New trends in the prevention of occupational noise-induced hearing loss.

Noise exposure during lifespan is one of the main causes of hearing loss. The highest risk of noise-induced hearing loss (NIHL) is related to exposures in the workplace, and affects about 7% of the population. Occupational NIHL is irreversible, thus its prevention must be considered a priority. Although current hearing conservation programs (HCPs) have proved to be very beneficial, the incidence of occupational NIHL is still high, reaching about 18% of overexposed workers. This paper reviews recent research on the effects of noise on hearing in pursuit of more effective methods for the prevention of occupational NIHL. The paper discusses the translational significance of noise-induced cochlear neuropathy, as recently shown in animals, and the concept of hidden hearing loss in relation to current NIHL damage risk criteria. The anticipated advantages of monitoring the incidents of the temporary threshold shift (TTS) in workers exposed to high levels of noise have been analyzed in regard to the preclinical diagnostics of NIHL, i.e., at the stage when hearing loss is still reversible. The challenges, such as introducing speech-in-noise audiometry and TTS computational predictive models into HCPs, have been discussed. Finally, the paper underscores the need to develop personalized medical guidelines for the prevention of NIHL and to account for several NIHL risk factors other than these included in the ISO 1999:2013 model. Implementing the steps mentioned above would presumably further reduce the incidence of occupational NIHL, as well as associated social costs. Int J Occup Med Environ Health. 2020;33(6):841-8.

Protection of Spiral Ganglion Neurons and Prevention of Auditory Neuropathy.

In the auditory system, the primary sensory neurons, spiral ganglion neurons (SGNs), transmit complex acoustic information from hair cells to the second-order sensory neurons in the cochlear nucleus for sound processing, thus building the initial bridge between the physical world of sound and the perception of that sound. Cochlear SGN loss causes irreversible hearing impairment because this type of neural cell cannot regenerate. A better understanding of the molecular mechanisms of formation, structure, degeneration, and protection of SGNs will help to design potential therapeutic strategies for preservation and replacement of them in the cochlear implant recipient. In this review, we described and summarized the following about SGNs: (1) their cell biology and their peripheral and central connections, (2) mechanisms of their neuronal damage and their protection, and (3) the neural and synaptic mechanism of auditory neuropathy and current options for hearing rehabilitation from auditory neuropathy. The updates of the research progress and the significant issues on these topics were discussed.

Importancia de la salud auditiva / Importance of hearing health

Se realiza un estudio sobre la exposición al ruido, sus efectos nocivos y la situación actual de lesiones auditivas en la juventud por el empleo excesivo de reproductores, así como exposición a niveles altos de ruido en discotecas. Se informa de la posibilidad de lesión auditiva en los músicos, técnicos de sonido y disk jockeys. Conscientes de esta problemática la Fundación Pedro Salesa Cabo está realizando un estudio conjuntamente con la Mutua Intercomarcal y la sociedad de prevención Prevint para el estudio de este problema y sus posibles soluciones. Este estudio «Impacto sonoro de la música en sus intérpretes y técnicos» comporta la realización de diversas pruebas auditivas en las personas afectadas (AU)

A study is made on the exposure to noise, on its harmful effects and the current situation on hearing problems in young people due to the excessive use of music players and to the exposure to high levels of noise in discotheques. Information is provided about possible hearing damage in musicians, sound technicians, and disk jockeys. The Pedro Salesa Cabo Foundation is aware of this problem and is conducting an extensive study, together with Mutua Intercomarcal and the society Prevint, to evaluate the problem and its possible solutions. This study "Impacto sonoro de la música en sus intérpretes y técnicos" is supported by different audiological tests in the people affected (AU)

Treatment of congenital cytomegalovirus infection: implications for future therapeutic strategies.

