Study of brainstem auditory evoked potentials in early diagnosis of congenital toxoplasmosis

IntroductionCongenital toxoplasmosis is an infectious disease with high prevalence in tropical countries. It is characterized by neurological, ophthalmological and auditory sequelae.ObjectiveThe aim of this study was to evaluate and describe the brainstem auditory evoked potential in infants aged 1–3 months diagnosed with congenital toxoplasmosis and to compare them with infants of the same age group without the infection.MethodsThis is an observational, analytical and cross-sectional study in which brainstem auditory evoked potential was investigated in infants with congenital toxoplasmosis. The following audiological exams were performed: transient-evoked otoacoustic emissions, clinical and automatic brainstem auditory evoked potential.Results100 children participated in the study, but the final sample consisted of 76 children. Of the 37 children with toxoplasmosis included in the study, 28 completed the neurological imaging evaluation, and of these, 3 (10.7%) showed an altered neurological examination. At the brainstem auditory evoked potential assessment, two children without toxoplasmosis and 10 children with congenital toxoplasmosis had results suggestive of alterations in the brainstem auditory pathway maturation.Conclusion10 (27%) children were identified with a possible unilateral alteration in the electrophysiological assessment. There was a 5-fold higher risk for a child between 1 and 3 months of age with toxoplasmosis to have an altered brainstem auditory evoked potential compared to a child of the same age range without the infection.     

Overview of newborn hearing screening programs in Brazilian maternity hospitals

IntroductionNewborn hearing screening has as its main objective the early identification of hearing loss in newborns and infants. In order to guarantee good results, quality indicators for newborn hearing screening programs are used as benchmarks.ObjectiveTo observe and describe the reality of national newborn hearing screening programs in Brazil, and to evaluate if they can be referred to as having quality indicators.MethodsIntegrative literature review in databases such as MEDLINE, LILACS, SciELO, and Google.Results22 articles were analyzed in relation to newborn hearing screening coverage, the place and period newborn hearing screening was performed, initial results, referral to diagnostic procedures, loss to follow-up, and occurrence of hearing loss.ConclusionTransient otoacoustic emissions were the most often used screening methodology. Coverage varied widely, and only a few maternity wards achieved 95% of the cases screened. Referral to diagnostic procedures was under 4%, but lack of adherence can be considered a barrier to successful follow-up. The occurrence of hearing loss ranged from 0% to 1.09%. The involvement of government, physicians, and society is necessary, so that the goals of newborn hearing screening can be achieved.     

Hearing screening in healthy newborns: feasibility of different methods with regard to test time

Clicked-evoked otoacoustic emissions and automated auditory brainstem response are both considered appropriate hearing screening tools. The aim of this study was to compare their practicability with respect to test duration. In the first part of the study, clicked-evoked otoacoustic emissions were recorded in 388 healthy infants on the newborn ward in the first days of life. To reduce false positive rates of screening, clicked-evoked otoacoustic emissions combined with automated auditory brainstem response measurement (A-ABR, Algo 1E and Algo 2) were used in a second investigation. Fifty-five newborns screened by this two-stage method recorded an increased pass rate. The new digital technique of automated auditory brainstem response measurement (Algo 1E and Algo 2) employed in the second part of the study has a test time even shorter than that of clicked-evoked otoacoustic emissions and is no longer a time-consuming test due to improved technology of the second generation of automated auditory brainstem response equipment. Screening including preparation and follow-up time took 9.43 min (Algo 1E) and 8.26 min (Algo 2) respectively and was thus less time-consuming than reported in former studies.     

