Long-term effects of chemotherapy for acute lymphoblastic leukemia on the medial olivocochlear bundle: effects of different cumulative doses of gentamicin.

OBJECTIVE: The treatment of acute lymphoblastic leukemia (ALL) often combines a neurotoxic chemotherapeutic protocol such as Berlin-Frankfurt-Munster-95 (BFM-95) with gentamicin, an antibiotic known to have an early and quickly reversed impact on olivocochlear reflex in animal studies. This study investigates whether this combination has any long-term side effects on the medial olivocochlear bundle (MOCB). METHODS: In all 47 children of the study suppression of distortion product otoacoustic emissions (DPOAEs) by contralateral application of white noise (WN) was used to assess the function of the MOCB. The population was divided into three groups depending on the time interval between the end of therapy and examination. The group examined shortly after chemotherapy included 12 children who had received low gentamicin doses (less than 13 days). The group evaluated 2 years after therapy involved another 12 children who had required medium gentamicin doses (more than 13, less than 23 days). The group examined 3 years after therapy included a subgroup of 12 children to whom low gentamicin doses were infused and another 11 children with high gentamicin doses (more than 23 days). RESULTS: Three years after therapy the olivocochlear reflex was efficiently produced in both subgroups of low and high gentamicin doses. Two years after therapy, contralateral WN induced increase of DPOAEs at 4 of the 12 examined frequencies. Shortly after therapy, WN increased, instead of suppressing, DPOAEs at five frequencies. CONCLUSION: This abnormal result of contralateral noise application perceived as impaired cochlear efferent innervation may indicate that ALL-BFM-95 exerts a toxic effect on the MOCB, which is slowly reversed within the first 3 years after chemotherapy and does not seem to be affected in the long term by different cumulative doses of gentamicin.

Etiological diagnosis of bilateral, sensorineural hearing impairment in a pediatric Greek population.

Early diagnosis, evaluation and treatment of childhood deafness are essential for a child's normal growth. Etiological diagnosis of hearing loss makes prevention, family scheduling and more effective therapy feasible goals. Etiological assessment of sensorineural deafness still remains difficult although recently with the progress of genetics it has become more efficient. In this retrospective study, the etiology of bilateral, sensorineural hearing loss with indication for hearing aids has been studied in 153 hearing impaired children. Etiological diagnosis was based on family and patient record, physical, audiological and laboratory examinations. Among the 94 children who completed the diagnostic protocol etiological groups revealed the following distribution: non-hereditary acquired hearing impairment was present in 36 children (38%) and hereditary was present in 44 (47%) children. The etiology remained unknown in 14 (15%) children. Non-syndromic autosomal dominant type accounted for 13 (29% of hereditary hearing loss) children, non-syndromic autosomal recessive type for 21 (48%) children and syndromic deafness for 10 (23%) children. Modern diagnostic methods, such as genetic testing, help diminish the number of cases with hearing impairment of unknown etiology, for the benefit of children who receive early and appropriate medical, audiologic, genetic and educational counseling based on the etiology of their hearing loss.

The change in the acoustic admittance phase angle: a study in children suffering from acute otitis media.

Middle ear mechanics, in normal and in pathological conditions, is the subject of this research, with acoustic impedance measurements as the cornerstone. Previous studies have established the importance of admittance-phase tympanograms, mainly in frequencies higher than the conventional 226 Hz. The purpose of the present study was to record how acute otitis media (AOM) affects the middle ear system and function by evaluating the recordings of the change in phase angle parameter (deltatheta) provided by an automated tympanometer using the sweep-frequency technique. Multifrequency and conventional tympanograms were obtained from 70 children suffering from AOM on consecutive visits. Values of deltatheta from these subjects were compared to normative data previously acquired in our Department. It appears that changes in the mechanical status of the middle ear after AOM are reflected in abnormal deltatheta values, despite the normal findings of conventional tympanometry. A positive history of AOM did not seem to influence the behaviour of the middle ear. In most cases, abnormal deltatheta values coexisted with abnormal values of resonance frequency (RF), i.e. the frequency at which mass and stiffness of the middle ear are in balance, and total susceptance (deltaB) reaches 0mmhos and the converse. The deltatheta seems to be an important indicator of middle ear mechanical status that can record changes occurring in the system after AOM and undetected by low probe-tone tympanometry.

