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Distortion product otoacoustic emissions (DPOAEs) are a time-efficient, non-invasive means of assessing the integrity of active inner ear mechanics. Unfortunately, the presence of even relatively minor conductive hearing loss (CHL) has been suggested to reduce the clinical utility of DPOAEs significantly. The primary aims of this study were to systematically evaluate the impact of CHL on DPOAE amplitude and to determine if ear-specific primary tone level manipulations can be used to mitigate CHL impact and recover DPOAE measurability. For 30 young adults (57 ears) with normal hearing, DPOAEs were obtained for f 2 = 1–6 kHz. Observed DPOAE amplitudes were used to generate ear- and frequency-specific models with the primary tone levels, L 1 and L 2, as inputs and predicted DPOAE amplitude, L DP , as output. These models were then used to simulate the effect of CHL (0–15 dB), as well as L 1 manipulations (0–15 dB), on DPOAE measurability. Mean L DP for every CHL condition was significantly different from that for all other conditions (p = <.001), with a mean L DP attenuation of 8.7 dB for every 5 dB increase in CHL. Mean DPOAE measurability in response to a standard clinical stimulation paradigm of L 1 /L 2 = 65/55 (dB SPL) was determined to be 99%, 84%, 37%, and 9% in the presence of 0, 5, 10, and 15 dB CHL, respectively. In the presence of 10 dB CHL, altering L 1 resulted in an approximately 25% increase in DPOAE responses. Subclinical CHL loss is sufficient to significantly impair DPOAE measurability in a meaningful proportion of otherwise healthy ears. However, through strategic alteration of primary tone levels, the clinician can mitigate CHL impact and at least partially recover DPOAE measurability. [ABSTRACT FROM AUTHOR]

Cisplatin is employed for chemotherapeutic purposes in several types of adult and pediatric cancer. However, side-effects including nephrotoxicity, ototoxicity, gastrointestinal effects and neuropathy restrict the use of the drug due to their adverse impacts on quality of life. This study aimed to determine whether levosimendan exhibits a protective effect against cisplatin-related ototoxicity in a rat model by means of functional, biochemical and histochemical analysis. The study was employed with 24 female Sprague Dawley rats. After distortion product otoacoustic emissions (DPOAE) tests applied to all rats, rats were randomly assigned into four groups of six animals each. A single intraperitoneal 15 mg/kg dose of cisplatin was administered to Cisplatin group. Levosimendan group received intraperitoneal levosimendan at a dose of 100 mg/kg for five consecutive days. Cisplatin + Levosimendan group received intraperitoneal levosimendan at a dose of 100 mg/kg for five consecutive days and a single intraperitoneal dose of 15 mg/kg cisplatin at 3rd day of the study. Control group received 8 mL/kg/day intraperitoneal saline solution for five consecutive days. The DPOAE test was repeated on the 6th day of the study. All rats were then sacrificed, the cochleas were removed and set aside for biochemical and histopathological analyses. A significant increase in levels of Malondialdehyde (MDA) and significantly lower activities of superoxide dismutase (SOD) and Glutathione peroxidase (GPx) were observed at rats of cisplatin group. Administration of levosimendan showed significantly lower cochlear MDA levels, while SOD and GPx activities both increased significantly. The DPOAE test performed at 6th day of the study showed a significant impairment in the signal-noise ratio (SNR) levels of rats in Cisplatin group. The SNR levels of rats treated with levosimendan were significantly higher than those of cisplatin group and were similar to those of the control group. Cisplatin impaired the cochlear structure and a severe Caspase 3 and 8-hydroxy-2' -deoxyguanosine (8-OHdG) immunopositivity was observed at cochlea of the rats of cisplatin group. Administration of levosimendan protected the structure of cochlea and there was a mild Caspase 3 and 8OHdG immunopositivity. Our data demonstrate that levosimendan protects hearing against cisplatin-induced ototoxicity and obviates cellular degeneration. It also significantly reduces oxidative stress and apoptosis, probable mechanisms involved in ototoxicity. [ABSTRACT FROM AUTHOR]