The importance of retesting the hearing screening as an indicator of the real early hearing disorder

IntroductionEarly diagnosis of hearing loss minimizes its impact on child development. We studied factors that influence the effectiveness of screening programs.ObjectiveTo investigate the relationship between gender, weight at birth, gestational age, risk factors for hearing loss, venue for newborn hearing screening and “pass” and “fail” results in the retest.MethodsProspective cohort study was carried out in a tertiary referral hospital. The screening was performed in 565 newborns through transient evoked otoacoustic emissions in three admission units before hospital discharge and retest in the outpatient clinic. Gender, weight at birth, gestational age, presence of risk indicators for hearing loss and venue for newborn hearing screening were considered.ResultsFull-term infants comprised 86% of the cases, preterm 14%, and risk factors for hearing loss were identified in 11%. Considering the 165 newborns retested, only the venue for screening, Intermediate Care Unit, was related to “fail” result in the retest.ConclusionsGender, weight at birth, gestational age and presence of risk factors for hearing loss were not related to “pass” and/or “fail” results in the retest. The screening performed in intermediate care units increases the chance of continued “fail” result in the Transient Otoacoustic Evoked Emissions test.     

Speech-in-noise perception ability can be related to auditory efferent pathway function: a comparative study in reading impaired and normal reading children

IntroductionDeficient auditory processing can cause problems with speech perception and affect the development and evolution of reading skills. The efferent auditory pathway has an important role in normal auditory system functions like speech-in-noise perception, but there is still no general agreement on this.ObjectiveTo study the performance of the efferent auditory system in a group of children with reading impairment in comparison with normal reading and evaluation of its relationship with speech-in-noise perception.MethodsA total of 53 children between the ages of 8–12 years were selected for the study of which 27 were with reading impairment and 26 were normal reading children. Transient evoked otoacoustic emissions suppression and auditory recognition of words-in-noise test were performed for all the children.ResultsThe average amplitude of transient evoked otoacoustic emissions suppression showed a significant difference between the two groups in the right (p = 0.004) and in the left ear (p = 0.028). Assessment of the relationship between transient evoked otoacoustic emissions suppression and monaural auditory recognition of words-in-noise scores showed a significant moderate negative relationship only in the right ear (p = 0.034, r = −0.41) of the normal reading children. Binaural auditory recognition of words-in-noise scores were significantly correlated with the amplitude of transient evoked otoacoustic emissions suppression in the right ear (p < 0.001, r = −0.75) and in the left ear (p < 0.001, r = −0.64) of normal reading children. In the reading impaired group, ?a weaker correlation was observed between binaural auditory recognition of words-in-noise scores and transient evoked otoacoustic emissions suppression in the right (p = 0.003, r = −0.55) and in the left ear (p = 0.012, r = −0.47).ConclusionsTransient evoked otoacoustic emissions suppression pattern in the reading impaired group was different compared with normal reading children, and this difference could be related to efferent system performance. Words-in-noise scores in children with impaired reading were lower than in normal reading children. In addition, a relationship was found between transient evoked otoacoustic emissions suppression and words-in-noise scores in both normal and impaired reading children.     

Auditory attention in individuals with tinnitus

IntroductionTinnitus is characterized by the presence of a sound in the absence of external sound stimulus. In individuals with normal audiometry, it may be associated with auditory attention difficulty, especially in those who report high tinnitus annoyance.ObjectiveTo investigate auditory attention ability in individuals with tinnitus complaint.MethodsCross-sectional analytical observational study. We evaluated 30 volunteers with normal hearing (up to 25 dBHL): 15 with tinnitus (test group) and 15 with no complaints (control group), aged between 18-40 years. The volunteers answered the tinnitus handicap inventory questionnaire and a visual analogue scale. Subsequently, a basic audiological evaluation (meatoscopy, tonal and vocal audiometry, and imittanciometry) and psychoacoustic measures of tinnitus (loudness and pitch) were performed. To evaluate auditory attention, the following tests were performed: auditory cognitive evoked potential (P300), central auditory processing tests (dichotic digits test and speech-in-noise test) and sustained auditory attention ability test.ResultsIn the tinnitus handicap inventory, individuals with tinnitus had a mean score of 37.78 (±27.05), characterized as moderate degree. In the dichotic digits test (binaural separation), a difference was observed between the groups in both ears. Moreover, there was a difference in the speech-in-noise test in both ears (RE: p = 0.044; LE: p = 0.019), in P300 (p = 0.049) and in total sustained auditory attention ability test (p = 0.032). Also, there is a negative correlation between sustained auditory attention ability test, decrease in attentiveness and binaural integration (RE: p = 0.044; LE: p = 0.048).ConclusionsIndividuals with tinnitus had a poorer performance compared to the control group regarding auditory attention ability. Therefore, it is inferred that tinnitus is associated with poor performance in selective and sustained auditory attention in the assessed volunteers. These aspects should be considered for the management of patients with tinnitus.     

