Doctor Educationis / Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).

The primary aim of the research was to describe hearing function in a group of children with chronic renal dysfunction receiving treatment in an academic hospital in Johannesburg, South Africa. Specific objectives in the study were to determine the prevalence of hearing loss in paediatric patients with chronic renal dysfunction; to describe the type, degree and configuration of the hearing loss; and to establish if there was a relationship between the presenting hearing loss and the severity of renal dysfunction, the different treatment regimens, duration of renal dysfunction, and the duration of treatment. One hundred children between the ages five -18 years participated in the study and comprised 65 males and 35 females. The mean age of the participants was 11.68 years. A cross-sectional, descriptive, quantitative research design was employed. All participants underwent a case history interview and a full audiological examination which included an otoscopic examination, immittance testing (tympanometry and ipsilateral acoustic reflex testing), pure tone audiometry including extended high frequency testing up to 16 kilohertz as well as diagnostic distortion product otoacoustic emission testing. A record review was also done. Both descriptive and inferential statistics were used to analyse the collected data. Inferential statistics included parametric measures using multiple regression measures as well as non parametric measures using the Kruskal-Wallis statistical analysis. Results revealed that there was a high prevalence of hearing loss in children with chronic renal dysfunction. Results from the extended high frequency pure tone testing as well as the diagnostic distortion product testing revealed that the most common hearing loss was a low and high to ultrahigh frequency mild sensorineural hearing loss. The study showed that there was no relationship between the severity of hearing loss and the severity of renal dysfunction, or the duration of renal dysfunction and the duration of treatment. However, the study showed that there was a relationship between the severity of hearing loss and certain treatments, that is, v haemodialysis and the use of ototoxic medication such as loop diuretics, tuberculosis medication, and antimalarial medication. As the potential to miss hearing loss in this population is high, the research highlighted the importance of extended high frequency audiometry as well as diagnostic distortion product otoacoustic emission testing for the use of ototoxic monitoring in patients with chronic renal dysfunction. The research also highlighted the need for further research in this area as well as the need for educating medical personnel and caregivers working with children with chronic renal disease.

When the cochlea is stimulated with two primary tones (f1 and f2) some of the energy is reflected back and propagates via the middle ear into the outer ear. Due to cochlear nonlinearities, distortion product otoacoustic emissions (DPOAEs), may be detected by a probe microphone sealed in the ear canal. Reduced DPOAEs may indicate subclinical cochlear lesions. The relationship between hearing sensitivity and the strength of DPOAEs is debatable, especially in the extended high frequency (EHF) region (≥8 kHz). Monitoring cochlea function corresponding to the EHF range is important for detecting early stages of hearing loss, which typically begins above 8 kHz. Complex interactions of high-frequency pure-tones in the ear canal result in standing waves that increases test-retest variability of DPOAEs measured for f2≥6 kHz. The aim of the project was to evaluate reliability of DPOAEs measured up to 12 kHz with a system used routinely in audiology clinics. Thirty-one adults (age, 18-30 yrs) with normal middle-ear function and normal hearing thresholds in the conventional region (≤8 kHz) participated. The EHF audiometry was performed for frequencies up to 16 kHz. The DPOAE data were collected for the f2 frequency varied from 1.5 to 12 kHz, twice for each ear with the probe removed and then repositioned after the first test. The EHF audiometric data of four participants showed elevated thresholds. Their DPOAEs were reduced or absent for f2≥9 kHz, i.e., supporting the sensitivity of DPOAEs for cochlear hearing loss above the conventional audiometry frequency range. Mean and standard deviations of DPOAE levels were calculated separately for the left and the right ears of subjects with normal EHF thresholds. There were no differences between mean DPOAE values in the left and the right ears. The intersubject variability of the DPOAE levels was moderate (SD≈6 dB or lower) but it increased significantly in the 12-kHz region, per the F-test for variances, possibly due to 1. effects of standing waves on the high-frequency DPOAE reliability and/or 2. subclinical pathology in the most basal portion (i.e., high-frequency region) of the cochlea. For each ear, absolute values of differences between test/retest levels of detectable DPOAEs were calculated. ANOVA showed the main effect of frequency for the data collected in the left and the right ears. Post-hoc analyses indicated that test/retest variability of DPOAEs was rather constant for f2 frequencies up to 10 kHz, but a statistically significant increase of test/retest variability for f2 of 11 and 12 kHz was found. This aspect needs to be considered when using DPOAE tests for longitudinal monitoring of cochlear function in the basal portion. Nevertheless, combining behavioral thresholds with DPOAEs collected for the EHF range is vital for detecting the initial stage of the cochlear pathology corresponding to the high-frequency region, e.g., due to ototoxicity or aging of the cochlea.