Abstract Background Seven hundred children were recalled for hearing screening at age 2–3 years due to a problem with their newborn hearing screen. They had all been well babies with no identified risk factors for hearing loss and hence were not scheduled for targeted follow-up to retest hearing. Methods There were 485 children (69%) that attended the recall. The average age was 36 months (SD 3.7). Family ethnicity was Pacific Island (36%), Asian (26%), NZ European (13%), and Māori (11%), and there was a high level of deprivation in the study population. Children were screened using distortion product otoacoustic emission (DPOAE) and a parent or caregiver completed a 14-item questionnaire about ear health. The children that did not pass screening were given appointments for audiology testing. Children with hearing loss and/or middle ear problems were referred for otolaryngology review and further hearing assessments. Results About one third (36%; n = 176) of children did not pass DPOAE screening; 82 (17%) had abnormal type B tympanograms and hearing loss; 29 underwent insertion of ventilation tubes, and one had a perforated tympanic membrane. There was a significant association between failed tympanometry and hearing loss (Chi-squared = 16.67, p <.001). Five children had permanent sensorineural hearing loss (SNHL), two of whom required cochlear implants for idiopathic hearing loss, with no specific risk factors. Overall 380 of 485 children screened were deemed to have normal hearing (i.e. 22% failed hearing). From the questionnaire, 15% of the caregivers with no suspicion of hearing problems did have children with significant hearing loss. Regression analysis showed that Pacific/Māori ethnicity was significantly associated with risk of hearing loss, together with questionnaire items identifying hearing problems and breathing problems. Conclusions There is a high proportion of children in South Auckland with unsuspected hearing loss; a different approach to hearing screening is warranted for this population with high rates of middle ear disease at age 3. [ABSTRACT FROM AUTHOR]

Objective The use of Mesna as a chemical dissector in higher concentrations may reduce the length of time of operation by providing more effective dissection as well as being used in otologic pathologies such as tympanosclerosis. In this study, it was aimed to assess the effect of Mesna on the internal ear, which was applied intra-tympanically in higher concentrations than the conventional use. Methods Twenty-four female rats were included in our study. The rats were randomly divided into three groups (Group 1: Mesna 50%, Group 2: Mesna 100%, Group 3: Saline). At the beginning of the study, DPOAE and ABR measurements were carried out on every rat on days 7 and 14. At the end of the study, cochleas of the rats were excised and histopathological assessments were carried out. Results Basal values and DPOAE and ABR values on day 7 and 14 of Group 1, Group 2, and Group 3 were similar to each other. No significant difference was detected among the three groups in the histopathological assessment carried out at the end of the study. Conclusion It was revealed by audiological and histopathological parameters that the use of Mesna at 50% and 100% concentrations did not create toxicity effects on the internal ear. Mesna would be more effective by being used in higher concentrations in audiological surgeries, that its duration of operation world reduce and could being used in different indications including tympanosclerosis. [ABSTRACT FROM AUTHOR]

Evaluation of Distortion Product Otoacoustic Emissions (DPOAEs) by combining Air Conduction (AC) and Bone Conduction (BC) stimuli in infants. Measurements were performed in 19 normal hearing infants, and in 23 adults serving as a control group. The stimulus consisted either of two AC tones, or of combined AC/BC tones. DPOAEs were measured for f2 at 0.7, 1, 2, 4 kHz, and a constant ratio of f2/f1 = 1.22. Sound pressure level of the primary stimulus L1 was held constant at 70 dB SPL, while the level of L2 was decreased in 10 dB steps from 70 to 40 dB SPL. A response was included for further analysis when DPOAEs reached a Signal to Noise Ratio (SNR) of ≥6 dB. Additional DPOAE responses of <6 dB SNR were included when visual inspection of the measurements indicated clear DPOAEs. DPOAEs could be elicited in infants at 2 and 4 kHz for the AC/BC stimulus. DPOAE amplitudes evoked by the AC/AC stimulus were larger than those by the AC/BC stimulus, with the exception of 1 kHz. The highest amplitudes of DPOAEs were registered for a stimulation level of L1 = L2 = 70 dB, with the exception of AC/AC at 1 kHz, where the highest amplitudes were with L1-L2 = 10 dB. We demonstrated that DPOAEs can be generated in infants by a combined AC/BC stimulus at 2 and 4 kHz. The high noise floor needs to be further reduced to achieve more valid measurements in frequencies <2 kHz. [ABSTRACT FROM AUTHOR]

