby reduces the migration of macrophages to delay the regeneration of hair cells.

Perspectives and practices of ototoxicity monitoring

BACKGROUND

Treatment of cancer with cisplatin can result in hearing loss. Given the increasing burden of cancer in Africa, appropriate and timely identification, intervention and management of hearing loss in affected patients is of paramount importance.

OBJECTIVES

This study describes the perspectives and practices of healthcare professionals in relation to cisplatin-associated ototoxicity at an institution treating patients diagnosed with cancer.

METHOD

A concurrent triangulation study design was used to collect quantitative data from seven oncologists, nine nurses and 13 pharmacists using self-administered questionnaires, and qualitative data from four audiologists through semi-structured interviews for this hospital-based study, conducted in South Africa.

RESULTS

Levels of awareness of cisplatin-associated ototoxicity varied with only 33% of the nursing personnel being aware in comparison to the oncologists and pharmacists. Oncologists were identified as the main custodians for providing information to patients. Whilst 82% of the participants considered the audiologist to be part of the oncology team, there was no provision for ototoxicity monitoring in the chemotherapy protocols, nor any ototoxicity-monitoring programme in place. There was no evidence that knowledge of cisplatin-associated ototoxicity translated into an appropriate management strategy for such patients.

CONCLUSION

Healthcare personnel overseeing the care and management of cancer patients need to improve their awareness of ototoxicity and refer timeously for audiological evaluation. Audiologists require greater awareness of monitoring programmes to appropriately implement and manage such programmes within a cancer platform and be part of a multidisciplinary team.

Ototoxic Adverse Drug Reactions: A Disproportionality Analysis Using the Italian Spontaneous Reporting Database

Introduction: The panorama of drug-induced ototoxicity has widened in the last decades; moreover, post-marketing data are necessary to gain a better insight on ototoxic adverse drug reactions (ADRs). The aim of this study was to perform an analysis of ADR reports describing drug-induced ototoxicity from the Italian spontaneous reporting system (SRS).

Methods: As a measure of disproportionality, we calculated the reporting odds ratios (RORs) and 95% confidence intervals (CIs) with a case/non-case methodology. Cases were all suspected ADR reports regarding drug-induced ototoxicity collected into the Italian SRS from 2001 to 2017. Non-cases included all other ADRs reported in the same period.

Results: Of 325,980 reports, 652 included at least one ototoxic ADR, compared with 325,328 non-cases. Statistically significant adjusted RORs were found for drugs for cardiovascular disorders, urologicals, teriparatide, amikacin, prulifloxacin, rifampicin and isoniazid, cisplatin, hormone antagonists, tacrolimus, pomalidomide, tramadol, and antidepressants. Significant adjusted RORs in relation to tinnitus were also observed for doxazosin (ROR 5.55, 95% CI 2.06–14.93), bisoprolol (4.28, 1.59–11.53), nebivolol (8.06, 3.32–19.56), ramipril (3.96, 2.17–7.23), irbesartan (19.60, 9.19–41.80), betamethasone (4.01, 1.28–12.52), moxifloxacin (4.56, 1.71–12.34), ethambutol (12.25, 3.89–38.57), efavirenz (16.82, 5.34–52.96), sofosbuvir/ledipasvir (5.95, 1.90–18.61), etoposide (7.09, 2.63–19.12), abatacept (6.51, 2.42–17.53), indometacin (6.30, 2.02–19.72), etoricoxib (5.00, 2.23–11.23), tapentadol (4.37, 1.09–17.62), and timolol combinations (23.29, 9.53–56.95). Moreover, significant adjusted RORs for hypoacusis regarded clarithromycin (3.95, 1.86–8.40), azithromycin (10.23, 5.03–20.79), vancomycin (6.72, 2.14–21.11), methotrexate (3.13, 1.00–9.81), pemetrexed (4.38, 1.40–13.76), vincristine (5.93, 1.88–18.70), vinorelbine (21.60, 8.83–52.82), paclitaxel (2.34, 1.03–5.30), rituximab (3.20, 1.19–8.63), interferon alfa-2b (17.44, 8.56–35.53), thalidomide (16.92, 6.92–41.38), and deferasirox (41.06, 20.07–84.01).

Conclusions: This study is largely consistent with results from literature. Nevertheless, propafenone, antituberculars, hormone antagonists, teriparatide, tramadol, and pomalidomide are unknown for being ototoxic. Hypoacusis after the use of vinorelbine, methotrexate, and pemetrexed is unexpected, such as tinnitus related with etoposide, nebivolol, betamethasone, abatacept, sofosbuvir/ledipasvir, and tapentadol, but these considerations require further investigation to better define the risk due to the paucity of data. Moreover, physicians should be aware of the clinical significance of ototoxicity and be conscious about the importance of their contribution to spontaneous reporting.

Fluctuating Sensorineural Hearing Loss

BACKGROUND

Several otologic conditions can present with fluctuating sensorineural hearing loss, including Ménière's disease, autoimmune inner ear disease, and enlarged vestibular aqueduct. Although these 3 etiologies vary greatly, distinguishing between these conditions at initial presentation can be challenging. Furthermore, initial treatment of these conditions is often similar. In this review, we discuss historical and current perspectives on diagnosis and treatment of these conditions.