Brainstem auditory evoked potentials in children with lead exposure

IntroductionEarlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated.ObjectiveTo investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test.MethodsContemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months).ResultsThe mean time-integrated cumulative blood lead index was 12 μg/dL (SD ± 5.7, range: 2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I–III, III–V, and I–V, and the cumulative lead values.ConclusionNo evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area.     

Hearing and communicative skills in the first years of life in children with congenital Zika syndrome

IntroductionMicrocephaly is recognized as one of the main consequences of congenital Zika syndrome, but other serious problems such as global hypertonia, irritability, excessive crying, swallowing disorders, seizures, visual impairment and sensorineural hearing loss have been identified as associated with the syndrome.ObjectiveDescribe the developmental characteristics of hearing and language skills in the first year of life of children with normal hearing thresholds’ and congenital Zika syndrome.MethodsThis is a cross-sectional study that evaluated hearing and language skills in the first year of life of 88 children with normal peripheral hearing and confirmed congenital Zika syndrome. All children were submitted to a behavioral auditory test and a validated questionnaire addressed to parents or caregivers, which was used as an instrument for assessing hearing and communicative skills.ResultsThe delay in communicative skills was present in 87.5% of the children, while 44.3% of them demonstrated a delay in hearing acuity. Only the alteration of cervical motor control presented as a statistically significant association with delays in both skills (p-value = 0.006 and <0.001 for hearing and communicative skills, respectively), while the presence of microcephaly and the degree of its severity were only associated with delayed development of communicative skills.ConclusionDespite a normal peripheral auditory system, children with congenital Zika syndrome may demonstrate delayed language development by having neurological damage at the center of auditory processing, requiring more specific studies to clarify language acquisition in this population.     

Protective effect of N-acetylcysteine against cisplatin ototoxicity in rats: a study with hearing tests and scanning electron microscopy

IntroductionOtotoxicity is a health problem appearing after powerful treatments in serious health conditions. It is sometimes inevitable when treatment of the serious disease is required. Cisplatin is an antineoplastic agent which was investigated previously to reveal increased nitrogen and reactive oxygen radicals that damages hair cells, resulting in ototoxicity. N-acetylcysteine, previously shown to decrease ototoxicity caused by different agents, is known to be a powerful in vitro antioxidant. Probably N-acetylcysteine, in addition to its antioxidant effect, blocks a cascade where reactive oxygen species result in apoptosis in the cochlea.ObjectivesThe possible preventive effect of N-acetylcysteine in cisplatin ototoxicity was studied with auditory brain stem responses, otoacoustic emissions, and histopathological investigation of the cochlea in a scanning electron microscopy.MethodsThis study was conducted on 21 Wistar Albino rats in four groups. 1 mL/kg/day three times in total intraperitoneal (i.p.) Saline (n = 5), 500 mg/kg/day i.p. three times in total N-acetylcysteine (n = 5), i.p. 15 mg/kg cisplatin alone (single dose) (n = 5) and i.p. 15 mg/kg cisplatin plus 500 mg/kg/day N-acetylcysteine (n = 6) were administered. The rats were anesthetized to study the hearing tests before and after the experiment. The rats were sacrificed to investigate the cochleas by scanning electron microscopy.ResultsAuditory brain stem responses and otoacoustic emissions values were attenuated in the cisplatin group. The group that received N-acetylcysteine in addition to cisplatin had better auditory brain stem responses thresholds and otoacoustic emissions. The samples obtained from the cisplatin group showed surface irregularities, degeneration areas, and total or partial severe stereocilia losses. The changes were milder in the cisplatin + N-acetylcysteine group.ConclusionCisplatin ototoxicity can be detected by auditory brain stem responses and otoacoustic emissions testing in rats. N-acetylcysteine may protect the cochlear cells from histopathological changes. We concluded that N-acetylcysteine given 4 h after cisplatin injection has a potential otoprotective effect against cisplatin ototoxicity. which suggests it could be used in clinical trials.     