Cytomegalovirus (CMV) infection is the most common cause of congenital infection in the developed world, occurring in approximately 1% of all liveborns. Symptomatic disease occurs in 10% of all congenitally infected infants, resulting in a spectrum of clinical manifestations that include microcephaly, chorioretinitis, hepatosplenomegaly and sensorineural hearing loss, among others. Even those children who are asymptomatic at birth have a risk of hearing loss, with approximately 8% experiencing this sequela. Overall, congenital CMV infection accounts for one-third of all cases of sensorineural hearing loss. The economic burden of disease exceeds $2 billion annually in the USA. Therefore, this infection has been the target for antiviral therapy. Studies performed by the National Institute of Allergy and Infectious Diseases Collaborative Antiviral Study Group (CASG) have evaluated ganciclovir for the treatment of symptomatic congenital CMV infection with central nervous system involvement. In a randomized, controlled clinical trial of ganciclovir treatment (6 mg/kg iv every 12 h for 6 weeks) brainstem-evoked responses were utilized as the primary endpoint and demonstrated stabilization of hearing both at 6 months and >1 year. Treatment was associated with neutropenia in over 60% of treated patients. Since ganciclovir must be given intravenously, studies with its prodrug, valganciclovir, have been performed to assess pharmacokinetics and pharmacodynamics. Currently, a clinical trial of 6 weeks versus 6 months of valganciclovir is being performed by the CASG. Notably, only intravenous ganciclovir and orally administered valganciclovir have been used to treat congenital CMV infection. Hopefully, other drugs such as maribavir will be available for evaluation in this population.

Protective effect of edaravone against tobramycin-induced ototoxicity.

CONCLUSION: It is suggested that simultaneous treatment with the radical scavenger edaravone has an effective protective effect against tobramycin ototoxicity in rat. Even if the edaravone treatment is postponed for 7 days, it can still prevent hearing loss, but a 14 day delay cannot protect from ototoxicity. OBJECTIVES: With the aim of alleviating hearing loss caused by aminoglycoside ototoxicity, we performed a trial to assess the hearing protective efficacy of the radical scavenger edaravone. MATERIALS AND METHODS: In part one of the study, 21 male Sprague-Dawley albino rats were used; 2 rats served as controls for the safety of edaravone. Eight rats each received 10 subcutaneous injections (s.c.) of tobramycin (160 mg/kg b.w.) once daily and saline injection intraperitoneally for 2 weeks. Eleven rats were given 10 s.c. tobramycin injections simultaneously with an intraperitoneal injection of edaravone (3 mg/kg b.w.). In part two, tobramycin was injected in 13 rats (as above). Five of these received two edaravone injections 7 days later and four rats similarly 14 days later. Auditory brainstem response (ABR) was used to assess hearing. RESULTS: All rats treated only with tobramycin showed a deterioration of hearing. None of the rats given simultaneous treatment with tobramycin and edaravone demonstrated hearing loss. A 7 day delay in edaravone injection still prevented hearing loss, but a 14 day delay had only a temporary prophylactic effect.

Auditory processing and learning/memory following erythropoietin administration in neonatally hypoxic-ischemic injured rats.

BACKGROUND: Hypoxia-ischemia (HI) is a common injury arising from prematurity/complications at birth and is associated with later language, auditory, and learning impairments. OBJECTIVE: To investigate the efficacy of two doses (300 or 1000 U/kg) of Erythropoietin (Epo) in protecting against neuropathological and behavioral impairments associated with HI injury in rats. METHODS: HI injury (right carotid artery cauterization and 120 min of 8% O(2)) was induced on postnatal day 7 (P7) and Epo or saline was administered i.p. immediately following the procedure. Auditory processing and learning/memory were assessed throughout development. RESULTS: Both doses of Epo provided behavioral protection following HI injury. Rats given 300 or 1000 U/kg of Epo performed significantly better than HI animals on a short duration complex auditory processing procedure, on a spatial Morris water maze assessing spatial learning/reference memory, and a non-spatial water maze assessing associative learning/reference memory. CONCLUSIONS: Given Epo's extant clinical use (FDA approved for pediatric patients with anemia secondary to prematurity), the current results add to a growing body of literature supporting the use of Epo as a potential protective agent for neurological and behavioral impairments following early HI injury in infants.

[Comparative analysis on the hearing ability of children in iodine deficiency areas born before and after iodine supplementation].

UNLABELLED: According to the detection of hearings ability of children in iodine deficiency areas who was born before and after iodine supplement, the effects of iodine supplement on hearing system development was evaluated. METHOD: Hearing was tested by AS-72 type pure zone diagnostic audiometer(made in Denmark). Hearing of 11-14 years old students were tested before iodine supplement in iodine deficiency areas in 1984, the control was students living in non-iodine deficiency areas. Iodine salt (50 mg/kg) were supplied by the end of 1984, the hearings of children born after one year of iodine supplied were tested in 1999. The result showed that the average hearing threshold of students before iodine supplied in iodine deficiency areas was significance higher than of non-iodine deficiency areas. The hearing of children born after one year of iodine salt supplied in deficient areas had no significant difference from that of normal areas. The development of hearing system might be deteriorated by iodine deficiency during pregnant. It was able to meet the need of iodine that pregnant women ate 1:20 thousands iodine salt.