SUMMARY

A literature search was performed regarding fluctuating hearing loss, and current treatment of these etiologies of fluctuating hearing loss was summarized. Immediate measures at the onset of acute hearing loss include corticosteroid therapy, while preventative and chronic therapies, which can limit disease severity and frequency, vary based on the specific condition treated. Key Messages: Fluctuating hearing loss can represent a range of pathologies, but the precise etiology may not be clear at initial presentation. Timely treatment and long-term follow-up, along with appropriate diagnostics, are necessary to optimize long-term hearing.

Predicting the Need for a Tier II Ototoxicity Study From Early Renal Function Data

History has established that many drugs, such as the antibiotics, chemotherapies, and loop diuretics, are capable of inducing both nephrotoxicity and ototoxicity. The exact mechanisms by which cellular damage occurs remain to be fully elucidated. Monitoring the indices of renal function conducted in the Food and Drug Administration's prescribed set of early investigational new drug (IND)-enabling studies may be the first signs of ototoxicity properties of the new drug candidate. In developing improved and efficacious new molecular entities, it is critically necessary to understand the cellular and molecular mechanisms underlying the potential ototoxic effects as early in the drug development program as possible. Elucidation of these mechanisms will facilitate the development of safe and effective clinical approaches for the prevention and amelioration of drug-induced ototoxicity prior to the first dose in man. Biomarkers for nephrotoxicity in early tier I or tier II nonclinical IND-enabling studies should raise an inquiry as to the need to conduct a full auditory function assay early in the game to clear the pipeline with a safer candidate that has a higher probability of continued therapeutic compliance once approved for distribution.

Furosemide as a functional marker of acute kidney injury in ICU patients: a new role for an old drug

New pharmacokinetics insight suggests that the furosemide pharmacology occurring in ICU patients with AKI is similar, but not equal to that described in chronic stable renal patients. Even if the diuretic response to furosemide is expressed by a steep dose-response curve positively correlated with renal function, pharmacodynamic limitations occur when creatinine clearance is < 20 ml/min or urine output is < 500 ml/12 h. In such cases, other factors specifically due to acute tubular injury can interfere with the furosemide-induced diuretic output. As modality of administration recent reports and metanalysis, even if not conclusive, suggest that for the same given dose a continuous infusion of furosemide was superior in diuretic response. For septic shock patients on CVVHDF where treatment adds an additional clearance of furosemide the maximum diuretic response is achieved by a continuous infusion of 20 mg/h of furosemide. At this infusion rate the reached plasma level was < 20 mg/L, a range considered safe and not ototoxic. Therefore, the severity of AKI establishes whether a patient will respond to furosemide. In this review we summarized all these recent updates, also suggesting that the diuretic response under continuous infusion may allow assessing glomerular and tubular functions with increased reliability than a bolus dose. However, validation studies are still needed to support continuous infusion as a stress test.

A Review of Cisplatin-Associated Ototoxicity

Cisplatin, an effective antineoplastic drug used in the treatment of many cancers, has ototoxic potential, thus placing cancer patients, receiving this treatment, at risk of hearing loss. It is therefore important for health care professionals managing these patients to be aware of cisplatin's ototoxic properties and its clinical signs to identify patients at risk of developing a hearing impairment. Eighty-five English peer-reviewed articles and two books, from January 1975 to July 2015, were identified from PubMed, ScienceDirect, and EBSCOhost. An overview of cisplatin-associated ototoxicity, namely its clinical features, incidence rates, molecular and cellular mechanisms, and risk factors, is presented in this article. This review further highlights the importance of a team-based approach to complement an audiological monitoring program in reducing any further loss in the quality of life of affected patients, as there is currently no otoprotective agent routinely recommended for the prevention of cisplatin-associated ototoxicity.

Lower ototoxicity and absence of hidden hearing loss point to gentamicin C1a and apramycin as promising antibiotics for clinical use

Spread of antimicrobial resistance and shortage of novel antibiotics have led to an urgent need for new antibacterials. Although aminoglycoside antibiotics (AGs) are very potent anti-infectives, their use is largely restricted due to serious side-effects, mainly nephrotoxicity and ototoxicity. We evaluated the ototoxicity of various AGs selected from a larger set of AGs on the basis of their strong antibacterial activities against multidrug-resistant clinical isolates of the ESKAPE panel: gentamicin, gentamicin C1a, apramycin, paromomycin and neomycin. Following local round window application, dose-dependent effects of AGs on outer hair cell survival and compound action potentials showed gentamicin C1a and apramycin as the least toxic. Strikingly, although no changes were observed in compound action potential thresholds and outer hair cell survival following treatment with low concentrations of neomycin, gentamicin and paromomycin, the number of inner hair cell synaptic ribbons and the compound action potential amplitudes were reduced. This indication of hidden hearing loss was not observed with gentamicin C1a or apramycin at such concentrations. These findings identify the inner hair cells as the most vulnerable element to AG treatment, indicating that gentamicin C1a and apramycin are promising bases for the development of clinically useful antibiotics.

