Hearing immaturity found by ABR and its clinical impact on otoneurologicalevaluation

Auditory Brainstem Response (ABR) is the most reliable and most frequently used procedure to evaluate audiological conditions in early infancy. Howeve r, several reports have demonstrated that developmental change in the centr al nervous system may affect the results of ABR in audiological evaluations . We examined statistically the reliability of ABR for the diagnosis of pro found deafness in early childhood according to our experience over the past 12 years of follow-up in our facility. Subjects included 371 children amon g 1,041 children who were admitted to Kanariya-Gakuen (institute for pre-sc hool deaf children) from April 1985 to March 1997. These children were exam ined with ABR to determine their hearing levels. In ive cases with an abnor mal hearing threshold determined by ABR and other audiological tests, repea led examinations carried out during a 5- to 6-month follow-up period reveal ed that they had normal hearing. Three of these children had been diagnosed previously with mental retardation and the remaining two were infants <5 m onths old. The specificity and sensitivity of ABR were calculated as 97.3% and 100%, respectively. The predictive value of a positive result was 94.7% . There remains the possibility of a false negative for such cases, althoug h the rate seems to be very low (<0.2%).