Objectives Hearing loss in neonatal intensive care unit (NICU) graduates range from 2% to 15% compared to 0.3% in full-term births, and the etiology of this discrepancy remains unknown. The majority of NICU admissions receive potentially ototoxic aminoglycoside therapy, such as gentamicin, for presumed sepsis. Endotoxemia and inflammation are associated with increased cochlear uptake of aminoglycosides and potentiated ototoxicity in mice. We tested the hypothesis that sepsis or systemic inflammatory response syndrome (SIRS) and intravenous gentamicin exposure increases the risk of hearing loss in NICU admissions. Methods The Institutional Review Board at Oregon Health & Science University (OHSU) approved this study design. Two hundred and eight infants met initial criteria, and written, informed consent were obtained from parents or guardians of 103 subjects ultimately enrolled in this study. Prospective data from 91 of the enrolled subjects at OHSU Doernbecher Children's Hospital Neonatal Care Center were processed. Distortion product otoacoustic emissions (DPOAEs; f 2 frequency range: 2063–10,031 Hz) were obtained prior to discharge to assess auditory performance. To pass the DPOAE screen, normal responses in >6 of 10 frequencies in both ears were required; otherwise the subject was considered a “referral” for a diagnostic hearing evaluation after discharge. Cumulative dosing data and diagnosis of neonatal sepsis or SIRS were obtained from OHSU's electronic health record system, and the data processed to obtain risk ratios. Results Using these DPOAE screening criteria, 36 (39.5%) subjects would be referred. Seventy-four (81%) subjects had intravenous gentamicin exposure. Twenty (22%) had ≥4 days of gentamicin, and 71 (78%) had <4 days. The risk ratio (RR) of referral with ≥4 days of gentamicin was 1.92 ( p = 0.01). Eighteen subjects had sepsis or met neonatal SIRS criteria, 9 of whom had ≥5 days of gentamicin and a DPOAE referral risk ratio of 2.12 ( p = 0.02) compared to all other subjects. Combining subjects with either vancomycin or furosemide overlap with gentamicin treatment yielded an almost significant risk ratio (RR = 1.77, p = 0.05) compared to the rest of the cohort. Conclusions We report an increased risk of referral with DPOAE screening for those receiving ≥4 days of intravenous gentamicin administration that may contribute to the greater prevalence of hearing loss in NICU graduates. We propose an expanded prospective study to gather a larger cohort of subjects, identifying those with sepsis or neonatal SIRS, to increase the statistical power of this study design. Subsequent studies also need to obtain follow-up diagnostic audiological data to verify whether the outcomes of DPOAE screening, in addition to the standard AABR screen, is a reliable predictor of permanent hearing loss following gentamicin exposure in the NICU. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Aminoglycoside antibiotics are known to have ototoxic effects and may induce sensorineural hearing loss. This study investigated the protective effect of trimetazidine, which has antioxidant and cytoprotective properties, against amikacin ototoxicity. Methods: Thirty-two male rats were divided into four groups – amikacin, amikacin+trimetazidine, trimetazidine, and control groups. Trimetazidine, 10mg/kg per day, was given for 14 days by oral gavage. Amikacin, 600mg/kg per day, was also given for 14 days, by the intramuscular route. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) tests were applied to the rats for hearing assessment. At the termination of the study, the biochemical parameters were calculated to evaluate the oxidative status. Results: The DPOAE values of the amikacin group were significantly lower on the 7th and 14th days than those of the trimetazidine+amikacin group and there was an increase in the ABR thresholds. The ABR thresholds for the amikacin group on the 7th and 14th days were significantly higher than the levels on the first day of the study, while there was no significant increase in those values in the trimetazidine+amikacin group. The total oxidant status (TOS) and oxidant status index (OSI) values of the amikacin group were significantly higher than those of the trimetazidine+amikacin group. The total antioxidant status (TAS) values of the amikacin group were lower than those of the trimetazidine+amikacin group. Conclusions: The audiologic tests and biochemical parameters investigated in this study both point to the protective effect of trimetazidine against amikacin-induced ototoxicity. [Copyright &y& Elsevier]