Isolation, cultivation, and characterization of primary bovine cochlear pericytes: A new in vitro model of stria vascularis

The study of strial pericytes has gained great interest as they are pivotal for the physiology of stria vascularis. To provide an easily accessible in vitro model, here we described a growth medium-based approach to obtain and cultivate primary bovine cochlear pericytes (BCP) from the stria vascularis of explanted bovine cochleae. We obtained high-quality pericytes in 8-10 days with a > 90% purity after the second passage. Immunocytochemical analysis showed a homogeneous population of cells expressing typical pericyte markers, such as neural/glial antigen 2 (NG2), platelet-derived growth factor receptorβ (PDGFRβ), α-smooth muscle actin (α-SMA), and negative for the endothelial marker von Willebrand factor. When challenged with tumor necrosis factor or lipopolysaccharide, BCP changed their shape, similarly to human retinal pericytes (HRPC). The sensitivity of BCP to ototoxic drugs was evaluated by challenging with cisplatin or gentamicin for 48 hr. Compared to human retinal endothelial cells and HRPC, cell viability of BCP was significantly lower ( p < 0.05) after the treatment with gentamicin or cisplatin. These data indicate that our protocol provides a simple and reliable method to obtain highly pure strial BCP. Furthermore, BCP are suitable to assess the safety profile of molecules which supposedly exert ototoxic activity, and may represent a valid alternative to in vivo tests.

Innovative pharmaceutical approaches for the management of inner ear disorders

The sense of hearing is essential for permitting human beings to interact with the environment, and its dysfunctions can strongly impact on the quality of life. In this context, the cochlea plays a fundamental role in the transformation of the airborne sound waves into electrical signals, which can be processed by the brain. However, several diseases and external stimuli (e.g., noise, drugs) can damage the sensorineural structures of cochlea, inducing progressive hearing dysfunctions until deafness. In clinical practice, the current pharmacological approaches to treat cochlear diseases are based on the almost exclusive use of systemic steroids. In the last decades, the efficacy of novel therapeutic molecules has been proven, taking advantage from a better comprehension of the pathological mechanisms underlying many cochlear diseases. In addition, the feasibility of intratympanic administration of drugs also permitted to overcome the pharmacokinetic limitations of the systemic drug administration, opening new frontiers in drug delivery to cochlea. Several innovative drug delivery systems, such as in situ gelling systems or nanocarriers, were designed, and their efficacy has been proven in vitro and in vivo in cochlear models. The current review aims to describe the art of state in the cochlear drug delivery, highlighting lights and shadows and discussing the most critical aspects still pending in the field.

Current practice of ototoxicity management across the United Kingdom (UK)

OBJECTIVE

Effective management of patients diagnosed with ototoxicity is needed to reduce hearing and balance damage which affects communication and life quality. Despite widespread recommendations to monitor and manage ototoxicity in an early and effective manner, there is limited evidence to support the actual implementation of these recommendations for affected patient groups in healthcare services across the UK with limited publications available. In this study, an online questionnaire analysed the current practice of ototoxicity management and patient pathways across the UK once the diagnosis of ototoxicity was confirmed, targeting Audiologists, ENTs/AVPs and GPs.

DESIGN

Qualitative Survey Study.

STUDY SAMPLE

A randomised sample of hearing services in the UK, including audiology departments; GP practices and local health settings were targeted with a total of 134 completed surveys.

RESULTS

About 72% reported the absence of ototoxicity management protocols within their centre. Results depicted great inconsistency and variation across the UK in ototoxicity management services provided, treatment modification, monitoring and referral pathways.

CONCLUSION

Developing and advocating national guidelines are intended not only to inform clinical decision making but to provide minimum standards of care in ototoxicity management and offer greater awareness and education to improve patients' quality of life.

Physiological assesment of vestibular function and toxicity in humans and animals

Physiological methods that can be similarly recorded in humans and animals have a major role in sensory toxicology, as they provide a bridge between human sensory perception data and the molecular and cellular data obtained in animal studies. Vestibular toxicity research lags well behind other sensory systems in many aspects, including the availability of methods for functional assessment in animals that could be robustly translated to human significance. Here we review the methods available for the assessment of vestibular function in both humans and laboratory animals, with an emphasis on their similarity or divergence, to highlight their potential utility for the predictive assessment of vestibular toxicity.

Research protocol: Cisplatin-associated ototoxicity amongst patients receiving cancer chemotherapy and the feasibility of an audiological monitoring program

Background

Cisplatin is an anti-cancer chemotherapy drug classified as an alkylating agent. It is used for the treatment of a variety of cancers such as cervical, breast, stomach, prostate, bladder and oesophageal, to name a few. However due to its expansive toxicity profile, patients receiving cisplatin can experience high frequency hearing loss, a side effect known as ototoxicity. The dearth of information on the extent and severity of cisplatin-associated ototoxicity in South Africa prevents the implementation of a context-specific audiological monitoring programme.

Methods

This study aims to determine the extent and severity of ototoxicity amongst patients with cervical cancer, receiving cisplatin-based chemotherapy and hence the feasibility of an ototoxicity monitoring program in the province of KwaZulu-Natal, South Africa. A concurrent mixed methods design will be employed in the study. This longitudinal study will involve interviewing oncology nurses, oncologists, pharmacists and audiologists to assess the level of awareness to ototoxicity, as well as conducting diagnostic audiological evaluations at regular intervals on 78 patients with cervical cancer to ascertain the progression of hearing loss during and after chemotherapy. The feasibility of the monitoring program will be assessed as a parallel process to the audiological evaluations, where patient outcomes and cost implications to the patient and the health sector will be considered. Data will be subjected to statistical analyses so as to strengthen knowledge in the field and inform appropriate policies, and healthcare providers.

Discussion

This study is the first longitudinal study in South Africa to determine the ototoxic effects of cisplatin therapy on patients diagnosed with cervical cancer. Thus, the results generated from this study is likely to bring novel information to the fore using an evidence-based approach that will influence policy and clinical practice which can vastly improve the quality of life of patients undergoing chemotherapy. Mitigation of any further loss in the quality of life of affected patients is of paramount importance and the data generated from this project can lay the basis for further effective dialogue towards policy formulation on an ototoxic monitoring programme and the resultant strengthening of health systems in limited resource settings.