Avaliação audiológica em crianças nascidas de mães soropositivas para o vírus da imunodeficiência humana / Audiological Evaluation in Children Born to HIV Positive Mothers

Presente trabalho teve como objetivo avaliar audiologicamente crianças nascidas de mães soropositivas para o HIV, verificando a ocorrência de alterações auditivas. Material e método: A população estudada constou de 143 crianças, 82 do sexo masculino e 61 do sexo feminino, na faixa etária entre um mês a dois anos e seis meses de idade. As crianças foram divididas em três grupos, de acordo com o Sistema de Classificação Revisado 16 para a infecção pelo HIV em crianças menores de 13 anos de idade, sendo estes denominados: infectado (I), sororrevertido (SR) e exposto (E). Os procedimentos empregados na avaliação audiológica foram a audiometria de observação comportamental, audiometria com reforço visual e medidas de imitância acústica. Analisando a amostra avaliada segundo as variáveis duração da gestação e peso ao nascimento, pôde ser observado um número maior de crianças nascidas a termo e com peso adequado para a idade gestacional. No estudo da ocorrência de alterações auditivas, foram utilizados os resultados da última avaliação audiológica obtidos nas 143 crianças da amostra. Resultados: A análise estatística revelou presença de alterações auditivas significantemente maior nas crianças infectadas. Nos grupos sororrevertido e exposto ocorreu exatamente o oposto, ou seja, houve predominância de ausência de alterações auditivas. Conclusão: O tipo de alteração auditiva mais freqüentemente encontrado no grupo infectado foi a sugestiva de alteração auditiva central, e nos demais grupos ocorreu similaridade entre as alterações de orelha média e as sugestivas de alterações auditivas centrais.

The aim of the present study was the audiological evaluation of children born to mothers serologically positive for HIV, in order to verify the occurrence of auditory disorders. Material and method: The population studied included 143 children - 82 males and 61 females - ranging in age from one month to two years and six months. The children were divided into three groups, following the revised classification systemt1 for human immunodeficiency virus infection in children less than 13 years of age, as infected (1), seroreverter (SR) or exposed (E). The audiological evaluation procedures employed were behavioral observation audiometry, visual reinforcement audiometry and acoustic immittance measurements. Analysis of the sample population for duration of gestation and birth weight showed that the majority of the children were born at term with a suitable weight for gestational age. For studying the incidence of auditory disorders, the results of the latest audiological examinations on the 143 children were used. Results: Statistical analysis showed a significantly higher incidence of auditory disorder in the infected children. Among the seroreverter and exposed children the inverse was the case, with the majority of the children showing no auditory disorder. Conclusion: Results suggesting central auditory disorders were predominant in the infected group, whereas the incidences of central and middle ear disorders were similar in the other two groups.

Acoustic neuroma update.

We have described refinements and alternative techniques in the management of acoustic neuromas. The outcome for patients with both unilateral and bilateral tumors continues to improve.

[Specificity and sensitivity of transient click-evoked otoacoustic emissions (TEOAE)]. / Untersuchungen zur Spezifität und Sensitivität transienter click-evozierter otoakustischer Emissionen (TEOAE).

Transient click evoked otoacoustic emissions (TEOAE) have been shown to be a good test of hearing impairment especially when used for infant screening. However, occasional cases of false positive results--TEOAEs in spite of severe hearing loss--have been reported. This study encompasses 243 children whose hearing thresholds were known from subjective hearing tests and--in questionable cases--derived from additional auditory evoked potentials. The TEOAEs proved to have a high sensitivity (93%) and a reasonable specificity (67%), if the margin between good and bad hearing was set at 30 dB. However, four ears showed good TEOAEs in spite of poor hearing thresholds. In three cases, the children proved to have a central auditory hearing loss due to a cerebral disorder. One child with bilaterally superb TEOAEs had a unilateral deafness of unclear origin with no obvious retrocochlear or central disorder. Possible explanations under discussion included the presence of a retrocochlear lesion which was too small to show up in the tests used or that the defect was located just between the outer hair cells and the first neuron, for example in the inner hair cells. Additionally, efferent inhibition might cause a functional deafness as described by Rajan (1989) for the guinea pig. The results also show that TEOAEs should always be used in the differential diagnosis of hearing impairment in generally disabled children. The need for hearing aids and especially their adjustment has to be discussed in case of good TEOAEs, i.e., normal peripheral hearing.(ABSTRACT TRUNCATED AT 250 WORDS)