Hearing loss in speech-language delayed children.

An infant begins to communicate with his/her environment from the first months of life. However, true words do not appear until the age of 12-15 months, following a rather predictable sequence. Delay or failure of normal language development is not a rare situation in childhood and may be due to a variety of reasons. Among these, hearing undoubtedly plays a leading part in the language acquisition process. The purpose of this study was to assess the percentage of hearing-impaired children in a group of phenotypically healthy children presenting with speech-language delay. Between March 1993 and March 1999, 726 speech-language delayed children were examined in our department. In 72 of them, various diseases or syndromes had already been diagnosed and so they were excluded from the study. The remaining 654 apparently healthy children entered the study and underwent a thorough audiological assessment for determination of their hearing thresholds. Eighty-seven children (13.3%) showed various degrees of hearing loss. Most of them (55 children, 8.4%) suffered from sensorineural hearing impairment, while in 32 children (4.9%) a conductive hearing loss was discovered. The increased prevalence of hearing impairment found in our population mandates a thorough hearing evaluation for every case of speech-language delay, even for those children who show no evidence of other handicaps. This will help in the early diagnosis of hearing loss, allowing proper management to be instituted as early as possible.

Incidence of hearing loss among children presented with speech-language delay.

Infants' first attempts to communicate with their environment begin shortly after birth. However, real words appear by age of 12-15 months. Any delay in expressing their needs verbally beyond this age is defined as speech delay and may be associated with a variety of pathological conditions. The aim of this study is to investigate the incidence of hearing impairment in those children presented with speech delay. Ninety-one speech-delayed children were audiologically assessed between March 1993 and March 1995. In 25 out of 91 children (27.4%) a moderate to severe hearing loss was detected, either sensorineural or conductive. The increased incidence of hearing impairment found in this group mandates a thorough hearing evaluation for any case of speech-language delay.

Towards a universal newborn hearing screening.

Hearing loss is a common problem which, if remaining undetected during early childhood, could affect the patient's linguistic and mental abilities permanently. Although recommended, mass hearing screening has so far been problematic or even impossible due to several reasons. The available otoacoustic emission devices appear to be effective tools for universal hearing screening. The aim of this study is to evaluate the reliability and practicability of a new device for recording click-evoked otoacoustic emissions (cEOEs) on a pediatric population. Sixty children aged between 6 days and 14 years were evaluated audiologically both by auditory brainstem responses (ABR) and otoacoustic emissions. The latter were obtained by using the well-known ILO88v3.92 otoacoustic analyser and a new, portable device ('Echocheck', Otodynamics Ltd, UK). Sensitivity and specificity of cEOEs recorded by 'Echocheck'was found to be 93% and 91%, respectively, when compared to ABR results. Additionally, 'Echocheck' recordings were proved to be much easier to perform, needing considerably less time in comparison with those of the ILO88 system. In our opinion, 'Echocheck' as well as all similar portable devices--screeners--may represent a much-desired solution for implementing universal hearing screening programmes.

Otoacoustic emissions--an approach for monitoring aminoglycoside induced ototoxicity in children.

OBJECTIVES: The early detection of hearing impairment caused by ototoxic drugs, such as aminoglycosides, has been the aim of research world-wide. Histopathological studies have shown that the outer hair cells are the most susceptible cochlear components to injury from ototoxic drugs like aminoglycosides. Otoacoustic emissions reflect the functional status of the outer hair cells and constitute the only non-invasive means of objective cochlear investigation. The aim of this study was to evaluate the potential of otoacoustic emissions in early identification of aminoglycoside-induced cochlear dysfunction. In addition, a comparison with pure-tone audiometry or auditory brainstem responses was performed in order to determine if this test might provide a more reliable method of monitoring early ototoxic insults to the cochlea. METHODS: Twenty four children receiving gentamicin (4 mg/kg once daily) for 6-29 days were included in the study. Eleven children received gentamicin for up to 7 days (group A), while 13 underwent longer-term therapy lasting 8-29 days (group B). Hearing was serially monitored using transient evoked otoacoustic emissions and pure-tone audiometry (0.25-12 kHz) or auditory brainstem responses for younger or uncooperative children. Transient evoked otoacoustic emissions data were analysed in terms of emission amplitude and response reproducibility as a function of frequency. RESULTS: All patients yielded a normal baseline audiometric assessment upon hospital admission. For group A patients no significant changes in hearing levels were observed either by pure-tone audiometry (P = 0.2), auditory brainstem responses (P = 0.3) or transient evoked otoacoustic emissions (mean response: P = 0.06, reproducibility by frequency: P > 0.05). For group B patients no significant changes in hearing levels measured by pure-tone audiometry (P = 0.1) or auditory brainstem responses (P = 0.4) were observed. Transient evoked otoacoustic emissions however revealed a statistically significant decrease in the mean response level (P = 0.017) and in the reproducibility over the whole frequency spectrum (1 kHz: P = 0.0057, 2 kHz: P = 0.0247, 3 kHz: P = 0.0134, 4 kHz: P = 0.0049, 5 kHz: P = 0.0019). CONCLUSIONS: The findings suggest that transient evoked otoacoustic emissions are an extremely sensitive measure of the early effects of aminoglycoside-induced injury to the peripheral auditory system. Therefore, their use is recommended for regular monitoring of cochlear function, in the presence of potentially toxic factors, aiming at prevention of permanent damage.