Electronic supplementary material

The online version of this article (10.1186/s12905-017-0486-8) contains supplementary material, which is available to authorized users.

Resolution of Cochlear Inflammation: Novel Target for Preventing or Ameliorating Drug-, Noise- and Age-related Hearing Loss

A significant number of studies support the idea that inflammatory responses are intimately associated with drug-, noise- and age-related hearing loss (DRHL, NRHL and ARHL). Consequently, several clinical strategies aimed at reducing auditory dysfunction by preventing inflammation are currently under intense scrutiny. Inflammation, however, is a normal adaptive response aimed at restoring tissue functionality and homeostasis after infection, tissue injury and even stress under sterile conditions, and suppressing it could have unintended negative consequences. Therefore, an appropriate approach to prevent or ameliorate DRHL, NRHL and ARHL should involve improving the resolution of the inflammatory process in the cochlea rather than inhibiting this phenomenon. The resolution of inflammation is not a passive response but rather an active, highly controlled and coordinated process. Inflammation by itself produces specialized pro-resolving mediators with critical functions, including essential fatty acid derivatives (lipoxins, resolvins, protectins and maresins), proteins and peptides such as annexin A1 and galectins, purines (adenosine), gaseous mediators (NO, H₂S and CO), as well as neuromodulators like acetylcholine and netrin-1. In this review article, we describe recent advances in the understanding of the resolution phase of inflammation and highlight therapeutic strategies that might be useful in preventing inflammation-induced cochlear damage. In particular, we emphasize beneficial approaches that have been tested in pre-clinical models of inflammatory responses induced by recognized ototoxic drugs such as cisplatin and aminoglycoside antibiotics. Since these studies suggest that improving the resolution process could be useful for the prevention of inflammation-associated diseases in humans, we discuss the potential application of similar strategies to prevent or mitigate DRHL, NRHL and ARHL.

Topical otic drugs in a multi-purpose manufacturing facility: a guide on determination and application of permitted daily exposure (PDE)

Due to newly introduced EU GMP (Good Manufacturing Practice) guideline for Medicinal Products for Human and Veterinary use, product specific permitted daily exposure (PDE) for toxicological evaluation in multi-purpose facilities are required within a documented process for risk assessment. European Medicines Agency (EMA) guidance on setting PDE limits so far focused on systemic administration routes such as intravenous (IV), oral or inhalation. This article provides guidance on setting PDE values for risk management purposes in multi-purpose facilities for active pharmaceutical ingredients (APIs) applied as topical otic drugs to the outer ear canal. The therewith determined PDE otic, is used for the calculation of maximum safe carry-over (MSC) in manufacturing scenarios where a topical otic product is manufactured followed by another topical otic product.

Cisplatin-Associated Ototoxicity: A Review for the Health Professional

Cisplatin is an effective drug used in the treatment of many cancers, yet its ototoxic potential places cancer patients, exposed to this drug, at risk of hearing loss, thus negatively impacting further on a patient's quality of life. It is paramount for health care practitioners managing such patients to be aware of cisplatin's ototoxic properties and the clinical signs to identify patients at risk of developing hearing loss. English peer-reviewed articles from January 1975 to July 2015 were assessed from PubMed, Science Direct, and Ebscohost. Seventy-nine articles and two books were identified for this review, using MeSH terms and keywords such as "ototoxicity", "cisplatin", "hearing loss", and "ototoxicity monitoring". This review provides an up-to-date overview of cisplatin-associated ototoxicity, namely, its clinical features, incidence rates, and molecular and cellular mechanisms and risk factors, to health care practitioners managing the patient with cancer, and highlights the need for a team-based approach to complement an audiological monitoring programme to mitigate any further loss in the quality of life of affected patients, as there is currently no otoprotective agent recommended routinely for the prevention of cisplatin-associated ototoxicity. It also sets the platform for effective dialogue towards policy formulation and strengthening of health systems in developing countries.

An open label study to evaluate the safety and efficacy of intratympanic golimumab therapy in patients with autoimmune inner ear disease

OBJECTIVE

To evaluate the safety and efficacy of intratympanically injected golimumab (GLM), a TNF-α inhibitor, as a steroid-sparing agent for patients with steroid-dependent autoimmune inner ear disease (AIED).

STUDY DESIGN

Open label.

SETTING

Tertiary referral center.

PATIENTS

Ten patients with steroid-dependent AIED were enrolled in Stage 2. The average patient age at enrollment was 59, with an average of 12.5 years from the start of bilateral hearing loss symptoms. The average dose of daily prednisone at the start of injections was 18 mg.

INTERVENTION

Intratympanic injection of GLM.

MAIN OUTCOME MEASURE

Hearing loss progression (treatment failure) was defined as either an increase in pure-tone thresholds by frequency or a decrease in word recognition score.

RESULTS

There were no serious adverse events. Five of seven per-protocol subjects experienced stable pure-tone thresholds in the injected ear, whereas 4 had stable word recognition scores. Two subjects experienced an improvement in word recognition scores. The results support the hypothesis that GLM may be a promising treatment.

CONCLUSIONS

The TNF-α inhibitor GLM stabilized hearing in 3 of 7 per-protocol subjects with AIED and allowed a complete tapering off of prednisone in those 7 subjects. Studies with larger samples sizes are warranted.