Transient evoked otoacoustic emissions and auditory brainstem response in infants with perinatal asphyxia

ObjectiveThe objective of this study was to verify the effects of perinatal asphyxia on different parts of the auditory system.MethodsThis was a non-concurrent cohort study conducted on a fixed population in a tertiary public hospital. Participants included 181 infants born at term who underwent the transient evoked otoacoustic emission test as a part of a neonatal hearing screening program, with a “pass” result in both ears, and by auditory brainstem response testing. The infants were divided into 3 groups: G1, 20 infants who had perinatal asphyxia; G2, 111 infants with an Apgar score lower than 4 in the first minute and/or lower than 6 in the fifth minute (called “low Apgar” at birth); and G3, 50 infants with first- and fifth-minute Apgar scores ≥7.ResultsThe signal-to-noise ratio of transient evoked otoacoustic emissions were greater in G3 compared with G1 and G2 at 4 kHz frequency for males. An increased latency of waves I and III in the auditory brainstem response of male infants in G1 was observed.ConclusionThis study demonstrated that alterations occurred in both the cochlear and the neural components in male infants who had perinatal asphyxia.     

Effectiveness of a TEOAE-based screening program. Can a patient-tracking system effectively be organized using modern information technology and central data management?

It has been shown that detecting and treating children with hearing loss at an early age will improve their speech and language development. The implementation of universal hearing screening programs is therefore one of the major goals in pediatric audiology. One problem of present screening programs is high lost to follow-up rates. The aim of this paper was to evaluate the effectiveness of a patient tracking system based on central data management and data transmission via the internet. The screening program was organized as a TEOAE (transitory evoked otoacoustic emissions)-based three-stage procedure and covered a complete German federal state (Saarland). The measurements of the first stage took place in well-baby nurseries (WBNs) as well as neonatal intensive care units (NICUs). Measurements of the second stage were performed by pediatricians and ENT physicians on an outpatient basis. The third stage comprised diagnostic ABR (auditory brainstem response) measurements performed by pediatric audiologists. Using a central data management system we were able to identify and follow every child not screened or with negative results. The overall coverage in the first stage was 93% of all newborns. A screening result of the second stage could be obtained for 90% of the children. Four out of 3,830 children screened turned out to have a relevant hearing loss and were fitted with hearing aids. A TEOAE-based newborn hearing screening system can be organized effectively. Central data management as well as interdisciplinary organization of the follow-up are important prerequisites for the success of a hearing screening program. A follow-up system as proposed in this paper can also be implemented in AABR (automated auditory brainstem response)-based programs.     

Hearing of neonates without risk indicators for hearing loss and use of antimalarial drugs during pregnancy: a historical cohort study in the Northern Region of Brazil

IntroductionStudies have demonstrated the ototoxic effects of antimalarial drugs in individuals who receive these drugs, but little is known regarding the toxicity of these drugs in the newborn auditory system when administered to the mother receive the drug during pregnancy.ObjectiveTo verify the incidence of hearing loss in neonates who have no other associated risk indicators, born to mothers treated for malaria during pregnancy.MethodsA retrospective, quantitative cohort study was developed at Hospital de Base Dr. Ary Pinheiro and Clínica Limiar, both located in the municipality of Porto Velho (Rondônia). The sample consisted of 527 newborns divided into two groups: exposed to antimalarials drugs during pregnancy group (n = 32) and non-exposed group (n = 495). Data collection took place from September 2014 to December 2015, through an interview with the mothers and/or guardians of the newborn, through the newborns’ and the mothers’ records, and the neonatal hearing screening database of the above-mentioned institutions.ResultsAll the neonates in the exposed group, assessed through the recording of transient otoacoustic emissions associated with the automated brainstem auditory evoked potential test, underwent neonatal hearing screening in the first examination. Among the newborns in the non-exposed group, 30 showed failure and were retested. Of these, one continued to fail and was referred for diagnosis, in whom the results showed to be within the normal range. Among the neonates of the exposed group, infection with Plasmodium vivax was the most frequent, and was similarly distributed among the gestational trimesters, and chloroquine was the most commonly used antimalarial drug treatment more often given during the third trimester; these findings did not show any influence on the audiological findings of the studied neonates.ConclusionThe present study did not identify any cases of hearing loss in neonates born to mothers who used antimalarial drugs during gestation.     