Microsurgery versus radiosurgery in the treatment of small acoustic neurinomas.

Microsurgical preservation of the facial nerve during removal of acoustic neurinomas can hardly be compared with microsurgery of the eighth cranial nerve. Many more anatomical and pathogenetic factors are involved that need careful consideration. In small neurinomas, of grades I and II, total extirpation of the tumour with preservation of both the facial nerve and segments of the vestibulocochlear nerve not directly involved by the tumour has become a safe and practical technique. In small acoustic neurinomas immediate facial nerve function could be preserved in 88% and "useful hearing" could be preserved in 78%. A number of different types of tumour-cranial nerve relationships could be established in small acoustic neurinomas, showing also the effects of adjusted surgical techniques on the preservation of hearing. Optimal selective separation of cranial nerves from the tumour is only possible through open surgical intervention, while radiosurgery requires the irradiation of the entire tumour/nerve complex.

Hearing preservation in acoustic tumour surgery.

900 acoustic neurinomas were removed by the suboccipital approach at Nordstadt Neurosurgical Department from 1978 to 1992 by the same surgeon (M. S.). While 247 patients were deaf on the involved side before surgery, there were 653 patients ears with some preoperative hearing. Preservation of the cochlear nerve was always attempted, and the overall-rate of hearing preservation was 38% (249 of 653), regardless of pre- and postoperative quality of hearing or of tumour sizes. In small tumour sizes below 3 cm of diameter preservation rate was 51%, in large tumours above 3 cm of diameter it was 22%. A classification system of hearing quality was made up considering pure tone audiometric hearing losses (PTA HL) at 1 to 3 kHz, and individual maximum speech discrimination scores. The usefulness of the preserved hearing is further evaluated considering the quality of hearing in the contralateral ear, and by application of other classification schemes. Presentation of the surgical strategies and their refinements by personal experience provide the base for discussion questioning whether and how further progress may still be anticipated.

Preservation of hearing in operations on acoustic tumors: an alternative to recording brain stem auditory evoked potentials.

The monitoring of auditory function by recording brain stem auditory evoked potentials in patients undergoing removal of acoustic tumors is hampered by the small amplitude of the brain stem auditory evoked potentials. Because several thousands of responses must be added, it takes several minutes to obtain an interpretable record. Recordings done directly from the exposed eighth nerve have much higher amplitudes, and, therefore, interpretable responses can be obtained after only a few responses have been added. However, it is difficult to place the recording electrode in an optimal position and the electrode may interfere with the removal of the tumor. In this report, we show that evoked potentials from the cochlear nucleus, which can be recorded by placing an electrode in the lateral recess of the fourth ventricle, have a large amplitude, and that the electrode placed in this way does not interfere with the removal of the tumor. This way of monitoring, therefore, yields interpretable responses within 15 to 20 seconds, or less, and makes it possible to detect injuries to the entire intracranial portion of the eighth nerve, just as brain stem auditory evoked potentials do, but 20 to 50 times faster.

The role of corticosteroids in infants and children with bacterial meningitis.

Bacterial meningitis continues to be a cause of substantial morbidity in infants and children. Hearing impairment is the most common sequela of this disease. Corticosteroids have been used in an attempt to reduce the incidence of meningitis-induced hearing loss. Some studies have demonstrated a decrease in the incidence of hearing impairment in patients treated with cefuroxime plus dexamethasone compared with cefuroxime alone. Similar data are lacking for other frequently used antibiotics. Based on these studies, the use of dexamethasone should be considered in infants and children greater than two months of age with suspected bacterial meningitis. Critical issues including the timing of steroid initiation in relation to antibiotic therapy and the appropriate antibiotic-corticosteroid regimen must be addressed. Studies should be performed to define the exact role of corticosteroids in the treatment of bacterial meningitis. Until additional data are available, we recommend the use of dexamethasone in pediatric patients older than two months of age with bacterial meningitis.