Abstract: Objective: The present study aimed to investigate the etiology, symptoms, diagnosis and prognosis of pediatric patients with non-organic hearing loss (NOHL), and to heighten awareness of this disorder among physicians. Methods: Between January 2000 and July 2009, we retrospectively reviewed the medical records of 47 pediatric patients (aged 6–18 years of age) diagnosed with NOHL. The diagnosis was made when there were audiometric discrepancies between the subjective and objective hearing thresholds of the patient in the absence of any organic disease. Results: Eighteen patients presented with unilateral hearing loss, and 29 showed bilateral hearing loss. Five patients received steroid treatment before the correct diagnosis was made, and six had secretory otitis media and underwent a tympanostomy tube placement. Conclusion: If physicians are unaware of the possibility of NOHL; they may misdiagnose children with idiopathic sudden sensorineural hearing loss and administer high-dose steroid treatments or exploratory tympanotomies. Otoacoustic emissions are abolished when NOHL patients have secretory otitis media. In these cases, after tympanostomy tube placement, they should undergo objective electrophysiologic examinations to reevaluate NOHL. [Copyright &y& Elsevier]

Very preterm infants are at a greater risk of developing neurodevelopmental impairments such as neuro-motor delays, vision and hearing deficits (Roze and Breart, 2004; Saigal and Doyle, 2008) [1,2]. The hearing difficulties in preterm infants vary depending on the co-morbid conditions. However, prematurity itself is considered as a risk factor that influence the functioning of auditory system. The current study aims to compare the DPOAEs in very preterm infants and term infants at 1 month, 3 months and 6 months of age (corrected age in preterm infants). DPOAEs were recorded in 72 very preterm infants and 30 term infants at 1 month, 3 months and 6 months of age. All these infants had obtained 'pass' results in newborn hearing screening using ABR. DPOAE f2 test frequency was measured at six frequencies (1500 Hz, 2000 Hz, 3000 Hz, 4500 Hz, 6000 Hz and 8000 Hz) with primary tone stimulus intensity L1 equal to 65 dBSPL and L2 equal to 55 dBSPL with primary tone f2/f1 frequency ratio of 1.2. Otoscopic examination and tympanometry was performed prior to DPOAE testing, to ascertain normal middle ear status. DPOAE amplitude did not change significantly between two groups from 1 month till 6 months of age (p > 0.05). DPOAE amplitude and noise floor in very preterm infants were not different from term infants and DPOAE amplitude did not vary significantly across f2 frequencies at various time periods. The current study findings provided evidence that prematurity did not constitute as a factor to influence the results of DPOAE in very preterm infants who passed newborn hearing screening test. Any significant reduction in DPOAE amplitude or absence of DPOAE in very preterm infants has to be considered and monitored effectively, as it may not reflect a developmental process of cochlear function; instead it could indicate the presence of inner ear or middle ear pathology. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To evaluate hearing in children diagnosed with shaken baby syndrome. Methods: A retrospective study conducted in a pediatric tertiary care center between 2006 and 2012. Children diagnosed with shaken baby syndrome were included for hearing evaluation by conventional audiometry, distortion product otoacoustic emissions and auditory brainstem responses. Results: Twenty-eight children were included (22 boys and 6 girls). The mean age of children at presentation was 8 months (range 1–26 months) and the mean delay before audiometric evaluation was 30 months (range 1–87 months). One child was diagnosed as having a moderate sensorineural hearing loss. The tympanic membrane mobility was normal (type A) for both ears in 22 children, one child had a reduced tympanic mobility in one ear, two children had a negative pressure, one child had a functional trans-tympanic tube and test was not performed in 2 patients. Conclusion: This is the first study reporting hearing loss as a possible result of shaken baby syndrome. However, further studies with larger number of children would be preferable. We recommend hearing evaluation for these children to rule out hearing loss. [Copyright &y& Elsevier]