Multiple-frequency tympanometry in children with acute otitis media.

Multiple-frequency tympanometry (MFT) is a sweep-frequency method of acoustic immittance measurement, recently introduced in clinical practice. It provides values for the resonant frequency of the middle ear system. The purpose of this study was to use MFT to collect information about the mechanoacoustical changes occurring to the middle ear system after acute otitis media and to compare it with the results of conventional, low probe-tone tympanometry. Children with acute otitis media were followed up with both methods for 1 month after an episode of acute infection. Also, children with normal hearing were studied to establish normative data. Resonant frequency of the middle ear was found to be lower than normal even 1 month past the initial episode, for all types of 226-Hz tympanograms. MFT seemed to record changes in the middle ear after acute otitis media that 226-Hz tympanometry was unable to detect, implying persistence of pathology. More extended research will illuminate the clinical value of this method in the follow-up of acute otitis media.

Otoacoustic emission-based hearing screening of a Greek NICU population.

The pressing need for early identification of hearing-disabled children has led to the development of several neonatal hearing screening programmes world-wide. Today otoacoustic emissions represent a widely used methodology for identification of neonatal hearing impairment. The purpose of the present study is to determine the sensitivity and specificity of click-evoked otoacoustic emissions (cEOAEs) in a Greek NICU population and compare the cEOAE data to the final hearing status of these children. A total of 438 ears of 223 neonates at high risk for hearing impairment were tested with both brainstem response audiometry (ABR) and cEOAEs. In 107 neonates the final hearing status was determined by using behavioural and playtone audiometry, at an age greater than 2 1/2 years. The sensitivity and specificity of the cEOAEs were found to be 90 and 92.4% when compared to ABR results and 90.9 and 91.1% when compared to the children's hearing status, respectively. Click-EOAEs have been proved to be highly effective in determining whether or not hearing impairment really exists. Since conventional ABR does not meet the requirements for large scale screening programmes, the cEOAEs represent a reliable alternative.

Evaluation of acoustic reflectometry in detecting otitis media in children.

Accurate detection of middle-ear effusion in children is not only useful but also necessary for diagnosis, management and follow-up of otitis media. A relatively new device, the Acoustic Otoscope (model 101, ENT Medical Devices) has been introduced for detecting middle-ear fluid in children. We tested 158 ears and the diagnosis was confirmed by acoustic admittance, acoustic reflex and pneumatic otoscopy. We propose 4.5 as a better breakpoint (the number on the vertical scale of the instrument which is the lower limit indicating middle-ear effusion) than 4.0 which is proposed by the manufacturer. In our results the 4.5 breakpoint maximizes both positive and negative predictive values (83 and 82% respectively) with satisfactory sensitivity and specificity (86 and 79% respectively) in detection of otitis media. Our clinical experience with this instrument, during the past 2 years, has led us to conclude that it is simple, non-invasive and objective. Unlike tympanometry, it requires no hermetic seal and is effective even if the child is crying. However, it is not sensitive enough when there are bubbles or negative pressure in the middle ear. When the user is aware of the flexibility of the instrument's breakpoints (in our opinion this is an advantage of the device) for different uses and different populations, the reflectometer often reduces the need for tympanometry and confirms the otoscopic examination.