Evaluation of the Words with Ipsilateral Competition test.

The Words with Ipsilateral Competition test was examined for test-retest reliability, item difficulty, and list differences. Results revealed that: (a) many test words contributed little or nothing to the overall test results; (b) list 1 and list 3 were not homogeneous in terms of item difficulty; (c) test performance was influenced by list order, and (d) test-retest reliability correlations were low but significant with test-retest differences ranging from -12% to 32%. Based on the present findings, it was recommended that use of the Words with Ipsilateral Competition test be discontinued until the test is revised.

Dexamethasone treatment for bacterial meningitis in children and adults.

Four hundred twenty-nine patients with bacterial meningitis were assigned on a nonselective alternating basis into one of two therapeutic regimens. Patients in Group I received dexamethasone in addition to standard antibacterial chemotherapy of ampicillin and chloramphenicol whereas those in Group II received antibacterial chemotherapy alone. Dexamethasone was given intramuscularly (8 mg to children younger than 12 years and 12 mg to adults every 12 hours for 3 days). Both treatment groups were comparable with regard to age, sex, duration of symptoms and state of consciousness at the time of hospitalization. A significant reduction in the case fatality rate (P less than 0.01) was observed in patients with pneumococcal meningitis receiving dexamethasone; only 7 of 52 patients died compared with 22 of 54 patients not receiving dexamethasone. A reduction in the overall neurologic sequelae (hearing impairment and paresis) was observed in patients receiving dexamethasone. This reduction was significant only in patients with Streptococcus pneumoniae meningitis; none of the 45 surviving patients receiving steroids had hearing loss whereas 4 of 32 patients not receiving dexamethasone had severe hearing loss (P less than 0.05). No significant difference was observed between the two groups with regard to time for patients to become afebrile or to regain consciousness or in the mean admission and 24- to 36-hour cerebrospinal fluid leukocyte count, glucose or protein content.

Is preservation of hearing in acoustic neuroma worthwhile?

In a series of 300 translabyrinthine removals of acoustic neuromas, comprising almost all tumours operated on in Denmark during a period of 10 years, the preoperative hearing in the tumour ear and in the contralateral ear was analysed in 72 patients with tumours smaller than 2 cm in extrameatal diameter. These patients constitute likely candidates for a hearing preserving operation via the suboccipital approach. In the tumour ear in 4 patients there was a pure-tone average (PTA) of 0-20 dB and a discrimination score (DS) of 81-100%. Applying this criterion to the whole series, 1% of the patients would be candidates for a hearing preserving procedure. Changing the criterion to a PTA of 0-40 dB and a DS of 61-100%, the number of candidates would increase to 8 patients (3%), and with a PTA of 0-50 dB and a DS of 51-100% 14 candidates (5%) would have been found. In all of these patients, contralateral hearing was normal (SRT 0-20 dB, DS 95-100%). Since preservation of hearing would be achieved in only half of those subjected to suboccipital removal and since the hearing retained in patients with successful operations is generally poorer than the preoperative level, the number of patients obtaining serviceable hearing is so modest that preservation of hearing cannot be considered an argument in favour of suboccipital tumour removal. It should be borne in mind that contralateral hearing is normal in these patients and that, according to most reports, the mortality rate is higher and paralysis of the facial nerve more frequent with the suboccipital approach than with the translabyrinthine procedure.

Acoustic neuroma surgery in northern Finland.

A series of 40 patients with acoustic neuromas were operated on using the suboccipital or the translabyrinthine approach. Some patients were operated on using both routes. The series extends back to 1977 and contain predominantly large tumours. There was no mortality in the translabyrinthine series of 14 patients. In the suboccipitally treated series of 29 patient, 3 were previously treated using translabyrinthine approach. In this series there was one death directly due to sequelae of neuroma extirpation and in another, additional causes were present. Preoperative facial pareses were frequent. There were several additional pareses in the translabyrinthine series and also several additional in the suboccipital series. Facial pareses were operated on by a plastic surgeon and they did not markedly detract from working capacity. Only 2 patients in the total series had small tumours and useful preoperative hearing. Cochlear function was preserved in them.