Canertinib induces ototoxicity in three preclinical models

Neuregulin-1 (NRG1) ligand and its epidermal growth factor receptor (EGFR)/ERBB family regulate normal cellular proliferation and differentiation in many tissues including the cochlea. Aberrant NRG1 and ERBB signaling cause significant hearing impairment in mice. Dysregulation of the same signaling pathway in humans is involved in certain types of cancers such as breast cancer or non-small cell lung cancer (NSCLC). A new irreversible pan-ERBB inhibitor, canertinib, has been tested in clinical trials for the treatment of refractory NSCLC. Its possible ototoxicity was unknown. In this study, a significant dose-dependent canertinib ototoxicity was observed in a zebrafish model. Canertinib ototoxicity was further confirmed in two mouse models with different genetic backgrounds. The data strongly suggested an evolutionally preserved ERBB molecular mechanism underlying canertinib ototoxicity. Thus, these results imply that clinical monitoring of hearing loss should be considered for clinical testing of canertinib or other pan-ERBB inhibitors.

Cochlear injury and adaptive plasticity of the auditory cortex

Growing evidence suggests that cochlear stressors as noise exposure and aging can induce homeostatic/maladaptive changes in the central auditory system from the brainstem to the cortex. Studies centered on such changes have revealed several mechanisms that operate in the context of sensory disruption after insult (noise trauma, drug-, or age-related injury). The oxidative stress is central to current theories of induced sensory-neural hearing loss and aging, and interventions to attenuate the hearing loss are based on antioxidant agent. The present review addresses the recent literature on the alterations in hair cells and spiral ganglion neurons due to noise-induced oxidative stress in the cochlea, as well on the impact of cochlear damage on the auditory cortex neurons. The emerging image emphasizes that noise-induced deafferentation and upward spread of cochlear damage is associated with the altered dendritic architecture of auditory pyramidal neurons. The cortical modifications may be reversed by treatment with antioxidants counteracting the cochlear redox imbalance. These findings open new therapeutic approaches to treat the functional consequences of the cortical reorganization following cochlear damage.

Sensory hair cell regeneration in the zebrafish lateral line

BACKGROUND

Damage or destruction of sensory hair cells in the inner ear leads to hearing or balance deficits that can be debilitating, especially in older adults. Unfortunately, the damage is permanent, as regeneration of the inner ear sensory epithelia does not occur in mammals.

RESULTS

Zebrafish and other non-mammalian vertebrates have the remarkable ability to regenerate sensory hair cells and understanding the molecular and cellular basis for this regenerative ability will hopefully aid us in designing therapies to induce regeneration in mammals. Zebrafish not only possess hair cells in the ear but also in the sensory lateral line system. Hair cells in both organs are functionally analogous to hair cells in the inner ear of mammals. The lateral line is a mechanosensory system found in most aquatic vertebrates that detects water motion and aids in predator avoidance, prey capture, schooling, and mating. Although hair cell regeneration occurs in both the ear and lateral line, most research to date has focused on the lateral line due to its relatively simple structure and accessibility.

CONCLUSIONS

Here we review the recent discoveries made during the characterization of hair cell regeneration in zebrafish.

Medication Associated with Hearing Loss

Objectives

Many medications have the potential for ototoxicity. To potentiate management of this risk, this study examines malpractice litigation trends of lawsuits involving hearing loss associated with medication use. As experts in hearing loss, it may benefit otolaryngologists to be familiar with this information.

Study Design

Retrospective review.

Setting

All US civil trials.

Subjects and Methods

Court records of legal trials from 1987 to 2012 were obtained from 2 major computerized databases. Data were compiled on the demographics of the defendant and plaintiff, use of otolaryngologists as expert witnesses, medication used, legal allegations, verdicts, and judgments.

Results

Forty-six unique cases met inclusion criteria and were selected for review. Antibiotics (72%), specifically aminoglycosides (47%), were the most common medications cited as causing hearing loss. Eleven (22%) cases were resolved through a settlement before a verdict was reached. Verdicts in favor of the plaintiffs (37%) were awarded an average of $1,134,242. Pediatric patients were more likely to have outcomes in their favor ( P = .03) compared to adults. Of the cases found in favor of the plaintiff, the most common reasons cited were inappropriate medication, dose, or duration (59%); failure to properly monitor (39%); and failure to choose a less toxic medication (18%).

Conclusions

Physicians must be aware of the potential effects of the medications they prescribe. An understanding of potential drug interactions, proper monitoring, and appropriate substitution with less toxic medications are important to improve patient care. Analyzing litigation trends may be used to prevent future lawsuits and improve physician awareness.

Insult-induced adaptive plasticity of the auditory system

The brain displays a remarkable capacity for both widespread and region-specific modifications in response to environmental challenges, with adaptive processes bringing about the reweighing of connections in neural networks putatively required for optimizing performance and behavior. As an avenue for investigation, studies centered around changes in the mammalian auditory system, extending from the brainstem to the cortex, have revealed a plethora of mechanisms that operate in the context of sensory disruption after insult, be it lesion-, noise trauma, drug-, or age-related. Of particular interest in recent work are those aspects of auditory processing which, after sensory disruption, change at multiple—if not all—levels of the auditory hierarchy. These include changes in excitatory, inhibitory and neuromodulatory networks, consistent with theories of homeostatic plasticity; functional alterations in gene expression and in protein levels; as well as broader network processing effects with cognitive and behavioral implications. Nevertheless, there abounds substantial debate regarding which of these processes may only be sequelae of the original insult, and which may, in fact, be maladaptively compelling further degradation of the organism's competence to cope with its disrupted sensory context. In this review, we aim to examine how the mammalian auditory system responds in the wake of particular insults, and to disambiguate how the changes that develop might underlie a correlated class of phantom disorders, including tinnitus and hyperacusis, which putatively are brought about through maladaptive neuroplastic disruptions to auditory networks governing the spatial and temporal processing of acoustic sensory information.