BACKGROUND: The aim of this study was to evaluate distortion product otoacoustic emissions (DPOAEs) and extended high-frequency (EHF) thresholds in a control group and in patients with normal hearing sensitivity in the conventional frequency range and reporting unilateral tinnitus. MATERIAL/METHODS: Seventy patients were enrolled in the study: 47 patients with tinnitus in the left ear (Group 1) and 23 patients with tinnitus in the right ear (Group 2). The control group included 60 otologically normal subjects with no history of pathological tinnitus. Pure-tone thresholds were measured at all standard frequencies from 0.25 to 8 kHz, and at 10, 12.5, 14, and 16 kHz. The DPOAEs were measured in the frequency range from approximately 0.5 to 9 kHz using the primary tones presented at 65/55 dB SPL. RESULTS: The left ears of patients in Group 1 had higher median hearing thresholds than those in the control subjects at all 4 EHFs, and lower mean DPOAE levels than those in the controls for almost all primary frequencies, but significantly lower only in the 2-kHz region. Median hearing thresholds in the right ears of patients in Group 2 were higher than those in the right ears of the control subjects in the EHF range at 12.5, 14, and 16 kHz. The mean DPOAE levels in the right ears were lower in patients from Group 2 than those in the controls for the majority of primary frequencies, but only reached statistical significance in the 8-kHz region. CONCLUSIONS: Hearing thresholds in tinnitus ears with normal hearing sensitivity in the conventional range were higher in the EHF region than those in non-tinnitus control subjects, implying that cochlear damage in the basal region may result in the perception of tinnitus. In general, DPOAE levels in tinnitus ears were lower than those in ears of non-tinnitus subjects, suggesting that subclinical cochlear impairment in limited areas, which can be revealed by DPOAEs but not by conventional audiometry, may exist in tinnitus ears. For patients with tinnitus, DPOAE measures combined with behavioral EHF hearing thresholds may provide additional clinical information about the status of the peripheral hearing.

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Abstract This research on military aviation noise was conducted because the personnel working with military aircraft were concerned about noise induced hearing damage. In addition, comprehensive data on hearing impairments and occupational exposure of military pilots in the Finnish Air Force was not available. Moreover, data on the effects of overflight noise of military jets was necessary for the evaluation of noise induced hearing deteriorations of members of the public who might be exposured accidentally for the low-level jets' overflights. The averaged noise exposure levels of pilots varied during a flight from 97 dB(A) to 106 dB(A) in the cockpit and from 83 dB(A) to 100 dB(A) at the entrance of the ear canal. Radio noise was 4–10 dB higher than background noise inside the helmet. The attenuation provided by air crew helmets varied from10 to 21 dB(A) in the laboratory, and was at the same level during real flights. The attenuation measured in the laboratory and in working conditions was about 30 dB(A) for earmuffs. An active noise cancellation (ANC) device decreased averaged noise exposure (LAeq8min) 4–8 dB over the noise attenuation of the same helmets when the ANC system was off. The noise of overflights by military jets were measured and the noise levels were lower than those known to cause the permanent threshold shifts. However, noise induced hearing damages might be possible in certain conditions. In order to assess the hearing loss risk of pilots, hearing thresholds were measured before and after one flight using both conventional and extended high frequency (EHF) audiometry. Minor temporary threshold shifts (TTS) were revealed. The risk of noise-induced damage at the studied exposure levels is, in all probability, rather small. A novel NoiseScan data management system proved to be an interesting tool in assessment of the risk of developing hearing impairment on the basis of known risk factors. Due to the small number of risk factors, the hearing of pilots was shown to be at considerably less risk than that of industrial workers in Finland.

A substantial body of research points to the benefits of fitting hearing instruments that provides extended high frequency amplification. Most published research were done on adults or in controlled laboratory settings. It is therefore necessary for peadiatric audiologists to critically assess the effects that this extended high frequency amplification has on the individual child fitted with hearing instruments. A quantitative research method was selected to explore the possible correlations between extended high frequency amplification and the influence this extended high frequency amplification has on speech recognition and functional performance in children with mild to severe sensory neural hearing loss. A quasiexperimental design was selected. This design accommodated a one-group (single-system) pre-test versus post-test design. Baseline assessments were done and all participants were subjected to pre- and post-intervention assessments. Six participants were fitted with hearing instruments which provided extended high frequency amplification. A baseline assessment was done with current hearing instruments after which participants were assessed with the hearing instruments with extended high frequency amplification. Aided audiological assessments were done without the extended high frequencies after which participants were evaluated with the added high frequencies. Speech recognition testing and functional performance questionnaires were used to compare the outcomes obtained with and without the extended high frequency amplification. A t-test was used for hypothesis testing to determine if extended range amplification increased speech recognition abilities and functional performance, and if these increases were statistically significant. Results were varied where some participants performed better and some performed worse with the added extended range amplification during speech recognition testing and functional performances observed at home. These varied results were statistically insignificant. However, statistically significant evidence was obtained to indicate that extended high frequency amplification increased the functional performance observed at school. The study concluded that the paediatric audiologist should know the effect fitting hearing instruments capable of extended high frequency amplification have on speech recognition abilities and functional performances. Fitting hearing instruments with extended high frequency amplification should however be done with caution because not all children benefited from extended bandwidth amplification. This underlines the importance of following a strict evidence-based approach that incorporates objective and subjective assessment approaches. This will provide the paediatric audiologist with real world evidence of the success of the amplification strategy that is followed. / Dissertation (MCommunication Pathology)--University of Pretoria, 2012. / Speech-Language Pathology and Audiology / Unrestricted