Electrophysiological and behavioral methods in early detection of hearing impairment

Changes in tonal audiometry in children with progressive sensorineural hearing loss and history of Neonatal Intensive Care Unit discharge. A 20 year long-term follow-up

OBJECTIVE

Newborns from Neonatal intensive care units (NICU) are at high-risk for sensorineural hearing loss (SNHL) a follow-up is needed for early diagnosis and intervention. Our objective here was to describe the features and changes of SNHL at different periods during a follow-up of almost 20 years.

METHODS

Risk factors for SNHL during development were analyzed. The audiological examination included: Brainstem auditory evoked potentials (BAEP), and Transient evoked otoacoustic emissions (TEOAE). At birth; tonal audiometry (between 125 and 8000 Hz), and tympanometry were performed at 5, 10, 15, and 20 years of age.

RESULTS

Sixty-five percent of cases presented bilateral absence of BAEP. At 5 years of age, the most frequent SNHL level was severe (42.5%), followed by moderate (22.5%), and profound level (20%), in all cases, the SNHL was symmetrical with a predominance of lesion for the high frequencies. Exchange transfusion was associated with a higher degree of SNHL (OR = 6.00, CI = 1.11-32.28, p < 0.02). In 55%, SNHL remained stable, but in 40% of the cases it was progressive. At the end of the study six cases with moderate loss progressed to the severe level and seven cases with severe level progressed to profound.

CONCLUSIONS

Forty percent of infants with SNHL discharged from NICU may present a progression in the hearing loss. Exchange transfusion was associated with a higher degree of SNHL. NICU graduates with SNHL merit a long-term audiological follow-up throughout their lifespan.

Are Auditory Steady-State Responses Useful to Evaluate Severe-to-Profound Hearing Loss in Children?

Objective. To evaluate Auditory Steady-State Responses (ASSR) at high intensities in pediatric cochlear implant candidates and to compare the results to behavioral tests responses. Methods. This prospective study evaluated 42 children with suspected severe-to-profound hearing loss, aged from 3 to 72 months. All had absent ABR and OAE responses. ASSR were evoked using binaural single frequency stimuli at 110 dB HL with a 10 dB down-seeking procedure. ASSR and behavioral test results were compared. Results. Forty-two subjects completed both ASSR and behavioral evaluation. Eleven children (26.2%) had bilateral responses. Four (9.5%) showed unilateral responses in at least two frequencies, all confirmed by behavioral results. Overall 61 ASSR responses were obtained, most (37.7%) in 500 Hz. Mean thresholds were between 101.3 and 104.2 dB HL. Among 27 subjects with absent ASSR, fifteen had no behavioral responses. Seven subjects showed behavioral responses with absent ASSR responses. No spurious ASSR responses were observed at 100 or 110 dB HL. Conclusion. ASSR is a valuable tool to detect residual hearing. No false-positive ASSR results were observed among 42 children, but in seven cases with absent ASSR, the test underestimated residual hearing as compared to the behavioral responses.

Hearing loss, auditory neuropathy, and neurological co-morbidity in children with birthweight <750 g

BACKGROUND AND AIMS

The current literature considers a birthweight <1,500 g as a risk factor for sensorineural hearing loss (SNHL, hearing threshold >25 decibels), auditory neuropathy (AN), and several neurological sequelae. The aim of the study was to determine the frequency and risk factors associated with SNHL, AN, and neurological morbidity in a group of children with birthweights of <750 g treated at a neonatal care unit and recruited into a long-term follow-up program.

METHODS

A case-control study was carried out. Inclusion criteria were birthweight <750 g and born between the years 2000 and 2010. We performed brainstem auditory-evoked potentials (BAEP), evoked otoacoustic emissions (EOAE) and free-field audiometry (FFA) in this population. Neonatal variables and procedures were compared between children with SNHL and children with normal bilateral hearing (NBH).

RESULTS

A total of 93 children with a mean age of 4 years were included in the follow-up. Six children (6.4%) had SNHL and 87 had NBH. We were unable to identify AN in the sample. Mean weight for this sample was 673 ± 68 g and gestational age 27.5 ± 2 weeks. Variables reflecting differences between groups included days under mechanical ventilation, furosemide treatment, and bronchopulmonary dysplasia. In the SNHL group, three patients had periventricular leukomalacia, two had hydrocephalus, and one patient had cerebral palsy.

CONCLUSIONS

Frequency of SNHL in children with birthweights <750 g was higher than in other premature infants and was related with mechanical ventilation, furosemide application, and bronchopulmonary dysplasia. Association with other neurological morbidities was frequent. Early diagnosis and intervention are required.

Audiometria de reforço visual com diferentes estímulos sonoros em crianças

TEMA: avaliação auditiva infantil. OBJETIVO: verificar os Níveis Mínimos de Resposta (NMR) por meio de Audiometria de Reforço Visual (ARV) em campo livre, em 50 crianças ouvintes e 25 deficientes auditivas, considerando as variáveis: lado de apresentação sonora, sexo, idade e tipo de estímulo. MÉTODO: realizou-se ARV com tons puros modulados em freqüência (warble) e com estímulos do Sistema Sonar nas crianças selecionadas. Os tons modulados foram produzidos pelo Audiômetro Pediátrico, nas freqüências de 500, 1000, 2000 e 4000Hz e nas intensidades de 80, 60, 40 e 20dBNA. Sendo estes apresentados em ordem decrescente de intensidade e utilizando o condicionamento estímulo-resposta-reforço visual. Utilizando os estímulos Sistema Sonar, o procedimento de avaliação e a apreciação das respostas foram os mesmos, porém para a apresentação destes foi utilizada uma caixa de amplificação sonora. Cada alto-falante com o reforço visual foi posicionado a aproximadamente a 90 azimute à direita e à esquerda da criança, em uma distância de aproximadamente 50cm. O reforço visual usado foi um palhaço iluminado. RESULTADOS: não houve diferença estatisticamente significante entre MNR em relação ao lado de apresentação. Os NMRs em 500 e 2000Hz do Sistema Sonar, foram menores no sexo masculino nos ouvintes. Neste grupo houve diminuição dos NMR com aumento da idade, para ambos estímulos. Ao comparar NMRs com dois estímulos houve diferença estatisticamente significante a favor do Sistema Sonar apenas para ouvintes com menos de dois anos. CONCLUSÃO: em ouvintes os NMRs reduzem com avanço da idade independente do estímulo e são inferiores com o Sistema Sonar. Nas deficientes auditivas não houve diferença significativa em relação a nenhuma variável estudada.