Underlying mechanisms of tinnitus: review and clinical implications

BACKGROUND

The study of tinnitus mechanisms has increased tenfold in the last decade. The common denominator for all of these studies is the goal of elucidating the underlying neural mechanisms of tinnitus with the ultimate purpose of finding a cure. While these basic science findings may not be immediately applicable to the clinician who works directly with patients to assist them in managing their reactions to tinnitus, a clear understanding of these findings is needed to develop the most effective procedures for alleviating tinnitus.

PURPOSE

The goal of this review is to provide audiologists and other health-care professionals with a basic understanding of the neurophysiological changes in the auditory system likely to be responsible for tinnitus.

RESULTS

It is increasingly clear that tinnitus is a pathology involving neuroplastic changes in central auditory structures that take place when the brain is deprived of its normal input by pathology in the cochlea. Cochlear pathology is not always expressed in the audiogram but may be detected by more sensitive measures. Neural changes can occur at the level of synapses between inner hair cells and the auditory nerve and within multiple levels of the central auditory pathway. Long-term maintenance of tinnitus is likely a function of a complex network of structures involving central auditory and nonauditory systems.

CONCLUSIONS

Patients often have expectations that a treatment exists to cure their tinnitus. They should be made aware that research is increasing to discover such a cure and that their reactions to tinnitus can be mitigated through the use of evidence-based behavioral interventions.

Vestibular damage in chronic ototoxicity: a mini-review

Ototoxicity is a major cause of the loss of hearing and balance in humans. Ototoxic compounds include pharmaceuticals such as aminoglycoside antibiotics, anti-malarial drugs, loop diuretics and chemotherapeutic platinum agents, and industrial chemicals including several solvents and nitriles. Human and rodent data indicate that the main target of toxicity is hair cells (HCs), which are the mechanosensory cells responsible for sensory transduction in both the auditory and the vestibular system. Nevertheless, the compounds may also affect the auditory and vestibular ganglion neurons. Exposure to ototoxic compounds has been found to cause HC apoptosis, HC necrosis, and damage to the afferent terminals, of differing severity depending on the ototoxicity model. One major pathway frequently involved in HC apoptosis is the c-jun N-terminal kinase (JNK) signaling pathway activated by reactive oxygen species, but other apoptotic pathways can also play a role in ototoxicity. Moreover, little is known about the effects of chronic low-dose exposure. In rodent vestibular epithelia, extrusion of live HCs from the sensory epithelium may be the predominant form of cell demise during chronic ototoxicity. In addition, greater involvement of the afferent terminals may occur, particularly the calyx units contacting type I vestibular HCs. As glutamate is the neurotransmitter in this synapse, excitotoxic phenomena may participate in afferent and ganglion neuron damage. Better knowledge of the events that take place in chronic ototoxicity is of great interest, as it will increase understanding of the sensory loss associated with chronic exposure and aging.

Validated reverse-phase high-performance liquid chromatography for quantification of furosemide in tablets and nanoparticles

A simple, sensitive, and specific method for furosemide (FUR) analysis by reverse-phase-HPLC was developed using a Spherisorb C18 ODS 2 column. A chromatographic analysis was carried out using a mobile phase consisting of acetonitrile and 10 mM potassium phosphate buffer solution: 70 : 30 (v/v) at pH 3.85, at a flow rate of 1 mL·min(-1). The UV-detection method was carried out at 233 nm at room temperature. Validation parameters including limit of detection (LOD), limit of quantitation (LOQ), linearity range, precision, accuracy, robustness, and specificity were investigated. Results indicated that the calibration curve was linear (r (2) = 0.9997) in the range of 5.2 to 25,000 ng·mL(-1), with ε value equal to 3.74 × 10(4) L·M(-1) ·cm(-1). The LOD and LOQ were found to be 5.2 and 15.8 ng·mL(-1), respectively. The developed method was found to be accurate (RSD less than 2%), precise, and specific with an intraday and interday RSD range of 1.233-1.509 and 1.615 to 1.963%. The stability of native FUR has also been performed in simulated perilymph and endolymph media (with respective potency in each medium of 99.8 ± 2.3% and 96.68 ± 0.7%, n = 3) after 6 hours. This method may be routinely used for the quantitative analysis of FUR from nanocarriers, USP tablets and release media related to hearing research.

Neurophysiologic measures of auditory function in fish consumers: associations with long chain polyunsaturated fatty acids and methylmercury

BACKGROUND

Determining if associations exist between child neurodevelopment and environmental exposures, especially low level or background ones, is challenging and dependent upon being able to measure specific and sensitive endpoints. Psychometric or behavioral measures of CNS function have traditionally been used in such studies, but do have some limitations. Auditory neurophysiologic measures examine different nervous system structures and mechanisms, have fewer limitations, can more easily be quantified, and might be helpful additions to testing. To date, their use in human epidemiological studies has been limited. We reviewed the use of auditory brainstem responses (ABR) and otoacoustic emissions (OAE) in studies designed to determine the relationship of exposures to methyl mercury (MeHg) and nutrients from fish consumption with neurological development. We included studies of experimental animals and humans in an effort to better understand the possible benefits and risks of fish consumption.