新生儿听力障碍常见危险因素及听力筛查方法研究进展

听力障碍严重影响新生儿言语和识字能力发育,阻碍儿童社交、认知和学习。影响新生儿听力的因素众多,发病机制和特点各异。新生儿的听力障碍非遗传因素主要包括早产、低出生体质量、新生儿高胆红素血症、新生儿缺氧、感染、耳毒性药物用药史等;遗传因素主要包括GJB2、GJB3、SLC26A4和线粒体基因MT-RNR1变异。耳声发射、自动听觉脑干反应和声导抗检查的联合应用可有效提高新生儿听力障碍筛查的准确率,有助于早期诊断和干预。     

Efferent inhibition of otoacoustic emissions in preterm neonates

IntroductionAbnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity.ObjectiveTo analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates.MethodsThis was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37–41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37–41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation.ResultsThe inhibitory effect of the efferent pathway in otoacoustic emissions was different (p = 0.012) between groups, and a mean reduction of 1.48 dB SPL in full-term births and of 1.02 dB SPL in preterm births was observed for the non-linear click-evoked stimulus.ConclusionThe results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates.     

Vestibular Function in Auditory Neuropathy

Auditory neuropathy is characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination out of proportion with this loss, absent or abnormal auditory brainstem responses and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We followed three patients in our clinic whom we classified as auditory neuropathy patients. These patients also complained of balance disorders and we report our auditory and vestibular system analyses of these patients. The data presented herein include results of audiometric tests (serial pure-tone audiometry and speech discrimination tests), otoacoustic emissions, auditory-evoked brainstem responses and vestibular function tests (clinical tests of balance, electronystagmography, damped rotation tests and vestibular-evoked myogenic potentials). In all patients, pure-tone audiometry revealed mild-to-moderate sensorineural hearing loss, markedly poor speech discrimination scores and absent auditory-evoked brainstem responses, all in the presence of normal otoacoustic emissions. Balance tests (caloric tests and damped rotation test) were abnormal. Saccades, smooth pursuit eye movements and optokinetic nystagmus were normal in all patients. Neurological and motor system evaluations were normal in all patients. These three auditory neuropathy patients manifest a disorder of cochlear nerve function in the presence of normal outer hair cell activity. They additionally manifest a disorder of the vestibular nerve and its end organs. We conclude that, in patients with isolated auditory neuropathy, the vestibular branch of the VIIIth cranial nerve and its innervated structures may also be affected. We suggest the use of the term "cochlear neuropathy" to characterize those patients with involvement of only the auditory branch of the VIIIth cranial nerve and its innervation.     

Performance of hearing skills in children with auditory neuropathy spectrum disorder using cochlear implant: a systematic review

IntroductionCurrently, there are no doubts about the benefits of cochlear implants for the development of children with severe or profound hearing loss. However, there is still no consensus among researchers and professionals regarding the benefits for the improvement of hearing skills in children with auditory neuropathy spectrum disorder using cochlear implants.ObjectiveReview the available evidence in the literature to answer the following: “What is the performance of hearing skills in children with auditory neuropathy spectrum disorder using cochlear implants?”MethodsSystematic review of the literature through electronic database consultation, considering publications in the period 2002–2013.ResultsTwenty-two studies met the criteria and were included in the systematic review.ConclusionThe analyzed studies demonstrated that after cochlear implant surgery, individuals with auditory neuropathy spectrum disorder improved their performance of hearing skills and had similar performance to that of children with sensorineural hearing loss using cochlear implant.     

Effect of hearing aids use on speech stimulus decoding through speech-evoked ABR

Introduction

The electrophysiological responses obtained with the complex auditory brainstem response (cABR) provide objective measures of subcortical processing of speech and other complex stimuli. The cABR has also been used to verify the plasticity in the auditory pathway in the subcortical regions.