Hyperbilirubinemia and Follow-up Auditory Brainstem Responses in Preterm Infants

OBJECTIVES.: Neonatal hyperbilirubinemia is considered one of the most common causative factors of hearing loss. Preterm infants are more vulnerable to neuronal damage caused by hyperbilirubinemia. This study aimed to evaluate the effect of hyperbilirubinemia on hearing threshold and auditory pathway in preterm infants by serial auditory brainstem response (ABR). In addition, we evaluate the usefulness of the unconjugated bilirubin (UCB) level compared with total serum bilirubin (TSB) on bilirubin-induced hearing loss. METHODS.: This study was conducted on 70 preterm infants with hyperbilirubinemia who failed universal newborn hearing screening by automated ABR. The diagnostic ABR was performed within 3 months after birth. Follow-up ABR was conducted in patients with abnormal results (30 cases). TSB and UCB concentration were compared according to hearing threshold by ABR. RESULTS.: The initial and maximal measured UCB concentration for the preterm infants of diagnostic ABR ≥40 dB nHL group (n=30) were statistically higher compared with ABR ≤35 dB nHL group (n=40) (P=0.031 and P=0.003, respectively). In follow-up ABR examination, 13 of the ABR ≥40 dB nHL group showed complete recovery, but 17 had no change or worsened. There was no difference in bilirubin level between the recovery group and non-recovery group. CONCLUSION.: UCB is a better predictor of bilirubin-induced hearing loss than TSB in preterm infants as evaluated by serial ABR. Serial ABR testing can be a useful, noninvasive methods to evaluate early reversible bilirubin-induced hearing loss in preterm infants.

Toxoplasmose congênita: evolução da função auditiva e da linguagem emcrianças diagnosticadas e tratadas precocemente / Congenital toxoplasmosis: auditory and language outcomes inearly diagnosed and treated children

A cross-sectional study included all children diagnosed with congenital toxoplasmosis, through the Minas Gerais State Neonatal Screening Program, from September 2006 to March 2007. All children received early treatment, initiated before the age of 2.5 months, and were periodically assisted by a team of specialists including pediatricians, ophthalmologists and speech-language therapists and audiologists. Hearing function was evaluated with the following procedures: tympanometry, transient evoked otoacoustic emissions, distortion product otoacoustic emissions, behavioral observation audiometry, and brainstem auditory evoked potentials. Hearing function and sensitivity was estimated and audiological results were classified as normal, conductive hearing loss, sensory-neural hearing loss and central dysfunction. Language performance was assessed and classified as normal or abnormal, according to test results. The following variables were studied: audiological results, neurological and ophthalmological conditions, language performance and presence of risk indicator for hearing loss other than congenital toxoplasmosis. Univariate analysis was conducted using the chi-square or Fisher?s Exact test. Results: From September 2006 to March 2007, 106 children were diagnosed with congenital toxoplasmosis through the neonatal screening program, and were included in the study. Data analysis showed normal hearing in 60 children (56.6%), while 13 children (12.3%) had conductive hearing loss, four children (3.8%) had sensory-neural hearing loss and 29 children (27.4%) presented central hearing dysfunction. There was association between hearing problems and language deficits. The comparison between children with additional risks for hearing loss other than toxoplasmosis and children who only presented toxoplasmosis as a risk factor showed no differences. This finding suggests that audiological problems were due to congenital toxoplasmosis alone.

Um estudo transversal descritivo incluiu todas as crianças diagnosticadas com toxoplasmose congênita (TC) pelo Prog. Est. de Tria. Neonatal de MG entre set. 2006 e mar. de 2007. Todas as crianças foram submetidas ao protocolo de tratamento com pirimetamina e sulfadiazina iniciado antes dos 2,5 meses de idade e com duração de 12 meses, tendo realizado acompanhamento pediátrico, oftalmológico e fonoaudiológico periódico. Para avaliar a audição foram usados, como instrumentos diagnósticos, medidas de imitância acústica, emissões otoacústicas evocadas por estímulo transiente e produto de distorção, potencial evocado auditivo de tronco encefálico e observação do comportamento auditivo. Foi avaliada a acuidade auditiva e as alterações auditivas foram classificadas em condutivas, neurossensoriais e retrococleares. O desempenho de ling. foi avaliado usando-se um instrumento de aval. do desenvolvimento da ling., e os resultados foram classificados como normais ou alterados. As seguintes variáveis foram estudadas: resultados audiológicos, condições neurológicas e oftalmológicas, linguagem e presença de fator de risco para perda auditiva além da TC. Foi realizada análise univariada pelo qui-quadrado ou teste exato de Fisher. Resultados: entre set. 2006 e mar. 2007, 106 crianças foram diagnos. com TC pelo programa de triagem neonatal, sendo incluídas no estudo. A análise dos dados mostrou que 60 crianças apresentavam audição normal (56,6%) e 46 crianças apresentavam audição alterada, sendo 13 crianças (12,3%) com alteração condutiva, 4 (3,8%) com perda auditiva neurossensorial e 29 (27,4%) com comprometimento retrococlear. Houve associação entre presença de alteração auditiva e déficit de linguagem. A comparação entre crianças que apresentavam outro fator de risco além da TC e crianças que apresentavam somente a toxoplasmose como fator de risco para alteração auditiva não mostrou diferenças.