OBJECTIVES

We reviewed the literature on the use of ABR and OAE to measure associations with environmental exposures that result from consuming a diet high in fish. We focused specifically on long chain polyunsaturated fatty acids (LCPUFA) and MeHg.

METHODS

We performed a comprehensive review of relevant studies using web-based search tools and appropriate search terms.

RESULTS

Gestational exposure to both LCPUFA and MeHg has been reported to influence the developing auditory system. In experimental studies supplemental LCPUFA is reported to prolong ABR latencies and human studies also suggest an association. Experimental studies of acute and gestational MeHg exposure are reported to prolong ABR latencies and impair hair cell function. In humans, MeHg exposure is reported to prolong ABR latencies, but the impact on hair cell function is unknown.

CONCLUSION

The auditory system can provide objective measures and may be useful in studying exposures to nutrients and toxicants and whether they are associated with children's neurodevelopment.

Cochlear implantation in patients deafened by ototoxic drugs

OBJECTIVE

To investigate the outcome of cochlear implantation (CI) in patients deafened by ototoxic drugs and to compare this, with the outcome of CI in sudden sensorineural hearing loss (SSNHL) with a similar duration of deafness.

METHODS

The Manchester Auditory Implant Centre database was reviewed to identify patients who were implanted to rehabilitate profound sensorineural hearing loss resulting from treatment with ototoxic agents and patients with SSNHL group. A retrospective case note review of selected patients was carried out. Primary outcome measure was post-implantation Bamford-Kowal-Bench (BKB) score in quiet in both the groups. Secondary outcome measure was any significant complications following implantation.

RESULTS

We identified 14 patients in the ototoxic group, which were matched with 13 patients in the SSNHL group. The post-operative BKB score in the ototoxic group ranged from 33 to 100% (median score 91%). One patient had bilateral CI. One patient required explantation following an infection. The post-operative BKB score in the SSNHL group ranged from 16 to 100% (median score 88%). One patient in this group could not be tested using this method as they did not have open set speech discrimination. Two patients in this group had bilateral CI. The data were analysed using Mann-Whitney U test. There was no statistically significant difference in the BKB scores in the two groups of patients (P value -0.983).

CONCLUSION

Patients with profound hearing loss secondary to ototoxic agents can be rehabilitated successfully with CI. The outcomes may be variable and may be dependent on the underlying pathology for which the ototoxic agents were prescribed.

Human ultrasonic hearing is induced by a direct ultrasonic stimulation of the cochlea

Ultrasound can be perceived by bone-conduction. The cochlear basal turn is involved in processing bone-conducted ultrasound (BCU) information. Previous studies have suggested that ultrasonic perception is induced by ultrasound itself. In contrast, it has also been suggested that a lower frequency sound is generated in non-linear process during the transmission pathway to the cochlea to induce an auditory sensations. To address this issue, we assessed cisplatin-induced changes in BCU sensitivity at 27, 30 and 33kHz in 20 participants (40 ears) who were scheduled to undergo cisplatin chemoradiation therapy. Following the treatment, 62.5% ears were diagnosed with hearing loss according to the criteria of the American Speech-Language-Hearing Association. As expected, significant increases in sensitivity threshold were observed for air-conducted sounds ranging from 8 to 14kHz. In contrast, the BCU threshold significantly decreased after the treatment. Considering that both air-conducted high-frequency sound and BCU are perceived in the cochlear basal turn, these findings indicate that ultrasonic perception is independent of hearing a lower frequency sound generated in non-linear process. In addition, our findings support the hypothesis that ultrasound itself induces ultrasonic perception in the cochlea. The observed cisplatin-induced increase in BCU sensitivity may be explained by hypersensitivity associated with outer hair cells' disorder.

Hearing impairment associated with oral terbinafine use: a case series and case/non-case analysis in the Netherlands Pharmacovigilance Centre Lareb database and VigiBase™

BACKGROUND

The Netherlands Pharmacovigilance Centre Lareb received reports of six cases of hearing impairment in association with oral terbinafine use. This study describes these cases and provides support for this association from the Lareb database for spontaneous adverse drug reaction (ADR) reporting and from Vigibase™, the ADR database of the WHO Collaborating Centre for International Drug Monitoring, the Uppsala Monitoring Centre.

OBJECTIVES

The objective of the current study was to identify whether the observed association between oral terbinafine use and hearing impairment, based on cases received by Lareb, constitutes a safety signal.

METHODS

Cases of hearing impairment in oral terbinafine users are described. In a case/non-case analysis, the strength of the association in Vigibase™ and the Lareb database was determined (date of analysis August 2011) by calculating the reporting odds ratios (RORs), adjusted for possible confounding by age, sex and ototoxic concomitant medication. For the purpose of this study, RORs were calculated for deafness, hypoacusis and the combination of both, defined as hearing impairment.

RESULTS

In the Lareb database, six reports concerning individuals aged 31-82 years, who developed hearing impairment after starting oral terbinafine, were present. The use of oral terbinafine was disproportionally associated with hypoacusis in both the Lareb database (adjusted ROR 3.9; 95% CI 1.7, 9.0) and in Vigibase™ (adjusted ROR 1.7; 95% CI 1.0, 2.8). Deafness was not disproportionally present in either of the databases.

DISCUSSION

Based on the described cases and the statistical analyses from both databases, a causal relationship between the use of oral terbinafine and hearing impairment is possible. The mechanism by which terbinafine could cause hearing impairment has not been elucidated yet. The pharmacological action of terbinafine is based on the inhibition of squalene epoxidase, an enzyme present in both fungal and human cells. This inhibition might result in a decrease in cholesterol levels in human cells, among which are the outer hair cells of the cochlea. It may be possible that the reduction in cochlear cholesterol levels leads to impaired cochlear function and possibly hearing impairment.

CONCLUSION

In this study we describe hearing impairment as a possible ADR of oral terbinafine, based on six case reports and statistical support from Vigibase™ and the Lareb database. To our knowledge this association has not been described before.

In vitro and in vivo models of drug ototoxicity: studying the mechanisms of a clinical problem

INTRODUCTION

Drug ototoxicity represents one of the main preventable causes of deafness. Ototoxicity is a trait shared by aminoglycoside and macrolide antibiotics, antimalarial medications, loop diuretics, platinum-based chemotherapeutic agents, some NSAIDs and most recently described, acetaminophen when abused with narcotic medication. These medications are prescribed despite their side effects, which includes inner ear toxicity, because they are life-saving drugs or there is a lack of better treatment.

AREAS COVERED

This review will discuss in vitro and in vivo models of ototoxicity highlighting recently published ototoxicity research. The reader will learn the strengths and limitations of different ototoxicity models and what molecular insights have been gained from their application. A better understanding of the cellular mechanisms of these ototoxins will help in the discovery of ways to prevent and treat hearing loss associated with ototoxic medications.

EXPERT OPINION

There are benefits to both in vitro and in vivo models of ototoxicity. Research of a particular medication and its ototoxic mechanisms should draw from several models, enabling a better answer to the clinical question of prevention and treatment of inner ear drug toxicity.

Symptom Reporting Compared with Audiometry for the Detection of Cochleotoxicity in Patients on Long-Term Aminoglycoside Therapy

Background

Aminoglycoside-associated auditory toxicity (cochleotoxicity) is a major concern in patients receiving prolonged aminoglycoside therapy. There are no published data comparing symptom monitoring to audiometry testing for the detection of aminoglycoside-induced cochleotoxicity; thus, agreement regarding the optimal monitoring of these patients for early detection of this effect is lacking.

Objective:

To compare the sensitivity of symptom monitoring to that of audiometry in identifying cochleotoxicity in patients on prolonged aminoglycoside therapy.

Methods:

A retrospective chart review of adult inpatients at Sunnybrook Health Sciences Centre prescribed prolonged aminoglycoside therapy (≥21 days) who completed at least 1 audiometry test between January 1, 1999, and December 31, 2009, was conducted. Data pertaining to results of audiometry testing and development of symptoms of auditory toxicity were collected. Symptom monitoring was compared with audiology testing for the detection of cochleotoxicity.

Results:

Forty eligible patients were included for analysis. Audiometry was significantly better than symptom monitoring to identify early cochleotoxicity (absolute risk reduction = 17.5% and number needed to treat = 6; p = 0.023). Compared to audiometry, symptom monitoring has a sensitivity, negative predictive value, and accuracy for the detection of early cochleotoxicity of 61%, 75%, and 82%, respectively.

Conclusions:

Audiometry testing is significantly better than monitoring symptoms to identify early aminoglycoside-induced auditory toxicity in patients prescribed prolonged aminoglycoside therapy (≥21 days). Subclinical cochleotoxicity identified with audiometry may allow early termination of aminoglycoside therapy to prevent progression of cochlear damage to the audible frequency range.

A review of the burden of vertigo

AIM AND OBJECTIVES

To provide an overview of vertigo and its management and identify its impact on individuals to offer strategies for managing the condition.

BACKGROUND

Dizziness and vertigo are symptoms common to many pathologies/dysfunctions ranging from the benign to the potentially serious; many are poorly understood. Although rarely life-threatening, vertigo is debilitating and significantly affects quality of life; it may be as disabling as paralysis or loss of a limb. Although 40-80% of cases remain unexplained, referral for specific investigation is rare.

DESIGN

A narrative literature review including descriptive, theoretical and empirical material reliant on the keywords 'dizziness' and 'vertigo' and the phrase 'vestibular disorders'. This provided diverse information that was used to address the research questions.

RESULTS

Vertigo is a widespread and potentially distressing symptom that may arise at any age and be acute or chronic. For most, it resolves spontaneously; for others, dizziness persists, causing significant distress. Its management is challenging, especially when the underlying cause is unclear. Pharmacological interventions, physiotherapy, psychotherapy or, rarely, surgery can be used in its management. Few nursing studies are available, suggesting that nursing knowledge may be limited.

RELEVANCE TO CLINICAL PRACTICE

Although nurses may frequently encounter patients with vertigo, there are few relevant nursing studies in this area; few consider appropriate nursing interventions or approaches to patient care. The information provided reveals that understanding the full impact of the condition and identification of patients' needs are essential to effective care. Some strategies to help affected patients are outlined.

CONCLUSIONS

Vertigo, a widespread, often intractable condition, affects significant numbers of people; diagnosis and management can be challenging. Treatment, care and support must be selected on an individual basis taking individuals into account. The primary goals are to maintain physical status, psychosocial interaction and quality of life.